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Co-expression and interaction of cubilin and megalin in the adult male rat reproductive system

By Oliver Van Praet

Abstract

Cubilin is a peripheral membrane protein that co-operates with the endocytic receptor megalin to mediate the endocytosis of ligands in various polarized epithelia. Megalin is expressed in the male reproductive tract where is has been implicated in the process of sperm membrane remodeling. A potential role for cubilin in the male reproductive tract has not been explored. Using RT-PCR, we found that cubilin and megalin mRNAs are expressed in the efferent ducts, corpus and cauda epididymides, and proximal and distal vas deferens. Immunohistological analysis revealed that cubilin was expressed in non-ciliated cells of the efferent ducts, principal cells of the corpus and cauda epididymides and vas deferens. Electron microscopic immunogold labeling showed cubilin in endocytic pits, endocytic vesicles and endosomes of these cells. The expression profile of cubilin in the male reproductive tract was coincident with that of megalin except in principal cells of the caput epididymidis. Double immunogold labeling showed that cubilin and megalin co-localized with one another within the endocytic apparatus and recycling vesicles of efferent duct cells. Neither protein was found in lysosomes. Injection of RAP, an antagonist of megalin interaction with cubilin, reduced the level of intracellular cubilin in cells of the efferent ducts and vas deferens. In conclusion, cubilin and megalin are co-expressed in cells of the epididymis and vas deferens and the endocytosis of cubilin in these tissues is dependent on megalin. Together, these findings highlight the potential for a joint endocytic role for cubilin and megalin in the male reproductive tract

Topics: Biology, Cell.
Publisher: McGill University
Year: 2002
DOI identifier: 10.1002/mrd.10245
OAI identifier: oai:digitool.library.mcgill.ca:29485
Provided by: eScholarship@McGill
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