Increased expression of ApoE and protection from amyloid-beta toxicity in transmitochondrial cybrids with haplogroup K mtDNA.
Mitochondrial (mt) DNA haplogroups, defined by specific single nucleotide polymorphism (SNP) patterns, represent populations of diverse geographic origins and have been associated with increased risk or protection of many diseases. The H haplogroup is the most common European haplogroup while the K haplogroup is highly associated with the Ashkenazi Jewish population. Transmitochondrial cybrids (cell lines with identical nuclei, but mtDNA from either H (n=8) or K (n=8) subjects) were analyzed by the Seahorse flux analyzer, quantitative polymerase chain reaction (Q-PCR) and immunohistochemistry (IHC). Cybrids were treated with amyloid-β peptides and cell viabilities were measured. Other cybrids were demethylated with 5-aza-2'-deoxycytidine (5-aza-dC) and expression levels for APOE and NFkB2 were measured. Results show K cybrids have (a) significantly lower mtDNA copy numbers, (b) higher expression levels for MT-DNA encoded genes critical for oxidative phosphorylation, (c) lower Spare Respiratory Capacity, (d) increased expression of inhibitors of the complement pathway and important inflammasome-related genes; and (e) significantly higher levels of APOE transcription that were independent of methylation status. After exposure to amyloid-β1-42 peptides (active form), H haplogroup cybrids demonstrated decreased cell viability compared to those treated with amyloid-β42-1 (inactive form) (p<0.0001), while this was not observed in the K cybrids (p=0.2). K cybrids had significantly higher total global methylation levels and differences in expression levels for two acetylation genes and four methylation genes. Demethylation with 5-aza-dC altered expression levels for NFkB2, while APOE transcription patterns were unchanged. Our findings support the hypothesis that mtDNA-nuclear retrograde signaling may mediate expression levels of APOE, a key factor in many age-related diseases. Future studies will focus on identification of the mitochondrial-nuclear retrograde signaling mechanism(s) contributing to these mtDNA-mediated differences.
Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA, United States.
Kunal
K
Thaker
Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA, United States.
Marilyn
M
Chwa
Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA, United States.
Shari R
SR
Atilano
Department of Neurobiology and Behavior, University of California Irvine, Irvine, CA, United States.
Pinar
P
Coskun
Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA, United States.
Javier
J
Cáceres-Del-Carpio
Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA, United States.
Nitin
N
Udar
Retina-Vitreous Associates Medical Group, Beverly Hills, CA, United States.
David S
DS
Boyer
Tulane Center for Aging and Department of Medicine, Tulane University, New Orleans, LA, United States.
S Michal
SM
Jazwinski
Tulane Center for Aging and Department of Medicine, Tulane University, New Orleans, LA, United States.
Michael V
MV
Miceli
Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA, United States; Cedars-Sinai Medical Center, Los Angeles, CA, United States.
Anthony B
AB
Nesburn
Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA, United States.
Baruch D
BD
Kuppermann
Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA, United States; Department of Pathology and Laboratory Medicine, University of California Irvine, Irvine, CA, United States. Electronic address: mkenney@uci.edu.
M Cristina
MC
Kenney
D000328:Adult; D000368:Aged; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D001057:Apolipoproteins E / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000235:genetics*; D005260:Female; D006239:Haplotypes; D006801:Humans; D008297:Male; D008875:Middle Aged; D008928:Mitochondria / Q000378:metabolism*; D010085:Oxidative Phosphorylation; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D055815:Young Adult
D016229:Amyloid beta-Peptides; D001057:Apolipoproteins E; D004272:DNA, Mitochondrial; D017382:Reactive Oxygen Species
APOE; Amyloid-β(1–42); Complement inhibitors; Cybrids; Epigenetics; Haplogroup; Inflammasome; Mitochondrial DNA