ISOTYPE SWITCHING IN A NEOPLASTIC B CELL MODEL BCL 1

我们的目标是研究与重链类相关的分子事件 小鼠B细胞淋巴瘤BCL 1的转换。 在第一批赠款中， 主要的焦点是获得可诱导的BCL 1， 各种发育表型和研究DNA重排 伴随配体诱导的分化。 这两个主要结果 研究为目前的建议提供了基础：首先，BCL 1可以 从IgM+IgD表达分化为稳定的IgM+IgG1， 等位基因排除的双生产，没有DNA重排的 重链恒定区基因。 第二，某些T细胞来源的 上清液含有诱导特异性的活性（BCDF γ）， 通过与细胞表面受体pupil相互作用表达IgG 1 通过单克隆抗体鉴定。 一个主要目标，使之成为可能， 独特的BCL 2系，是为了确定详细的分子机制， 双重Mu和Gamma1同种型生产。 使用表达的BCL 2克隆， 我们将确定Mu与Gamma1的不同比例， 调节相对同种型水平及其膜和分泌 形式被运用。 双重IgM和IgG的产生可能是一个中间过程， 表型（例如，记忆细胞）到终末分化。 因此我们 将尝试诱导BCL 2非分泌亚克隆进行进一步的 使用BCDF γ、其抗受体抗体和其他 配体。 为了测试BCDF γ作用的机制，我们将确定是否 受体阳性BCL 1细胞转染了有效重排的 γ 1和γ 3载体将经历配体诱导的分化。 最后，BCL 1染色质改变的研究旨在测试 是否有一个分子基础的“预先承诺”开关到伽玛1 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.