Nogo-B Silencing Expedites the Senescence of Platelet-Derived Growth Factor-BB-Induced Human Hepatic Stellate Cells Via Autophagy.

ABSTRACT

Liver fibrosis is a severe liver pathology in response to chronic or iterative liver injury. Senescence has emerged as a protective mechanism against liver fibrosis. Nogo-B has been well established as a significant contributor to liver fibrosis. Nonetheless, researches regarding the role of Nogo-B in cell senescence during liver fibrosis are few. In platelet-derived growth factor-BB (PDGF-BB)-treated human hepatic stellate cell line LX-2, cell proliferation was assayed by CCK-8 method. Western blotting estimated the expression of Nogo-B and fibrosis markers. After Nogo-B was silenced in LX-2 cells pretreated by an autophagy activator Rapamycin and PDGF-BB, CCK-8 method was used to assess cell proliferation. Fibrosis was measured by western blotting and immunofluorescence. Cell cycle was subjected to flow cytometry analysis and cell senescence was evaluated by SA-ß-gal staining. Immunofluorescence staining assessed autophagy. Nogo-B was elevated in PDGF-BB-exposed LX-2 cells. Nogo-B silencing suppressed the proliferation, fibrosis, and autophagy while induced cell cycle arrest and senescence of LX-2 cells. Additionally, pretreatment with Rapamycin partially restored the effects of Nogo-B knockdown on the autophagy, proliferation, fibrosis, cell cycle, and senescence of LX-2 cells upon exposure to PDGF-BB. Collectively, inactivation of autophagy mediated by Nogo-B deficiency might elicit protective activities against the development of liver fibrosis.