SIRT5-mediated GLS and GDH desuccinylation attenuates autophagy in MAC-T cells induced by ammonia

Our previous research revealed that NH3 regulated autophagy dependent on SIRT5 in MAC-T cells. Interestingly, SIRT5 reduced the content of NH3 and glutamate by inhibiting GLS activity, ADP/ATP value also declined. In this study, SIRT5 interacted with endogenous GLS and GDH, and had no effect on endogenous GLS and GDH expression. SIRT5 declined significantly the succinylation levels of GLS and GDH, and further reduced the enzymatic activity of GLS and GDH. SIRT5 declined the glutamine metabolism, which attenuated ammonia release in MAC-T cells, accompanying with cellular autophagy decline, reducing the formation of autophagosome. Deletion of SIRT5 increased the content of NH3 and glutamate, as well as promotes autophagy, which could be alleviated by SIRT5 overexpression. SIRT5 KO was associated with increased succinylation and activity of GLS and GDH, as well as autophagy response in MAC-T cells. Furthermore, SIRT5 promoted the maintenance of mitochondria homeostasis. Mechanistically, SIRT5 modulated the succinylation levels and enzymatic activities of GLS and GDH in mitochondria and promoted the maintenance of mitochondria homeostasis, further attenuating ammonia-stimulated autophagy in MAC-T cells.