Ultrastructural evidence that basally located cells in the epididymal epithelium constitute distinct cell types with unique gene regulators.

Abstract : The epididymal epithelium contains several distinct basally located cells, including basal cells, CD11c+ dendritic cells and monocytic/F4/80‐positive macrophages. All of these cells appear inconspicuous by LM in contrast to the dominant principal cells spanning the length of the epithelium. However, evidence based on EM observations that would substantiate distinguishing features of diverse populations of basally located cells is lacking. Basal cells, initially highlighted by the glutathione S transferase marker GST‐Yf, were also characterized by expression of Keratin 5 and claudin 1 (Cldn1). Basal cells were small elongated or spherical cells with corresponding nuclear shapes, contacting the basement membrane (BM) and revealing sparse ER cisternae, few small dense lysosomes, but an abundance of polysomes, all features suggestive of undifferentiated cells. Gene profiling classified them as potential stem cells as evidenced by expression of the p63 transcription factor, which was not found in principal cells. p63 regulated several classes of genes, including Cldn1. ChIP studies indicated that p63 bound to two response elements located on the promoter region of the Cldn1 gene, which may serve to regulate high expression levels of this gene in basal cells and account for their unique features. In addition to classic basal cells, by EM, a second population of basally located cells demonstrated a strikingly different morphology. Such cells contacting the BM occupied a larger space of the epithelial base at the expense of adjacent principal cells. Distinguishing features were the nuclei with highly irregular shapes often lobulated with elongated lobes folding upon themselves and demonstrating thin connections. Deep furrows and clefts and large clumps of heterochromatin were prominent but not indicative of degeneration. The defining feature of the cytoplasm was the presence of one or many huge spherical and often irregularly shaped lysosomal elements containing lipidic inclusions. This suggested an active role in endocytosis of substances from the adjacent dilated intercellular spaces, which were at times filled with membranous profiles.They may be correspond to dendritic cells. The fact that each basally located cell type contacted the BM served to distinguish them from blood‐borne monocytic/F4/80‐positive macrophages. The latter were larger than the classic basal cells, but while demonstrating large lysosomal elements, they did not have irregular nuclear profiles nor contact the BM. In conclusion, our study defines several populations of basally located cells, including the classic basal cell, monocytic/F4/80‐positive macrophages and putative dendritic cells, each with their own distinctive features. (Supported by CIHR).
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Poster
Annual Meeting of the American-Society-for-Cell-Biology (ASCB), Dec 2016, San Francisco, United States. Molecular Biology of the Cell, 27 (25), pp.P1592, 〈10.1091/mbc.E16-10-0736 〉
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Soumis le : jeudi 29 juin 2017 - 18:34:22
Dernière modification le : lundi 5 février 2018 - 15:22:10

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L. Hermo, R. Oliveira, J. Dufresne, M. Gregory, Daniel G Cyr. Ultrastructural evidence that basally located cells in the epididymal epithelium constitute distinct cell types with unique gene regulators.. Annual Meeting of the American-Society-for-Cell-Biology (ASCB), Dec 2016, San Francisco, United States. Molecular Biology of the Cell, 27 (25), pp.P1592, 〈10.1091/mbc.E16-10-0736 〉. 〈pasteur-01551029〉

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