Regulation of Gβγi-dependent PLC-β3 activity in smooth muscle: inhibitory phosphorylation of PLC-β3 by PKA and PKG and stimulatory phosphorylation of Gαi-GTPase-activating protein RGS2 by PKG.
Regulation of Gβγi-dependent PLC-β3 activity in smooth muscle: inhibitory phosphorylation of PLC-β3 by PKA and PKG and stimulatory phosphorylation of Gαi-GTPase-activating protein RGS2 by PKG.
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DOI：
10.1007/s12013-014-9992-6
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发表时间：
2014-11
影响因子：
2.6
通讯作者：
Murthy, Karnam S.
中科院分区：
文献类型：
--
作者：
Nalli, Ancy D.;Kumar, Divya P.;Al-Shboul, Othman;Mahavadi, Sunila;Kuemmerle, John F.;Grider, John R.;Murthy, Karnam S.
在胃肠平滑肌中，与G i偶联受体结合的激动剂优先通过G β γ激活PLC-β 3，刺激磷酸肌醇（PI）水解并产生1，4，5-三磷酸肌醇（IP 3），导致IP 3依赖性Ca 2+释放和肌肉收缩。本研究探讨了cAMP依赖性蛋白激酶（PKA）和cGMP依赖性蛋白激酶（PKG）抑制PLC-β 3依赖性PI水解的机制。腺苷A1受体激动剂环戊基腺苷（CPA）以浓度依赖性方式引起PI水解增加; GRK 2（495 - 689）（G β γ-清除肽）或G α i小基因（而非G α q小基因）的羧基末端序列的表达可阻断CPA的刺激。异丙肾上腺素和S-亚硝基谷胱甘肽（GSNO）可诱导PLC-β 3磷酸化，抑制CPA诱导的PI水解、Ca~（2+）释放和肌肉收缩。PKA抑制剂、豆蔻酰化PKI或AKAP抑制剂Ht-31抑制异丙肾上腺素对所有三种反应的作用，而PKG抑制剂Rp-cGMPS选择性抑制GSNO的作用。GSNO，而不是异丙肾上腺素也磷酸化G α i-GTP酶激活蛋白，RGS2，并增强G α i3-GTP和RGS2的结合。GSNO对PI水解的作用在（i）表达组成型活性GTP酶抗性G α i突变体（Q204 L）、（ii）磷酸化位点缺陷型RGS2突变体（S46 A/S64 A）或（iii）RGS2 siRNA的细胞中部分逆转。我们的结论是PKA和PKG通过直接磷酸化PLC-β 3来抑制G β γ i依赖的PLC-β 3活性。PKG而不是PKA也通过涉及RGS2的磷酸化及其与G α i-GTP的缔合的机制间接抑制PI水解。这使得RGS2能够加速G i-GT β 1活性，增强G β γ 1三聚体形成并抑制G β γ 1依赖性PLC-β 3活性。
In gastrointestinal smooth muscle, agonists that bind to Gi-coupled receptors activate preferentially PLC-β3 via Gβγ to stimulate phosphoinositide (PI) hydrolysis and generate inositol 1,4,5-trisphosphate (IP3) leading to IP3-dependent Ca2+ release and muscle contraction. In the present study, we identified the mechanism of inhibition of PLC-β3-dependent PI hydrolysis by cAMP-dependent protein kinase (PKA) and cGMP-dependent protein kinase (PKG). Cyclopentyl adenosine (CPA), an adenosine A1 receptor agonist caused an increase in PI hydrolysis in a concentration-dependent fashion; stimulation was blocked by expression of the carboxyl terminal sequence of GRK2 (495–689), a Gβγ-scavenging peptide, or Gαi minigene but not Gαq minigene. Isoproterenol and S-nitrosoglutathione (GSNO) induced phosphorylation of PLC-β3, and inhibited CPA-induced PI hydrolysis, Ca2+ release and muscle contraction. The effect of isoproterenol on all three responses was inhibited by PKA inhibitor, myristoylated PKI, or AKAP inhibitor, Ht-31, whereas the effect of GSNO was selectively inhibited by PKG inhibitor, Rp-cGMPS. GSNO, but not isoproterenol also phosphorylated Gαi-GTPase activating protein, RGS2 and enhanced association of Gαi3-GTP and RGS2. The effect of GSNO on PI hydrolysis was partly reversed in cells (i) expressing constitutively active GTPase-resistant Gαi mutant (Q204L), (ii) phosphorylation-site deficient RGS2 mutant (S46A/S64A), or (iii) siRNA for RGS2. We conclude that PKA and PKG inhibit Gβγi-dependent PLC-β3 activity by direct phosphorylation of PLC-β3. PKG, but not PKA also inhibits PI hydrolysis indirectly by a mechanism involving phosphorylation of RGS2 and its association with Gαi-GTP. This allows RGS2 to accelerate G i-GTPase activity, enhance G βγi trimer formation and inhibit Gβγi-dependent PLC-β3 activity.
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影响因子：
64.5
作者：
BERSTEIN, G;BLANK, JL;ROSS, EM
通讯作者：
ROSS, EM
DOI：
10.1016/s1357-2725(01)00141-8
发表时间：
2002-05-01
影响因子：
4
作者：
Kehrl, JH;Sinnarajah, S
通讯作者：
Sinnarajah, S
影响因子：
4.8
作者：
Fukao, M;Mason, HS;Keef, KD
通讯作者：
Keef, KD
影响因子：
16.2
作者：
Han, Jing;Mark, Melanie D.;Herlitze, Stefan
通讯作者：
Herlitze, Stefan
影响因子：
4.8
作者：
Chidiac, P;Ross, EM
通讯作者：
Ross, EM