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Mini Review

Three faces of mortalin: A housekeeper, guardian and killer

Sunil C. Kaul a , Custer C. Deocaris a,b , Renu Wadhwa a,b, *a National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Central 4, 1-1-1 Higashi, Tsukuba, Ibaraki 305 8562, Japan

b Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, Hongo, Tokyo 113-8656, Japan

Received 1 August 2006; received in revised form 5 October 2006; accepted 24 October 2006

Abstract

Mortalin was rst cloned as a mortality factor that existed in the cytoplasmic fractions of normal, but not in immortal, mouse bro-blasts. A decade of efforts have expanded its persona from a house keeper protein involved in mitochondrial import, energy generationand chaperoning of misfolded proteins, to a guardian of stress that has multiple binding partners and to a killer protein that contributesto carcinogenesis on one hand and to old age disorders on the other. Being proved to be an attractive target for cancer therapy, it alsowarrants attention from the perspectives of management of old age diseases and healthy aging.

2006 Elsevier Inc. All rights reserved.

Keywords: Mortalin/mthsp70/Grp75/PBP74; Overexpression; Lifespan extension; Immortalization; Cancer; Silencing; Growth arrest; Chaperone; Oldage diseases

1. The discovery of twin mortalins

Mortalin has come a long way since it was rst clonedand identied to be associated with cellular mortality byvirtue of its presence in the cytosolic fractions of seriallypassaged mouse embryonic broblasts (MEF), and of mortal hybrids obtained by the fusion of mortal(MEF) and immortal (MN48-1, derivative of NIH 3T3)cells. Immortal cells seemed to lack this protein in theircytosolic fractions. cDNA cloning and homology searchplaced it in the heat shock protein 70 (hsp70) family(Wadhwa et al., 1993a ). Mouse immortal cells were laterfound to harbor an allelic form of mortalin, mot-2 that

differ from mot-1 by two amino acids and located inthe perinuclear region of a cell ( Wadhwa et al.,1993b,c; Kaul et al., 2000a ). Two forms of murinemortalins were seen to have contrasting functions:whereas an overexpression of the pancytosolic mot-1protein to NIH 3T3 cells induced cellular senescence,the perinuclear mortalin expressed by mot-2 cDNAinduced their malignant transformation ( Wadhwa et al.,

1993c; Kaul et al., 1998). The phenomenon of differentialsubcellular distribution of mortalin in mortal and immor-tal broblasts was conserved in human broblasts ( Wad-hwa et al., 1993b; Ran et al., 2000 ). However, geneticcloning has not revealed the existence of more thanone human mortalin cDNAs. Human mortalin cDNAwas found to have transforming activity similar to mousemot-2 protein and thus was called hmot-2 ( Kaul et al.,1998). By chromosomal mapping mouse and humanmortalin have been assigned to chromosomes 18 and5q31.1 (gene name – HSPA9B), respectively ( Kaulet al., 1995; Ohashi et al., 1995). Expression and genomicanalysis of human mortalin revealed the presence of

2.8 kb human mortalin transcribed from an 18 kb regionon chromosome 5q31.1 that consisted of 17 exons withboundaries almost identical to its murine counterpart(Michikawa et al., 1993; Xie et al., 2000 ).

Mortalin is a 679 amino acids long (molecular weight73,913 daltons) heat un-inducible member of Hsp70 familyof proteins. It has a high degree of identity with othermembers of the Hsp70 family, including Escherichia coli DnaK, Saccharomyces cerevisiae SSClp, the constitutivecytosolic Hsp70 from rat, Hsc70 and the rat endoplasmicreticulum isoform, BiP. The precursor protein has a

0531-5565/$ - see front matter 2006 Elsevier Inc. All rights reserved.

doi:10.1016/j.exger.2006.10.020

* Corresponding author. Tel.: +81 29 861 9464; fax: +81 29 861 2900.E-mail address: [email protected] (R. Wadhwa).

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Please cite this article in press as: Kaul, S.C. et al., Three faces of mortalin: A housekeeper, guardian and killer, Exp. Gerontol.(2007), doi:10.1016/j.exger.2006.10.020

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46-amino acid long mitochondrial-targeting signal peptide.It undergoes Ca-dependent autophosphorylation, has mul-tiple subcellular sites and binding partners, and functionsrelated to the control of cell proliferation and stressresponse (Kaul et al., 1993; Wadhwa et al., 1993b,2002a). The crystal structure of mortalin has not been

elucidated so far. Based on its evolutionary conservationwithin the Hsp70 family, it is expected to have two princi-pal domains (the N-terminal ATPase and C-terminalregion) joined by a protease-sensitive site with its chaper-one activities intimately linked with ATP-hydrolysis

(Fig. 1) (Deocaris et al., 2006a ). A kettle pot model struc-ture has been proposed in which the ATPase domain(44-kDa) is expected to consist of four sub-domains thatfold into a pair of lobes forming a deep catalytic-cleft(Fig. 1) (Sriram et al., 1997; Deocaris et al., 2006a ). Studieson E. coli Hsp70, DnaK, have demonstrated that its

ATPase activity can be cyclically stimulated by co-chaper-ones DnaJ and GrpE. DnaJ permits the hydrolysis of Hsp70-bound ATP allowing the ADP-bound Hsp70 tointeract more strongly with unfolded proteins. The nucleo-tide exchange factor GrpE enables the recycling of Hsp70

Fig. 1. Homology modeling based structure of mortalin. Kettle pot model of the structure that includes its N-terminal ATP binding domain (pot handle),middle substrate-binding domain (SBD) (pot) and C-terminal (lid) is shown on the left. Structure of the SBD and the lid as derived from the homology toE. coli DnaK, were produced by SWISS-MODEL ( http://swissmodel.expasy.org ), INSIGHT II (Accelrys) and MOLSCRIPT ( Kraulis, 1991). Universallatch and mortalin-specic latch (that arises because of the electrostatic interactions among Arg574, Arg578 and Asp628, and should be largely perturbedby the Gly624 Arg mutation) are shown. Chaperone function of mortalin adapted to its kettle pot structure is diagrammed to shown entry of unfolded

peptides into the SBD, chaperoning in the closed kettle pot and its release by unlocking and opening of the lid ensured by structural features of the protein.

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back into an ATP-bound state permitting the efficientrelease of its substrate ( Harrison, 2003; Deocaris et al.,2006a). As these cycles of ATP-hydrolysis occur, allostericchanges in the N-terminus are transmitted to the 18-kDasubstrate-binding domain (SBD), made-up of two sets of four-stranded anti-parallel beta-sheets that forms a twisted

sandwich (Fig. 1). While the ATPase domains are strictlyconserved, the SBD domain shows a greater sequence var-iation resulting in the diversication of the client peptidesand substrate specicity. Flanking the SBD is a 10-kDalong C-terminal helix made-up of ve helical domains(A–E). This interesting structure, called the ‘‘substratelid’’, does not contact the peptide substrate directly andhas the ability to ip-op to allow entry of unfolded pep-tides and release of folded peptides after chaperoning(Fig. 1). The lid also functions as a molecular ‘‘latch’’ thatlocks-in substrates during an ADP-bound state ( Zhu et al.,1996; Moro et al., 2004, 2005; Fernandez-Saiz et al., 2006 )(Fig. 1). Recent biophysical studies have provided newclues to the mystery underlying the opposing functions of the two mouse mortalin alleles ( Deocaris et al., 2006c).The helix ‘A’ shows high sequence conservation amongthe Hsp70 proteins whereas the distal portion of helix(B–E) is divergent. The two-amino acid differences betweenthe two murine mortalin isoforms reside within this regionof the C-terminal helix. The V618M (mot-l:mot-2) aminoacid substitution is buried in the helix ‘C’ and the R624G(mot-l:mot-2) occurs near a critical helical bend and thesubstitution of G (mot-2) into R (mot-1) causes somechanges in the inter-domain salt bridges. This can be appre-ciated from the understanding of the exible lid structure

above the substrate cleft of mortalin where electrostatic‘‘latches’’ between the lid and the cleft appear to be impor-tant for its functioning as a chaperone. One ‘‘latch’’ con-sisting of Asp477, Arg513, Glu586 and His590 iscommon with other HSP70s ( Mayer et al., 2000 ), whilean additional ‘‘latch’’ that we identied on the oppositeend, consisting of Arg574, Arg578 and Glu628, is morta-lin-specic. A replacement of Gly624 (in mot-2), locatedat the C-terminus of a-helix C, by Arg (in mot-1) is likelyto extend the a-helix C. In contrast, Gly, a strong helixbreaker, shortens the L3 (C–D) loop. The latter should per-turb the structure of the ‘‘mortalin-specic latch’’, presum-ably pulling apart the electrostatic attractions that couldresult in the loss of the chaperone action of the molecule.

