Stimulatory Effect of Pituitary Adenylate Cyclase-Activating Polypeptide on Catecholamine Synthesis in Cultured Bovine Adrenal Chromaffin Cells: Involvements of Tyrosine Hydroxylase Phosphorylation Caused by Ca2+ Influx and cAMP

Abstract

ABSTRACT-In cultured bovine adrenal chromaffin cells, pituitary adenylate cylase-activating polypeptide (PACAP) stimulated [14C]catecholamine synthesis from [14C]tyrosine (but not from [14C]DOPA) in a con centration-dependent manner, causing maximal stimulation at 10' M. The stimulatory action of PACAP was not affected by staurosporine (an inhibitor of protein kinase C) or in the cells in which protein kinase C was down-regulated by prolonged exposure to TPA (an activator of protein kinase C), whereas it was partial ly attenuated in Ca"-free medium. PACAP (10-'M) increased the formation of [3H]inositol phosphates, [Ca2+]; and 41 Ca' uptake as well as cAMP. The peptide also stimulated the phosphorylation of tyrosine hydroxylase, the enzyme catalyzing the rate-limiting step in catecholamine synthesis. Catecholamine syn thesis and tyrosine hydroxylase phosphorylation stimulated by the maximal effective concentration of dibutyryl cAMP or high K+, which activates Ca 21 uptake, were further enhanced by PACAP, suggesting that both cAMP and Ca2+-dependent protein kinases may be involved in the stimulation of tyrosine hydroxylase phosphorylation and catecholamine synthesis caused by PACAP.

Pituitary Adenylate Cyclase-Activating Polypeptide and Its Receptors: 20 Years after the Discovery

“…In adrenal chromaffin cells, PACAP exerts a stimulatory action on catecholamine secretion Isobe et al, 1993;Chowdhury et al, 1994;Guo and Wakade, 1994;Houchi et al, 1994;Perrin et al, 1995;Neri et al, 1996;Jorgensen et al, 2000;Fukushima et al, 2002;Douglas et al, 2008;Valiante et al, 2008). PACAP also stimulates the release of brain natriuretic peptide and enkephalins, two regulatory peptides that are cosequestered with catecholamines in chromaffin granules (Babinski et al, 1996;Hahm et al, 1998) as well as a 15-fold increase in VIP mRNA expression (Lee et al, 1999a).…”

“…PACAP-induced catecholamine secretion is significantly greater after the induction of hypoglycemia and PACAP(Ϫ/Ϫ) mouse exhibit a delayed normalization of plasma glucose levels in response to insulin injection , suggesting that PACAP may play a beneficial role in glucose counter-regulatory mechanisms in the adrenal medulla during hypoglycemia. The effect of PACAP on catecholamine secretion is associated with activation of AC and elevation of cytosolic calcium concentrations (Isobe et al, 1993;Houchi et al, 1994;Isobe et al, 1994;Perrin et al, 1995;Chamoux et al, 1998). Incubation of adrenomedullary cells in calcium-free medium or blockage of voltage-operated calcium channels suppresses the PACAP-evoked stimulation of catecholamine secretion (Isobe et al, 1993;Houchi et al, 1995; PITUITARY ADENYLATE CYCLASE-ACTIVATING POLYPEPTIDE Przywara et al, 1996;O'Farrell and Marley, 1997), indicating that the effect of PACAP on chromaffin cells is mediated through calcium influx.…”

“…Concurrently, in bovine and human, PACAP increases calcium levels from ryanodine/caffeine-sensitive calcium stores (Houchi et al, 1995;Tanaka et al, 1996Tanaka et al, , 1998Shibuya et al, 1999;Payet et al, 2003). The effect of PACAP on catecholamine release is associated with an increase in the expression of tyrosine hydroxylase, dopamine ␤-hydroxylase, and phenylethanolamine N-methyltransferase (Houchi et al, 1994;Rius et al, 1994;Isobe et al, 1996;Marley et al, 1996;Tönshoff et al, 1997;Hong et al, 1998;Choi et al, 1999;Park et al, 1999). It has been shown that the stimulatory effect of PACAP on tyrosine hydroxylase activity is mediated through activation of the AC/PKA transduction pathway (Marley et al, 1996) and can be accounted for by phosphorylation of TH at Ser 40 (Bobrovskaya et al, 2007).…”

Multiple calcium channels are required for pituitary adenylate cyclase-activating polypeptide-induced catecholamine secretion from bovine cultured adrenal chromaffin cells

“…The receptor is coupled to G-proteins and activates two distinct signalling pathways within chromaffin cells, adenylate cyclase and generation of cyclic AMP (Watanabe et al 1992;Perrin et al 1995), and phospholipase C and the generation of inositol 1,4,5-trisphosphate and diacylglycerol (Arimura, 1992;Spengler et al 1993). In addition, PACAP increases calcium influx and raises cytosolic calcium levels (Houchi et al 1994;Tanaka et al 1996). This peptide is one of the most potent chromaffin cell secretagogues with the magnitude of secretion similar to the response to K + depolarisation and nicotinic receptor agonists (compare Perrin et al 1995with Burgoyne, 1991.…”

Endothelin‐1 stimulates sodium‐dependent calcium efflux from bovine adrenal chromaffin cells in culture

“…After incubation, the medium was discarded and the cells were washed ®ve times with 1 ml of ice cold BSS. Then the intracellular 45 Ca 2+ was extracted with 1 ml of 1% Triton X-100 and measured in a liquid scintillation counter (Houchi et al, 1994a).…”