Vitamin A modulation of basement membrane production by purified testicular myoid cells

Purified myoid cells, isolated from prepubertal rat testes, cultured in a c hemically defined medium for up to 1 week. do not change their metabolic ac tivities, evaluated as protein synthesis and secretion, during the culture time. We report that fibronectin, collagen IV, and laminin are synthesized and secreted by myoid cells as demonstrated by immunocytochemical and bioch emical methods. The deposition of all three proteins was spotty, with diffe rent regional localizations. The effect of vitamin A on the synthesis and t he secretion of the basement membrane components was also evaluated. Retino l supplementation induces a higher synthesis of fibronectin and laminin, wh ereas it does not change collagen TV synthesis and secretion. The secretion of the other two molecules is differentially regulated by retinol; in fact fibronectin secretion is increased, whereas laminin secretion is reduced. Similar results were obtained utilizing retinoic acid. The data we report i n this paper show, for the first time, that purified testicular myoid cells synthesize and secrete fibronectin, collagen TV, and laminin and that synt hesis and secretion of these components of the basement membrane are regula ted by retinol. These findings reveal a new effect of vitamin A in the regu lation of mammalian spermatogenesis. (C) 1999 Academic Press.