2. Mortalin in its housekeeping mode

Mortalin is the major mitochondrial protein ( Bhatta-charyya et al., 1995 ) and it plays a central role in the elab-orate translocation system for efficient import and exportof proteins ( Koehler, 2004; Rehling et al., 2004; Wiede-mann et al., 2004 ). Its role in cell viability and mitochon-drial biogenesis was underscored by experimental dataincluding (i) the yeast cells knocked out for mortalinhomologue (Sscl) were lethal ( Craig et al., 1987) and (ii)

the loss of function mutations of mthsp70 caused aggrega-

tion of yeast mitochondria ( Kawai et al., 2001 ). Duringimport of mitochondrial-targeted proteins, the proteinspass through the membranes via the outer membrane(TOM) and followed by the inner membrane (TIM) chan-nels. In the process, bulky proteins are required to unfoldto permeate through a translocation pore and are then

refolded back to their native conformers to regain function(Voos and Rottgers, 2002 ). There are two controversialhypotheses on how the mortalin machinery performs itsprotein translocation function across the two mitochondri-al membranes, the ‘‘trapping’’ ( Strub et al., 2000; Geissleret al., 2001) and the ‘‘motor’’ models ( Glick, 1995; Horstet al., 1997; Voos et al., 1996; Deocaris et al., 2006a ).Yamamoto et al. (2005) have identied 15-kDa Timl5/Ziml7 protein that associates and cooperates with morta-lin/mthsp70 to facilitate import of presequence-containingproteins into the matrix. Self-aggregation of mortalin/mthsp70 is prevented by Hepl ( Sichting et al., 2005). Fol-lowing the translocation of proteins into the mitochondria,they refold back and assemble to its native oligomeric stateand sort into various compartments of the organelle toperform their functions. Newly imported mitochondrialpre-proteins interact with mortalin/mthsp70 and Hsp60as soon as they reach the matrix compartment ( Mahlkeet al., 1990; Langer and Neupert, 1991; Hartl et al.,1992). The activity of these mitochondrial chaperones islife-essential as was demonstrated in yeast and mammaliancells (Cheng et al., 1989; Wadhwa et al., 2005; Deocariset al., 2006a). Interestingly, overexpression of mortalin,but not hsp60, resulted in lifespan extension of normalhuman broblasts ( Wadhwa et al., 2005 ). A recent study

identied mortalin in the lipid rafts from different mouseorgans, supporting its role as a component of the oxida-tion–reduction respiratory chain ( Kim et al., 2006). Rivol-ta and Holley (2002) have reported that the mitochondriain general, and mortalin in particular, were asymmetricallydistributed during cell division and are involved in cell fatedetermination. Another house keeping function of morta-lin is predicted from its involvement in proteasomal degra-dation of proteins, mediated by its interactions with CHIP(carboxyl terminus of Hsc70-Interacting Protein with ubiq-uitin E3-ligase activity) ( Li et al., 2005; Deocaris et al.,unpublished observation).

3. Mortalin in its guardian mode

The biological impact of mortalin function is notrestricted to its mitochondrial locale. Subcellular fraction-ation and immunouorescence microscopy have revealedthat mortalin is not only present in mitochondria but alsoin other extra-mitochondrial sites ( Ran et al., 2000; Poin-dexter et al., 2002). In parallel, its multiple binding partnershave revealed its diverse functional skills ( Fig. 2). Althoughmortalin did not consent with other members of heat shockprotein 70 family due to its un-inducibility to heat shock(Domanico et al., 1993; Wadhwa et al., 1993a; Bhattachar-

yya et al., 1995; Mitchell et al., 2002), various mild stress

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responses including glucose-deprivation, low doses of ion-izing radiation and calorie restriction were shown to inducemortalin ( Massa et al., 1995; Merrick et al., 1997; Sadek-ova et al., 1997; Gao et al., 2003; Um et al., 2003b; Tsu-chiya et al., 2004; Liu et al., 2005). Besides, it ensuresnal destiny of other proteins, modies their functionsand act as a guardian against stress and apoptosis ( Taurinet al., 2002; Um et al., 2003a; Craven et al., 2005; Jin et al.,

2006a) (Fig. 2).

3.1. Intracellular trafficking

Fibroblast growth factor-1 (FGF-1) regulates cellgrowth and differentiation. It lacks signal peptide and isintracellularly localized as a result of endogenous expres-sion or endocytosis. Mortalin was isolated as a FGF-1-binding protein from rat L6 cells. Additionally, the twoproteins were found to share the same intracellular nicheand interact physically suggesting that mortalin is involvedin the trafficking and/or signaling by FGF-1 ( Mizukoshiet al., 1999, 2001). FGF-1 added to the culture mediumof quiescent BALB/c3T3 cells was shown to interact withmortalin in the cells in a regulated manner. Although boththe internalized FGF-1 and mortalin were present at highlevels throughout the FGF-1-initiated cell cycle, their inter-action became apparent only in late Gl phase. Mortalinwas preferentially tyrosine phosphorylated at Gl. Whencells were treated with vanadate, a strong interactionbetween mortalin and FGF-1 was established. Conversely,treatment with tyrosine phosphatase abrogated mortalin– FGF-1 interactions suggesting that the interactions occurpreferentially in late Gl phase of the cell cycle, and are reg-ulated by tyrosine phosphorylation of mortalin ( Mizukoshi

et al., 1999, 2001).

3.2. Internalization of receptors

Interleukin-1 (IL-1) is a major proinammatory cytokinemediating local and systemic responses of the immune sys-tem. Two types of IL-1 receptors are known, but only theIL-1 receptor type I initiates biological responses. It was

shown that mortalin is associated with the IL-1 receptortype I and is involved in internalization of the receptor(Sacht et al., 1999). Receptor for hyaluronan mediatedmotility (RHAMM), a centrosomal and microtubal, hyalu-ronan-binding protein was shown to interact with mortalinin interphase microtubules, but not in mitotic spindles. Itwas proposed that mortalin–RHAMM complexes maystabilize microtubules in the interphase ( Kuwabara et al.,2006). Mortalin was also found to be upregulated inisolated rodent islets exposed to cytokines. In tworat strainsthat showed different sensitivity to the toxic effects of cyto-kines, a signicant differences in IL-1beta mediated morta-lin expression was observed suggesting its role in cytokineinduced beta-cell destruction ( Johannesen et al., 2004 ).

3.3. Protein modications

Mevalonate pyrophosphate decarboxylase (MPD), anenzyme that furnish prenyl groups required for prenylation(protein modication that is essential for the activity of many proteins including p21Ras) was identied as a bind-ing partner for mortalin. A functional link between mot-2(mortalin), MPD and p21Ras in control of cell prolifera-tion was proposed ( Wadhwa et al., 2003b ). Voltage-depen-dent anion-selective channel 1 (VDAC1), a eukaryotic

porin that functions as a channel in membranous struc-tures, was found to interact with the dynein light chainTctex-1 and mortalin in vivo. The functional relevance of the identied protein interactions was analyzed in planarlipid bilayer (PLB) experiments in which both recombinantbinding partners altered the electrophysiological propertiesof hVDACl. While rTctex-1 increases the voltage-depen-dence of hVDAC1 slightly, mortalin drastically minimizedthe voltage-dependence, indicating a modulation of chan-nel properties ( Schwarzer et al., 2002 ). Grp94, Glucose reg-ulated protein 94, a member of the hsp90 family, wasshown to interact with mortalin ( Takano et al., 2001 ).

3.4. Stress and immune responses

Several studies have indicated that an upregulation of mortalin suppresses the engagement of apoptosis from var-ious stressors, e.g., arsenite in rat lung epithelial cells ( Lauet al., 2004), mercury in renal cells (Stacchiotti et al., 2006 ;differentiation agent 1,25-dihydroxyvitamin D3 in rat glio-mas (Baudet et al., 1998 ), and glucose starvation and ische-mia reperfusion in Chinese Hamster Lung (CHL) cells(Gao et al., 2003 ). High level of mortalin has been detectedas an adaptive response to high activity such as treadmillrunning ( Mattson et al., 2000 ). Taurin et al. (2002) have

shown that the transient transfection of vascular smooth

Fig. 2. A diagram showing mortalin (grey star) and its interacting proteins(white ovals).


