MOLECULAR BIOLOGY AND BIOCHEMICAL STRUCTRUE OF ENDOGENOUS PROVIRUSES OF MICE

我们之前已经从BALB/c中分离到了几个内源性MuLV前病毒 和AKR/J小鼠DNA。黄曲霉毒素的分子生物学特性 克隆的内源MuLV DNA表明，约50%与已知的 MULV PRORUS(I类)。限制性内切酶与核苷酸序列 分析表明，I类内源MuLV DNA可能是 与已知的传染性MULV前病毒不同，因为存在 在它们的LTRs中有一个类似转座子的190个碱基的细胞插入，并且是独一无二的 限制点。此外，与 大多数这样的内源性MuLV DNA与存在于 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区序列几乎完全相同 携带白血病MCF-MuLV env基因。我们已经确定了基因组 A-12前病毒位于13号或18号染色体上。不同于其他 内源MuLV DNA，A-12内源性前病毒存在于几个 近亲繁殖的和野生的老鼠DNA。两株病毒的核苷酸序列比较 白血病(MCF-13)和非白血病(NHL)的LTR、3‘Pol和env区 (McF-111a)MULV表明环境中的碱基同源性很高 区域。MCF-13的LTR值与存在的LTR值高度相关 而与MCF-111a相关的LTR是相同的 除1个BP伴生态型MuLV前病毒LTRS外，其余均为LTRS。的3‘POL区域 MCF-13含有一个12bp的白血病致病MCF特征序列 MuLV。这在MCF-111a MuLV DNA中是不存在的。白血病的致病潜能 对体外构建的重组小鼠肺泡巨噬细胞进行检测。这些病毒 包含5‘MCF-13 LtR、Gag、Pol1和env序列和3’内源小鼠白血病病毒 Env和ltr序列。给新生AKR小鼠接种这种重组 病毒在大约3个月内发展为胸腺淋巴瘤。组织特异性 内源性MCF相关mRNAs在不同AKR/N中的表达 小鼠组织采用P32标记的MCF env特异性合成DNA探针。一个 在胸腺中发现了7.2kb的信使核糖核酸，它可能参与了 重组嗜胸腺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.