Diabetic cardiomyopathy, an increasingly global epidemic and a major cause of heart failure with preserved ejection fraction (HFpEF), is associated with hyperglycemia, insulin resistance, and intracardiomyocyte calcium mishandling. Here we identify that, in db/db mice with type 2 diabetes–induced HFpEF, abnormal remodeling of cardiomyocyte transverse-tubule microdomains occurs with downregulation of the membrane scaffolding protein cardiac bridging integrator 1 (cBIN1). Transduction of cBIN1 by AAV9 gene therapy can restore transverse-tubule microdomains to normalize intracellular distribution of calcium-handling proteins and, surprisingly, glucose transporter 4 (GLUT4). Cardiac proteomics revealed that AAV9-cBIN1 normalized components of calcium handling and GLUT4 translocation machineries. Functional studies further identified that AAV9-cBIN1 normalized insulin-dependent glucose uptake in diabetic cardiomyocytes. Phenotypically, AAV9-cBIN1 rescued cardiac lusitropy, improved exercise intolerance, and ameliorated hyperglycemia in diabetic mice. Restoration of transverse-tubule microdomains can improve cardiac function in the setting of diabetic cardiomyopathy and can also improve systemic glycemic control.
Jing Li, Bradley Richmond, Ahmad A. Cluntun, Ryan Bia, Maureen A. Walsh, Kikuyo Shaw, J. David Symons, Sarah Franklin, Jared Rutter, Katsuhiko Funai, Robin M. Shaw, TingTing Hong