MOLECULAR BIOLOGY AND BIOCHEMICAL STRUCTRUE OF ENDOGENOUS PROVIRUSES OF MICE

我们以前从BALB/c中分离出几种内源性MuLV前病毒 和AKR/J小鼠DNA。 的分子和生物化学表征 克隆的内源性MuLV DNA表明，约50%与已知的MuLV相关， MuLV前病毒（I类）。 限制性内切酶和核苷酸序列 分析表明，I类内源性MuLV DNA可能是 与已知的感染性MuLV前病毒不同，因为存在 转座子样190 bp的细胞插入在他们的LTR和独特的 限制性位点。 此外，与病毒相关的env序列 大多数这样的内源性MuLV DNA类似于存在于 重组MCF MuLV。 事实上，一个克隆的内源性AKR MuLV DNA， 命名为A-12，其5 ′ env区序列几乎相同 白血病MCF-MuLV env基因。 我们已经确定了 A-12前病毒的位置在染色体13或18上。 不像其他 内源性MuLV DNA，A-12内源性前病毒存在于几个 近交系和野生小鼠的DNA。 核苷酸序列比较 LTR，3' pol和env区的白血病（MCF-13）和非白血病 （MCF-111 A）MuLV在env中具有高度的碱基同源性， 地区 MCF-13的LTR与MCF-13中存在的LTR高度相关。 异嗜性MuLV，而与MCF-111 A相关的LTR相同 除了亲嗜性MuLV前病毒LTR的1bp。 的3'极区 MCF-13含有致白血病MCF的特征性12 bp序列 MuLV。 这在MCF-111 A MuLV DNA中不存在。 致白血病的可能性 的体外构建的重组MuLV进行了测试。 这些病毒 含有5' MCF-13 LTR、gag、pol和env序列， env和LTR序列。 用这种重组体接种的新生AKR小鼠 病毒在约3个月内发展成胸腺淋巴瘤。 组织特异 在不同的AKR/N中检测到内源性MCF相关mRNA的表达， 小鼠组织中使用P32标记的MCF env特异性合成DNA探针。 一 7.2在胸腺中鉴定出kb mRNA种类，其可能参与 重组亲胸腺MCF病毒的产生。

We had previously isolated several endogenous MuLV proviruses from BALB/c and AKR/J mouse DNAS. Molecular and biochemical characterization of the cloned endogenous MuLV DNAs indicated that about 50% were related to known MuLV proviruses (Class I). Restriction enzyme and nucleotide sequence analysis indicated that the Class I endogenous MuLV DNAs could be distinguished from known infectious MuLV proviruses due to the presence of a transposon-like 190 bp cellular insert in their LTRs and unique restriction sites. Furthermore, the env sequences associated with the majority of such endogenous MuLV DNAs were similar to those present in recombinant MCF MuLVs. In fact, one cloned endogenous AKR MuLV DNA, designated as A-12, was almost identical in sequence of its 5' env region with leukemogenic MCF-MuLV env genes. We have determined the genomic location of the A-12 provirus to be on chromosome 13 or 18. Unlike other endogenous MuLV DNAs, the A-12 endogenous provirus was present in several inbred as well as wild mouse DNAs. Nucleotide sequence comparison of the LTR, 3' pol and env regions of leukemogenic (MCF-13) and non-leukemogenic (MCF-111A) MuLVs indicated a high degree of base homology in the env region. The LTR of MCF-13 was highly related to the LTR present in xenotropic MuLVs whereas, the LTR associated with MCF-111A was identical except for 1 bp with ecotropic MuLV proviral LTRs. The 3' pol region of MCF-13 contained a 12 bp sequence characteristic of leukemogenic MCF MuLVs. This was absent in MCF-111A MuLV DNA. The leukemogenic potential of in vitro constructed recombinant MuLVs was tested. These viruses contained 5' MCF-13 LTR, gag, pol and env sequences and 3' endogenous MuLV env and LTR sequences. Newborn AKR mice inoculated with such recombinant viruses developed thymic lymphomas in about 3 months. Tissue-specific expression of endogenous MCF-related mRNAs was detected in various AKR/N mouse tissues using P32-labeled MCF env-specific synthetic DNA probe. A 7.2 kb mRNA species was identified in the thymus which could be involved in the generation of recombinant thymotropic MCF viruses.