The nonciliated epithelial cells of the efferent ducts are specialized in internalizing luminal fluid. They possess an extensive endocytic apparatus which provides an ideal system to study the kinetics of endocytosis. The nonciliated cells actively endocytose sulfated glycoprotein-1 (SGP-1, 70 kDa), a major secretory protein of Sertoli cells. A second form of SGP-1 (65 kDa) present in the secondary lysosomes of Sertoli and nonciliated cells of the efferent ducts is believed to be the equivalent of human prosaposin, the precursor of four small heat stable proteins (saposins A, B, C and D) required for the hydrolysis of sphingolipids by specific lysosomal hydrolases. This study was undertaken to investigate the contribution of Sertoli-derived SGP-1 as well as a putative endogenous SGP-1 within the secondary lysosomes of nonciliated cells. The hormonal control of endogenous lysosomal SGP-1, specifically the influence of testosterone withdrawal and its subsequent replacement was also examined. The results provide evidence that the nonciliated cells of the efferent ducts are involved in the clearance of testicular SGP-1 and reveal the presence of 15 kDa saposins and their 65 kDa precursor in secondary lysosomes of these cells. In addition, the production of an endogenous lysosomal SGP-1 targeted from the Golgi apparatus to the lysosomes after its glycosylation has also been demonstrated. The results further reveal that the endocytosis and lysosomal targeting of SGP-1 in nonciliated cells of the efferent ducts appear to be pituitary controlled.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.68250 |
| Date | January 1994 |
| Creators | Rosenthal, Allison Lianne |
| Contributors | Hermo, Louis (advisor), Morales, Carlos (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Anatomy and Cell Biology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001397810, proquestno: AAIMM94508, Theses scanned by UMI/ProQuest. |
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