Role Of Autophagy On Rat Liver Regeneration

The liver is an important organ in mammals involved in metabolism and detoxification, and has a vigorous ability of regeneration. Induced by liver injury, the remnant hepatocytes proliferate rapidly to compensate the lose or impaired liver tissue and restore the biological function of the liver. The excessively proliferous cells will be removed by apoptosis, and the unable update and aging cells will be digested by autophagy. Autophagy is an catabolic pathway with protein degradation and cell organelles turnover to maintain the intracellular homeostasis. Autophagy is an evolutionarily conserved response that can be activated in response to stress, involves in regulation of cell survival. However, a presistent and massive autophagy can damage the cells, even lead to cell death. Studies have indicated that autophagy plays an important regulating role in the liver, and participate in the adjustment of the liver function or disease, but the role of autophagy remains unclear in rat’s liver regeneration.To survey the expression level of autophagy in rats’ liver regeneration, Western blotting,immunofluorescence(IF) analysis were used to investigate expression of the autophagy-related proteins,and autolysosomes were investigated by MDC staining in the regenerating liver after two-thirds of hepatectomy. The results indicated that the levels of LC3-II and Atg5 were elevated in 24-120 h after two-thirds of hepatectomy. The levels of SQSTM1/p62 was increased in 2-12 h, then decreased in 24-168 h.LC3, an autophagy-specific protein were detected by IF, the signals were weak and dispersed in normal liver. However, the levels of LC3 proteins became elevated, speci?c punctate distribution of endogenous LC3-II increased, and MDC fluorescence accumulation spots were also increased after two-thirds of hepatectomy. It’s indicated that two-thirds of hepatectomy induced a high level of autophagy with a time-effect manner. To explore the effect of autophagy on liver regeneration, the rats intraperitoneal injection with hydroxychloroquine(CQ, an autophagy inhibitor) for a week co-treatment with two-thirds of hepatectomy. We used immunofluorescence analysis to investigate the expression of LC3, MDC staining to exhibit autolysosomes, liver coefficient and HE staining to investigate growth and structure of the remnent liver, Hoechst 33258 staining to survey the apoptosis. The results showed that the LC3 puncta were observed in the liver afte pretreatment with CQ. Furthermore, co-treatment with two-thirds of hepatectomy increased autophagy. The spots of MDC fluorescence were also discovered in the liver afte pretreatmentwith CQ, and the increase in levels of MDC following two-thirds of hepatectomy treatment. Compared with the coefficient of regenerating liver, the coefficient of regenerating liver following CQ treatment was no significant difference at 2-36 h, but observably decreased at 72-120h(P<0.01). Moreover, the liver lobule was disordered, hepatic cords was disappeared and the nucleus were fragmentation after treatment of CQ co-treatment with two-thirds of hepatectomy. In conclusion, Autophagy plays a importantly protective role in rat liver regeneration, and may promote the liver regeneration by inhibiting apoptosis of the liver cells.