SUMO Protease SENP3 Regulates Starvation-induced Autophagy In Mouse Tissues

Aim.Autophagy is an important cellular functional activity in almost all eukaryotic cells and plays an pivotal role in the metabolism,renewal,and homeostasis of various tissue cells.The SUMOylation and de-SUMOyaltion are new ways of post-translational modification of proteins that have been recognized for nearly 10 years.However,there are few reports about dynamic sumoylation on the regulation of autophagy.In this study,we used the SUMO protease SENP3 knockout heterozygous mouse(SENP3+//)to observe autophagic structure of various kinds of cells in heart,liver,lung,kidney,stomach and colon tissues of mice induced by starvation,which may provide general knowledge about in vivo autopohgy.Meanwhile,the present study focus on testicular tissue with high expression of SENP3 to demonstrate the regulative role of desumoylation mediated by SENP3.Methods.Mice were fasted for two days.When needed,the autophagy inhibitor or si-ATG7 was pretreated.The autophagy structure of tissue cells was observed by transmission electron microscopy.The autophagy index,lipidation of LC3 was detected by immunoblotting and the formation of of LC3 spots were detected by immunocytochemical and immunofluorescence in testis.Immunofluorescence and immunoblotting techniques to detect the localization,quantity of SENP3 and amount of testis-specific protein ABP and PDLIM1.Results.Autophagic structure in different tissues was observed under electron microscopy.When fed,some autolysosome were detweted in various cells,including cardiomyocytes,cardiac interstitial cells,pulmonary ciliated cells,typeⅡalveolar cells,glomeruli mesangial cells and gastrointestinal smooth musle cells.Mitophagy-like structure appeared in colorectal epithilial cells.After 48 hours of starvation,autophagy increased in cardiomyocytes and alveolar type Ⅱ epithelial cells,and lipophagy appeared in hepatocytes,while autophagy in gastric smooth muscle cells was slightly reduced.Compared with SENP3+/+,SENP3+/-increased autophagy in liver tissue.At the same time,starvation also induces autophagy in the testes,mainly in Sertoli cells.SENP3 is localized to the nuclear and cytoplasm of Sertoli,which is dominated by nuclei,and autophagy increases in SENP3+/-mice,but has no effect on the structure of the seminiferous tubules and the amount of specific protein.Conclusion.Electron microscopy has the advantage of distinguishing cell type and autophagic type in detecting autophagy in vivo.The levels of autophagy in different cells in the tissues are different,and the sensitivity to autophagy induction in response to starvation is different.SENP3 can inhibit autophagy in testicular Sertoli cells and play a role in controlling the level of autophagy induced by nutrient deficiency.The first part of the study explored the regulation of SENP3 on autophagy in mouse testis tissue.The second part of the study was to detect autophagy in the heart,liver,lung,kidney,stomach and colon tissue of mice induced by starvation,and to primarily explore the regulation of SENP3.