RNA Processing Regulation of Immunoglobulin Gene Expression

人类基因组被发现编码的基因数量少得惊人。然而，多达60%的基因可能会被交替处理，以产生更多多样性的蛋白质。因此，为了充分了解基因表达，必须了解替代RNA加工的复杂过程是如何调节的。这将需要使用成熟的监管过程模型来破译这些过程的机械细节。小鼠免疫球蛋白Mu基因作为调节B淋巴细胞发育过程中RNA加工的模型系统已被研究多年。该基因包含一个与剪接反应竞争的切割-聚腺苷酸化位点；当B细胞成熟为浆细胞时，这两种加工方式的相对使用受到调节。在RNA加工调控中，Ig u Pre-mRNA中RNA加工信号的排列和相对强度比基因特异性的顺式作用调控序列更重要。这表明，B细胞和浆细胞之间的调节必须涉及到一般RNA处理机制的组件的变化。随着B细胞向浆细胞的成熟，切割-聚腺苷酸化和剪接活性都发生了变化。此外，RNA代谢的其他步骤，包括转录延长、核质mRNA运输和RNA稳定性，已经被证明在B细胞和浆细胞之间是不同的。该项目的目标是识别参与调节替代Ig u mRNA加工的蛋白质，以更好地了解这一调节机制。有大量证据表明，B细胞的终末分化程序，包括u-S/u-mmRNA处理的变化，是由一种复杂的转录调控因子相互作用驱动的。微阵列筛选将被用来识别在B细胞向浆细胞发育过程中表达变化的基因；其中一些差异表达的基因将编码与RNA加工调控相关的产物。候选蛋白的过度表达和抑制将决定它们在B细胞成熟过程中对RNA代谢的作用。这项研究将涉及研究生、本科生以及可能的高中生。

The human genome has been found to encode a surprisingly small number of genes. However, as many as 60% of all genes may be alternatively processed to generate a much greater diversity of proteins. Thus, to fully understand gene expression, how the complex process of alternative RNA processing is regulated must be understood. This will require that well-established models for regulated processing be used to decipher the mechanistic details of these processes. The mouse immunoglobulin mu gene has been studied for many years as a model system for regulated RNA processing during B lymphocyte development. This gene contains a cleavage-polyadenylation site that is in competition with a splice reaction; the relative use of these two processing options is modulated as B cells mature to plasma cells. The arrangement and relative strengths of RNA processing signals in the Ig mu pre-mRNA is more important than gene-specific cis-acting regulatory sequences for the RNA processing regulation. This indicates that the regulation between B cells and plasma cells must involve changes in components of the general RNA processing machinery. Both cleavage-polyadenylation and splicing activity have been shown to change as B cells mature to plasma cells. In addition, other steps of RNA metabolism, including transcriptional elongation, nuclear:cytoplasmic mRNA transport and RNA stability have been shown to differ between B cells and plasma cells. The goal of this project is to identify proteins involved in regulating alternative Ig mu mRNA processing to better understand this regulatory mechanism. There is substantial evidence that the terminal differentiation program of B cells, including changes in mu-s/mu-m mRNA processing, is driven by a complex interplay of transcriptional regulators. Microarray screening will be used to identify genes whose expression changes during the developmental transition of B cells to plasma cells; some of these differentially expressed genes will encode products relevant to RNA processing regulation. Over-expression and inhibition of candidate proteins will determine their role in RNA metabolism during B cell maturation. This research will involve graduate, undergraduate, and, potentially, high school students.