The BAI subfamily of adhesion GPCRs: synaptic regulation and beyond

• BAI1, BAI2, and BAI3 are receptors that can regulate neuronal function and synaptogenesis.
• BAI1 has been shown to signal via both G protein and independent pathways.
• Genetic studies link BAI1–3 to a variety of psychiatric and neurological disorders.
• The BAI subtypes may prove to be beneficial therapeutic targets for these disorders.

The brain-specific angiogenesis inhibitors 1–3 (BAI1–3) comprise a subfamily of adhesion G-protein-coupled receptors (GPCRs). These receptors are highly expressed in the brain and were first studied for their ability to inhibit angiogenesis and tumor formation. Subsequently, BAI1 was found to play roles in apoptotic cell phagocytosis and myoblast fusion. Until recently, however, little was known about the physiological importance of the BAI subfamily in the context of normal brain function. Recent work has provided evidence for key roles of BAI1–3 in the regulation of synaptogenesis and dendritic spine formation. In this review, we summarize the current understanding of the BAI subfamily with regard to downstream signaling pathways, physiological actions, and potential importance as novel drug targets in the treatment of psychiatric and neurological diseases.