Histamine‐Evoked Chromaffin Cell Scinderin Redistribution, F‐Actin Disassembly, and Secretion: In the Absence of Cortical F‐Actin Disassembly, an Increase in Intracellular Ca²⁺ Fails to Trigger Exocytosis

Abstract

Histamine is a known chromaffin cell secretagogue that induces Ca" -dependent release of catecholamines . However, conflicting evidence exists as to the source of Ca t ' utilized in histamine-evoked secretion .Here we report that histamine-H, receptor activation induces redistribution of scinderin, a Ca t +-dependent Factin severing protein, cortical F-actin disassembly, and catecholamine release . Histamine evoked similar patterns of distribution of scinderin and filamentous actin . The rapid responses to histamine occurred in the absence of extracellular Ca t + and were triggered by release of Ca" from intracellular stores . The trigger for the release of Ca t ' was inositol 1,4,5-trisphosphate because U-73122, a phospholipase C inhibitor, but not its inactive isomer (U-73343), inhibited the increases in IP 3 and intracellular Ca" levels, scinderin redistribution, cortical F-actin disassembly, and catecholamine release in response to histamine . Thapsigargin, an agent known to mobilize intracellular Ca", blocked the rise in intracellular Ca t ' concentration, scinderin redistribution, F-actin disassembly, and catecholamine secretion in response to histamine . Calphostin C and chelerythrine, two inhibitors of protein kinase C, blocked all responses to histamine with the exception of the release of Ca" from intracellular stores . This suggests that protein kinase C is involved in histamine-induced responses . The results also show that in the absence of F-actin disassembly, rises in intracellular Ca t ' concentration are not by themselves capable of triggering catecholamine release .Abbreviations used : D,8H, dopamine ß-hydroxylase ; FITC, fluorescein isothioeyanate; IP3 , inositol 1,4,5-trisphosphate ; MARCKS, myristoylated alanine-rich C-kinase substrate ; NA, noradrenaline; PIP, phosphatidylinositol 4,5-bisphosphate ; PKC, protein kinase C; PLC, phospholipase C; PNMT, phenyl-N-methyltransferase ; U-73122, 1-16-l117[3-3-methoxyestra-1,3,5(10)-trien-17-yl]aminolhexyl ]-IH-pyrrole-2,5-dione .

Potentiation of Exocytosis by Phospholipase C-Coupled G-Protein-Coupled Receptors Requires the Priming Protein Munc13-1

“…Together, our pharmacology data indicate that histamineinduced potentiation of stimulus-coupled exocytosis depends on the activation of PLC and a downstream DAG receptor other than PKC. These results are in agreement with previous biochemical studies on histamine-evoked catecholamine release in unclamped chromaffin cells in which similar differences between the effectiveness of inhibitors that act at the kinase domain (Donald et al, 2002) versus DAG regulatory domain were also observed (Zhang et al, 1995).…”

“…Activated PLC generates the second messengers IP 3 and DAG. IP 3 -induced Ca 2ϩ release from stores is known to be required for histamine potentiation of secretion (von Ruden and Neher, 1993;Pan and Fox, 2000); the role of DAG-regulated proteins such as PKC is unclear (Zhang et al, 1995;Donald et al, 2002). The functionality of PKC and of alternative nonkinase DAG receptors is reported to be severely impaired by the C1-domain antagonist calphostin C .…”

“…E, Mean Ϯ SEM percentage change in exocytotic efficiency induced by histamine in noninfected cells (n ϭ 8) compared with adenoviral infected cells expressing EGFP (n ϭ 11). **p Ͻ 0.01. potassium channels in chromaffin cells are well documented (von Ruden and Neher, 1993;Zhang et al, 1995;Pan and Fox, 2000;Marley, 2003). Histamine activates H 1 receptors that couple exclusively to the pertussis toxin-insensitive G␣ q subunit (Hill et al, 1997).…”

Pituitary Adenylate Cyclase‐Activating Polypeptide Causes Ca2+ Release from Ryanodine/Caffeine Stores Through a Novel Pathway Independent of Both Inositol Trisphosphates and Cyclic AMP in Bovine Adrenal Medullary Cells

“…It is reported that einnarizine, known as a Ca2~-channelblocker, blocked 1P 3-induced Ca 2~release from isolated platelet membrane vesicles (Seiler et al, 1987) and inhibited Ca2r elease induced by muscat-inc in canine adrenal chromaffin cells (Ohtsuki et al, 1992). We have also confirmed that in bovine adrenal chromaffin cells, cinnarizine, when added to perifusion medium, selectively and completely suppressed Ca2~release induced by histamine, which is reported to cause Ca2~release selectively through 1P 3-dependent pathways (Cheek et al, 1994;Zhang et al, 1995), without affecting Ca 2r elease caused by caffeine in bovine chromafflu cells (Tanaka et al, 1996). The results indicate that cinnari-FIG.…”

Chromaffin Cell F-actin Disassembly and Potentiation of Catecholamine Release in Response to Protein Kinase C Activation by Phorbol Esters Is Mediated through Myristoylated Alanine-rich C Kinase Substrate Phosphorylation

“…Previous experiments from our laboratory showed that PMA treatment of intact chromaffin cells disrupted cortical F-actin (4,17) and increased both the number of chromaffin vesicles in the release-ready vesicle pool and the initial rate of exocytosis (4). In support of a role for PKC in the modulation of cortical F-actin was the observation that PKC inhibitors sphingosine, staurosporine, and calphostin C blocked, in a concentrationdependent manner, PMA-induced cortical F-actin network disassembly (17,44). MARCKS is a member of a family of PKC substrates that potentially can interact with F-actin and calmodulin, proteins that are widely distributed in the nervous system (see scheme in Fig.…”