Role of Lbc RhoGEF in Gα12/13-induced signals to Rho GTPase
Role of Lbc RhoGEF in Gα12/13-induced signals to Rho GTPase
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DOI：
10.1016/s0898-6568(03)00132-3
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发表时间：
2004-02-01
影响因子：
4.8
通讯作者：
Toksoz, D
中科院分区：
文献类型：
--
作者：
Dutt, P;Nguyen, N;Toksoz, D
异三聚体 Galpha12/13 信号诱导细胞反应，例如通过 Rho GTPase 介导的血清反应元件 (SRE) 介导的基因转录。鸟嘌呤核苷酸交换因子 (GEF) 是将 Got 信号与 Rho 连接起来的有力候选因子。例如，p 115 RhoGEF 将 Galpha13 信号转导至 Rho，并通过与 Galpha 亚基相连的 RhoGEF LH 结构域抑制 Galpha12/13 信号。在这里，我们评估了 Lbc RhoGEF 在 Galpha12/13 信号背景下的信号传导能力。体外 GEF 测定表明杆状病毒表达的原 Lbc 具有最小的交换活性，这意味着体内 Lbc 活性需要刺激。 HEK293T 细胞中催化失活的原 Lbc 突变体的表达减弱了 Galpha12 和凝血酶诱导的 SRE 转录报告基因的激活，并且观察到的抑制水平与用类似的 p 115 RhoGEF 突变体获得的抑制水平相似。 proto-Lbc 突变体表达还导致体内 Galpha12 诱导的 RhoA 激活水平降低。检测到 Galpha12 和 Lbc 形式之间的复合物形成。对 Lbc 肽序列的分析揭示了一个先前未检测到的区域，该区域可能与 Got 亚基信号相关。这些发现支持 Lbc 在 Galpha12 诱导的 Rho 信号通路中的作用。 (C) 2003 Elsevier Inc. 保留所有权利。
Heterotrimeric Galpha12/13 signals induce cellular responses such as serum response element (SRE)-mediated gene transcription via Rho GTPase. Guanine nucleotide exchange factors (GEFs) are strong candidates for linking Got signals to Rho. For example, p 115 RhoGEF transduces Galpha13 signals to Rho and inhibits Galpha12/13 signals via the RhoGEF LH domain which links to Galpha subunits. Here, we have evaluated the signaling capacity of Lbc RhoGEF in the context of Galpha12/13 signals. In vitro GEF assays indicate that baculoviral-expressed proto-Lbc has minimal exchange activity, implying that a stimulus is required for Lbc activity in vivo. Expression of a catalytically inactive proto-Lbc mutant in HEK293T cells attenuates Galpha12- and thrombin-induced activation of an SRE transcriptional reporter, and the levels of inhibition observed is similar to that obtained with an analogous p 115 RhoGEF mutant. proto-Lbc mutant expression also led to decreased levels of Galpha12-induced RhoA activation in vivo. Complex formation between Galpha12 and Lbc forms was detected. Analysis of the Lbc peptide sequence reveals a previously undetected region which may link to Got subunit signals. These findings support a role for Lbc in Galpha12-induced signaling pathways to Rho. (C) 2003 Elsevier Inc. All rights reserved.