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muscle cells (VSMCs) with mortalin cDNA led to a delayedapoptotic response after serum deprivation. The expressionof tumor suppressor gene, p53, in mortalin transfected cellswas delayed to the same extent, and the expressed proteinshowed abnormal perinuclear distribution suggesting thatp53 is retained and inactivated by mortalin. The study

dened a novel mortalin-mediated [Na+

]i/[K+

]i-responsivesignaling pathway that may play an important role in theregulation of programmed cell death in VSMCs. Remodel-ing of vessel walls is one of the major determinants of long-term blood pressure elevation and an independent risk fac-tor for cardiovascular morbidity and mortality. Drugs thatare known to protect vascular cells from apoptotic stimuli,such as cardiotonic steroids (CTS), have been shown to tar-get the Na/K-ATPase pump. Another study has detectedthe role of mortalin in CTS-inhibited apoptosis of vascularsmooth muscles cells (Orlov and Hamet, 2006 ). Associatedwith onset of glucose-deprivation treatment is the rapidincrease in ROS accumulation that is reduced with morta-lin overexpression suggesting that mortalin could inhibitthe ROS accumulation, and has a cytoprotective effect(Liu et al., 2005). In another study, mortalin/mthsp70was identied as one of the proteins stimulated after tran-sient exposure of human endothelial cells to sub-lethal lev-els of hydroperoxides suggesting its involvement inoxidative stress response ( Mitsumoto et al., 2002 ). Orsiniet al. (2004) showed that a fraction of cytosolic p66Shc(regulates lifespan in mammals and is a critical componentof the apoptotic response to oxidative stress) localizes with-in mitochondria where it forms a complex with mitochon-drial Hsp70/mortalin. Mortalin was shown to inhibit

p66Shc function activated during oxidative stress (ultravio-let radiation) that induced the dissociation of p66Shc– mortalin complexes. Saretzki et al. (2004) have identiedmortalin as one of the factors responsible for superiorstress defense in murine embryonic stem cells. It was iden-tied to mediate cellular response to low dose ionizing radi-ations. Treatment of cells with antisense mortalinoligonucleotide was found to sensitize cells to ionizing radi-ation ( Sadekova et al., 1997 ). Um et al. (2003a) have pro-posed mortalin/mthsp70 as a DNA-PK regulated protein(plays a protective role against drug-induced apoptosis)that can be a determinant of drug sensitivity.

Another important major function of surface-expressedmortalin is its captivating role in immune response, i.e.,antigen presentation and in innate immunity. Comple-ment-mediated cell death is caused by C5b-9, the mem-brane attack complex (MAC) that inicts damage to thetarget cells. For protection, cells eliminate the MAC fromtheir surface either by ectocytosis (direct emission of mem-brane vesicles) or by endocytosis (internalization). Recent-ly, the involvement of mortalin in MAC elimination hasbeen suggested. Extracellular application of antibodiesdirected to mortalin increased cell sensitivity to MAC-med-iated lysis. Other pore formers, such as streptolysin O andmelittin, did not induce release of mortalin. Mortalin was

shown to bind to complement C8 and C9 and is shed in

vesicles containing C9 and complement MACs. Theseresults suggest that mortalin promotes the shedding of membrane vesicles loaded with complement MAC and pro-tects cells from complement-mediated lysis ( Pilzer andFishelson, 2005; Pilzer et al., 2005 ).

As described above, besides playing a prime role in bio-

energetics-associated transport, sorting and refolding, asmortalin travels outside the mitochondria, it collaborateswith a repertoire of binding partners and acquires moreexpansive cellular roles. These mortalin-mediated manifoldof intracellular trajectories are exploited in a two-waysword: while strengthening the ‘‘yin’’ of cellular energeticand stress pathways, it leads to ‘‘yang’’ for mortalin’s killerinstincts behind many old age-associated diseases and can-cer in particular.

4. Mortalin in its killer mode

4.1. In cancers

Tumors are known to lead more ‘‘stressful’’ lives com-pared to the normal cells. This is particularly the case con-sidering that its immortal state carries added demands forcontinuous rapid proliferation; competition for basic cellu-lar needs (space, nutrient and oxygen); hostility of new cel-lular environments, particularly for ‘‘adventurous’’metastases; and most signicantly, the accumulation of mutated proteins as a result of genomic instability. Justas senescence is considered, at least in the Darwinianschool of thought, consequential to the declining force of

natural selection as a function of biological time; cancercan be considered as a corrupted phenotype that escapedthis selective pressure. A notable survival strategy of cancercells is its considerable investments in bolstering its innatemolecular chaperones allowing the endowment of survivaladvantages, such as, (a) in counteracting the ‘‘stress’’ of senescence and apoptosis, (b) in its function as an ‘‘mi-cro-evolutionary buffer’’ that neutralizes conformationalconsequences of mutant proteins, (c) aids in the acquisitionof gain-of-functions of chaperone-stabilized rogue pro-teins, (d) promotion of invasiveness and cell motility, (e)co-ordination hyper-activation of proliferation signalsand (f) resistance to radiation, heat, hormones and chemo-therapeutic agents ( Soti and Csermely, 2000, 2002; Sotiet al., 2003).

Hsps serve as safeguards to maintain homeostasis andintegrity of protein interactions. The observation thattumor cells often have elevated levels of Hsps may be asso-ciated to a pre-malignant cell’s response to the selectionprocess occurring during tumorigenesis. By virtue of theiractivities as molecular chaperones, several of these Hspsnot just contribute to cellular immortalization, but alsoenhance a neoplasia’s survival advantages. Primarily theHsp70 family, the constitutive Hsc70 (HS7C) and the heatshock-inducible Hsp70 (HSPA1A); the Hsp90 family,

Hsp90b (HSPCB) and Hsp90a; and the mitochondrial


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Hsp27 (HSPB1), have been most widely ascribed withoncogenic roles ( Mosser and Morimoto, 2004 ).

The level of mortalin expression was found to beelevated in many human tumors, and in all of the tumor-derived and in vitro immortalized cells examined ( Wadhwaet al., 2006). In human embryonic broblasts immortalized

with an expression plasmid for hTERT, the telomerase cat-alytic subunit, with or without human papillomavirus E6and E7 genes, the subclones with spontaneously increasedmortalin expression levels became anchorage-independentand acquired the ability to form tumors in nude mice.Furthermore, overexpression of mortalin was sufficientto increase the malignancy of breast carcinoma cellssuggesting that an upregulation of mortalin contributes sig-nicantly to tumorigenesis ( Wadhwa et al., 2006 ). Quanti-tative estimation of level of mortalin expression hasrevealed that the tumor cells with higher level of mortalinexpression have more aggressive tumor phenotypes suchas metastasis ( Wadhwa et al., 2006 ) (Fig. 3). The role of mortalin has been more extensively probed in three tumortypes: brain, colon and leukemia.

4.1.1. Brain tumorsImmunohistochemical studies of mortalin in normal and

tumor human brain sections revealed that in normal brainsections, the expression was seen mainly as being connedto neurons. Normal astrocytes showed undetectableexpression of mortalin. Three grades of astrocyte tumors(low-grade astrocytoma, anaplastic astrocytoma and glio-blastoma), however, showed an increasing number of mortalin-positive cells. Other types of brain tumors, such

as meningiomas, neurinomas, pituitary adenomas andmetastases, also showed elevated levels of mortalin expres-sion compared to those in the normal brain. An increase innumber of mortalin-positive cells with malignant progres-sion of brain tumors and its correlation with Ki-67 (a cellproliferation marker)-positive cells further suggested aninvolvement of nonpancytosolic mortalin(s) in malignanttransformation of cells in vivo (Takano et al., 1997 ).

4.1.2. Colon cancersComparative proteomic analysis identied overexpres-

sion of mortalin in colorectal adenocarcinomas. By immu-nostaining on a colorectal cancer tissue microarray linkedto a patient database, mortalin overexpression was foundto correlate with poor patient survival. The ndings dem-

onstrated that mortalin overexpression may predict out-come in colorectal cancer and suggested that mortalin isinvolved in colorectal neoplasia ( Dundas et al., 2004 ).

