Depolarization-induced ERK phosphorylation depends on the cytosolic Ca2+ level rather than on the Ca2+ channel subtype of chromaffin cells

Mendoza, IE; Schmachtenberg, O.; Tonk, E; Fuentealba, J; Diaz-Raya, P; Lagos, VL; Garcia, AG; Cárdenas AM

Abstract

The contribution of Ca2+ entry through different voltage-activated Ca2+ channel (VACC) subtypes to the phosphorylation of extracellular signal regulated kinase (ERK) was examined in bovine adrenal-medullary chromaffin cells. High K+ depolarization (40 mM, 3 min) induced ERK phosphorylation, an effect that was inhibited by specific mitogen-activated protein kinase kinase inhibitors. By using selective inhibitors, we observed that depolarization-induced ERK phosphorylation completely depended on protein kinase C-? (PKC-?), but not on Ca2+/calmodulin-dependent protein kinase nor cyclic AMP-dependent protein kinase. Blockade of L-type Ca2+ channels by 3 ?M furnidipine, or blockade of N channels by 1 ?M ?-conotoxin GVIA reduced ERK phosphorylation by 70%, while the inhibition of P/Q channels by 1 ?M ?-agatoxin IVA only caused a 40% reduction. The simultaneous blockade of L and N, or P/Q and N channels completely abolished this response, yet 23% ERK phosphorylation remained when L and P/Q channels were simultaneously blocked. Confocal imaging of cytosolic Ca2+ elevations elicited by 40 mM K+, showed that Ca2+ levels increased throughout the entire cytosol, both in the presence and the absence of Ca2+ channel blockers. Fifty-eight percent of the fluorescence rise depended on Ca2+ entering through N channels. Thus, ERK phosphorylation seems to depend on a critical level of Ca2+ in the cytosol rather than on activation of a given Ca2+ channel subtype.

Más información

Título según WOS: Depolarization-induced ERK phosphorylation depends on the cytosolic Ca2+ level rather than on the Ca2+ channel subtype of chromaffin cells
Título según SCOPUS: Depolarization-induced ERK phosphorylation depends on the cytosolic Ca 2+ level rather than on the Ca2+ channel subtype of chromaffin cells
Título de la Revista: JOURNAL OF NEUROCHEMISTRY
Volumen: 86
Número: 6
Editorial: WILEY-BLACKWELL
Fecha de publicación: 2003
Página de inicio: 1477
Página final: 1486
Idioma: English
URL: http://doi.wiley.com/10.1046/j.1471-4159.2003.01965.x
DOI:

10.1046/j.1471-4159.2003.01965.x

Notas: ISI, SCOPUS