1α,25(OH)2-vitamin D3 stimulates rapid plasma membrane calcium influx via MAPK activation in immature rat Sertoli cells

It was characterized that the rapid response to 1 alpha,25(OH)(2)-vitamin D-3 (1,25D(3)) on Ca-45(2+) influx in rat Sertoli cells was mediated by voltage-dependent Ca2+ channels (VDCCs), PKC, ERK1/2 and p38 MAPK pathways. In primary culture of 10 day-old rat Sertoli cells as well as in the whole testis, the time-course of Ca-45(2+) influx did not change significantly in basal conditions. However, 1,25D(3) showed stimulatory effect on Ca-45(2+) influx from 10(-15) to 10(-8) M after 60 s of incubation. The maximum effect was around 140% at 10(-12) M on purified Sertoli cells showing a steady state on Ca-45(2+) influx between 10(-11) and 10(-9) M. Under this experimental condition, 1,25D(3) stimulated Ca-45(2+) influx from 73% to 106% and no effect was observed at 10(-16), 10(-8) and 10(-7) M in whole testis. VDCC activities are mandatory for a full and complete stimulatory effect of 1,25D(3) in these approaches. K+ and Cl- channels also are strongly involved in this rapid response coordinated by 1,25D(3). The participation of some selected kinases, points to PKC and ERK1/2 upstream activity to p38 MAPK activation suggesting an intracellular cross-talk between rapid Ca-45(2+) influx and nuclear events. In addition, the comparative effect of microtubule disassembles and CIC-3 channel blocker on Ca-45(2+) influx provides evidence of secretory activity of Sertoli cells triggered by 1,25D(3). Our results suggest that 1,25D(3) activates p38 MAPK and reorganizes microtubules, involving Ca2+, PKC and ERK1/2 as upstream regulators and that extracellular Ca2+ have a central role to rapidly start hormone-induced gene transcription and/or the secretory activity of Sertoli cell. (C) 2011 Elsevier Masson SAS. All rights reserved.