Male Reproductive Tract

Gene Expression Profiling and Its Relevance to the Blood-Epididymal Barrier in the Human Epididymis

Abstract
The luminal environment along the epididymal duct is important for spermatozoal maturation. This environment is unique and created by the bloodepididymal barrier formed by tight and adhering junctions. In the human epididymis, little information exists on proteins comprising these junctions. Our objectives were to assess gene expression profiles in the different segments of the human epididymis and to identify specific proteins comprising the blood-epididymal barrier. Using microarrays, we identified 2980 genes that were differentially expressed by at least two-fold between the various segments. Of the many genes involved in diverse functions, some encoded adhesion proteins (cadherins and catenins) and tight junctional proteins (claudins (CLDN) and others). PCR analyses confirmed the microarray data. Immunolocalization of CLDN1, 3, 4, 8, and 10 revealed that the localization of CLDN proteins differed along the epididymis. In all three segments, CLDN1, 3 and 4 were localized to tight junctions, along the lateral margins of adjacent principal cells and at the interface between basal and principal cells. CLDN8 was localized to tight junctions in all three segments, in addition to being localized in the caput along the lateral margins of principal cells, and in the corpus, at the interface between principal and basal cells. CLDN10, tight junction protein 1 and occludin were exclusively localized to tight junctions in all three epididymal segments. These data indicate that the epididymis displays a complex pattern of gene expression including genes that are implicated in the formation of the bloodepididymal barrier, thus suggesting a complex regulation of this barrier.

Key words: Male Reproductive Tract • Epididymis • Gene regulation

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