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This Article Full Text Full Text (PDF) All Versions of this Article: 71/5/1677    most recent biolreprod.104.031666v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Castella, S. Articles by Dacheux, F. Search for Related Content PubMed PubMed Citation Articles by Castella, S. Articles by Dacheux, F. Agricola Articles by Castella, S. Articles by Dacheux, F.

Train A, an RNase A-Like Protein Without RNase Activity, Is Secreted and Reabsorbed by the Same Epididymal Cells under Testicular Control¹

Equipe "Gamète Mâle et Fertilité" UMR 6175 INRA-CNRS-Université,³ PRC, INRA, 37380 Nouzilly, France CBM CNRS UPR 4301,⁴ 45 071 Orléans cedex 2, France Unitat de Bioquimica i Biologia Molecular,⁵ Departament de Biologia, Universitat de Girona, Spain

Most of the proteins secreted in the epididymis are produced by the proximal region, and several of them are secreted in abundance. Many of these major proteins have now been identified, including a new epididymis-specific RNase A-like Train A protein, which has been recently described in several mammals. This protein is expressed and secreted exclusively in the initial part of the epididymis. RNase A activity was analyzed in the fluids from the testis and from different epididymal regions, but in no case was the Train A protein found to have RNase A activity. The protein was present only in the luminal fluid of the epididymal region that secreted it. Using an in vitro/in vivo microperfusion technique and immunogold electron microscopy labeling, we demonstrated that the epithelium that secreted it specifically reabsorbed the protein that was present in the lumen of the tubule. Thus, the presence of Train A protein in epididymal fluid was the result of a steady state between secretion and absorption. The transcription and translation of Train A mRNA were simultaneous and actively regulated by testicular factors. The function of this protein is unknown, but it does not seem to interact directly with sperm. As for other members of the RNase family (e.g., angiogenin), its biological activity might be expressed after its cellular reabsorption. This new compound might therefore participate in an unknown function in the epithelial cells of this first part of the epididymis by an autocrine pathway.

¹ This study was supported by grants from the Institut National de la Recherche Agronomique (INRA, France), and from the Région Centre (France).

² Correspondence: Françoise Dacheux, UMR INRA-CNRS 6073, 37380 Nouzilly, France. FAX: 33 02 47 42 77 43; dacheux{at}tours.inra.fr

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