IMMUNOGLOBULIN GENE EXPRESSION IN MYELOMA MUTANTS

骨髓瘤突变体中的免疫球蛋白基因表达

基本信息

批准号：
3174210
负责人：
Christine Ann Milcarek
金额：
$ 13.32万
依托单位：
UNIVERSITY OF PITTSBURGH AT PITTSBURGH
依托单位国家：
美国
项目类别：
财政年份：
1983
资助国家：
美国
起止时间：
1983-08-01 至 1988-01-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/3174210
关键词：
B lymphocyte chromosome deletion gene expression genetic manipulation genetic recombination genetic transcription immunoglobulin genes immunoglobulins messenger RNA molecular cloning mutant neoplasm /cancer genetics nucleic acid sequence radiotracer

项目摘要

The molecular basis of a heavy-chain, disease-like gamma 2B immunoglobulin protein has been investigated in a murine model system. DNA sequencing of the expressed gamma 2b gene in the mutant showed a deletion of 99 nucleotides around the 3' end of the CH1 domain, which removed the splice site and neighboring DNA. The sequence deleted in the mutant is flanked by short direct repeats of the octameric sequence CCAGCCAG in the wild-type gene. In the mutant, one copy of the repeat in addition to the sequences between the repeats has been lost. This explains why no CH1 sequences are found in the mRNA. A deletion between repeated pentanucleotides has also been characterized in another mutant. The effect of direct repeats on deletion formation will be examined as well as the mechanisms by which the deletions arose. The metabolism of the mutant mRNAs produced by the altered genes is being studied by measurements of the rates of synthesis and degradation. The differential expression of two forms of mRNA, coding for proteins with either secretory or membrane anchoring carboxyl-termini, from a single gamma 2b gene is being investigated. The immunoglobulin gene has been transfected, in collaboration with Dr. S. L. Morrison, into cell lines fixed at various stages of B-cell development. We find that the transfected gene is differentially expressed in the various cell lines. Constructs with deletions of portions of the immunoglobulin genes have been shown to differentially produce membrane-\or secretory-specific mRNAs with sequences 3' of the secretory polyadenylation site important for correct 3' end formation. Equimolar transcription of the entire gamma 2b gene, secretory plus membrane exons, has been observed. In isolated nuclei, the secretory polyadenylstion site is preferentially used by cells producing primarily secretory mRNA. Selective use of alternate polyadenylation sites can, therefore, modulate the production of the two forms of mRNA from one gene. (AB)

重链疾病样 γ 2B 免疫球蛋白的分子基础蛋白质已在小鼠模型系统中进行了研究。 DNA 测序突变体中表达的 γ 2b 基因显示缺失 99 CH 1 结构域 3' 端周围的核苷酸，去除了剪接位点和邻近的 DNA。突变体中删除的序列两侧是野生型中八聚体序列 CCAGCCAG 的短同向重复序列基因。在突变体中，除了序列之外，还有一份重复序列重复之间已经丢失。这解释了为什么没有 CH 1 序列存在于 mRNA 中。重复五核苷酸之间的缺失在另一个突变体中也得到了表征。直接重复的影响将检查缺失的形成以及缺失的机制出现了删除。突变体 mRNA 的代谢通过测量合成速率来研究改变的基因和退化。两种形式的 mRNA 的差异表达，编码具有分泌或膜锚定羧基末端，来自单个 γ 2b 基因正在研究中。免疫球蛋白基因已被与 S. L. Morrison 博士合作转染至细胞系固定在 B 细胞发育的各个阶段。我们发现转染基因在不同细胞系中差异表达。删除了部分免疫球蛋白基因的构建体已被显示出差异化地产生膜特异性或分泌特异性 mRNA 分泌性多腺苷酸化位点的 3' 序列对于正确的 3' 很重要结束形成。整个 gamma 2b 基因的等摩尔转录，已观察到分泌性加膜外显子。在孤立的原子核中，分泌性多腺苷酸化位点优先被细胞产生主要是分泌性mRNA。选择性使用替代多聚腺苷酸化位点因此，可以调节一种mRNA的两种形式的产生基因。 (AB)