The adipocyte-enriched secretory protein tetranectin exacerbates type 2 diabetes by inhibiting insulin secretion from ß cells.

Pancreatic ß cell failure is a hallmark of diabetes. However, the causes of ß cell failure remain incomplete. Here, we report the identification of tetranectin (TN), an adipose tissue-enriched secretory molecule, as a negative regulator of insulin secretion in ß cells in diabetes. TN expression is stimulated by high glucose in adipocytes via the p38 MAPK/TXNIP/thioredoxin/OCT4 signaling pathway, and elevated serum TN levels are associated with diabetes. TN treatment greatly exacerbates hyperglycemia in mice and suppresses glucose-stimulated insulin secretion in islets. Conversely, knockout of TN or neutralization of TN function notably improves insulin secretion and glucose tolerance in high-fat diet-fed mice. Mechanistically, TN binds with high selectivity to ß cells and inhibits insulin secretion by blocking L-type Ca2+ channels. Our study uncovers an adipocyte-ß cell cross-talk that contributes to ß cell dysfunction in diabetes and suggests that neutralization of TN levels may provide a new treatment strategy for type 2 diabetes.

Mitochondrial stress-activated cGAS-STING pathway inhibits thermogenic program and contributes to overnutrition-induced obesity in mice.

Obesity is a global epidemic that is caused by excessive energy intake or inefficient energy expenditure. Brown or beige fat dissipates energy as heat through non-shivering thermogenesis by their high density of mitochondria. However, how the mitochondrial stress-induced signal is coupled to the cellular thermogenic program remains elusive. Here, we show that mitochondrial DNA escape-induced activation of the cGAS-STING pathway negatively regulates thermogenesis in fat-specific DsbA-L knockout mice, a model of adipose tissue mitochondrial stress. Conversely, fat-specific overexpression of DsbA-L or knockout of STING protects mice against high-fat diet-induced obesity. Mechanistically, activation of the cGAS-STING pathway in adipocytes activated phosphodiesterase PDE3B/PDE4, leading to decreased cAMP levels and PKA signaling, thus reduced thermogenesis. Our study demonstrates that mitochondrial stress-activated cGAS-STING pathway functions as a sentinel signal that suppresses thermogenesis in adipose tissue. Targeting adipose cGAS-STING pathway may thus be a potential therapeutic strategy to counteract overnutrition-induced obesity and its associated metabolic diseases.