CYTOKERATIN 5 EXPRESSION IN SERTOLI CELLS OF HGSNAT KNOCKOUT MICE

CARVELLI L; HERMO L; PSHEZHETSKY AV; SOSA MA; MORALES CR

Virtual-San Luis

Congreso; XXXIX Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2021

Sociedad de Biología de Cuyo

The somatic Sertoli cells of the testis are involved in secretion and endocytosis of proteins, phagocytosis of residual bodies and in the formation of the blood-testis barrier. Sertoli cells rest on a well characterized and elaborate basement membrane (BM) benefitting cell growth, differentiation, and sperm development. The BM is a thin extracellular layer composed of glycoproteins, type IV collagen and the proteoglycan heparan sulphate (HS). Degradation of HS occurs in the lysosome in a stepwise manner, involving heparin α-glucosaminide N-acetyltransferase (HGSNAT) enzyme. A deficiency in HGSNAT causes a severe lysosomal storage disorder, mucopolysaccharidosis IIIC (MPS IIIC, also known as Sanfilippo syndrome), leading to a significant accumulation of HS within lysosomes and major disruption of various tissues and organs. Integrin molecules in the plasma membrane of the epithelial cell provide a strong attachment connecting the BM with the intracellular cytokeratin network. Binding of integrin to components of BM activates the cytoplasmic signaling enzyme FAK (Focal Adhesion Kinase). It has previously been shown that loss of FAK in mouse embryonic fibroblast cells led to an epithelial phenotype where cells expressed E-cadherin, Cytokeratin-18, and Desmoplakin. As cytokeratins 8 and 18 are expressed in the Sertoli cells of testes from patients with dystopia, atrophia and/or oligospermia, it is suggested that detection of cytokeratins in these cells could be a sensitive marker for damaged testes. Given that HS turnover is affected in MPS IIIC, we tested if the expression and distribution of cytokeratin 5 (CK5) in Sertoli cells are modified in a HGSNAT deficient mice model (HGSNAT KO). Immunohistochemical (IHC) staining and immunoblots were performed comparing HGSNAT KO and wild type testes of 7 (n=3) and 11-month-old mice (n=3). LM-IHC analysis of wild type testis confirmed expression of CK5 in Sertoli cells, with no apparent difference in staining intensity at the different ages. In comparison, a more intense reaction was noted in Sertoli cells of HGSNAT KO mice, with an age-dependent increased expression also noted. Immunoblot analysis showed a statistically significant increase of CK5 in KO vs. WT testes at p  0.05. This is the first characterization of a functional link between CK5 and heparan sulfate metabolism in Sertoli cells. In HGSNAT KO mice, Sertoli cells at the EM reveal an increase in size and number of lysosomes leading to a difference in the overall shape and size of these cells. Such a situation may affect the integrity of the cell to adhere to the BM which may be altered. Hence, the Sertoli cell may produce more CK5 to compensate for this condition.