Da Sylva Tanya R, Fong Ivan C, Cunningham Lesley A, Wu Gillian E
Faculty of Pure and Applied Science, York University, Room 136, Farquharson Building, 4700 Keele St., Toronto, Ont., Canada M3J 1P3.
Mol Immunol. 2007 Feb;44(5):889-99. doi: 10.1016/j.molimm.2006.03.022. Epub 2006 May 15.
The expression of RAG1 and RAG2 is essential for V(D)J rearrangement of the immunoglobulin (Ig) locus in developing B cells. In mature B cells further V(D)J rearrangement is suppressed and RAG1/2 proteins decline to undetectable levels. However, there is evidence that mature B cells in the periphery may re-express RAG1/2. In humans evidence of RAG1/2 re-expression is often linked with an autoimmune state, indicating that further understanding of re-expression may be crucial to understanding immune disorders. We have investigated the molecular consequences of RAG1/2 expression in mature lymphocytes using a cell culture system (M12 and DR3). M12 (IgG+, Igkappa+ and RAG-) is a mouse B cell lymphoma. DR3 is a RAG1+/RAG2+ line derived from M12 by introduction of stable plasmids carrying RAG1 and RAG2 cDNAs. RAG1/2 mediated receptor revision occurs in the DR3 line, as evidenced by both the deletion of the endogenous rearranged Igkappa gene segment (present in the parent M12 lines) and the presence of a new Iglambda rearrangement. Gene expression profiles obtained through microarray analysis and RT-PCR found differences in expression levels between the two lines for: fibronectin, lysyl oxidase, TAP2, B220, Igkappa, TIS11B, HMG2 and DNAPKcs. Thus, the expression of RAG1/2 in a previously RAG- cell line results in multiple changes to the gene expression profile as well as receptor revision. The significance of the changes found in this model of RAG re-expression is discussed.
RAG1和RAG2的表达对于发育中的B细胞免疫球蛋白（Ig）基因座的V（D）J重排至关重要。在成熟B细胞中，进一步的V（D）J重排受到抑制，RAG1/2蛋白水平下降至无法检测。然而，有证据表明外周成熟B细胞可能重新表达RAG1/2。在人类中，RAG1/2重新表达的证据通常与自身免疫状态相关，这表明进一步了解重新表达可能对理解免疫紊乱至关重要。我们使用细胞培养系统（M12和DR3）研究了成熟淋巴细胞中RAG1/2表达的分子后果。M12（IgG +、Igκ +且RAG -）是一种小鼠B细胞淋巴瘤。DR3是通过导入携带RAG1和RAG2 cDNA的稳定质粒从M12衍生而来的RAG + /RAG2 +细胞系。RAG1/2介导的受体编辑发生在DR3细胞系中，内源性重排的Igκ基因片段（存在于亲本M12细胞系中）的缺失以及新的Igλ重排的存在均证明了这一点。通过微阵列分析和RT-PCR获得的基因表达谱发现，两细胞系在以下基因的表达水平上存在差异：纤连蛋白、赖氨酰氧化酶、TAP2、B220、Igκ、TIS11B、HMG2和DNA-PKcs。因此，在先前RAG -的细胞系中RAG1/2的表达导致基因表达谱发生多种变化以及受体编辑。本文讨论了在该RAG重新表达模型中发现的变化的意义。
