Integrity of actin-network is involved in uridine 5'-triphosphate evoked store-operated Ca2+ entry in bovine adrenocortical fasciculata cells.
Store-operated Ca(2+) entry channels (SOCs) play an important role in the regulation of diverse non-excitable cell functions. However, the precise mechanism of SOCs activation is still controversial. Uridine 5'-triphosphate (UTP) was shown to induce Ca(2+) entry in a dihydropyridines-insensitive manner and accelerated steroidogenesis in bovine adrenocortical fasciculata cells (BAFCs) via the Gq/11 protein-coupled P2Y(2) receptor. Therefore we investigated whether UTP is involved in SOCs activation and the mechanism of UTP-induced SOCs activation. Fura 2-loaded BAFCs were used for the measurement of intracellular concentration of Ca(2+) ([Ca(2+)](i)) mobilization. Extracellular UTP evoked Ca(2+) release from intracellular stores followed by an increase in Ca(2+) entry. The Ca(2+) influx elicited by UTP was inhibited not by nifedipine, but by Zn(2+), Cd(2+), and Ni(2+) (potency order: Zn(2+) > Cd(2+) >> Ni(2+)), and the effect of UTP was also attenuated by a phospholipase C inhibitor (U73122). These results indicate that UTP activates SOCs in BAFCs. The increase in [Ca(2+)](i) by UTP was attenuated by ML-9, a myosin-light chain kinase inhibitor, and calmodulin inhibitors, W-7 and E6 berbamine, in a concentration-dependent manner. These reagents depolymerized actin filaments with rhodamine staining in BAFCs. Cytochalasin D also inhibited UTP-activated SOCs and depolymerized actin filaments. From these results, we proposed that calcium/calmodulin dependent myosin-light chain kinase is involved in the mobilization of actin filaments and the integrity of actin-network plays an important role in UTP-induced SOCs activation in BAFCs.
Kawamura
Masahiro
M
Department of Pharmacology (I), Jikei University School of Medicine, Tokyo, Japan. pharmacology@jikei.ac.jp
Terasaka
Osamu
O
Ebisawa
Takanori
T
Kondo
Ichiro
I
Masaki
Eiji
E
Ahmed
Ashram
A
Kagata
Miyuki
M
D000199:Actins / Q000737:chemistry*; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D001381:Azepines / Q000494:pharmacology; D044182:Benzylisoquinolines; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002412:Cations / Q000494:pharmacology; D002417:Cattle; D002478:Cells, Cultured; D015638:Cytochalasin D / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D005456:Fluorescent Dyes; D007211:Indoles / Q000494:pharmacology; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D014544:Uridine Triphosphate / Q000494:pharmacology*; D015383:Zona Fasciculata / Q000166:cytology / Q000378:metabolism*
D000199:Actins; D000470:Alkaloids; D001381:Azepines; D044182:Benzylisoquinolines; D002121:Calcium Channel Blockers; D002412:Cations; D004791:Enzyme Inhibitors; D004963:Estrenes; D005456:Fluorescent Dyes; D007211:Indoles; D019384:Nucleic Acid Synthesis Inhibitors; D011760:Pyrrolidinones; D013449:Sulfonamides; C056218:ML 9; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D015638:Cytochalasin D; C017967:W 7; D019284:Thapsigargin; D009219:Myosin-Light-Chain Kinase; D002118:Calcium; D014544:Uridine Triphosphate; C027870:berbamine; C000543:cyclopiazonic acid