Study on molecular mechanisms of integrin-regulated adhesion in immune responses

整合素调控免疫反应粘附的分子机制研究

基本信息

批准号：
14370112
负责人：
KINASHI Tatsuo
金额：
$ 8.83万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14370112/
关键词：
small GTPase Rap1 RAPL LFA-1 integrin lymphocyte homing chemokine cell polarization ICAM-1 inside-outシグナル接着分子 VCAM-1 VLA-4 免疫反応アポトーシス

项目摘要

We have reported that the small GTPase Rap1 is a intracellular signaling molecule that increase integrin adhesiveness that is triggered by stimulation with chemokines or antigens. Rap1 activation by chemokines robustly stimulates lymphocyte motility. We have also demonstrated that Rap1 activation by chemokines is required in lymphocyte transmigration through endothelial monolayers under physiological shear flow. Furthermore, Rap1 activation induces cell polarization, which is accompanied with development of the leading edge and uropod and relocalization of chemokine receptor CXCR4 and CD44 to the leading edge and uropod, respectively. In order to clarigy the molecular mechanism in these processes, we have identified and characterized a novel Rap1 effector RAPL. RAPL is a Rap1-GTP binding 30 kD protein isolated by yeast two-hybrid screening with an active Rap1 mutant. RAPL is preferentially expressed in spleen, lymph nodes, and thymus, in particular T and B cells. RAPL overexpression stimulated LFA-1-mediated adhesion to ICAM-1, whereas a N-terminal deletion mutant acted as a dominant negative mutant and inhibited adhesion to ICAM-1 triggered by TCR and chemokines. RAPL augment ligand-binding affinity of LFA-1 and lymphocyte polarization. Upon stimulation with chemokines, RAPL forms a complex with LFA-1 and translocates to the leading edge, depending on Rap1 activation. Taken together, these results indicate that when RAPL binds to Rap1-GTP, it induce cell polarization and translocates LFA-1, resulting in an increase of adhesiveness through modulation of affinity and clustering of LFA-1.

我们报告说，小的GTPase RAP1是一种细胞内信号分子，可提高整联蛋白粘附性，这是由趋化因子或抗原刺激触发的。 RAP1通过趋化因子激活鲁棒性刺激淋巴细胞运动。我们还证明，在生理剪切流下，通过内皮单层迁移时需要趋化因子激活RAP1。此外，RAP1激活诱导细胞极化，该细胞极化伴随着前缘和乌拉托的发展以及趋化因子受体CXCR4和CD44的重新定位，分别为前缘和uropod。为了使这些过程中的分子机制相关，我们已经确定并表征了一种新型的Rap1效应子Rapl。 RAPL是一种用活性RAP1突变体酵母筛选分离的RAP1-GTP结合30 KD蛋白。 RAPL优先用脾，淋巴结和胸腺，特别是T和B细胞表达。 RAPL过表达刺激了LFA-1介导的对ICAM-1的粘附，而N端缺失突变体充当显性阴性突变体，并抑制了由TCR和趋化因子触发的ICAM-1的粘附。 LFA-1和淋巴细胞极化的Rapl增强配体结合亲和力。用趋化因子刺激后，RAPL形成具有LFA-1的复合物，并根据RAP1激活而转移到前缘。综上所述，这些结果表明，当RAPL与RAP1-GTP结合时，它会诱导细胞极化并易位LFA-1，从而通过调节LFA-1的亲和力和聚类来提高粘附性。