Phosphoinositide 3-Kinase γ Mediates Angiotensin II-induced Stimulation of L-type Calcium Channels in Vascular Myocytes

Jean-François Quignard, Jean Mironneau, Valérie Carricaburu, Bernard Fournier, Aleksei Babich, Bernd Nürnberg, Chantal Mironneau, Nathalie Macrez
Journal of Biological Chemistry. 2001-08-01; 276(35): 32545-32551
DOI: 10.1074/jbc.M102582200

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1. J Biol Chem. 2001 Aug 31;276(35):32545-51. Epub 2001 Jul 6.

Phosphoinositide 3-kinase gamma mediates angiotensin II-induced stimulation of
L-type calcium channels in vascular myocytes.

Quignard JF(1), Mironneau J, Carricaburu V, Fournier B, Babich A, Nurnberg B,
Mironneau C, Macrez N.

Author information:
(1)Laboratoire de Signalisation et Interactions Cellulaires, CNRS UMR 5017,
Université Bordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux, France.

Previous results have shown that in rat portal vein myocytes the betagamma dimer
of the G(13) protein transduces the angiotensin II-induced stimulation of calcium
channels and increase in intracellular Ca(2+) concentration through activation of
phosphoinositide 3-kinase (PI3K). In the present work we determined which class I
PI3K isoforms were involved in this regulation. Western blot analysis indicated
that rat portal vein myocytes expressed only PI3Kalpha and PI3Kgamma and no other
class I PI3K isoforms. In the intracellular presence of an anti-p110gamma
antibody infused by the patch clamp pipette, both angiotensin II- and
Gbetagamma-mediated stimulation of Ca(2+) channel current were inhibited, whereas
intracellular application of an anti-p110alpha antibody had no effect. The
anti-PI3Kgamma antibody also inhibited the angiotensin II- and Gbetagamma-induced
production of phosphatidylinositol 3,4,5-trisphosphate. In Indo-1 loaded cells,
the angiotensin II-induced increase in [Ca(2+)](i) was inhibited by intracellular
application of the anti-PI3Kgamma antibody, whereas the anti-PI3Kalpha antibody
had no effect. The specificity of the anti-PI3Kgamma antibody used in functional
experiments was ascertained by showing that this antibody did not recognize
recombinant PI3Kalpha in Western blot experiments. Moreover, anti-PI3Kgamma
antibody inhibited the stimulatory effect of intracellularly infused recombinant
PI3Kgamma on Ca(2+) channel current without altering the effect of recombinant
PI3Kalpha. Our results show that, although both PI3Kgamma and PI3Kalpha are
expressed in vascular myocytes, the angiotensin II-induced stimulation of
vascular L-type calcium channel and increase of [Ca(2+)](i) involves only the
PI3Kgamma isoform.

DOI: 10.1074/jbc.M102582200
PMID: 11443116 [Indexed for MEDLINE]

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