Gelatinase A secretion and its control in peritubular and Sertoli cell cultures: effects of hormones, second messengers and inducers of cytokine production

Abstract

Extracellular matrix components as well as enzymes and enzyme-inhibitors controlling the turn-over of these components play an important role in the local control of testicular function. Zymographic analysis was used to study the secretion and the control of the secretion of gelatinase A (MMP-2) and B (MMP-9) by primary cultures of rat Sertoli cells and by subcultures of peritubular cells. Data on gelatinase A were complemented by measurement of the corresponding mRNA by Northern blot analysis. The agonists investigated included hormones (FSH, testosterone), second messengers (dbcAMP, phorbolester and a Ca 2+-ionophore), interleukin-1β (IL-1β) and inducers of cytokine production (Concanavalin A: ConA; lipopolysaccharide: LPS; double stranded RNA: PIC). It is demonstrated that Sertoli cells originally secrete both gelatinase A and B. When maintained in serum-free medium, however, they rapidly lose the ability to secrete gelatinase B. After 3 days of culture gelatinase A remains the only measurable gelatinase in both Sertoli and peritubular cell cultures. The production in peritubular cells, however, exceeds that in Sertoli cells some 25-fold. This was confirmed by a 30-fold difference in the level of steady-state gelatinase A mRNA levels. Gelatinase A secretion and gelatinase A mRNA were stimulated by ovine FSH in Sertoli cells and by dbcAMP and ConA in both Sertoli and peritubular cells. IL-1β displayed measurable but limited stimulatory effects in both cell types. Interestingly, in peritubular cells but not in Sertoli cells, ConA stimulated the production of a lower MW species probably representing an activated form of gelatinase A. It is concluded that both the amounts of gelatinase A produced, the levels of the corresponding mRNA and the regulation differ in cultured peritubular cells and Sertoli cells. The lectin concanavalin A is a novel and potent inducer of gelatinase A. It resembles cytochalasin D in selectively inducing an activated form of gelatinase A in peritubular cells. The mechanism responsible for this selective effect warrants further investigation.