P70 Involvement of endogenous hydrogen sulfide and T-type calcium channels in cyclic AMP-induced neuronal differentiation in ng108-15 cells

Abstract

Hydrogen sulfide (H 2 S) is a gasotransmitter synthesized by multiple enzymes including cystathionine-gamma-lyase (CSE) in the mammalian body. H 2 S donors cause neuronal differentiation characterized by neuritogenesis via activation of Ca v 3.2 T-type Ca 2+ channels (T-channels) in NG108-15 cells. Recently, we have shown that the cAMP/PKA pathway induces prompt phosphorylation and sensitization of Ca v 3.2 in NG108-15 cells. Thus, we investigated roles of the endogenous H 2 S/Ca v 3.2 pathway in the cAMP-dependent neuritogenesis in NG108-15 cells. Neuritogenesis was produced by stimulation with dibutyryl cAMP (db-cAMP) or Na 2 S, an H 2 S donor, for 16 h. The db-cAMP-induced neuritogenesis was suppressed by inhibitors of PKA, CSE, and T-channels, while the Na 2 S-induced neuritogenesis was reduced by inhibitors of T-channels, but not PKA. Stimulation with db-cAMP for 6 h caused functional and protein upregulation of Ca v 3.2, but did not alter CSE protein expression. A CSE inhibitor suppressed the persistently enhanced T-currents by 6-h db-cAMP stimulation, although it did not affect the rapid facilitation of T-currents by 10-min db-cAMP stimulation. Our data suggest that the cAMP/PKA pathway does not only cause rapid phosphorylation-mediated Ca v 3.2 sensitization, but also long-lasting functional facilitation of Ca v 3.2 through protein upregulation and of the CSE/H 2 S pathway that further enhances Ca v 3.2 function, resulting in neuritogenesis and possibly neuronal differentiation in NG108-15 cells.