AUTHOR=Guo Chun , Hildick Keri L. , Jiang Juwei , Zhao Alice , Guo Wenbin , Henley Jeremy M. , Wilkinson Kevin A. 

TITLE=SENP3 Promotes an Mff-Primed Bcl-xL-Drp1 Interaction Involved in Cell Death Following Ischemia

JOURNAL=Frontiers in Cell and Developmental Biology

VOLUME=Volume 9 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/cell-and-developmental-biology/articles/10.3389/fcell.2021.752260

DOI=10.3389/fcell.2021.752260

ISSN=2296-634X

ABSTRACT=Dysregulation of the mitochondrial fission machinery has been linked to cell death following ischemia. The fission event is largely dependent on Dynamin-related protein 1 (Drp1), and is initiated by the recruitment of Drp1 to the mitochondria. During this cellular event Mitochondrial fission factor (Mff) is the major docking protein for Drp1. Drp1 is subject to a protein post-translational modification known as SUMOylation. SUMOylation affects the Drp1-Mff interaction, and Drp1 deSUMOylation, mediated by the SUMO protease SENP3, enhances the Drp1-Mff interaction to promote cell death evoked by reoxygenation following oxygen and glucose deprivation (OGD), an in vitro model for ischemia. Another interacting partner for Drp1 is the Bcl-2 family member Bcl-xL, an important protein in cell death and survival pathways. However, whether SUMOylation/deSUMOyation regulate the Drp1-Bcl-xL interaction, and whether this interaction is involved in ischemic cell death, is unknown. Here we demonstrate that preventing Drp1 SUMOylation by mutating its SUMO target lysines enhances the Drp1-Bcl-xL interaction in vivo and in vitro. Consistent with this, SENP3 promotes the Drp1-Bcl-xL interaction. Mff appears to prime the binding of Drp1 to Bcl-xL at the mitochondria. Interestingly, Mff and Bcl-xL also appear to interact directly, independent of Drp1, through their transmembrane domains. Importantly, SENP3 loss in cells subjected to OGD correlates with reduced Drp1-Bcl-xL interaction, whilst recovery of SENP3 levels in cells subjected to reoxygenation following OGD correlates with increased Drp1-Bcl-xL interaction. Expressing a Bcl-xL mutant with defective binding sites for Drp1 reduces OGD plus reoxygenation-evoked cell death. Thus, SENP3-mediated deSUMOlyation promotes an Mff-primed Drp1-Bcl-xL interaction that contributes to cell death following ischemia.