4.1.3. LeukemiaHuman Chromosome 5q31.1 is frequently deleted in

myeloid leukemias and myelodysplasia suggesting thatmortalin may be a candidate gene ( Xie et al., 2000). Myelo-dysplastic syndrome (MDS) comprises a heterogeneousgroup of clonal blood disorders characterized by ineffectivehematopoiesis arising from dysplasia and accelerated apop-totic death of multipotential hematopoietic progenitorsand their progeny. These syndromes display signicantclinical variability that ranges from anemia, erythroid dys-plasia, fatal multi-lineage peripheral cytopenia or acutemyeloid leukemia (AML). The majority of patients withMDS die within 3–4 years. Deletions at 5q31 are associatedwith more aggressive forms of MDS, often progressing rap-idly to leukemia. A critical deleted region (CDR) at chro-mosome 5q31 has been dened containing nine candidategenes, including mortalin/HSPA9B, but causative geneshave yet to be identied and are rather critical for diagno-sis, improved therapies, and prevention.

Hematopoiesis is well characterized in zebrash and hasbeen demonstrated to have a high degree of conservation

with mammalian counterparts. zebrash mutants withabnormalities at various stages in blood development havebeen isolated by genetic screens and present mutants thatmodel human hematopoietic diseases. A developmentalblood mutant, crimsonless ( crs ), is anemic at the onset of circulation and display defective blood cell differentiationfollowed by apoptosis and a reduction in erythrocytes,granulocytes and hematopoietic progenitors resemblingthe symptoms of MDS. Using positional cloning, RNA res-cue and morpholino knockdown, Craven et al. (2005) haveidentied the mutated gene in crs mutants in zebrash.Hspa9b (mortalin/mthsp70/GRP75) that shows 84.8%identity and 89.4% similarity with human HSPA9B. A sin-gle amino acid mutant (G492E) within the substrate-bind-ing domain of HSPA9B was shown to be the cause of thecrs phenotype. A near-identical mutation in the conservedglycine at position 443 in DnaK (53.5% identity and 63.3%similarity to zebrash mortalin) completely abolished pro-peptide binding, rendering the chaperone functionless(Burkholder et al., 1996 ). To verify that the mutation inHspa9b is sufficient to cause the crs phenotype, Cravenet al. (2005) had used both rescue and antisense morpholi-no knockdown strategies. Injection of capped RNA encod-ing wild-type HSPA9B rescued approximately 95% (53 of 56) injected mutant embryos. The blood of rescued animals

was no longer hypochromic. Conversely, inactivation of

Fig. 3. A quantitative estimation of mortalin expression in humantransformed cells showing the relationship of mortalin expression level

and metastatic property.


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Zebrash mortalin using antisense morpholino-modiedoligonucleotides that targeted the 5 0 untranslated region(UTR) and rst methionine recapitulated the anemic phe-notype observed in crs mutants in 80% of the injected ani-mals. This study has very strongly proved that a singleamino acid mutation, G492E that abolishes chaperone

function of mortalin is the cause of crs phenotype in Zebra-sh, a model of human MDS. In an independent compar-ative proteomic study, Pizzatti et al. (2006) have identiedmortalin as one of the 31 differentially expressed proteins inprotein proles from chronic myeloid leukemia and healthybone marrow donors.

Mortalin and p53 interactions were rst identied in thecytoplasm of tumor cells. It was shown that mortalinsequesters p53 in the cytoplasm and inhibits normal tran-scriptional activation function of p53 ( Wadhwa et al.,1998, 2000a,b, 2002b; Kaul et al., 2001; Taurin et al.,2002; Mihara et al., 2003 ). Mortalin binding p53 peptideswere shown to reactivate p53 function, associated withgrowth arrest of cancer cells ( Kaul et al., 2005). Mostrecently, wild-type p53 and mortalin interactions were alsodemonstrated in the cytoplasm of the soft shell leukemic,but not normal, clam hemocytes that develop a fatal neo-plasm sharing molecular similarity with an unrelated groupof human cancers. Mortalin–p53 interactions were abro-gated both in the mammalian and clam cells by a cationicinhibitor of mortalin (MKT-077) resulting in reactivationof wild-type p53 function ( Wadhwa et al., 2000b, 2002a;Walker et al., 2006 ). A recent study on the comparativemass spectrometric analysis of unduplicated and duplicatedcentrosomes identied mortalin as a protein that associates

preferentially with duplicated centrosomes. For the rsttime, it was localized to centrosomes where it formed phys-ical complexes with p53 during late G1, S and G2, and dis-sociated from centrosomes during mitosis. Overexpressionof mortalin over-ruled the p53-dependent suppression of centrosome duplication, assigning it as an upstream regula-tor of p53 function in control of centrosome duplication(Ma et al., 2006). Mortalin–p53 complexes in the cyto-plasm or in centrosome compromise wild-type p53 activi-ties leading to uncontrolled proliferation, a hallmark of cancers. Overexpression of mortalin in normal human cellswas able to extend their in vitro lifespan of broblasts(Kaul et al., 2000b; Wadhwa et al., 2005 ). Since morta-lin–p53 interactions have not been detected in normal cells,it is likely that lifespan extension is the result of mortalinfunctions independent to that of p53-inactivation.

4.2. In other old age diseases

4.2.1. DiabetesHyperglycemia induces the production of reactive oxy-

gen species (ROS) from the mitochondria. During diabetichyperglycemia, levels and induction response of Hsp70, butnot Hsp105 and Hsp90, are markedly decreased in the liver(Yamagishi et al., 2004; Muranyi et al., 2005 ). An anti-

diabetic response based on the enhanced efficiency of

import of anti-oxidative enzymes such as superoxide dis-mutase and glutathione peroxidase with the boosting of the mitochondrial import machinery has been proposed(Matsuoka et al., 2005 ).

4.2.2. Neurodegenerative diseases

The demise of specic neuronal populations due to theaccumulation of abnormal polypeptides forms the etiologicbasis of several neurodegenerative diseases, such as Alzhei-mer’s disease, Parkinson’s disease, Huntington disease,spinocerebellar ataxia, etc. Such misfolded protein con-formers have a strong tendency to form neurotoxic insolu-ble protein aggregates. A very important consequence isthe impairment of the ubiquitin-proteasome degradationsystem and suppression of the heat shock and oxidativestress response. Accumulation of the aggregated proteinsalso activates signal transduction pathways that lead to celldeath ( Soti and Csermely, 2002 ).

A study on the hippocampus from ApoE knockoutmice, a model for Alzheimer’s disease, revealed that mort-alin is among the six oxidized proteins suggesting it to beinvolved in risk and progression of Alzheimer’s disease(Choi et al., 2004). In another study, on unbiased quanti-tative proteomic approach, nigral mitochondrial proteinsof Parkinson’s disease (PD) patients were compared withthose from age-matched control. Mortalin was found tobe substantially decreased in PD brains. Manipulationsof mortalin level in dopaminergic neurons resulted in sig-nicant changes in sensitivity to PD phenotypes via path-ways involving mitochondrial and proteasomal functionas well as oxidative stress suggesting that it is a target

for oxidative stress, a marker for PD pathology ( Jinet al., 2006a). It is suggestive that mortalin is a regulatorof oxidative stress and apoptosis, and contributes to agingand old age pathologies. Li et al. (2005) have shown thatDJ-1, a causative gene for familial form of the PD, asso-ciates with chaperones including Hsp70, CHIP, and mort-alin/mtHsp70 and gets translocated to mitochondria uponoxidative stress. Another study has identied mortalin asone of the ve major proteins (mortalin, nucleolin, grp94,calnexin and clathrin) binding to a-synuclein and DJ-1,two critical proteins in PD pathogenesis ( Jin et al.,2006b). In parallel to the extended lifespan of worms overexpressing mortalin/hsp70F, it was seen todecrease during normal nematode aging. Of note,HSP70F siRNA caused reduction in worm lifespan andearly appearance of progeria like – phenotype and age pig-ments (Yokoyama et al., 2002 ) (Kimura et al., personalcommunication).

These studies have suggested that mortalin may serve asa longevity factor due to its diverse functions describedabove. In the battle of its longevity functions, its activitiesmay be compromised by its structural and chemical modi-cations. Some modications may even convert it from anefficient-chaperone to a sick-chaperone or to an anti-chap-erone molecule that would build up the garbage catastro-

phe often considered as a marker of old age disorders.


