Exchange proteins activated directly by cyclic adenosinemonophosphate-mediated signal pathway and its role in the retina

Exchange proteins activated directly by cyclic adenosinemonophosphate (Epac) is one of cyclic adenosinemonophosphate (cAMP)-regulated guanine nucleotide exchange factors. When Epac closely binds with cAMP, it can activate many downstream signal molecules, such as Rap and Ras, etc. By activating several effectors, Epac regulates a multitude of important physiological and pathological processes. Ras and Rap play important effects on the differentiation and proliferation of photoreceptors. Ras may participate in the pathogenesis and development of age-related macular degeneration (AMD) and prolifereative vitreo-retinopathy (PVR) through Ras/Raf-1/MEK/ERK cascade. Therefore, further studies about the role of Epac and its downstream signals in the retina may provide numerous directions both in research and treatment of retinal diseases. The researching progress in Epac and the functions of the downstream signaling molecules of Epac in the retina were reviewed.