PICK1-Deficient Mice Maintain Their Glucose Tolerance During Diet-Induced Obesity

CONTEXT: Metabolic disorders such as obesity represent a major health challenge. Obesity alone has reached epidemic proportions, with at least 2.8 million people worldwide dying annually from diseases caused by overweight or obesity. The brain–metabolic axis is central to maintain homeostasis under metabolic stress via an intricate signaling network of hormones. Protein interacting with C kinase 1 (PICK1) is important for the biogenesis of various secretory vesicles, and we have previously shown that PICK1-deficient mice have impaired secretion of insulin and growth hormone. OBJECTIVE: The aim was to investigate how global PICK1-deficient mice respond to high-fat diet (HFD) and assess its role in insulin secretion in diet-induced obesity. METHODS: We characterized the metabolic phenotype through assessment of body weight, composition, glucose tolerance, islet morphology insulin secretion in vivo, and glucose-stimulated insulin secretion ex vivo. RESULTS: PICK1-deficient mice displayed similar weight gain and body composition as wild-type (WT) mice following HFD. While HFD impaired glucose tolerance of WT mice, PICK1-deficient mice were resistant to further deterioration of their glucose tolerance compared with already glucose-impaired chow-fed PICK1-deficient mice. Surprisingly, mice with β-cell–specific knockdown of PICK1 showed impaired glucose tolerance both on chow and HFD similar to WT mice. CONCLUSION: Our findings support the importance of PICK1 in overall hormone regulation. However, importantly, this effect is independent of the PICK1 expression in the β-cell, whereby global PICK1-deficient mice resist further deterioration of their glucose tolerance following diet-induced obesity.