Alteration of cell membrane proteoglycans impairs FSH receptor/Gs coupling and ERK activation through PP2A-dependent mechanisms in immature rat Sertoli cells.

BACKGROUND

During the pre-pubertal life, the cessation of Sertoli cell proliferation and the onset of differentiation are associated with a shift in the FSH-mediated signaling leading to inhibition of the ERK-mitogenic pathway and to a concomitant sensitization of cAMP/PKA pathway.

METHODS

To highlight the role of cell proteoglycans (PGs) in the shift of FSH signaling, both FSH-induced cAMP production and ERK1/2 inactivation were studied in untreated and sodium chlorate PG-depleted cultured Sertoli cells from 20day-old rats.

RESULTS

Depletion of cell membrane PGs by sodium chlorate reduced FSH-, but not cholera toxin-stimulated cAMP production as well as basal ERK phosphorylation through an okadaic acid (OA)-sensitive mechanism. Involvement of PP2A was further substantiated by a marked decrease in membrane- associated PP2A activity under SC conditions and by the OA-induced restoration of PKA-dependent ERK inactivation in SC-treated cells.

CONCLUSIONS

In 20-day-old rat Sertoli cells, transmembrane cell PGs, through tethering/activation of PP2A activity exerts regulatory control on both FSH receptor/Gs coupling and ERK phosphorylation.

GENERAL SIGNIFICANCE

Besides their antiproliferative roles, cell PGs such as syndecan-1, could be involved in the increase in cAMP response to FSH occurring in Sertoli cells at the time of transition between proliferative and differentiated states.