Selective binding of nuclear alpha-synuclein to the PGC1alpha promoter under conditions of oxidative stress may contribute to losses in mitochondrial function: implications for Parkinson's disease.
Alpha-synuclein has been reported to be present in the nucleus and levels enhanced by oxidative stress. Herein, we sought to investigate the mechanistic role of nuclear alpha-synuclein. We found that alpha-synuclein nuclear localization coincided with enhanced chromatin binding both in an in vitro and a corresponding in vivo brain oxidative stress model previously characterized by our laboratory as well as in PD brain tissues. Genome-wide chromatin immunoprecipitation (ChIP)-on-chip analysis of alpha-synuclein:promoter binding in response to oxidative stress in vitro revealed that binding occurs at several promoters belonging to a range of functional categories including transcriptional regulation. Interestingly, given the important role of mitochondrial dysfunction in PD, this included binding to the promoter for the master mitochondrial transcription activator, PGC1alpha in vitro, in vivo, and in human brain tissue with age and PD. To test the possible mechanistic impact of alpha-synuclein PGC1alpha promotor binding, we assessed PGC1alpha promoter activity, mRNA, and protein levels and expression of candidate PGC1alpha target genes in our in vitro model. All were found to be reduced in conjunction with increased levels of aberrant mitochondrial morphology and impaired mitochondrial function. Exogenous PGC1alpha expression was found to attenuate alpha-synuclein-mediated mitochondrial dysfunction and subsequent neurotoxicity in vitro. Our data suggest that nuclear alpha-synuclein localization under conditions of oxidative stress may impact on mitochondrial function in part via the protein's capacity to act as a transcriptional modulator of PGC1alpha. This represents a novel role for alpha-synuclein as it relates to mitochondrial dysfunction in PD.
Buck Institute for Age Research, 8001 Redwood Boulevard, Novato, CA 94945, USA.
Almas
A
Siddiqui
Shankar J
SJ
Chinta
Jyothi K
JK
Mallajosyula
Subramanian
S
Rajagopolan
Ingrid
I
Hanson
Anand
A
Rane
Simon
S
Melov
Julie K
JK
Andersen
D000368:Aged; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D042967:Electron Transport Complex I / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000235:genetics*; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D008875:Middle Aged; D008928:Mitochondria / Q000378:metabolism* / Q000502:physiology; D018384:Oxidative Stress; D016716:PC12 Cells; D010300:Parkinson Disease / Q000378:metabolism*; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D051381:Rats; D014157:Transcription Factors / Q000235:genetics*; D051844:alpha-Synuclein / Q000378:metabolism*
D002843:Chromatin; D006360:Heat-Shock Proteins; C486497:PPARGC1A protein, human; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D014157:Transcription Factors; D051844:alpha-Synuclein; D042967:Electron Transport Complex I