Bister K, Ramsay G M, Hayman M J
J Virol. 1982 Mar;41(3):754-66. doi: 10.1128/JVI.41.3.754-766.1982.
The viral RNAs of three nonconditional mutants of avian myelocytomatosis virus MC29 were analyzed. These mutants, which were originally isolated from the quail producer line Q10 and were designated 10A, 10C, and 10H, have lost most of the ability to transform hematopoietic cells in vitro and to induce tumors in vivo, but they still transform cultured fibroblasts with the same efficiency as wild-type (wt) MC29. Electrophoretic analyses showed that the mutant genomic RNAs were smaller than the 5.7-kilobase genome of wt MC29; the genomes of mutants 10A, 10C, and 10H were about 5.5, 5.3, and 5.1 kilobases long, respectively. Analyses of the transformation-specific sequences of these mutant RNAs by a combination of T(1) oligonucleotide fingerprinting and hybridization with cDNA from the transformation-specific sequences myc of wt MC29 or competition hybridization including wt MC29 RNA revealed that deletions of myc-specific sequences had occurred. The deletions in all three mutants overlapped, since they all had lost one particular myc-specific oligonucleotide. In agreement with the size of the genomic RNAs, mutants 10C and 10H had lost two additional myc oligonucleotides, and mutant 10A contained a modified myc oligonucleotide. The locations of the deletions were deduced from comparisons with previously established oligonucleotide maps of several members of the MC29 subgroup of acute leukemia viruses and by hybridization of wt and mutant RNAs to molecularly cloned subgenomic fragments of wt MC29 proviral DNA, representing the 5' and 3' domains of the myc sequence. We found that the deleted sequences represented overlapping internal segments of the myc sequence and that the borders of myc with the partial complements of the virion genes gag and env appeared to be conserved in mutant and wt MC29 RNAs. The correlation between the altered transforming potential for hematopoietic cells and the partial deletion of myc in the mutant RNAs provided direct genetic evidence for the involvement of myc in oncogenesis. However, the unaffected efficiency of these mutants in fibroblast transformation suggested that the deleted sequences are not essential for the fibroblast-transforming potential of the onc gene of MC29.
对禽成髓细胞瘤病毒MC29的三个非条件突变体的病毒RNA进行了分析。这些突变体最初从鹌鹑生产系Q10中分离出来，分别命名为10A、10C和10H，它们在体外转化造血细胞和在体内诱导肿瘤的能力大部分丧失，但它们仍能以与野生型（wt）MC29相同的效率转化培养的成纤维细胞。电泳分析表明，突变体基因组RNA比wt MC29的5.7千碱基基因组小；突变体10A、10C和10H的基因组长度分别约为5.5、5.3和5.1千碱基。通过T(1)寡核苷酸指纹图谱与wt MC29的转化特异性序列myc的cDNA杂交或包括wt MC29 RNA的竞争杂交相结合，对这些突变体RNA的转化特异性序列进行分析，结果显示myc特异性序列发生了缺失。所有三个突变体中的缺失部分重叠，因为它们都丢失了一个特定的myc特异性寡核苷酸。与基因组RNA的大小一致，突变体10C和10H还丢失了另外两个myc寡核苷酸，而突变体10A含有一个修饰的myc寡核苷酸。通过与急性白血病病毒MC29亚组的几个成员先前建立的寡核苷酸图谱进行比较，以及通过wt和突变体RNA与wt MC29前病毒DNA的分子克隆亚基因组片段杂交（这些片段代表myc序列的5'和3'结构域），推断出缺失的位置。我们发现，缺失的序列代表myc序列的重叠内部片段，并且在突变体和wt MC29 RNA中，myc与病毒体基因gag和env的部分互补序列的边界似乎是保守的。突变体RNA中造血细胞转化潜能的改变与myc的部分缺失之间的相关性，为myc参与肿瘤发生提供了直接的遗传学证据。然而，这些突变体在成纤维细胞转化中不受影响的效率表明，缺失的序列对于MC29癌基因的成纤维细胞转化潜能并非必不可少。
