Ca2+-independent phospholipase A2 is a novel determinant of store-operated Ca2+ entry.
Store-operated cation (SOC) channels and capacitative Ca(2+) entry (CCE) play very important role in cellular function, but the mechanism of their activation remains one of the most intriguing and long lasting mysteries in the field of Ca(2+) signaling. Here, we present the first evidence that Ca(2+)-independent phospholipase A(2) (iPLA(2)) is a crucial molecular determinant in activation of SOC channels and store-operated Ca(2+) entry pathway. Using molecular, imaging, and electrophysiological techniques, we show that directed molecular or pharmacological impairment of the functional activity of iPLA(2) leads to irreversible inhibition of CCE mediated by nonselective SOC channels and by Ca(2+)-release-activated Ca(2+) (CRAC) channels. Transfection of vascular smooth muscle cells (SMC) with antisense, but not sense, oligonucleotides for iPLA(2) impaired thapsigargin (TG)-induced activation of iPLA(2) and TG-induced Ca(2+) and Mn(2+) influx. Identical inhibition of TG-induced Ca(2+) and Mn(2+) influx (but not Ca(2+) release) was observed in SMC, human platelets, and Jurkat T-lymphocytes when functional activity of iPLA(2) was inhibited by its mechanism-based suicidal substrate, bromoenol lactone (BEL). Moreover, irreversible inhibition of iPLA(2) impaired TG-induced activation of single nonselective SOC channels in SMC and BAPTA (1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid)-induced activation of whole-cell CRAC current in rat basophilic leukemia cells. Thus, functional iPLA(2) is required for activation of store-operated channels and capacitative Ca(2+) influx in wide variety of cell types.
Smani
Tarik
T
Boston University School of Medicine, Boston, Massachusetts 02118, USA.
Zakharov
Sergey I
SI
Leno
Endri
E
Csutora
Peter
P
Trepakova
Elena S
ES
Bolotina
Victoria M
VM
D000818:Animals; D001011:Aorta / Q000166:cytology; D001792:Blood Platelets / Q000166:cytology / Q000201:enzymology*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D054522:Group VI Phospholipases A2; D006801:Humans; D019169:Jurkat Cells; D008345:Manganese / Q000493:pharmacokinetics; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000201:enzymology*; D009281:Naphthalenes / Q000494:pharmacology; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010741:Phospholipases A / Q000235:genetics / Q000378:metabolism*; D054467:Phospholipases A2; D011753:Pyrones / Q000494:pharmacology; D011817:Rabbits; D051381:Rats
D015220:Calcium Channels; D009281:Naphthalenes; D016376:Oligonucleotides, Antisense; D010726:Phosphodiesterase Inhibitors; D011753:Pyrones; D008345:Manganese; C068314:6-(bromomethylene)tetrahydro-3-(1-naphthaleneyl)-2H-pyran-2-one; D010741:Phospholipases A; D054522:Group VI Phospholipases A2; C516475:PLA2G6 protein, human; D054467:Phospholipases A2; C516476:Pla2g6 protein, mouse; D002118:Calcium