Although the oxidative phosphorylation (OXPHOS) system has been found in mitochondria and the plasma membrane of various mammalian cell lines, understanding the physiological functions of the plasma membrane OXPHOS system is challenging. Here, we demonstrated that OXPHOS I, II, III, IV and V subunits were expressed in the plasma membrane of HepG2 cells and primary mouse hepatocytes, as determined by non-permeabilized immunofluorescence, total internal reflection fluorescence (TIRF) microscopy, cell surface-biotin labeling and plasma membrane and lipid raft isolation. Next, we demonstrated that NADH administration generated extracellular superoxide and improved insulin signaling in HepG2 cells and primary mouse hepatocytes. The NADH-dependent generation of extracellular superoxide was prevented by knockdown of NDUFV-1, the first subunit of OXPHOS I receiving electrons from NADH and the NADH-improved insulin signaling was abolished by extracellular catalase. Thus, we conclude that the OXPHOS system in the plasma membrane may be required for the generation of extracellular ROS and the regulation of insulin signaling.
|Number of pages||11|
|Journal||Free Radical Biology and Medicine|
|Publication status||Published - 2017 Nov|
Bibliographical noteFunding Information:
This work was supported by grants awarded to Y.-G. Ko from the Korea Health Industry Development Institute ( HI14C2739 ) and the National Research Foundation ( 2015R1A5A1009024 ). This was also partially supported by a Korea University grant (to Y.-G. Ko).
- Detergent-resistant lipid rafts
- Extracellular superoxide
- Insulin signaling
- Plasma membrane oxidative phosphorylation
ASJC Scopus subject areas
- Physiology (medical)