HGAL 和 Grb2 蛋白之间的相互作用调节 B 细胞受体信号转导。

Interplay between HGAL and Grb2 proteins regulates B-cell receptor signaling.

机构信息

Division of Oncology-Hematology, Department of Medicine, University of Miami Miller School of Medicine, Sylvester Comprehensive Cancer Center, Miami, FL.

Department of Physics, University of Calabria, Rende, Italy.

出版信息

Blood Adv. 2019 Aug 13;3(15):2286-2297. doi: 10.1182/bloodadvances.2018016162.

Abstract

Human germinal center (GC)-associated lymphoma (HGAL) is an adaptor protein expressed in GC B cells. HGAL regulates cell motility and B-cell receptor (BCR) signaling, processes that are central for the successful completion of the GC reaction. Herein, we demonstrate phosphorylation of HGAL by Syk and Lyn kinases at tyrosines Y80, Y86, Y106Y107, Y128, and Y148. The HGAL YEN motif (amino acids 107-109) is similar to the phosphopeptide motif pYXN used as a binding site to the growth factor receptor-bound protein 2 (Grb2). We demonstrate by biochemical and molecular methodologies that HGAL directly interacts with Grb2. Concordantly, microscopy studies demonstrate HGAL-Grb2 colocalization in the membrane central supramolecular activation clusters (cSMAC) following BCR activation. Mutation of the HGAL putative binding site to Grb2 abrogates the interaction between these proteins. Further, this HGAL mutant localizes exclusively in the peripheral SMAC and decreases the rate and intensity of BCR accumulation in the cSMAC. Furthermore, we demonstrate that Grb2, HGAL, and Syk interact in the same complex, but Grb2 does not modulate the effects of HGAL on Syk kinase activity. Overall, the interplay between the HGAL and Grb2 regulates the magnitude of BCR signaling and synapse formation.

摘要

人类生发中心(GC)相关淋巴瘤(HGAL)是一种在 GC B 细胞中表达的衔接蛋白。HGAL 调节细胞迁移和 B 细胞受体(BCR)信号转导,这些过程是 GC 反应成功完成的关键。在此,我们证明了 Syk 和 Lyn 激酶在 HGAL 的酪氨酸残基 Y80、Y86、Y106、Y107、Y128 和 Y148 上对其进行磷酸化。HGAL 的 YEN 基序(氨基酸 107-109)类似于磷酸肽基序 pYXN,可作为与生长因子受体结合蛋白 2(Grb2)的结合位点。我们通过生化和分子方法证明 HGAL 可直接与 Grb2 相互作用。一致地,显微镜研究表明,在 BCR 激活后,HGAL-Grb2 共定位在膜中央超分子激活簇(cSMAC)中。将 HGAL 与 Grb2 相互作用的假定结合位点突变为丙氨酸后,可破坏这些蛋白质之间的相互作用。此外,这种 HGAL 突变体仅定位于外周 SMAC 中,并降低了 BCR 在 cSMAC 中的积累速度和强度。此外,我们证明了 Grb2、HGAL 和 Syk 相互作用于同一复合物中,但 Grb2 不会调节 HGAL 对 Syk 激酶活性的影响。总的来说,HGAL 和 Grb2 之间的相互作用调节了 BCR 信号转导和突触形成的幅度。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/2243/6693015/0126f682f809/advances016162absf1.jpg

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