Calcium influx through voltage-operated calcium channels is required for proopiomelanocortin protein expression in Xenopus melanotropes.
Melanotrope cells of Xenopus laevis generate transitory increases in intracellular Ca(2+), known as Ca(2+) oscillations. These oscillations arise from the influx of Ca(2+) through voltage-operated Ca(2+) channels (VOCCs). Such oscillations are the driving force for secretion of a-melanophore-stimulating hormone (alpha-MSH) from the cell. The influx of Ca(2+) through VOCCs initiates the mobilization of intracellular Ca(2+) to generate a Ca(2+) wave. The function of the Ca(2+) wave in the melanotrope is unknown, but its presence in the nucleus suggests a role in the regulation of gene expression, perhaps that of proopiomelanocortin (POMC), the precursor protein for alpha-MSH. To determine the possible function of Ca(2+) waves in Xenopus melanotropes, we addressed whether functional VOCCs, which are an established requirement for both secretion and Ca(2+) wave initiation, are also required to maintain POMC gene expression.
van den Hurk
M J J
MJ
Department of Cellular Animal Physiology, Radboud University Nijmegen, the Netherlands.
Scheenen
W J J M
WJ
Roubos
E W
EW
Jenks
B G
BG
D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism* / Q000502:physiology; D015220:Calcium Channels / Q000096:biosynthesis* / Q000235:genetics; D002478:Cells, Cultured; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism*; D011333:Pro-Opiomelanocortin / Q000096:biosynthesis* / Q000235:genetics; D014982:Xenopus laevis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
D015220:Calcium Channels; D011333:Pro-Opiomelanocortin; D002118:Calcium