PKB/Akt signaling in heart development and disease.

In mammals, there are three Akt/PKB (protein kinase B) isoforms termed Akt1/PKBalpha, Akt2/PKBbeta, and Akt3/PKBgamma (hereafter referred to as Akt) that are encoded by three distinct genes localized on different chromosomes. Although the three Akt proteins share high homology and display similar domain structures, mouse genetic studies have demonstrated that they play over-lapping but also differential roles in development and physiology. In this review, we summarize recent advances in understanding the roles of Akt signaling in heart development and disease, together with discussion on Akt signaling connection to key signaling pathways in early cardiac specification. The pioneering work on Akt's function in cardiomyocytes performed by Kenneth Walsh's group, was first reported in the new millennium and thus, it is now the right time to look back at some of the discoveries of Akt's role in cardiac biology over the past decade.