RasGRP4-dependent Responses in Mast Cells

肥大细胞中 RasGRP4 依赖性反应

• 批准号: 6917454
• 负责人: Richard L Stevens
• 金额: $ 42.1万
• 依托单位: BRIGHAM AND WOMEN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-02-15 至 2010-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6917454
• 关键词: cell line; developmental immunology; genetic regulation; genetic transcription; guanine nucleotide exchange factors; human genetic material tag; immunogenetics; laboratory mouse; mast cell; posttranslational modifications; protein isoforms; protein tyrosine kinase

DESCRIPTION (provided by applicant): We recently cloned the cDNAs and genes that encode the fourth member of the Ras Guanine Nucleotide Releasing Protein (RasGRP) family of signaling proteins. RasGRP4 is a mast cell (MC) restricted, cation-dependent, guanine nucleotide exchange factor. It also is a diacylglycerol/phorbol ester receptor that plays a prominent role in dictating which protease, cytokine, and eicosanoid mediators are expressed in MC lines. Allelic variants of RasGRP4 have been identified, as well as functionally different isoforms of RasGRP4 that are the result of differential splicing of its gene. Earlier gene-linkage studies of C3H/HeJ mice revealed a prominent site on chromosome 7A3-B1 that controls its intrinsic airway reactivity to methacholine. We recently found that the MCs developed from this hyporesponsive mouse produce a defective isoform of mRasGRP4. The accumulated data suggest that RasGRP4 is of critical importance in MC development and that the expression of abnormal isoforms of RasGRP4 can lead to MC dysfunction. Complementary approaches will be used in the proposed studies to test these hypotheses and to expand our knowledge concerning the recently identified RasGRP family of signaling proteins. In Specific Aim 1, the transcriptional and posttranscriptional mechanisms that regulate the expression of mouse and human RasGRP4 will be identified. In Specific Aim 2, the functional importance of allelic isoforms of RasGRP4 and its different domains will be evaluated. The predominant genes and signaling pathways in MCs that are regulated by RasGRP4 also will be identified, as well as the control mechanisms that dampen RasGRP4- dependent signaling events in MCs. In Specific Aim 3, RasGRP4-deficient, non transformed MCs will be created to evaluate the importance of this signaling protein in MC development and function in vivo. Because RasGRP4 is a MC-restricted signaling protein that appears to act downstream of the tyrosine kinase receptor Kit, it is anticipated that the obtained data will significantly advance our knowledge concerning the poorly defined Kit-dependent pathway that dominantly controls MC development and function. It also is anticipated that targeted disruption of RasGRP4 expression and/or activity in humans using pharmaceutical and other approaches will be beneficial in MC-dependent disorders.

描述（由申请人提供）：我们最近克隆了编码RAS鸟嘌呤核苷酸释放蛋白（RASGRP）家族的cDNA和基因。 RASGRP4是肥大细胞（MC）受限，阳离子依赖性的鸟嘌呤核苷酸交换因子。它也是一种二酰基甘油/佛波尔酯受体，在决定哪种蛋白酶，细胞因子和类花生酸介质在MC系中发挥了重要作用。已经鉴定出RASGRP4的等位基因变体，以及RASGRP4的功能不同的同工型，这是其基因差异剪接的结果。对C3H/HEJ小鼠的较早基因链接研究表明，在7A3-B1染色体上的一个突出位点，可控制其内在气道对甲基苯胺的反应性。我们最近发现，从这种反应性小鼠发育的MC会产生MRASGRP4的缺陷同工型。累积数据表明RASGRP4在MC开发中至关重要，并且RASGRP4异常同工型的表达可能导致MC功能障碍。拟议的研究将使用互补方法来检验这些假设，并扩大有关最近确定的RASGRP信号蛋白家族的知识。在特定的目标1中，将确定调节小鼠和人RasGRP4表达的转录和转录后机制。在特定的目标2中，将评估RASGRP4等位基因同工型及其不同域的功能重要性。还将鉴定由RASGRP4调节的MC中的主要基因和信号通路，以及抑制MC中RASGRP4依赖性信号事件的控制机制。在特定的目标3中，将创建RASGRP4缺陷的非转化MC，以评估该信号蛋白在体内MC开发和功能中的重要性。 由于RASGRP4是一种MC限制的信号蛋白，似乎在酪氨酸激酶受体试剂盒的下游作用，因此预计所获得的数据将显着促进我们关于依赖不当的套件依赖性途径的知识，从而显着控制MC的开发和功能。还可以预料，使用药物和其他方法对人类中RASGRP4表达和/或活动的有针对性破坏将对MC依赖性疾病有益。