Role of guanine nucleotide-binding proteins ras-family or trimeric proteins or both in Ca2+ sensitization of smooth muscle
Role of guanine nucleotide-binding proteins ras-family or trimeric proteins or both in Ca2+ sensitization of smooth muscle
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DOI：
10.1073/pnas.93.3.1340
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发表时间：
1996-02-06
影响因子：
11.1
通讯作者：
Somlyo, AP
中科院分区：
文献类型：
--
作者：
Gong, MC;Iizuka, K;Somlyo, AP
本研究的目的是鉴定鸟嘌呤核苷酸结合蛋白（G蛋白）参与激动剂-和鸟嘌呤5′-[γ -硫代]三磷酸（GTP[γ - s]）诱导的20- kda肌球蛋白轻链（MLC(20)）磷酸化和收缩的Ca2+敏感性增加，A组成型活性，重组val14p21(rhoA)GTP在杆状病毒/Sf9系统中表达，而不是在大肠杆菌中未经翻译后修饰表达的蛋白。在恒定Ca2+ (pCa 6.4)诱导下，与β -escin渗透的平滑肌中MLC（20）磷酸化从19.8%增加到29.5% （P < 0.05）相关的缓慢收缩，val14p21(rhoA) GTP的作用被adp -核糖化蛋白抑制，在Triton X-100广泛渗透的平滑肌中不存在。内源性p21（rho）与表皮细胞分化抑制剂（EDIN）的adp -核糖基化抑制了GTP[在兔肠系膜动脉（RIMA）和兔回肠平滑肌中]、碳二酚（在兔回肠中）和内皮素（在RMA中）诱导的Ca2+致敏，但不抑制苯肾上腺素（在RMA中），并且在恒定Ca2+浓度下，1 μ M GTP[γ - s]只减慢了RMA诱导的收缩速度，而不降低收缩幅度。鸟苷5′-[β -硫]二磷酸（GDP[β - s]）和EDIN均能抑制AIF(4) -诱导的Ca2+致敏，EDIN还能在较小程度上抑制RMA和家兔回肠中单独Ca2+ (pCa 6.4)诱导的收缩，百日毒三聚体G蛋白的adp核糖基化不抑制Ca2+致敏。我们得出结论，p21（rho）可能作为辅助因子与其他信使一起在生理Ca2+敏化中发挥作用，而不是作为平滑肌MLC（20）磷酸酶的唯一直接抑制剂。
The purpose of this study was to identify guanine nucleotide-binding proteins (G proteins) involved in the agonist- and guanosine 5'-[gamma-thio]triphosphate (GTP[gamma-S])induced increase in the Ca2+ sensitivity of 20-kDa myosin light chain (MLC(20)) phosphorylation and contraction in smooth muscle, A constitutively active, recombinant val14p21(rhoA)GTP expressed in the baculovirus/Sf9 system, but not the protein expressed without posttranslational modification in Escherichin coli, induced at constant Ca2+ (pCa 6.4) a slow contraction associated with increased MLC(20) phosphorylation from 19.8% to 29.5% (P < 0.05) in smooth muscle permeabilized with beta-escin, The effect of val14p21(rhoA) GTP was inhibited by ADP-ribosylation of the protein and was absent in smooth muscle extensively permeabilized with Triton X-100, ADP-ribosylation of endogenous p21(rho) with epidermal cell differentiation inhibitor (EDIN) inhibited Ca2+ sensitization induced by GTP [in rabbit mesenteric artery (RIMA) and rabbit ileum smooth muscles], by carbachol (in rabbit ileum), and by endothelin (in RMA), but not by phenylephrine (in RMA), and only slowed the rate without reducing the amplitude of contractions induced in RMA by 1 mu M GTP[gamma-S] at constant Ca2+ concentrations, AIF(4)(-)-induced Ca2+ sensitization was inhibited by both guanosine 5'-[beta-thio] diphosphate (GDP[beta-S]) and by EDIN, EDIN also inhibited, to a lesser extent, contractions induced by Ca2+ alone (pCa 6.4) in both RMA and rabbit ileum, ADP-ribosylation of trimeric G proteins with pertussis toxin did not inhibit Ca2+ sensitization. We conclude that p21(rho) may play a role in physiological Ca2+ sensitization as a cofactor with other messengers, rather than as a sole direct inhibitor of smooth muscle MLC(20) phosphatase.