Cloning, Developmental Expression, and Tissue Distribution of a Retinally–Expressed Isoform of Xenopus Caveolin–1

Abstract

Abstract: : Purpose: Caveolin–1 (Cav–1) is an important lipid raft–associated protein expressed in several retinal cell–types that may regulate photoreceptor function. In the process of generating cDNA clones for expression studies, we isolated a retinally–expressed cDNA encoding a novel isoform of Xenopus laevis Cav–1. Our cDNA was identical to a clone of unknown function deposited in GenBank (BC070672). The predicted translation of our sequence is more similar to human Cav–1 than the previously published Xenopus Cav–1 sequence (AF455402). The purpose of this study was to characterize the tissue distribution and developmental expression of the retinally–expressed Cav–1 cDNA. Methods: To determine tissue specificity and developmental expression of our Cav–1 clone, we isolated various adult tissues and whole embryos at various embryonic stages. We used RT–PCR to measure Cav–1 mRNA expression. Results: The retinally–expressed isoform of Xenopus Cav–1 is not retina–specific as message was detectable by PCR screening in a variety of adult frog tissues including lung, heart, skeletal muscle and brain. Furthermore, temporal expression of our isoform of Xenopus Cav–1 in whole frog embryos during development is qualitatively similar to that observed for the previously published isoform. The translated product of this isoform is 79% identical to human caveolin–1 and contains all previously–identified functional domains including the caveolin scaffolding domain. Conclusions: We are currently using this isoform of retinally–expressed Cav–1 to generate fusion proteins in Xenopus photoreceptors and in Escherichia coli for functional and biochemical analyses, respectively. Given the similarity to human caveolin–1, experiments using this isoform will provide essential information about the function of this important lipid raft–associated protein. Support: NIH EY11504, EY12190, EY13674, EY00871, EY04149, and RR17703; Foundation Fighting Blindness C–OK05–0799–0084; and Research to Prevent Blindness, Inc.

Keywords: photoreceptors • gene/expression • cell membrane/membrane specializations