Abstract
Purpose :
Our previous study found reversal of mitochondrial morphological and functional injuries during degeneration and subsequent recovery of neuronal cells. Here we studied the role of mitochondrial quality control (fission/fusion, biogenesis, mitophagy) in both neuronal degeneration and recovery.
Methods :
Cell death was induced in neuronal PC12 cells by ethanol (EtOH, 5%, v/v). Cell recovery was enabled by washing away EtOH and further culturing cells in fresh medium. Western blot and qPCR were used to measure protein and mRNA expression. Immunofluorescence was performed to study mitophagy with LC3-I/II antibody. Autophagosomes were detected by electron microscopy. Inhibitor SR-18292 was used to block the activity of PGC-1α.
Results :
Results showed that autophagy was activated only during the degeneration phase (EtOH treatment) but not in the recovery phase (EtOH removed); this activation was not dependent on the Parkin/PINK1 mediated mitophagy pathway. Regarding mitochondrial fusion and fission, EtOH treatment had no influence on total mRNA and protein expression of Drp1, but induced increased protein expression of phospho-Drp1Ser616 and transformation of L-OPA1 to S-OPA1, all of which recovered to normal levels after washing EtOH. Both mRNA and protein expression of mitofusion 1 and 2 were decreased by EtOH treatment and recovered to normal levels after removing EtOH. Regarding mitochondrial biogenesis, both mRNA and protein expression of PGC-1α were decreased by EtOH and increased after removing EtOH. Incubation of cells with PGC-1α inhibitor SR-18292 after washing EtOH, inhibited mitochondrial recovery, neurite regeneration, and cell survival in a concentration dependent manner.
Conclusions :
Our study documents changes in mitochondrial fission/fusion, biogenesis and mitophagy during the process of degeneration and recovery of neuronal cells. In particular, the study reveals that PGC-1α mediated mitochondrial biogenesis plays a critical role in the cellular recovery. This molecular mechanism could be a target for neuroprotection and neurorescue in neurodegenerative diseases.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.