Thematic Review Series: Lipids and Lipid Metabolism in the Eye Lipid second messengers and related enzymes in vertebrate rod outer segments

Rod outer segments (ROSs) are specialized light- sensitive organelles in vertebrate photoreceptor cells. Lip- ids in ROS are of considerable importance, not only in providing an adequate environment for effi cient phototrans- duction, but also in originating the second messengers in- volved in signal transduction. ROSs have the ability to adapt the sensitivity and speed of their responses to ever-changing conditions of ambient illumination. A major contributor to this adaptation is the light-driven translocation of key signal- ing proteins into and out of ROS. The present review shows how generation of the second lipid messengers from phos- phatidylcholine, phosphatidic acid, and diacylglycerol is modulated by the different illumination states in the verte- brate retina. Findings suggest that the light-induced translocation of phototransduction proteins infl uences the enzymatic activities of phospholipase D, lipid phosphate phosphatase, diacylglyceride lipase, and diacylglyceride kinase, all of which are responsible for the generation of the second messenger molecules. —Giusto, N. M., S. J. Pasquare, G. A. Salvador, and M. G. Ilincheta de Boschero. Lipid sec- ond messengers and related enzymes in vertebrate rod outer segments. J. Lipid Res . 2010. 51: 685-700.