Signaling mechanisms and physiological functions of G-protein Gα13 in blood vessel formation, bone homeostasis, and cancer.

Heterotrimeric G-proteins are cellular signal transducers. They mainly relay signals from G-protein-coupled receptors (GPCRs). GPCRs function as guanine nucleotide-exchange factors to active these G-proteins. Based on the sequence and functional similarities, these G-proteins are grouped into four subfamilies: Gs , Gi , Gq , and G12/13 . The G12/13 subfamily consists of two members: G12 and G13 . G12/13 -mediated signaling pathways play pivotal roles in a variety of physiological processes, while aberrant regulation of this pathway has been identified in various human diseases. Here we summarize the signaling mechanisms and physiological functions of Gα13 in blood vessel formation and bone homeostasis. We further discuss the expanding roles of Gα13 in cancers, serving as oncogenes as well as tumor suppressors.