Adipocytes from SERCA2 knockout mice exhibit a dysregulation in the secretion of adiponectin and resistin

Abstract: Obesity leading to Type-2-diabetes is a major health issue all over the world. Obesity characterized by expansion of adipose tissue, in particular white adipose tissue (WAT) which controls the metabolic physiology in the body by secreting proteins like adiponectin and resistin. Adiponectin has a protective role against diabetes development whereas resistin causes insulin resistance. Protein folding, maturation and translocation is performed by the Endoplasmic reticulum using calcium ions. The calcium homeostasis is maintained by calcium pumps and channels, chief of this is sarco-/endoplasmic reticulum (SR/ER) Ca2+ ATPase pump (SERCA) which restores calcium back to the ER. To study the effect of SERCA2 on adiponectin and resistin secretion in different adipose tissue depots using an adipocyte specific tamoxifen-inducible SERCA2 Knock-out mice, short term secretion experiments were performed. Chemical inhibition of SERCA2 and ER stress was performed in in-vitro experiments using adipocyte like 3T3-L1 cell line. The experiments revealed that SERCA2 dysfunction led to decrease in adiponectin and resistin secretion in normal and stimulant conditions in both male and female mice. In-vitro experiments revealed that ER stress led to misfolded protein accumulation affecting exocytotic events of adiponectin containing vesicles. Therapeutic agents can be formulated to tackle the SERCA2 dysfunction and to maintain calcium homeostasis by identifying these key mechanisms for diabetes and related metabolic disorders.