IN VIVO ROLE OF CAVEOLIN-1 IN KNOCKOUT AND TRANSGENIC MOUSE RETINA

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The goal of this project is to examine the in vivo function of caveolin-1 (Cav-1), a protein that localizes to specialized lipid raft domains in cell membranes of photoreceptors. Cav-1 is an important regulator of signal transduction and membrane trafficking in cells. However, its role in retinal cell function is unknown. Several important proteins involved in photoreceptor structure and function cofractionate with Cav-1 in biochemical preparations of lipid rafts. These include proteins that are clearly associated with retinal disease including the cGMP-phosphodiesterase, transducin, ROM-1, rhodopsin, and guanylate cyclase. Many of these proteins associate with lipid rafts in an activity- or signal-dependent manner suggesting functional relevance to such associations. The mechanisms by which these proteins localize to lipid rafts and how their activities are modulated within these domains is not well understood. Cav-1 may mediate the organization of signaling complexes within rafts and/or may organize the lipid environment of photoreceptor membranes. To address the function of Cav-1 in vivo, we have begun to study animal models that will provide insight into the function of Cav-1 in the retina: (1) Cav-1 global null mice and (2) transgenic frogs (Xenopus laevis) that express Cav-1 in rod photoreceptors. Preliminary results suggest a retinal phenotype in Cav-1 null mice. Using these in vivo systems we propose to examine the direct effect of Cav-1 expression on fundamental photoreceptor processes. In this project, the function of Cav-1 in modulating the activities of phototransduction proteins and in regulating the membrane environment of photoreceptors will be studied. The membrane composition of photoreceptors is an essential modulator of phototransduction. The multiple analytical approaches used in the proposed project including, fluorescence/confocal microscopy, biochemistry, molecular biology and electrophysiology will provide insight into the in vivo function of this important protein.