ISOTYPE SWITCHING IN A NEOPLASTIC B CELL MODEL BCL 1

我们的目标是研究与重链类有关的分子事件 切换为小鼠B细胞淋巴瘤，BCL1。在第一笔赠款中， 主要的重点是获得BCL1的诱导版本，该版本显示了 不同发育表型和DNA重排的研究 伴随配体诱导分化。由此得出的两个主要结果 研究为本建议提供了依据：第一，《基本法》第1条可以 经历从IgM+IgD表达到稳定的IgM+IgG1的分化， 等位排除的双生产，不需要DNA重排 重链恒定区基因。第二，某些T细胞来源 上清液含有一种活性(BCDFGamma)，它能诱导特定的 推测是通过与细胞表面受体相互作用来表达IgG1 由一种单抗鉴定。主要目标，使之成为可能 唯一的BCL2系，是为了确定详细的分子机制 双Mu和Gamma1同型生产。使用BCL2克隆来表达 不同的Mu和Gamma1的比例，我们将确定 相对同型水平及其膜和分泌的调节 形式是施展的。免疫球蛋白和免疫球蛋白双重产生可能是一种中间产物 从表型(如记忆细胞)到终末分化。因此我们 将尝试诱导BCL2非分泌性亚克隆进一步经历 BCDFGamma及其抗受体抗体等与肿瘤分化的关系 配基。为了测试BCDFGamma的作用机制，我们将确定 高效重排基因转染受体阳性的BCL1细胞 Gamma1和Gamma3载体将经历配体诱导分化。 最后，设计了一项关于bcl1染色质变化的研究，以测试 “预先承诺”转换为Gamma1是否有分子基础 在这些细胞中观察到。

Our goal is to study the molecular events related to heavy chain class switching in a murine B cell lymphoma, BCL1. In the first grant the primary focus was to obtain inducible versions of BCL1 that displayed various developmental phenotypes and to study the DNA rearrangements accompanying ligand-induced differentiation. Two major results from these studies have provided the basis for the present proposal: First, BCL1 can undergo differentiation from IgM+IgD expression to stable IgM+IgG1, allelically excluded double-production without DNA rearrangement of the heavy chain constant region genes. Second, certain T cell-derived supernatants contain an activity (BCDFGamma) that induces specific expression of IgG1 by interaction with a cell surface receptor, putatively identified by a monoclonal antibody. A primary objective, made possible by the unique BCL2 line, is to determine the detailed molecular mechanism for dual Mu and Gamma1 isotype production. Using BCL2 clones which express different ratios of Mu to Gamma1 we will determine the point at which regulation of the relative isotype levels and their membrane and secreted forms is exerted. Dual IgM and IgG production may be an intermediate phenotype (e.g., memory cell) to terminal differentiation. Therefore we will attempt to induce BCL2 nonsecreting subclones to undergo further differentiation using BCDFGamma, its anti-receptor antibody and other ligands. To test the mechanism of BCDFGamma action, we will determine if receptor-positive BCL1 cells transfected with productively rearranged Gamma1 and Gamma3 vectors will undergo ligand induced differentiation. Finally, a study of the chromatin alterations in BCL1 is designed to test whether there is a molecular basis for the "precommitted" switch to Gamma1 observed in these cells.