Regulation of vascular L-type Ca2+ channels by phosphatidylinositol 3,4,5-trisphosphate.
Modulation of voltage-gated L-type Ca2+ channels by phosphoinositide 3-kinase (PI3K) regulates Ca2+ entry and plays a crucial role in vascular excitation-contraction coupling. Angiotensin II (Ang II) activates Ca2+ entry by stimulating L-type Ca2+ channels through Gbeta-sensitive PI3K in portal vein myocytes. Moreover, PI3K and Ca2+ entry activation have been reported to be necessary for receptor tyrosine kinase-coupled and G protein-coupled receptor-induced DNA synthesis in vascular cells. We have previously shown that tyrosine kinase-regulated class Ia and G protein-regulated class Ib PI3Ks are able to modulate vascular L-type Ca2+ channels. PI3Ks display 2 enzymatic activities: a lipid-kinase activity leading to the formation of phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3 or PIP3] and a serine-kinase activity. Here we show that exogenous PIP3 applied into the cell through the patch pipette is able to reproduce the Ca2+ channel-stimulating effect of Ang II and PI3Ks. Moreover, the Ang II-induced PI3K-mediated stimulation of Ca2+ channel and the resulting increase in cytosolic Ca2+ concentration are blocked by the anti-PIP3 antibody. Mutants of PI3K transfected into vascular myocytes also revealed the essential role of the lipid-kinase activity of PI3K in Ang II-induced Ca2+ responses. These results suggest that PIP3 is necessary and sufficient to activate a Ca2+ influx in vascular myocytes stimulated by Ang II.
Le Blanc
Catherine
C
Laboratoire de Signalisation et Interactions Cellulaires, Université de Bordeaux II, Bordeaux, France.
Mironneau
Chantal
C
Barbot
Caroline
C
Henaff
Morgana
M
Bondeva
Tzvetanka
T
Wetzker
Reinhard
R
Macrez
Nathalie
N
D000730:Androstadienes / Q000494:pharmacology; D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001464:Barium / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000187:drug effects* / Q000502:physiology; D002148:Calmodulin-Binding Proteins / Q000494:pharmacology; D002478:Cells, Cultured / Q000187:drug effects / Q000502:physiology; D058544:Class Ib Phosphatidylinositol 3-Kinase; D003600:Cytosol / Q000378:metabolism; D004095:Dihydropyridines / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015640:Ion Channel Gating / Q000187:drug effects; D017136:Ion Transport / Q000187:drug effects; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D050356:Lipid Metabolism; D008564:Membrane Potentials / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000494:pharmacology; D051579:Neurogranin; D018408:Patch-Clamp Techniques; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000502:physiology*; D018129:Phosphatidylinositol Phosphates / Q000037:antagonists & inhibitors / Q000494:pharmacology* / Q000502:physiology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D011169:Portal Vein; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D011993:Recombinant Fusion Proteins / Q000502:physiology; D013379:Substrate Specificity; D014162:Transfection; D000077191:Wortmannin
D000730:Androstadienes; D000804:Angiotensin II; D001464:Barium; D002118:Calcium; D020746:Calcium Channels, L-Type; D002148:Calmodulin-Binding Proteins; D058544:Class Ib Phosphatidylinositol 3-Kinase; D004095:Dihydropyridines; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D009419:Nerve Tissue Proteins; D051579:Neurogranin; D019869:Phosphatidylinositol 3-Kinases; D018129:Phosphatidylinositol Phosphates; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011993:Recombinant Fusion Proteins; D000077191:Wortmannin; C496651:Nrgn protein, rat; C060974:phosphatidylinositol 3,4,5-triphosphate; C546765:Pik3cg protein, rat; C053783:oxodipine