HAPLOGROUP COMPATIBILITY AND HOW mtDNA CAN INFLUENCE TRAITS BEYOND DISEASE

Doug Wallace

Center for Mitochondrial and Epigenomic Medicine

Children’s Hospital of Philadelphia

THE mtDNA CONTROLS THE MITOCHONDRIAL POWER PLANT CAPACITOR AND THUS IS THE POWER PLANT WIRING DIAGRAM: IT IS NOT TRIVIAL

Tissue Specific Manifestations:Brain: Continuous energy demand. 2% body weight but consumes 20% oxygen.Heart>Muscle>Renal>Endocrine>Intestinal: Episodic energy demand.

THE mtDNA CAN HARBOR BOTH DISEASE CAUSING AND BENEFICIAL VARIANTS

THE MITOCHONDRIAL GENOME:~ 1500 Dispersed nDNA Genes

37 mtDNA Genes

High Mutation Rate (ROS-Repair-etc.)THREE CLASSES OF mtDNA VARIANTS

Ancient Functional PolymorphismsRecent Deleterious Mutations

Somatic Mutations

HUMAN mtDNA CHANGED AS OUR ANCESTORS MIGRATED OUT-OF-AFRICA PERMITTING THEM TO ADAPT TO DIFFERENT

ENVIRONMENTSfrom http://www.mitomap.org

Mutation rate = 2.2 – 2.9% / MYRTime estimates are YBP

Haplogroup H5a: Ancient polymorphism

ANCIENT mtDNA VARIANTS CAN BE BOTH GOOD AND BAD DEPENDING ON CONTEXT

EUROPEAN tRNAGln 4336A>G VARIANT BECAME ESTABLISHED BUT NOW REDISPOSES TO

ALZHEIMER & PARKINSON DISEASE

AD = 3.3%, PD = 5.3%, AD+PD =

6.8%, CNTL = 0.4%

ASSOCIATIONS BETWEEN mtDNA HAPLOGROUPS & HUMAN TRAITS

• NEURODEGENERATIVE DISEASES– Alzheimer Disease– Parkinson Disease– Macular Degeneration– Migraine– Psychiatric Disorders

• NEUROLOGICAL DISEASES– Stoke

• METABOLIC DISEASES– Diabetes– Cardiovascular Disease– Metabolic Syndrome

• INFLAMMATORY & INFECTIOUS DISEASES– Sepsis– IgE Levels– Asthma– AIDS progression– Anti-AIDS HAAT* Lipodystrophy– Osteoarthritis

• AGING• CANCERS• ATHLETIC PERFORMANCE (L0>L3>N>H>J-U-T)* HAAT- highly active anti-retroviral therapy

H > J = T > U (Uother > U4 = U5a1 > Uk).

Differentiated cell

Sperm

Egg

CYTOPLAMIC MIXING TO INCREASE FERTILITY OF INFERTILE EGGS HAS CREATED HETEROPLASMY

Infertile Mother

Unrelated Younger

Donor

Recipient oocyte

Heteroplasmic child

Heteroplasmic Heteroplasmic zygotezygote

Father ♂♂

Donor oocyte

♀

Barritt JA, Brenner CA, Malter HE, & Cohen J. Mitochondria in human offspring from ooplasmic transplantation. Human Reproduction 16: 513-516 (2001).

ICSI

Ooplasmic Transfer

Disaggregate

Female ES Cybrids (Heterplasmic NZB-

129 mtDNA)

129 ES Cell Cells

Pseudopregnantmother

Female Chimera

HETEROPLASMY BETWEEN mtDNA HAPLOGROUPS CAN CAUSE NEUROPSYCHIATRIC DISEASES AND LEARNING PROBLEMS

HETEROPLASMY OF TWO “NORMAL” (NZB+129) mtDNAs IS ELIMINATED

LM(TK-) (mtDNA NZB)

