POSSIBLE INVOLVEMENT OF MICROFILAMENTS IN THE REGULATION OF SERTOLI-CELL AROMATASE-ACTIVITY

Recent observations indicate that Sertoli cell aromatase activity decr eases when cultures are performed at high density. Increasing cell den sity modifies cell shape in culture from flat cells with visible ancho rage sites and abundant intercellular spaces to cells with higher prof iles that form a uniform epithelial sheet with no intercellular spaces . Changes in cell architecture are associated with reorganization of t he cytoskeleton components. In this report, we have tested whether dis ruption of microfilaments and microtubules by cytochalasin B and colch icine, respectively, has any effect on the ability of FSH to stimulate aromatase activity. Cytochalasin B, but not colchicine, significantly enhanced aromatase activity in FSH and dbcAMP stimulated cells. The i ncrease in aromatase activity was accompanied by a striking change in cell morphology. Time course studies suggested that microfilament orga nization is involved in some metabolic event which occurs sometime bet ween 2 and 4 h after the initial steps of FSH action. The reversibilit y of the biochemical and morphological changes induced by cytochalasin B was demonstrated. The effect of cytochalasin B was observed in high but not in low-density cultures, suggesting that microfilament organi zation in high-density cultures constrains FSH stimulation of aromatas e activity. The last two observations made suggest the existence of a dynamic interplay between microfilament organization and FSH action in Sertoli cells.