SIRT1 and obesity due to melanocortin 4 receptor deficiency: In addition, cAMP has been established to activate pathways involving AMP-activated protein kinase (AMPK), sirtuin 1 (SIRT1), an evolutionary conserved NAD+-dependent deacetylase, and PPARγ coactivator-1α (PGC1α)6, 7, 8, 9, 10, which in turn acts to protect mice from diet-induced obesity and insulin resistance6, 11, 12.