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Some examples of such modications of mortalin havealready been found ( Bruschi et al., 1993; Bruschi and Lind-say, 1994; Cooper et al., 2001; Choi et al., 2004 ).

5. Perspectives: mortalin-based interventions

Bearing in mind the three egos of mortalin i.e., as anessential housekeeping gene, as a guardian chaperone thatis activated during stress and cause killing of the old, it mayseem rather audacious to therapeutically control this chap-erone’s temperaments. Some hints, however, at ne-tuningthese mortalin paradoxes for achieving healthy aging andto forward novel approaches in treating of aging-associateddiseases, such as cancer, can be glimpsed from several keybasic studies over the past decade.

5.1. Strengthening the guardian

The level of mortalin protein was found to decrease insenescent human broblasts (MRC5 and HFF) and inaged worms (unpublished data). Its overexpression leadsto the lifespan extension in both systems suggesting thatthe decline in mortalin level and thus its function(s) deter-mines xed proliferation potential of normal cells andaging, respectively. The lifespan of human foreskin bro-blasts (HFF5), cultured under standard in vitro condi-tions, was extended slightly by expression of exogenousmortalin, but not by the catalytic subunit of telomerase,hTERT. Together, mot-2 (mortalin) and hTERT permit-ted bypass of senescence, a substantial extension of life-span, and possibly immortalization demonstrating that

mortalin and telomerase can cooperate in the immortali-zation process ( Kaul et al., 2003 ). Since upregulation of mortalin expression and activation of telomerase are com-mon features of cancers, it is likely that these cooperatein vivo during the development of human cancers. On asimilar context, transient induction of hsp70F led to aslight (

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(mot-2) and abrogates its interactions with the tumor sup-pressor protein, p53. In cancer cells, but not in normalcells, MKT-077 induced release of wild-type p53 from cyto-plasmically sequestered p53–mot-2 complexes and rescuedits transcriptional activation function. Thus, MKT-077could be one of the candidates for therapy of cancers with

wild-type p53 (Wadhwa et al., 2000b; Walker et al., 2006 ).Induction of senescence like growth arrest by bromodeoxy-uridine (Michishita et al., 1999 ) and of 5-aza-2 0 deoxycyti-dine (Widodo et al., unpublished observation) also causedshift of subcellular distribution of mortalin from perinucle-ar to pancytoplasmic type.

5.2.2. Synthetic peptidesMortalin binds to a carboxyl terminus region of the

tumor suppressor protein p53. By in vivo co-immunopre-cipitation of mortalin with p53 and its deletion mutants,the mot-2-binding site of p53 was mapped to carboxyl ter-minus 312–352 amino acid residues of mortalin. Further-more, mot-2–p53 interactions were disrupted byoverexpression of the short p53 carboxyl-terminal peptidesthat bind to mortalin. This was accompanied by nucleartranslocation of p53 and growth arrest of human osteosar-coma and breast carcinoma cells ( Kaul et al., 2005 ).

5.2.3. ImmunotherapyA challenging hypothesis ‘‘mimotope-hormesis’’, which

shows evidence for epitope mimicry (mimotopy) betweenmortalin and various hsp70s of infectious agents has beenproposed ( Deocaris et al., 2005 ). From this mimotope phe-nomenon, it has been proposed that assaults of infection

during early adulthood could fortify the immune systemto evoke more potent defenses against late-onset diseases,such as cancer, via autoimmunity. Interestingly, bothexperimental and clinical data support the benecial roleof autoimmunity in long-term cancer survivors. Thus,among the clinical applications, mortalin-based vaccineor antibody treatment will certainly be a powerful tool inour ght against cancer.

Acknowledgement

Authors thank Zeenia Kaul for the artwork.

References

Baudet, C., Perret, E., Delpech, B., Kaghad, M., Brachet, P., Wion, D.,Caput, D., 1998. Differentially expressed genes in C6.9 glioma cellsduring vitamin D-induced cell death program. Cell Death Differ. 5,116–125.

Bhattacharyya, T., Karnezis, A.N., Murphy, S.P., Hoang, T., Freeman,B.C., Phillips, B., Morimoto, R.I., 1995. Cloning and subcellularlocalization of human mitochondrial hsp70. J. Biol. Chem. 270, 1705– 1710.

Bruschi, S.A., Lindsay, J.G., 1994. Mitochondrial stress protein actionsduring chemically induced renal proximal tubule cell death. Biochem.Cell. Biol. 72, 663–667.

Bruschi, S.A., West, K.A., Crabb, J.W., Gupta, R.S., Stevens, J.L., 1993.

Mitochondrial HSP60 (PI protein) and a HSP70-like protein (mort-

alin) are major targets for modication during S -(1,1,2,2-tetrauoro-ethyl)-L-cysteine-induced nephrotoxicity. J. Biol. Chem. 268, 23157– 23161.

Burkholder, W.F., Zhao, X., Zhu, X., Hendrickson, W.A., Gragerov, A.,Gottesman, M.E., 1996. Mutations in the C-terminal fragment of DnaK affecting peptide binding. Proc. Natl. Acad. Sci. USA 93,10632–10637.

Cheng, M.Y., Hartl, F.U., Martin, J., Pollock, R.A., Kalousek, F.,Neupert, W., Hallberg, E.M., Hallberg, R.L., Horwich, A.L.,1989. Mitochondrial heat-shock protein hsp60 is essential forassembly of proteins imported into yeast mitochondria. Nature337, 620–625.

Choi, J., Forster, M.J., McDonald, S.R., Weintraub, S.T., Carroll, C.A.,Gracy, R.W., 2004. Proteomic identication of specic oxidizedproteins in ApoE-knockout mice: relevance to Alzheimer’s disease.Free Radic. Biol. Med. 36, 1155–1162.

Cooper, A.J., Wang, J., Gartner, C.A., Bruschi, S.A., 2001. Co-purica-tion of mitochondrial HSP70 and mature protein disulde isomerasewith a functional rat kidney high-M(r) cysteine S-conjugate beta-lyase.Biochem. Pharmacol. 62, 1345–1353.

Craig, E.A., Kramer, J., Kosic-Smithers, J., 1987. SSC1, a member of the70-kDa heat shock protein multigene family of Saccharomycescerevisiae , is essential for growth. Proc. Natl. Acad. Sci. USA 84,4156–4160.

Craig, E.E., Chesley, A., Hood, D.A., 1998. Thyroid hormone modiesmitochondrial phenotype by increasing protein import without alteringdegradation. Am. J. Physiol. 275, C1508–C1515.

Craven, S.E., French, D., Ye, W., de Sauvage, F., Rosenthal, A., 2005.Loss of Hspa9b in zebrash recapitulates the ineffective hematopoiesisof the myelodysplastic syndrome. Blood 105, 3528–3534.

Deocaris, C.C., Taira, K., Kaul, S.C., Wadhwa, R., 2005. Mimo-tope-hormesis and mortalin/grp75/mthsp70: a new hypothesis onhow infectious disease-associated epitope mimicry may explainlow cancer burden in developing nations. FEBS Lett. 579, 586– 590.

Deocaris, C.C., Kaul, S.C., Wadhwa, R., 2006a. On the brotherhood of the mitochondrial chaperones mortalin and heat shock protein 60. CellStress Chaperones 11, 116–128.

Deocaris, C.C., Shrestha, B.G., Kraft, D.C., Yamasaki, K., Kaul, S.C.,Rattan, S.I., Wadhwa, R., 2006b. Geroprotection by glycerol: insightsto its mechanisms and clinical potentials. Ann. NY Acad. Sci. 1067,488–492.

Deocaris, C.C., Yamasaki, K., Kaul, S.C., Wadhwa, R., 2006c. Structuraland functional differences between mouse mot-1 and mot-2 proteinsthat differ in two amino acids. Ann. NY Acad. Sci. 1067, 220–223.

Domanico, S.Z., DeNagel, D.C., Dahlseid, J.N., Green, J.M., Pierce,S.K., 1993. Cloning of the gene encoding peptide-binding protein 74shows that it is a new member of the heat shock protein 70 family.Mol. Cell. Biol. 13, 3598–3610.

Dundas, S.R., Lawrie, L.C., Rooney, P.H., Murray, G.I., 2004. Mortalinis over-expressed by colorectal adenocarcinomas and correlates withpoor survival. J. Pathol. 205, 74–81.

