Molecular mechanisms of ERM regulation

ERM调节的分子机制

• 批准号: 7733400
• 负责人: James Shaw
• 金额: $ 30.68万
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7733400
• 关键词: Actins; Acute; Biological Assay; Biology; CD44 gene; Cell membrane; Cells; Cytoplasmic Tail; Cytoskeleton; Cytosol; Dependence; Event; Family; Hydrolysis; In Vitro; Lipids; Lymphocyte; Lymphocyte Activation; Manuscripts; Mediating; Mediator of activation protein; Membrane; Modeling; Molecular; Mutation; Phosphatidylinositol 4,5-Diphosphate; Phosphatidylinositols; Phospholipase C; Phospholipids; Phosphoric Monoester Hydrolases; Phosphorylation; Protein Dephosphorylation; Proteins; Regulation; Role; Signal Transduction; Stromal Cell-Derived Factor 1; Transfection; chemokine; ezrin; inhibitor/antagonist; moesin; radixin protein

We first described several years ago the finding that chemokine (SDF-1) stimulation of lymphocytes induces very rapid (onset less than or equal to 5 sec) ERM dephosphorylation and inactivation. Given the evidence that phosphorylation contributes to ERM activation, it was plausible that dephosphorylation mediated the inactivation. However, membrane phospho-lipid, especially PIP2, is an additional key mediator of ERM activation. We hypothesized that acute reduction of PIP2 could contribute to ERM inactivation. Specifically, we considered the possibility that chemokine: 1) activates phospholipase C (PLC); which 2) mediates reduction of phosphatidylinositol 4,5-bisphosphate (PIP2); which 3) releases ERM from its association with the plasma membrane; and 4) triggers ERM dephosphorylation. This proposed model is supported by multiple findings we have made, including the following. PLC inhibitor blocks these events. Translocation of GFP-tagged moesin into cytosol and ERM dephosphorylation can be induced either by: transfection with active PLC construct; or by acute targeting of phosphoinositide 5-phosphatase to the plasma membrane. PIP2 dependence cannot be replaced by phosphorylation (modeled by T558D mutation) in either of two assays: association with plasma membrane in cells or in vitro association with cytoplasmic tails of proteins like CD44. These results demonstrate a powerful new role of PLCs in rapid cytoskeletal remodeling and an additional key role of PIP2 in ERM biology, namely hydrolysis-mediated ERM inactivation. A manuscript on these studies is currently under review.

几年前，我们首先描述了趋化因子（SDF-1）对淋巴细胞的刺激诱导非常快速（发作小于或等于5秒）ERM DEPHOPHORITAN和失活。 鉴于证据表明磷酸化有助于ERM激活，因此去磷酸化介导了失活是合理的。然而，膜磷酸脂质，尤其是PIP2是ERM活化的另一个关键介体。我们假设PIP2的急性减少可能导致ERM失活。具体而言，我们考虑了趋化因子的可能性：1）激活磷脂酶C（PLC）； 2）介导磷脂酰肌醇4,5-双磷酸的还原（PIP2）； 3）释放ERM与质膜的关联； 4）触发ERM去磷酸化。我们提出的模型得到了我们已经做出的多个发现的支持，包括以下内容。 PLC抑制剂阻止这些事件。 GFP标记的Moesin转移到细胞质中，ERM去磷酸化可以通过以下方式诱导：用活性PLC构建体转染；或通过将磷酸肌醇5-磷酸酶急性靶向到质膜。 PIP2依赖性不能被两种测定中的任何一个中的任何一个磷酸化（由T558D突变建模）所取代：与细胞中的质膜相关，或与CD44（如CD44）的细胞质尾巴相关。这些结果表明，PLC在快速细胞骨架重塑中起着强大的新作用，以及PIP2在ERM生物学中的其他关键作用，即水解介导的ERM失活。这些研究的手稿目前正在审查中。