Nicotine and prostaglandin E induce secretogranin II levels in bovine chromaffin cells.

The synthesis regulation of secretogranin II was investigated in bovine chromaffin cells by treatment with various first messengers. Nicotine and prostaglandin E2 elevated secretogranin II mRNA and protein up to three-fold. Angiotensin II, atrial natriuretic peptide, apomorphine, bradykinin and clonidine on the other hand had no effect. The prostaglandin E induced elevation of secretogranin II mRNA was transduced via the calcium/calmodulin pathway but not via the protein kinase A or C pathways as shown by using specific inhibitors. Exposure of chromaffin cells to drugs specifically activating second messenger pathways both elevated and decreased secretogranin II mRNA. The calcium channel agonist Bay K, forskolin and phorbol esters increased secretogranin II mRNA whereas 8-Br-cGMP repressed the secretogranin II message. Thus, although secretogranin II expression can be altered by all major second messenger transduction systems, regulation of secretogranin II in vivo occurs mainly via the calcium/calmodulin pathway. Chromogranin A and B mRNA were not changed by any of the first messengers investigated indicating a differential synthesis regulation of components co-stored in bovine chromaffin granules.