Fernandez-Saiz, V., Moro, F., Arizmendi, J.M., Acebron, S.P., Muga, A.,2006. Ionic contacts at DnaK substrate binding domain involved in theallosteric regulation of lid dynamics. J. Biol. Chem. 281, 7479–7488.

Gao, C.X., Zhang, S.Q., Yin, Z., Liu, W., 2003. Molecular chaperoneGRP75 reprove cells from injury caused by glucose deprivation. ShiYan Sheng Wu Xue Bao 36, 381–387.

Geissler, A., Rassow, J., Pfanner, N., Voos, W., 2001. Mitochondrialimport driving forces: enhanced trapping by matrix Hsp70 stimulatestranslocation and reduces the membrane potential dependence of loosely folded preproteins. Mol. Cell. Biol. 21, 7097–7104.

Glick, B.S., 1995. Pathways and energetics of mitochondrial proteinimport in Saccharomyces cerevisiae . Methods Enzymol. 260, 224–231.

Gonzalez, B., Hernando, R., Manso, R., 2000. Stress proteins of 70 kDain chronically exercised skeletal muscle. Pugers Arch. 440, 42–49.

Harrison, C., 2003. GrpE, a nucleotide exchange factor for DnaK. Cell

Stress Chaperones 8, 218–224.


ARTICLE IN PRESS


8/18/2019 Kaul - Mortalin - 2007

10/12

Hartl, F.U., Martin, J., Neupert, W., 1992. Protein folding in the cell: therole of molecular chaperones Hsp70 and Hsp60. Annu. Rev. Biophys.Biomol. Struct. 21, 293–322.

Horst, M., Oppliger, W., Rospert, S., Schonfeld, H.J., Schatz, G., Azem,A., 1997. Sequential action of two hsp70 complexes during proteinimport into mitochondria. EMBO J. 16, 1842–1849.

Jin, J., Hulette, C., Wang, Y., Zhang, T., Pan, C., Wadhwa, R., Zhang, J.,2006a. Proteomic identication of a stress protein, mortalin/mthsp70/GRP75: relevance to Parkinson’s disease. Mol. Cell Proteomics 5,1193–1204.

Jin, J., Li, G.J., Davis, J., Zhu, D., Wang, Y., Pan, C, Zhang, J., 2006b.Identication of novel proteins interacting with both a -synuclein andDJ-1. Mol. Cell Proteomics [Epub ahead of print].

Johannesen, J., Pie, A., Karlsen, A.E., Larsen, Z.M., Jensen, A., Vissing,H., Kristiansen, O.P., Pociot, F., Nerup, J., 2004. Is mortalin acandidate gene for T1DM? Autoimmunity 37, 423–430.

Kaul, S.C., Wadhwa, R., Komatsu, Y., Sugimoto, Y., Mitsui, Y., 1993.On the cytosolic and perinuclear mortalin: an insight by heat shock.Biochem. Biophys. Res. Commun. 193, 348–355.

Kaul, S.C., Wadhwa, R., Matsuda, Y., Hensler, P.J., Pereira-Smith, O.M.,Komatsu, Y., Mitsui, Y., 1995. Mouse and human chromosomalassignments of mortalin, a novel member of the murine hsp70 familyof proteins. FEBS Lett. 361, 269–272.

Kaul, S.C., Duncan, E.L., Englezou, A., Takano, S., Reddel, R.R.,Mitsui, Y., Wadhwa, R., 1998. Malignant transformation of NIH3T3cells by overexpression of mot-2 protein. Oncogene 17, 907–911.

Kaul, S.C., Duncan, E., Sugihara, T., Reddel, R.R., Mitsui, Y., Wadhwa,R., 2000a. Structurally and functionally distinct mouse hsp70 familymembers Mot-1 and Mot-2 proteins are encoded by two alleles. DNARes. 7, 229–231.

Kaul, S.C., Reddel, R.R., Sugihara, T., Mitsui, Y., Wadhwa, R., 2000b.Inactivation of p53 and life span extension of human diploidbroblasts by mot-2. FEBS Lett. 474, 159–164.

Kaul, S.C., Reddel, R.R., Mitsui, Y., Wadhwa, R., 2001. An N-terminalregion of mot-2 binds to p53 in vitro . Neoplasia 3, 110–114.

Kaul, S.C., Yaguchi, T., Taira, K., Reddel, R.R., Wadhwa, R., 2003.Overexpressed mortalin (mot-2)/mthsp70/GRP75 and hTERT coop-erate to extend the in vitro lifespan of human broblasts. Exp. Cell Res.286, 96–101.

Kaul, S.C., Aida, S., Yaguchi, T., Kaur, K., Wadhwa, R., 2005.Activation of wild type p53 function by its mortalin-binding,cytoplasmically localizing carboxyl terminus peptides. J. Biol. Chem.280, 39373–39379.

Kawai, A., Nishikawa Si, S., Hirata, A., Endo, T., 2001. Loss of themitochondrial Hsp70 functions causes aggregation of mitochondria inyeast cells. J. Cell Sci. 114, 3565–3574.

Kim, K.B., Lee, J.W., Lee, C.S., Kim, B.W., Choo, H.J., Jung, S.Y., Chi,S.G., Yoon, Y.S., Yoon, G., Ko, Y.G., 2006. Oxidation–reductionrespiratory chains and ATP synthase complex are localized indetergent-resistant lipid rafts. Proteomics 6, 2444–2453.

Koehler, C.M., 2004. New developments in mitochondrial assembly.Annu. Rev. Cell Dev. Biol. 20, 309–335.

Kraulis, P., 1991. MOLSCRIPT: a program to produce both detailed andschematic plots of protein structures. J. Appl. Cryst. 24, 946–950.Kuwabara, H., Yoneda, M., Hayasaki, H., Nakamura, T., Mori, H., 2006.

Glucose regulated proteins 78 and 75 bind to the receptor forhyaluronan mediated motility in interphase microtubules. Biochem.Biophys. Res. Commun. 339, 971–976.

Langer, T., Neupert, W., 1991. Heat shock proteins hsp60 and hsp70: theirroles in folding, assembly and membrane translocation of proteins.Curr. Top Microbiol. Immunol. 167, 3–30.

Lau, A.T., He, Q.Y., Chiu, J.F., 2004. A proteome analysis of the arseniteresponse in cultured lung cells: evidence for in vitro oxidative stress-induced apoptosis. Biochem. J. 382, 641–650.

Li, H.M., Niki, T., Taira, T., Iguchi-Ariga, S.M., Ariga, H., 2005.Association of DJ-1 with chaperones and enhanced association andcolocalization with mitochondrial Hsp70 by oxidative stress. Free

Radic. Res. 39, 1091–1099.

Liu, Y., Liu, W., Song, X.D., Zuo, J., 2005. Effect of GRP75/mthsp70/PBP74/mortalin overexpression on intracellular ATP level, mitochon-drial membrane potential and ROS accumulation following glucosedeprivation in PC 12 cells. Mol. Cell Biochem. 268, 45–51.

Ma, Z., Izumi, H., Kanai, M., Kabuyama, Y., Ahn, N.G., Fukasawa, K.,2006. Mortalin controls centrosome duplication via modulatingcentrosomal localization of p53. Oncogene 25, 5377–5390.

Mahlke, K., Pfanner, N., Martin, J., Horwich, A.L., Hartl, F.U., Neupert,W., 1990. Sorting pathways of mitochondrial inner membraneproteins. Eur. J. Biochem. 192, 551–555.

Massa, S.M., Longo, F.M., Zuo, J., Wang, S., Chen, J., Sharp, F.R., 1995.Cloning of rat grp75, an hsp70-family member, and its expression innormal andischemic brain. J. Neurosci. Res. 40, 807–819.

Matsuoka, T., Wada, J., Hashimoto, I., Zhang, Y., Eguchi, J., Ogawa, N.,Shikata, K., Kanwar, Y.S., Makino, H., 2005. Gene delivery of tim44reduces mitochondrial superoxide production and ameliorates neoin-timal proliferation of injured carotid artery in diabetic rats. Diabetes54, 2882–2890.

Mattson, J.P., Ross, C.R., Kilgore, J.L., Musch, T.I., 2000. Induction of mitochondrial stress proteins following treadmill running. Med. Sci.Sport. Exer. 32, 365–369.

Mayer, M.P., Rudiger, S., Bukau, B., 2000. Molecular basis forinteractions of the DnaK chaperone with substrates. Biol. Chem.381, 877–885.

