Retinal fascin: Functional nature, subcellular distribution, and chromosomal localization

PURPOSE. To investigate the functional properties, subcellular localization , and chromosomal location of retinal fascin. METHODS. Recombinant retinal fascin protein was prepared by using a baculov irus-insect expression system. Actin-binding and -bundling assays were perf ormed with chick actin purified from skeletal muscle. Western blot analysis and immunohistochemistry were performed with a polyclonal antibody raised against bovine retinal fascin. A human retinal cDNA library was screened wi th an expressed sequence tag cDNA fragment. Chromosomal location was determ ined with fluorescent in situ hybridization. RESULTS. The actin-binding and actin-bundling activities of retinal fascin were demonstrated by high- and low-speed centrifugation assays. Formation o f filamentous (F)-actin bundles by retinal fascin in vitro was also morphol ogically confirmed by fluorescence microscopy and electron microscopy. Immu nohistochemical analysis revealed that retinal fascin protein was localized specifically in the outer and inner segments of the photoreceptor cells in the retina. Two splicing variants of human retinal fascin cDNA were also l ocated. One clone encoded 492 amino acids, and the other encoded 516 amino acids. The gene encoding retinal fascin was localized to human chromosome 1 7, region q24-25. CONCLUSIONS. These results suggest that retinal fascin may play a role in f ormation of unique morphologic structures of the photoreceptor cells and is a candidate gene for retinal degenerative disorders.