STRUCTURAL AND FUNCTIONAL STUDIES OF MAMMALIAN ENDOGENOUS RETROVIRAL SEQUENCES

哺乳动物基因组包含与逆转录病毒相关的多个拷贝 序列。其中大部分是病毒缺陷。 表达；然而，有些可以产生亚基因组RNA。年龄- 研究内源性逆转录病毒序列的依赖表达 利用内源性MULV和人在野鼠和人的肌肉中的应用 4-1个DNA探针。在这两个案例中，都在肾脏中检测到了转录本， 脑和肝组织，但在肾脏中表达最高。 与MuLV相关的RNA，8.4kb、3.0kb和1.8kb贯穿始终 寿命(18天胚胎-28个月龄)，并随着年龄的增加而增加。 在人体组织中发现了3.0kb和1.8kb的转录本，从8个 月胎--85岁。这些RNA似乎也增加了 随着年龄的增长。研究结果表明，中国的基因控制有所放松 哺乳动物细胞随着年龄的增长。 克隆了一个新的5.0kb逆转录类元件B-13。 Balb/c小鼠胚胎DNA测序。它是远亲 与已知的MuLV DNA：&lt；在Gag和Pols中发现75%的同源性 区域；缺少env序列。分离到的另外两个克隆DNA 从BALB/c小鼠基因组中含有类似B-13的基因 不同的侧翼细胞序列。几份B-13的副本- 在近亲交配和近缘野生动物中检测到相关基因 小鼠基因组。这些结果表明，类B-13元素是 在小鼠基因组中扩增和分散。 在5‘端发现了两个新的蛋白结合位点 所有与MULV相关的LTRs均以30bP齐聚物为探针在凝胶中 迁移率变化分析。这些高度保守的遗址存在 在指定为上游的区域中的增强子的上游 保守区域(UCR)和结合核因子被指定为 L和UCRF-U。UCRF-L是小鼠中的优势种 而UCRF-U主要存在于细胞系中。北方 对5个不同品系的小鼠的分析表明， MuLV核糖核酸表达与尿激素性肾衰L活性的相关性研究这 在自发性和内毒素诱导的情况下都可以看到这种关系 MuLV RNAs。这些结果表明负调控功能。 UCRF-L对MULV基因的表达。

Mammalian genomes contain multiple copies of retroviral-related sequences. The majority of these are defective for virus expression; however, some can produce subgenomic RNAs. Age- dependent expression of endogenous retroviral sequences was studied in Mus musculus wild mouse and man using endogenous MuLV and human 4-1 DNA probes. In both cases transcripts were detected in kidney, brain, and liver tissues, but expression was highest in the kidney. MuLV-related RNAs, 8.4 kb, 3.0 kb, and 1.8 kb were seen throughout life (18 day old embryo - 28 months of age) and increased with age. Transcripts, 3.0 kb and 1.8 kb, were seen in human tissues from 8 month fetus -85 years of age. These RNAs also appeared to increase with age. The results suggest a relaxation of gene control in mammalian cells with aging. A novel 5.0 kb retrotransponson-like element, B-13, was cloned from BALB/c mouse embryo DNA and sequenced. It was distantly related to known MuLV DNAs: <75% homology was seen in the gag and pol regions; env sequences were absent. Two other cloned DNAs isolated from the BALB/c mouse genome contained B-13-like genes but different flanking cellular sequences. Several copies of B-13- related genes were detected in inbred and closely related wild mouse genomes. These results indicate that B-13-like elements are amplified and dispersed in the mouse genome. Two novel protein binding sites were identified at the 5' end of all MuLV-related LTRs using 30 bp oligomers as probes in gel mobility shift assays. These highly conserved sites were present upstream of the enhancer in a region designated as the upstream conserved region (UCR) and bound nuclear factors designated as UCRF-L and UCRF-U. UCRF-L was the prominent species in murine tissue whereas UCRF-U predominated in cell lines. Northern analysis of 5 different mouse strains indicated a good inverse correlation between MuLV RNA expression and UCRF-L activity. This relationship was seen in case of both spontaneous and LPS-induced MuLV RNAs. These results suggest a negative regulatory function of UCRF-L in MuLV gene expression.