michael jeltsch tyrosine kinases
TRANSCRIPT
Michael Jeltsch
Tyrosine Tyrosine kinaseskinasesTyrosine Tyrosine kinaseskinases
http://msbl.helsinki.fi/tkseminar
Producercell
Targetcell
Receptor binding
Signaling molecules
Signal trans-duction
Activation ofGene expression
proliferation, differentiation, migration, metabolism, etc.proliferation, differentiation, migration, metabolism, etc.
RNA
Biological Biological responsesresponses
Cell surface Cell surface receptorsreceptors
ion-channel-linked
guanylylcyclases
tyrosinekinases
tyrosine kinaseassociated
tyrosinephosphatases
serin/threoninekinases
enzyme-linked G-protein-linked
extracellular
juxtamembranetransmembrane
tyrosine kinase
carboxy-terminal tail
a
ligand binding
NH2
COOH
ATP
substratebinding
Receptor Tyrosine Receptor Tyrosine KinasesKinases
Michael Jeltsch
VEGF xVEGF xVEGF-R1VEGF-R1
ssss
ss
ss
EGF-R IGF-1-R FGF-RPDGF-R VEGF-R3
RTK RTK subclassessubclasses
I II III IV
Modular structure of EC Modular structure of EC domainsdomains
RTK RTK ligandsligands
• Some RTKs need two ligands for activation
• Extracellular matrix components (HSPGs)
• Membrane-bound proteins (ephrins)
• Cytokines (EGF, FGF, CSF-1, insulin)
a
a
aa
PPPPPP
Signaling through an RTKSignaling through an RTK
aa
PPPPPP
a
a
a
a
a
a
a
a
a
Dimerization or oligomerizationDimerization or oligomerization
• Bivalent ligand(e.g. VEGF, PDGF)
• Ligand-induced conformational change(probably EGF)
• Intracomplex conformational change(e.g. insulin)
Transmembrane signal Transmembrane signal transfertransfer
• Exact mechanism unknown
• Same or similar mechanism for allRTKs (evidence from hybrid receptors)
AutophosphorylationAutophosphorylation
• Purposes:- Regulation of tyrosine kinase activity- Recruitment of signaling molecules
• Specific Tyr residues, usually outside thetyrosine kinase domain (juxtamembranedomain, cytoplasmic tail, kinase insert)
• SH2 (Src-homolgy 2)
• WW
• SH3 (Src-homolgy 3)
• PH (pleckstrin homology)/FYVE
• PTB (phosphotyrosine binding)
Signaling proteins are modular moleculesSignaling proteins are modular molecules
SH2 PTB SH3 PH/FYVE PZB WW
• PDZ
SH2 (Src-homology 2)/SH2 (Src-homology 2)/PTB (phosphotyrosine binding)PTB (phosphotyrosine binding)
• Bind to PY (and sometimes Y)
• Specificity is achieved through the context
• SH2: 1-6 amino acids C-terminal to PY
• PTB: 3-5 amino aids N-terminal to PY (or Y)
SH3 (Src-homology 3)SH3 (Src-homology 3)
• Binds to proline motif PXXP
WWWW
• Binds to proline motif PXPX
SH3 & SH3 & WWWW
PH (pleckstrin homology)/FYVEPH (pleckstrin homology)/FYVE
• PH domain binds to phosphoinositides (membrane-
localization)
• FYVE domain binds specifically PtdIns-3-P
PDZ (PSD-95, DDLP, ZP1)PDZ (PSD-95, DDLP, ZP1)
• Bind to hydrophobic C-terminal strtches of target proteins
PH/FYVE/PDZPH/FYVE/PDZ
SH2
PTB
P
P
PH/FYVE SH3 WW PDZEnzymatic
activity
KinasesPhosphatasesPLC-Ras-GAPRho-GRF
Cellular Targets
membrane
Assembly of a specific signaling Assembly of a specific signaling complexcomplex
Myristyl. PTB
PH
TM P P P P P
P P P P P P
P P P
Membranelocalization
Receptorbinding Tyrosines
PP
P
FRS2
Dos
LAT
Indirect recruitment is the main recruitment methodfor some receptors (insulin receptor, FGF receptors)
Docking Docking proteinsproteins
Topics in activation of effector Topics in activation of effector proteinsproteins
1. Activation by Membrane Translocation
2. Activation by a Conformational Change
3. Activation by Tyrosine Phosphorylation
1. Membrane translocation
2. ConformationalChange 3. Tyrosine Phosphorylation
Activation of signaling molecules: PDGF Activation of signaling molecules: PDGF receptorreceptor
Intracellular Signaling Intracellular Signaling PathwaysPathways
Signal Signal TerminationTermination
• Ligand-induced oligomerization orconformational change
• Autophosphorylation/crossphosphorylation
• Recruitment of signaling molecules tophosphorylated tyrosines (“signalingcomplexes”)• Termination of Signaling (endocytosis)
3 Steps to 3 Steps to activationactivation
Intracellular vs. Transmembrane Receptor Tyrosine Intracellular vs. Transmembrane Receptor Tyrosine Kinases:Kinases:
Phylogenetic tree of tyrosine kinasesPhylogenetic tree of tyrosine kinases
Cytoplasmic Tyrosine Cytoplasmic Tyrosine KinasesKinases
Tyrosine kinase-derived Tyrosine kinase-derived oncogenesoncogenes
oncogene retrovirus cellular counterpart
v-src Rous sarcoma c-srcv-erbB avian erythroblastosis EGF receptorv-fms McDonough feline
sarcomaCSF-1 receptor
v-kit feline sarcoma SCF receptorv-abl Abelson murine
leukemiac-abl
v-sis simian sarcoma PDGF
ss
VEGF-R3
Dominant Negative Dominant Negative
Receptors:Receptors:VEGFR-3 mutations in hereditary
lymphedema
S641P
P1114L
Further Further
readingreadingSchlessinger, J. (2000): Cell Signaling by Receptor Tyrosine Kinases.Cell, Vol. 103, 211-225.