Merrick, B.A., Walker, V.R., He, C., Patterson, R.M., Selkirk, J.K., 1997.Induction of novel Grp75 isoforms by 2-deoxyglucose in human andmurine broblasts. Cancer Lett. 119, 185–190.

Michikawa, Y., Baba, T., Arai, Y., Sakakura, T., Kusakabe, M., 1993.Structure and organization of the gene encoding a mouse mitochon-drial stress-70 protein. FEBS Lett. 336, 27–33.

Michishita, E., Nakabayashi, K., Suzuki, T., Kaul, S.C., Ogino, H., Fujii,M., Mitsui, Y., Ayusawa, D., 1999. 5-Bromodeoxyuridine inducessenescence-like phenomena in mammalian cells regardless of cell typeor species. J. Biochem. 126, 1052–1059.

Mihara, M., Erster, S., Zaika, A., Petrenko, O., Chittenden, T., Pancoska,P., Moll, U.M., 2003. p53 has a direct apoptogenic role at themitochondria. Mol. Cell 11, 577–590.

Mitchell, C.R., Harris, M.B., Cordaro, A.R., Starnes, J.W., 2002. Effect of body temperature during exercise on skeletal muscle cytochrome coxidase content. J. Appl. Physiol. 93, 526–530.

Mitsumoto, A., Takeuchi, A., Okawa, K., Nakagawa, Y., 2002. A subsetof newly synthesized polypeptides in mitochondria from humanendothelial cells exposed to hydroperoxide stress. Free Radic. Biol.Med. 32, 22–37.

Mizukoshi, E., Suzuki, M., Loupatov, A., Uruno, T., Hayashi, H.,Misono, T., Kaul, S.C., Wadhwa, R., Imamura, T., 1999. Fibroblastgrowth factor-1 interacts with the glucose-regulated protein GRP75/mortalin. Biochem. J. 2, 461–466.

Mizukoshi, E., Suzuki, M., Misono, T., Loupatov, A., Munekata, E.,Kaul, S.C., Wadhwa, R., Imamura, T., 2001. Cell-cycle dependenttyrosine phosphorylation on mortalin regulates its interaction withbroblast growth factor-1. Biochem. Biophys. Res. Commun. 280,

1203–1209.Moro, F., Fernandez-Saiz, V., Muga, A., 2004. The lid subdomain of DnaK is required for the stabilization of the substrate-binding site. J.Biol. Chem. 279, 19600–19606.

Moro, F., Fernandez-Saiz, V., Slutsky, O., Azem, A., Muga, A., 2005.Conformational properties of bacterial DnaK and yeast mitochondrialHsp70. Role of the divergent C-terminal alpha-helical subdomain.FEBS J. 272, 3184–3196.

Mosser, D.D., Morimoto, R.I., 2004. Molecular chaperones and the stressof oncogenesis. Oncogene 23, 2907–2918.

Muranyi, M., He, Q.P., Fong, K.S., Li, P.A., 2005. Induction of heatshock proteins by hyperglycemic cerebral ischemia. Brain Res. Mol.Brain Res. 139, 80–87.

Ohashi, M., Oyanagi, M., Hatakeyama, K., Inoue, M., Kominami, R.,1995. The gene encoding PBP74/CSA/motalin-1, a novel mouse hsp70,

maps to mouse chromosome 18. Genomics 30, 406–407.


ARTICLE IN PRESS


8/18/2019 Kaul - Mortalin - 2007

11/12

Orlov, S.N., Hamet, P., 2006. The death of cardiotonic steroid-treatedcells: evidence of Na+i, K+i-independent H+i-sensitive signalling.Acta Physiol. (Oxf.) 187, 231–240.

Ornatsky, O.I., Connor, M.K., Hood, D.A., 1995. Expression of stressproteins and mitochondrial chaperonins in chronically stimulatedskeletal muscle. Biochem. J. 311, 119–123.

Orsini, F., Migliaccio, E., Moroni, M., Contursi, C., Raker, V.A., Piccini,D., Martin-Padura, L., Pelliccia, G., Trinei, M., Bono, M., Puri, C.,Tacchetti, C., Ferrini, M., Mannucci, R., Nicoletti, I., Lanfrancone,L., Giorgio, M., Pelicci, P.G., 2004. The life span determinant p66Shclocalizes to mitochondria where it associates with mitochondrial heatshock protein 70 and regulates trans -membrane potential. J. Biol.Chem. 279, 25689–25695.

Pilzer, D., Fishelson, Z., 2005. Mortalin/GRP75 promotes release of membrane vesicles from immune attacked cells and protection fromcomplement-mediated lysis. Int. Immunol. 17, 1239–1248.

Pilzer, D., Gasser, O., Moskovich, O., Schifferli, J.A., Fishelson, Z., 2005.Emission of membrane vesicles: roles in complement resistance,immunity and cancer. Springer Semin. Immunopathol. 27, 375–387.

Pizzatti, L., Sa, L.A., de Souza, J.M., Bisch, P.M., Abdelhay, E., 2006.Altered protein prole in chronic myeloid leukemia chronic phaseidentied by a comparative proteomic study. Biochim. Biophys. Acta1764, 929–942.

Poindexter, B.J., Pereira-Smith, O., Wadhwa, R., Buja, L.M., Bick, R.J.,2002. 3D reconstruction and localization of mortalin by deconvolutionmicroscopy. Micros. Anal. 89, 21–23.

Ran, Q., Wadhwa, R., Kawai, R., Kaul, S.C., Sifers, R.N., Bick, R.J.,Smith, J.R., Pereira-Smith, O.M., 2000. Extramitochondrial localiza-tion of mortalin/mthsp70/PBP74/GRP75. Biochem. Biophys. Res.Commun. 275, 174–179.

Rehling, P., Brandner, K., Pfanner, N., 2004. Mitochondrial import andthe twin-pore translocase. Nat. Rev. Mol. Cell Biol. 5, 519–530.

Rivolta, M.N., Holley, M.C., 2002. Asymmetric segregation of mitochon-dria and mortalin correlates with the multi-lineage potential of innerear sensory cell progenitors in vitro . Brain Res. Dev. Brain Res. 133,49–56.

Sacht, G., Brigelius-Flohe, R., Kiess, M., Sztajer, H., Flohe, L., 1999.ATP-sensitive association of mortalin with the IL-1 receptor type I.Biofactors 9, 49–60.

Sadekova, S., Lehnert, S., Chow, T.Y., 1997. Induction of PBP74/mortalin/Grp75, a member of the hsp70 family, by low doses of ionizing radiation: a possible role in induced radioresistance. Int. J.Radiat. Biol. 72, 653–660.

Saretzki, G., Armstrong, L., Leake, A., Lako, M., von Zglinicki, T., 2004.Stress defense in murine embryonic stem cells is superior to that of various differentiated murine cells. Stem Cells 22, 962–971.

Schwarzer, C., Barnikol-Watanabe, S., Thinnes, F.P., Hilschmann, N.,2002. Voltage-dependent anion-selective channel (VDAC) interactswith the dynein light chain Tctex1 and the heat-shock protein PBP74.Int. J. Biochem. Cell Biol. 34, 1059–1070.

Sichting, M., Mokranjac, D., Azem, A., Neupert, W., Hell, K.,2005. Maintenance of structure and function of mitochondrial

Hsp70 chaperones requires the chaperone Hepl. EMBO J. 24,1046–1056.Singh, M., Dykens, J.A., Simpkins, J.W., 2006. Novel mechanisms for

estrogen-induced neuroprotection. Exp. Biol. Med. (Maywood) 231,514–521.

Soti, C., Csermely, P., 2000. Molecular chaperones and the aging process.Biogerontology 1, 225–233.

Soti, C., Csermely, P., 2002. Chaperones and aging: role in neurodegen-eration and in other civilizational diseases. Neurochem. Int. 41, 383– 389.

Soti, C., Sreedhar, A.S., Csermely, P., 2003. Apoptosis, necrosis andcellular senescence: chaperone occupancy as a potential switch. AgingCell 2, 39–45.

Sriram, M., Osipiuk, J., Freeman, B., Morimoto, R., Joachimiak, A.,1997. Human Hsp70 molecular chaperone binds two calcium ions

within the ATPase domain. Structure 5, 403–414.

