Molecular analysis of BCR signaling pathways

Chan博士和Kurosaki博士共同研究了BLNK（一种衔接分子）参与BCR信号通路的分子机制。通过重组研究，我们发现T细胞表达的BLNK相关衔接分子SLP-76可以在BLNK缺陷的DT 40 B细胞中重建BCR功能。这可能是由于抗原受体交联后SLP-76不能被募集到富含糖脂的微区（GEMS）中。支持这一观点，当膜相关的SLP-76嵌合体被强制定位于GEMS时，BCR功能可以恢复。此外，向SLP-76中添加LAT和Gads两者允许SLP-76被募集到GEM中，由此重建BCR功能。与SLP-76相比，BLNK不需要Grb 2家族的参与就能募集到GEM中。因此，这些数据表明BLNK和SLP-76之间的功能重叠，同时强调在靶向GEM时需要额外的衔接分子的差异。Clark和Kurosaki博士共同研究了BCR信号传导中另一种衔接分子Bam 32的功能。通过分析Bam 32缺陷的DT 40 B细胞，我们提供了Bam 32参与BCR介导的/钙通路的证据，可能解释了缺陷的NF-AT和NF-KB激活。

Drs. Chan and Kurosaki have coworked the molecular mechanisms by which BLNK, an adaptor molecule, participates in BCR signaling pathways. Using reconstitution studies, we found that SLP-76, BLNK-related adaptor molecule expressed in T cells, canhot reconstitute BCR functions in BLNK-deficient DT40 B cells. This could be attributable to inability of SLP-76 to be recruited into glycolipid-enriched microdomains (GEMS) after antigen receptor cross-linking. Supporting this idea, the BCR function can be restored when a membrane-associated SLP-76 chimera is enforcedly localized to GEMS. Moreover, addition of both LAT and Gads to SLP-76 allows SLP-76 to be recruited into GEMs, whereby the BCR function is reconstituted. The Gads function can be replaced by overexpression of Grb2.In contrast to SLP-76.BLNK did not require Grb2 families for its recruitment to GEMs. Hence, these data suggest a functional overlap between BLNK and SLP-76, while emphasizing the difference in requirement for additional adaptor molecules in their targeting to GEMs.Drs. Clark and Kurosaki coworked the function of Bam32, another adaptor molecule, in BCR signaling. By analyzing Bam32-deficient DT40 B cells, we have provided the evidence that Bam32 is involved in BCR-mediated/calcium pathway, presumably explaining the defective NF-AT and NF-KB activation.