Abstract 17019: Mitochondrial Biogenesis in Myocardial Ischemia/Reperfusion Injury is Controlled by Parkin-dependent Elimination of PARIS, Which is Also Regulated by Sumoylation & SENP5
Background: PARIS (Parkin Interacting Substrate) is a recently identified zinc finger protein acting as a transcriptional inhibitor for PGC-1α. Previous studies showed that Parkin ubiquitinates PARIS and thus marks it for degradation. However, the role of PARIS in the heart has not been studied. The objective of this study is to elucidate the role of PARIS in the context of mitochondrial biogenesis after myocardial ischemia or ischemia/reperfusion.
Methods: Parkin knockout (PKO) mice and wild-type (WT) C57BL/6J littermates were subjected to 15 mins ischemia followed by 30 mins reperfusion (I/R). Ischemic and non-ischemic region were carefully dissected under microscope and protein fractionation for cytosol, mitochondria and nucleus was performed. For in vitro simulated ischemia (sI) /reperfusion, HL-1 cardiomyocyte in which PARIS was overexpressed or silenced were subjected to 1 hr ischemia or followed by reperfusion. PGC1α and COX4, markers of mitochondrial biogenesis, were measured by RT-PCR and western blot.
Results: Our results show that HL-1 cells subjected to sI showed a decrease in PARIS and an increase in markers of mitochondrial biogenesis. Overexpression of PARIS suppressed the upregulation of PGC1α after sI. Knockdown of PARIS via siRNA did not alter markers of mitochondrial biogenesis under basal conditions, but increased mitochondrial biogenesis 24h after recovery from ischemia. In WT mouse hearts, PGC1α mRNA increased after I/R but not in PKO hearts. Similarly, COX4 protein increased in WT mice after I/R but not in PKO mice. PARIS abundance decreased after I/R in WT mouse heart but not PKO. Furthermore, we found that PARIS is modified by SUMO (Small Ubiquitin-related Modifier) under basal conditions in WT mice. Finally, we noted that SENP5, a de-SUMOylase, increased with I/R in WT mice.
Conclusions: These results suggest that SUMOylation of PARIS may mediate nuclear translocation resulting in suppression of PGC1α transcription under basal conditions, followed by de-repression of PGC1α during I/R. Parkin plays a role in regulation of PARIS and mitochondrial biogenesis in response to ischemic stress.
Author Disclosures: C. Huang: None. M. Islam: None. A.M. Andres: None. A. Stotland: None. R. Gottlieb: None.
- © 2016 by American Heart Association, Inc.