Metabolic reprogramming of murine cardiomyocytes during autophagy requires the extracellular nutrient sensor, decorin

The extracellular matrix is a master regulator of tissue homeostasis in health and disease. Here we examined how the small, leucine-rich extracellular matrix proteoglycan, decorin, regulates cardiomyocyte metabolism during fasting in vivo. First, we validated in Dcn-/- mice that decorin plays an essential role in autophagy induced by fasting. High-throughput metabolomics analyses of cardiac tissue in Dcn-/- mice subjected to fasting revealed striking differences in the hexosamine biosynthetic pathway resulting in aberrant cardiac O--Nacetylglycosylation as compared to wild-type mice. Functionally, Dcn-/- mice maintained cardiac function at a level comparable to non-fasted animals whereas fasted wild-type mice showed reduced ejection fraction. Collectively, our results suggest that reduced sensing of nutrient deprivation in the absence of decorin preempts functional adjustments of cardiac output associated with metabolic reprogramming.