Blocking AMPK β1 myristoylation enhances AMPK activity and protects mice from high-fat diet-induced obesity and hepatic steatosis
Katyayanee Neopane, Natalie Kozlov, Florentina Negoita, Lisa Murray‐Segal, Robert Brink, Ashfaqul Hoque, Ashley J. Ovens, Gavin Tjin, Luke M. McAloon, Dingyi Yu, Naomi X.Y. Ling, Matthew J. Sanders, Jonathan S. Oakhill, John W. Scott, Gregory R. Steinberg, Kim Loh, Bruce E. Kemp, Kei Sakamoto, Sandra Galić
Abstract
AMP-activated protein kinase (AMPK) is a master regulator of cellular energy homeostasis and a therapeutic target for metabolic diseases. Co/post-translational N-myristoylation of glycine-2 (Gly2) of the AMPK β subunit has been suggested to regulate the distribution of the kinase between the cytosol and membranes through a "myristoyl switch" mechanism. However, the relevance of AMPK myristoylation for metabolic signaling in cells and in vivo is unclear. Here, we generated knockin mice with a Gly2-to-alanine point mutation of AMPKβ1 (β1-G2A). We demonstrate that non-myristoylated AMPKβ1 has reduced stability but is associated with increased kinase activity and phosphorylation of the Thr172 activation site in the AMPK α subunit. Using proximity ligation assays, we show that loss of β1 myristoylation impedes colocalization of the phosphatase PPM1A/B with AMPK in cells. Mice carrying the β1-G2A mutation have improved metabolic health with reduced adiposity, hepatic lipid accumulation, and insulin resistance under conditions of high-fat diet-induced obesity.