Molecular Genetics of the Red Cell Membrane Skeleton

描述(申请人提供)：这项建议的长期目标是阐明膜骨架蛋白编码基因的表达所涉及的分子机制，特别是编码血影蛋白的基因，这是红细胞和非红系细胞膜骨架的重要组成部分。对这些基因的研究具有科学意义，因为这些基因在红系和非红系细胞中产生不同的异构体。这种多样性提供了在分子水平上研究特定组织中组织特异性基因表达的机制的机会，包括染色质结构的相关变化，替代启动子的使用和调控，以及组织特异性选择性剪接的调控。利用结构非常相似但在不同组织中表达模式非常不同的基因家族成员对这些机制进行详细分析，可以为真核生物中基因表达的分子生物学提供重要的见解。此外，血影蛋白具有生物学和医学价值，因为红系基因突变与遗传性溶血性贫血有关，而且非红系基因产物与一些重要的神经功能有关。拟议的实验包括：识别和表征调控红系β-血影蛋白基因组织特异性转录的顺式决定因素；研究β-血影蛋白基因嵌入红系细胞和表达该基因的肌肉细胞中的染色质结构；以及研究转录后前mRNA加工事件所涉及的分子机制，如交替切割-多腺苷基化和选择性剪接，这些事件导致不同组织产生不同的β-血影蛋白C末端亚型。

DESCRIPTION (provided by applicant): This proposal has as its long-term objective the elucidation of molecular mechanisms involved in the expression of genes encoding proteins of the membrane skeleton, in particular the genes encoding the spectrins, important constituents of the membrane skeleton of erythrocytes as well as nonerythroid cells. Study of these genes is of scientific interest because of the diversity of isoforms that these genes produce in erythroid and nonerythroid cells. This diversity presents the opportunity to investigate at the molecular level mechanisms involved in tissue-specific gene expression in specialized tissues, including associated changes in chromatin structure, use and regulation of alternative promoters and regulation of tissue-specific alternative splicing. A detailed analysis of these mechanisms using members of a gene family that are structurally very similar, but behave very differently in their pattern of expression in various tissues, can provide important insights in the molecular biology of gene expression in eukaryotes. In addition, there is biological and medical interest in the spectrins because mutations in the erythroid gene are associated with hereditary hemolytic anemias, and because the non-erythroid gene products have been implicated in some important neurological functions. The proposed experiments include: identification and characterization of cis determinants that regulate the tissue specific transcription of the erythroid beta-spectrin gene; study of the chromatin structure in which the beta-spectrin gene is embedded in erythroid and muscle cells that express the gene; and study of the molecular mechanisms involved in the post-transcriptional pre-mRNA processing events, such as alternative cleavage-polyadenylation and alternative splicing, that result in the production of different C-terminal isoforms of beta-spectrin in different tissues.