Stacchiotti, A., Ricci, F., Rezzani, R., Li Volti, G., Borsani, E., Lavazza,A., Bianchi, R., Rodella, L.F., 2006. Tubular stress proteins and nitricoxide synthase expression in rat kidney exposed to mercuric chlorideand melatonin. J. Histochem. Cytochem. 54, 1149–1157.

Stevens, T.A., Meech, R., 2006. BARX2 and estrogen receptor-alpha(ESR1) coordinately regulate the production of alternatively splicedESR1 isoforms and control breast cancer cell growth and invasion.Oncogene. 25, 5426–5435.

Strub, A., Lim, J.H., Pfanner, N., Voos, W., 2000. The mitochondrialprotein import motor. Biol. Chem. 381, 943–949.

Takano, S., Wadhwa, R., Yoshii, Y., Nose, T., Kaul, S.C., Mitsui, Y.,1997. Elevated levels of mortalin expression in human brain tumors.Exp. Cell Res. 237, 38–45.

Takano, S., Wadhwa, R., Mitsui, Y., Kaul, S.C., 2001. Identication andcharacterization of molecular interactions between glucose-regulatedproteins (GRPs) mortalin/GRP75/peptide-binding protein 74 (PBP74)and GRP94. Biochem. J. 357, 393–398.

Taurin, S., Seyrantepe, V., Orlov, S.N., Tremblay, T.L., Thibault, P.,Bennett, M.R., Hamet, P., Pshezhetsky, A.V., 2002. Proteome analysisand functional expression identify mortalin as an antiapoptotic geneinduced by elevation of [Na + ]i/[K+ ]i ratio in cultured vascular smoothmuscle cells. Circ. Res. 91, 915–922.

Tsuchiya, T., Dhahbi, J.M., Cui, X., Mote, P.L., Bartke, A., Spindler,S.R., 2004. Additive regulation of hepatic gene expression by dwarsmand caloric restriction. Physiol. Genomics 17, 307–315.

Um, J.H., Kang, C.D., Hwang, B.W., Ha, M.Y., Hur, J.G., Kim, D.W.,Chung, B.S., Kim, S.H., 2003a. Involvement of DNA-dependentprotein kinase in regulation of the mitochondrial heat shock proteins.Leuk. Res. 27, 509–516.

Um, J.H., Kim, S.J., Kim, D.W., Ha, M.Y., Jang, J.H., Chung, B.S.,Kang, C.D., Kim, S.H., 2003b. Tissue-specic changes of DNA repairprotein Ku and mtHSP70 in aging rats and their retardation by caloricrestriction. Mech. Ageing Dev. 124, 967–975.

Voos, W., Rottgers, K., 2002. Molecular chaperones as essential media-tors of mitochondrial biogenesis. Biochim. Biophys. Acta 2, 51–62.

Voos, W., von Ahsen, O., Muller, H., Guiard, B., Rassow, J., Pfanner, N.,1996. Differential requirement for the mitochondrial Hsp70–Tim44complex in unfolding and translocation of preproteins. EMBO J. 15,2668–2677.

Wadhwa, R., Kaul, S.C., Ikawa, Y., Sugimoto, Y., 1993a. Identication of a novel member of mouse hsp70 family. Its association with cellularmortal phenotype. J. Biol. Chem. 268, 6615–6621.

Wadhwa, R., Kaul, S.C., Mitsui, Y., Sugimoto, Y., 1993b. Differentialsubcellular distribution of mortalin in mortal and immortal mouse andhuman broblasts. Exp. Cell Res. 207, 442–448.

Wadhwa, R., Kaul, S.C., Sugimoto, Y., Mitsui, Y., 1993c. Induction of cellular senescence by transfection of cytosolic mortalin cDNA in NIH3T3 cells. J. Biol. Chem. 268, 22239–22242.

Wadhwa, R., Takano, S., Robert, M., Yoshida, A., Nomura, H., Reddel,R.R., Mitsui, Y., Kaul, S.C., 1998. Inactivation of tumor suppressorp53 by mot-2, a hsp70 family member. J. Biol. Chem. 273, 29586– 29591.

Wadhwa, R., Kaul, S.C., Takano, S., Reddel, R.R., Mitsui, Y., Wadhwa,R., 2000a. Transcriptional inactivation of p53 by deletions and singleamino acid changes in mouse mot-1 protein. Biochem. Biophys. Res.Commun. 279, 602–606.

Wadhwa, R., Sugihara, T., Yoshida, A., Nomura, H., Reddel, R.R.,Simpson, R., Maruta, H., Kaul, S.C., 2000b. Selective toxicity of MKT-077 to cancer cells is mediated by its binding to the hsp70 familyprotein mot-2 and reactivation of p53 function. Cancer Res. 60, 6818– 6821.

Wadhwa, R., Taira, K., Kaul, S.C., 2002a. An Hsp70 family chaperone,mortalin/mthsp70/PBP74/Grp75: what, when, and where? Cell StressChaperones 7, 309–316.

Wadhwa, R., Yaguchi, T., Hasan, M.K., Mitsui, Y., Reddel, R.R., Kaul,S.C., 2002b. Hsp70 family member, mot-2/mthsp70/GRP75, binds tothe cytoplasmic sequestration domain of the p53 protein. Exp. Cell

Res. 274, 246–253.


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Wadhwa, R., Ando, H., Kawasaki, H., Taira, K., Kaul, S.C., 2003a.Targeting mortalin using conventional and RNA-helicase-coupledhammerhead ribozymes. EMBO Rep. 4, 595–601.

Wadhwa, R., Yaguchi, T., Hasan, M.K., Taira, K., Kaul, S.C., 2003b.Mortalin-MPD (mevalonate pyrophosphate decarboxylase) interac-tions and their role in control of cellular proliferation. Biochem.Biophys. Res. Commun. 302, 735–742.

Wadhwa, R., Takano, S., Taira, K., Kaul, S.C., 2004. Reduction inmortalin level by its antisense expression causes senescence-like growtharrest in human immortalized cells. J. Gene Med. 6, 439–444.

Wadhwa, R., Takano, S., Kaur, K., Aida, S., Yaguchi, T., Kaul, Z.,Hirano, T., Taira, K., Kaul, S.C., 2005. Identication and character-ization of molecular interactions between mortalin/mtHsp70 andHSP60. Biochem. J. 391, 185–190.

Wadhwa, R., Takano, S., Kaur, K., Deocaris, C.C., Pereira-Smith, O.M.,Reddel, R.R., Kaul, S.C., 2006. Upregulation of mortalin/mthsp70/Grp75 contributes to human carcinogenesis. Int. J. Cancer 118, 2973– 2980.

Walker, C., Bottger, S., Low, B., 2006. Mortalin-based cytoplasmicsequestration of p53 in a nonmammalian cancer model. Am. J. Pathol.168, 1526–1530.

Wiedemann, N., Frazier, A.E., Pfanner, N., 2004. The protein importmachinery of mitochondria. J. Biol. Chem. 279, 14473–14476.

Xie, H., Hu, Z., Chyna, B., Horrigan, S.K., Westbrook, C.A., 2000.Human mortalin (HSPA9): a candidate for the myeloid leukemiatumor suppressor gene on 5q31. Leukemia 14, 2128–2134.

Yamagishi, N., Ishihara, K., Hatayama, T., 2004. Hsp105alpha suppressesHsc70 chaperone activity by inhibiting Hsc70 ATPase activity. J. Biol.Chem. 279, 41727–41733.

Yamamoto, H., Momose, T., Yatsukawa, Y., Ohshima, C., Ishikawa, D.,Sato, T., Tamura, Y., Ohwa, Y., Endo, T., 2005. Identication of anovel member of yeast mitochondrial Hsp70-associated motor andchaperone proteins that facilitates protein translocation across theinner membrane. FEBS Lett. 579, 507–511.

Yokoyama, K., Fukumoto, K., Murakami, T., Harada, S., Hosono, R.,Wadhwa, R., Mitsui, Y., Ohkuma, S., 2002. Extended longevity of Caenorhabditis elegans by knocking in extra copies of hsp70F, ahomolog of mot-2 (mortalin)/mthsp70/Grp75. FEBS Lett. 516, 53–57.

Zhu, X., Zhao, X., Burkholder, W.F., Gragerov, A., Ogata, C.M.,Gottesman, M.E., Hendrickson, W.A., 1996. Structural analysis of substrate binding by the molecular chaperone DnaK. Science 272,1606–1614.


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