What mechanism protects the heart from fasting-induced atrophy?
Skeletal muscles atrophy upon systemic fasting, when blood glucose and insulin levels are low. However, the heart is relatively protected, and atrophy to a much lesser extent than skeletal muscles. We demonstrate that despite the low levels of circulating insulin, insulin-PI3K-AKT signaling is enhanced in the heart and promotes basal rates of protein synthesis. The activation of this pathway reduces degradation of myofibrillar and soluble proteins, enabling preservation of cardiac muscle mass. Consistently, chemical labeling of cellular proteins followed by mass spectrometry analysis indicated that proteasome and ribosome subunits are reduced in amounts. Maintenance of insulin-PI3K-AKT activity is critical for protecting the heart from atrophy, and the underlying mechanisms appear independent from the ligand insulin.
ZOOM Link: https://technion.zoom.us/j/94709397738