Saule S, Coll J, Righi M, Lagrou C, Raes M B, Stehelin D
EMBO J. 1983;2(6):805-9. doi: 10.1002/j.1460-2075.1983.tb01506.x.
The four avian defective leukemia retroviruses (DLVs) MC29, CMII, MH2 and OK10 all transform primarily macrophages in an in vitro bone marrow transformation assay, and contain specific nucleotide sequences closely related to the myc gene of MC29. These viruses were thought to express their oncogenic potential through a gag-myc fusion polyprotein, since fusion polyproteins were found in all tested cells transformed by MC29. We show here that MH2 virus does not conform to this model. Whereas MC29 produces only one mRNA detectable by RNA blotting in productively transformed cells, we reported recently that OK10 induced the synthesis of two myc-containing mRNAs, the smaller species being a spliced mRNA and a possible candidate for a transforming protein lacking gag determinants. However, the studies with OK10 were ambiguous because this virus produced also, in infected cells, a fusion protein containing gag, pol and myc determinants. We have therefore investigated the transcription pattern of the two other members of this group of viruses, namely CMII and MH2. Our results show that CMII resembles MC29 whereas MH2 produces, as OK10, two mRNAs containing myc-related sequences. However, unlike OK10, the MH2 fusion protein of 100 kd described previously cannot contain myc determinants and thus is likely to produce from its subgenomic mRNA a v-myc protein-lacking gag determinants. We thus conclude that the product of the v-myc oncogene is transforming with (MC29) or without (MH2) its fusion to gag determinants and that the multiple oncogenic spectrum is not basically affected since MH2 and MC29 both transform macrophages, fibroblasts and epithelial cells.
四种禽源缺陷型白血病逆转录病毒（DLV），即MC29、CMII、MH2和OK10，在体外骨髓转化试验中主要转化巨噬细胞，并且含有与MC29的myc基因密切相关的特定核苷酸序列。这些病毒被认为通过gag-myc融合多聚蛋白来表达其致癌潜能，因为在所有经MC29转化的测试细胞中都发现了融合多聚蛋白。我们在此表明，MH2病毒并不符合这一模型。MC29在有效转化的细胞中通过RNA印迹法仅能检测到一种mRNA，而我们最近报道OK10诱导合成了两种含myc的mRNA，较小的一种是剪接后的mRNA，可能是缺乏gag决定簇的转化蛋白的候选者。然而，对OK10的研究并不明确，因为这种病毒在感染细胞中还产生了一种包含gag、pol和myc决定簇的融合蛋白。因此，我们研究了这组病毒的另外两个成员，即CMII和MH2的转录模式。我们的结果表明，CMII与MC29相似，而MH2与OK10一样，产生两种含myc相关序列的mRNA。然而，与OK10不同的是，先前描述的100kd的MH2融合蛋白不可能包含myc决定簇，因此很可能从其亚基因组mRNA产生一种缺乏gag决定簇的v-myc蛋白。我们因此得出结论，v-myc癌基因的产物在与gag决定簇融合（MC29）或不融合（MH2）的情况下都具有转化能力，并且由于MH2和MC29都能转化巨噬细胞、成纤维细胞和上皮细胞，所以多种致癌谱基本上不受影响。
