IHEM   20887
INSTITUTO DE HISTOLOGIA Y EMBRIOLOGIA DE MENDOZA DR. MARIO H. BURGOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Heparin-α-glucosaminide N-acetyltransferase gene inactivation affects the lysosomal integrity of epididymal epithelial cells and the morphology of spermatozoa in adult mice
Autor/es:
CARVELLI L; MORALES CR; HERMO L; PSHEZHETSKY AV
Lugar:
San Francisco, California
Reunión:
Congreso; 2016 ASCB Annual Meeting; 2016
Institución organizadora:
American Society for Cell Biology
Resumen:
The epithelial cells lining the epididymis provide a unique environment for sperm maturation controlled in part by the secretion of proteins into the lumen and endocytosis of substances from the lumen and basal compartment. Heparan sulfate is a component of the extracellular matrix, basement membranes and the apical cell surface, and is abundant in the testis and epididymis. After endocytosis, heparan sulfate is degraded in a stepwise fashion by the action of several enzymes but mainly heparin-alpha-glucosaminide N-acetyltransferase (HGSNAT). Although HGSNAT is not a hydrolase, it catalyzes the transmembrane acetylation of terminal glucosamine residues of heparan sulfate prior to its hydrolysis by α-N-acetylglucosaminidase. In mice, inactivation of the HgsNat gene shows defects in sperm motility and reduced liter sizes. The objective of this investigation was to determine the morphological effects of HgsNat inactivation on the epithelial cells of the testis and epididymis and epididymal spermatozoa of adult mice by light (LM) and electron microscopy (EM). To this end, the testes and epididymides of both wild type and Hgsnat -/- adult mice at different ages, ranging from 7-14 months were fixed and processed for EM analysis, or immersed in Bouin?s fixative for LM immunocytochemical studies. In Hgsnat deficient mice, seminiferous tubules revealed highly vacuolated areas, while others demonstrated a major depletion of the germ cell population. Approximately 20% of the tubules were decreased in size. In wild type mice, the epididymal epithelial principal and clear cells contained small to medium sized dense spherical lysosomes. This contrasted the HgsNat deficient mice, where numerous large to gigantic membranous vacuoles of different shapes appeared both supranuclearly and infranuclearly; they were confirmed to be lysosomes with anti-cathepsin D and prosaposin antibodies. Such large vacuoles were also prominent in basal, halo and myoid cells, all of which were also greatly increased in size. Occasional huge cells occupied the mid/basal region of the epithelium which based on morphological criteria were identified as detached principal and clear cells. In the epididymal lumen, numerous spermatozoa presented abnormal tails and head shapes, which were also prominent in differentiating spermatids of the testis. All of the above observations, although evident in all epididymal regions, were especially prominent in the corpus region. Our results reveal that upon Hgsnat inactivation, defects appear in the tails of sperm, as well as a severe alteration of epididymal epithelial cell morphology, which may affect sperm maturation.