Backcross 129 nDNA (NZB + 129 mtDNAs)females to B6 males > 9 generations

Rhodamine 6G

129 Agouti Mice

91 “129” vs “NZB” mtDNAs differences: 91 “129” vs “NZB” mtDNAs differences: 15 aaΔ +5 tRNA +7 rRNA + 11 CR

MIXING TWO NORMAL MOUSE mtDNAs (NZB + 129) CAUSES NEUROPSYCOLOGICAL PHENOTYPES

M NW

BamBamH A4276GH A4276G

0 2000 4000 6000 8000 10000 12000 14000 16000

I I II I II I III II I II III I I I II III I I I II I I II III I I II I II IIIII I IIII II I III I II I I I I IIIIII I II I IIII II I I III

Backcrossed 20 generations onto C57BL/6L nDNA.

Permitted nZB-129 mtDNAs to segregate.

Correlated mtDNA NZB-129 genotypes with behavior.

CREATION OF NZB-129 HETEROPLASMIC MICE

GENERTATION FROM THE

HETEROPLASMIC MICE OF

HOMOPLASMIC DERIVATIVES TO

ASSESS THE DIFFERENTIAL

EFFECTS OF THE HETEROPLASMIC

MIXING

NZB-129 HETEROPLASMIC MICE EXHIBIT DIMINISHED ACTIVITY, FOOD CONSUMPTION, & METABOLIC RATE BUT HEIGHTEN RESPONSE TO STRESS

REDUCED COGNITIVE CAPACITY OF NZB-129 HETEROPLASMIC MICE

Mitochondrial DNA modifies cognition in interaction with

nuclear genome and age in mice. Roubertoux PL et al. (2003)

Nature Genetics 35:65-69

a) Radial Maze: 3 months.b) Krushinsky Test: 3 months.c) Morris Hidden Platform Water

Maze: 3, 6, 12 months.d) Probe Test-No Platform: 3

months.

H H mtN

N mtH

NSIMPLY TRANSFERRING

mtDNAs FROM ONE NUCLEUS TO ANOTHER HAS MAJOR EFFECTS

ON LEARNING AND BEHAVIOR

SUGGESTIONS RELATING TO mtDNA HAPLOGROUPS

Apply spindle transfer only to women with severe mtDNA mutations, preferably with previous reproductive failure.

-Cost-Benefit Ratio justified.-Negative outcome for child otherwise assured.

Avoid heteroplasmy.Use haplogroup matched mtDNA donors.

- For heteroplasmic women, preferably use female donor on maternal lineage prior to occurrence of mutant mtDNA.

-When maternal relatives not available use haplogroup matched donor.

Prohibit for now the use of spindle transfer to treat advanced maternal age infertility.

-Cost-Benefit Ratio not justified.-Possible long-term risk to society too great if spindle transferred

proves deleterious and used for thousands of children.

A MITOCHONDRIAL ETIOLOGY OF COMPLEX DISEASE

mtDNA Damage &Somatic Mutations

↓ENERGY,↑ ROS,Δ REBOX, Δ Ca++

PROGRESSIVE BIOENERGETIC

DECLINEApoptosis

mtDNA VariantsAncient Adaptive Polymorphisms

Recent Deleterious Mutations nDNA Variation

MutationsDeleterious Mutations,

Mito Gene PolymorphismsEpigenomics

Histone Modifications,Signal Transduction,

Redox Controls

NeuropsychologicalBlindness, Deafness AD, PD, Depression

MuscleMyalgia, Fatigability

CardiomyopathyRenal Failure

OXPHOSDYSFUNCTION

Environmental FactorsEnergy SourcesCarbohydrates,

Fats, Amino AcidsEnergy Uses

Growth,Maintenance,Reproduction

Toxins

MetabolicType II Diabetes, Obesity

Hypertension, CVDStress

Thermal, Trauma

AgingPenetrance & Expressivity

Delayed-Onset & Progression,

Inflammation, Immunity MS, Type I Diabetes

(DAMPs)Infection Predisposition

Sepsis, AIDS(Zhang Q et al, 2010, Nature 464:104)

CancerEnergy Production,

ROS & Redox