Sex-specific effects of 17 beta-estradiol and dihydrotestosterone (DHT) on growth plate chondrocytes are dependent on both ER alpha and ER beta and require palmitoylation to translocate the receptors to the plasma membrane

Rat costochondral cartilage growth plate chondmcytes exhibit cell sex-specific responses to 17 beta-estradiol (E-2), testosterone, and dihydrotestosterone (DHT). Mechanistically, E-2 and DHT stimulate proliferation and extracellular matrix synthesis in chondrocytes from female and male rats, respectively, by signaling through protein kinase C (PKC) and phospholipase C (PLC). Estrogen receptors (ER alpha; ER beta) and androgen receptors (ARs) are present in both male and female cells, but it is not known whether they interact to elicit sex-specific signaling. We used specific agonists and antagonists of these receptors to examine the relative contributions of ERs and ARs in membrane-mediated E-2 signaling in female chondrocytes and DHT signaling in male chondrocytes. PKC activity in female chondrocytes was stimulated by agonists of ER alpha and ER beta and required intact caveolae; PKC activity was inhibited by the E-2 enantiomer and by an inhibitor of ER beta. Western blots of cell lysates co-immunoprecipitated for ER alpha suggested the formation of a complex containing both ER alpha and ER beta with E-2 treatment. DHT and DHT agonists activated PKC in male cells, while AR inhibition blocked the stimulatory effect of DHT on PKC. Inhibition of ER alpha and ER beta also blocked PKC activation by DHT. Western blots of whole-cell lysates, plasma membranes, and caveolae indicated the translocation of AR to the plasma membrane and specifically to caveolae with DHT treatment. These results suggest that E-2 and DHT promote chondrocyte differentiation via the ability of ARs and ERs to form a complex. The results also indicate that intact caveolae and palmitoylation of the membrane receptor(s) or membrane receptor complex containing ER alpha and ER beta is required for E-2 and DHT membrane-associated PKC activity in costochondral cartilage cells.

Automated summary

Rat costochondral cartilage growth plate chondrocytes exhibit cell sex-specific responses to 17 beta-estradiol (E-2), testosterone, and dihydrotestosterone (DHT). Mechanistically, E-2 and DHT stimulate proliferation and extracellular matrix synthesis through protein kinase C (PKC) and phospholipase C (PLC). The study found that E-2 and DHT promote chondrocyte differentiation via the ability of androgen receptors (ARs) and estrogen receptors (ERs) to form a complex.