The Oxidative State of Cysteine Thiol 144 Regulates the SIRT6 Glucose Homeostat

Control of glucose homeostasis plays a critical role in health and lifespan and its dysregulation contributes to inflammation, cancer and aging. NAD + dependent Sirtuin 6 (SIRT6) is a glucose homeostasis regulator in animals and humans and its regulation at the molecular level is unknown. Here, we report that a cysteine thiol redox sensor contributes to the role of SIRT6 in controlling glucose homeostasis. Sulfenylation of SIRT6 occurs in THP1 cells and primary human promonocytes during inflammation and in splenocytes from mice with sepsis. Inhibiting xanthine oxidase, a major reactive oxygen species (ROS) contributor during acute inflammation, reduces sulfenylation of SIRT6, glucose transporter Glut1 expression, glucose uptake, and glycolysis. A block in glycolysis associated with monocyte deactivation by endotoxin, a process contributing to immunometabolic paralysis in human and mouse sepsis monocytes, can be reversed by increasing H2O2 and sulfenylating SIRT6. Mutation analysis of SIRT6 Cys144, which lies in its phylogenetically conserved zinc-associated Cys-X-X-Cys motif near the catalytic domain of the protein, decreases SIRT6 deacetylase activity and promotes glycolysis. These results suggest that direct and reversible cysteine thiol 144 may play a functional role in SIRT6-dependent control over monocyte glycolysis, an important determinant of effector innate immune responses.