Hepatitis C Virus Non-Structural Protein 5A (NS5A) Disrupts Mitochondrial Dynamics and Induces Mitophagy

Abstract

Mitophagy is a selective form of autophagy, targeting damaged mitochondria for lysosomal degradation. Although HCV infection has been shown to induce mitophagy, the precise underlying mechanism and the effector protein responsible remain unclear. Herein, we demonstrated that the HCV non-structural protein 5A (NS5A) plays a key role in regulating cellular mitophagy. Specifically, the expression of HCV NS5A in the hepatoma cells triggered hallmarks of mitophagy including mitochondrial fragmentation, loss of mitochondrial membrane potential, and Parkin translocation to the mitochondria. Furthermore, mitophagy induction through the expression of NS5A led to an increase in autophagic flux as demonstrated by an accumulation of LC3II in the presence of bafilomycin and a time-dependent decrease in p62 protein level. Intriguingly, the expression of NS5A concomitantly enhanced reactive oxygen species (ROS) production, and treatment with an antioxidant attenuated the NS5A-induced mitophagy event. These phenomena are similarly recapitulated in the NS5A-expressing HCV subgenomic replicon cells. Finally, we demonstrated that expression of HCV core, which has been documented to inhibit mitophagy, blocked the mitophagy induction both in cells harboring HCV replicating subgenomes or expressing NS5A alone. Our results, therefore, identified a new role for NS5A as an important regulator of HCV-induced mitophagy and have implications to broadening our understanding of the HCV-mitophagy interplay.

URB597 protects against NLRP3 inflammasome activation by inhibiting autophagy dysfunction in a rat model of chronic cerebral hypoperfusion

“…The tight interactions between ROS accumulation and microglial overactivation and autophagy are mainly reflected in two ways: the induction of autophagy by ROS accumulation or microglial overactivation [49][50][51] and the reduction of ROS accumulation or microglial overactivation via autophagy [52,53], which is complex, and depends on the region, severity and phase of the insult. In our present study, CCH might impair the processes of autophagy and mitophagy through upregulation of ROS generation and microglial overactivation, indicating that neuroinflammation may play a more dominant role than impaired autophagy at the stage of chronic cerebral ischemic injury.…”

Regulation of Autophagy in Cells Infected With Oncogenic Human Viruses and Its Impact on Cancer Development

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Targeting Autophagy Augments Berberine-Mediated Cell Death in Human Hepatoma Cells Harboring Hepatitis C Virus RNA

“…The human hepatoma Huh-7 cells were cultured in DMEM containing 10% FBS, 1% gentamycin, 1% amphotericin B, and incubated at 37 • C in a 5% CO 2 incubator. The AB12-A2 Huh-7 replicon cells carrying the HCV genotype 1b subgenomic RNA (denoted as 'Huh-7.HCVrep') were similarly maintained in DMEM, but supplemented with 1 mg/mL of G418 (InvivoGen; San Diego, CA, USA), as previously described [46]. Huh-7 cells persistently producing infectious cell culture-derived HCV particles (denoted as 'Huh-7.HCVcc') were initially established by electroporation of the full-length HCV genome Jc1FLAG2 (p7-nsGluc2A), as previously described [47], and then continuously passaged in media containing HCVcc particles until all cells tested positive for HCV NS5A expression.…”