Mitochondrial DNA damage initiates a cell cycle arrest by a Chk2-associated mechanism in mammalian cells.
Previous work from our laboratory has focused on mitochondrial DNA (mtDNA) repair and cellular viability. However, other events occur prior to the initiation of apoptosis in cells. Because of the importance of mtDNA in ATP production and of ATP in fuel cell cycle progression, we asked whether mtDNA damage was an upstream signal leading to cell cycle arrest. Using quantitative alkaline Southern blot technology, we found that exposure to menadione produced detectable mtDNA damage in HeLa cells that correlated with an S phase cell cycle arrest. To determine whether mtDNA damage was causatively linked to the observed cell cycle arrest, experiments were performed utilizing a MTS-hOGG1-Tat fusion protein to target the hOGG1 repair enzyme to mitochondria and enhance mtDNA repair. The results revealed that the transduction of MTS-hOGG1-Tat into HeLa cells alleviated the cell cycle block following an oxidative insult. Furthermore, mechanistic studies showed that Chk2 phosphorylation was enhanced following menadione exposure. Treatment of the HeLa cells with the hOGG1 fusion protein prior to menadione exposure resulted in an increase in the rate of Chk2 dephosphorylation. These results strongly support a direct link between mtDNA damage and cell cycle arrest.
Department of Cell Biology and Neuroscience, University of South Alabama, Mobile, Alabama 36688.
Christopher A
CA
Koczor
Department of Cell Biology and Neuroscience, University of South Alabama, Mobile, Alabama 36688.
Inna N
IN
Shokolenko
Department of Cell Biology and Neuroscience, University of South Alabama, Mobile, Alabama 36688.
Amy K
AK
Boyd
Department of Cell Biology and Neuroscience, University of South Alabama, Mobile, Alabama 36688.
Shawn P
SP
Balk
Department of Cell Biology and Neuroscience, University of South Alabama, Mobile, Alabama 36688.
Glenn L
GL
Wilson
Department of Cell Biology and Neuroscience, University of South Alabama, Mobile, Alabama 36688. Electronic address: sledoux@usouthal.edu.
Susan P
SP
LeDoux
D000255:Adenosine Triphosphate / Q000235:genetics / Q000378:metabolism; D000818:Animals; D064447:Checkpoint Kinase 2; D004249:DNA Damage / Q000187:drug effects / Q000502:physiology*; D045647:DNA Glycosylases / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair / Q000187:drug effects / Q000502:physiology*; D004272:DNA, Mitochondrial / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016196:S Phase / Q000187:drug effects / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D024483:Vitamin K 3 / Q000494:pharmacology; D014815:Vitamins / Q000494:pharmacology
D004272:DNA, Mitochondrial; D011993:Recombinant Fusion Proteins; D014815:Vitamins; D024483:Vitamin K 3; D000255:Adenosine Triphosphate; D064447:Checkpoint Kinase 2; C578634:CHEK2 protein, human; C578632:Chek2 protein, rat; D017346:Protein Serine-Threonine Kinases; D045647:DNA Glycosylases; C479058:oxoguanine glycosylase 1, human