DeFeo D, Gonda M A, Young H A, Chang E H, Lowy D R, Scolnick E M, Ellis R W
Proc Natl Acad Sci U S A. 1981 Jun;78(6):3328-32. doi: 10.1073/pnas.78.6.3328.
Harvey murine sarcoma virus (Ha-MuSV) is a mouse-rat recombinant retrovirus that encodes a protein designated p21, required for virally induced transformation. Using a radiolabeled DNA fragment from the p21 coding region, we have detected homologous DNA sequences in the normal DNA of rats and of several other vertebrate species. Moreover, many tested cells from these species contain low levels of a p21 protein that is highly related to viral 21. Now we report two independent fragments from normal rat DNA containing sequences (sarc) homologous to the Ha-MuSV transforming region that were cloned in the bacteriophage vector Charon 4A. Sarc sequences in the one fragment are completely colinear with the viral sequences and share apparently all restriction endonuclease sites. Sarc sequences in the second fragment have several sets of intervening sequences and lack some restriction endonuclease sites found in the viral transforming region. Despite the presence of these intervening sequences in the second sarc fragment, we have been able to ligate this sarc fragment to the long terminal repeat sequence of HaMuSV and to induce cellular transformation and high levels of p21 expression upon transfection of this DNA to NIH 3T3 mouse cells. These results suggest that elevated levels of p21, normally expressed at low levels in a variety of cells, can induce cellular transformation.
哈维鼠肉瘤病毒（Ha-MuSV）是一种鼠-大鼠重组逆转录病毒，它编码一种名为p21的蛋白质，该蛋白质是病毒诱导转化所必需的。利用来自p21编码区的放射性标记DNA片段，我们在大鼠以及其他几种脊椎动物的正常DNA中检测到了同源DNA序列。此外，来自这些物种的许多测试细胞含有低水平的与病毒p21高度相关的p21蛋白。现在我们报告从正常大鼠DNA中分离出的两个独立片段，它们含有与Ha-MuSV转化区同源的序列（sarc），这些片段被克隆到噬菌体载体Charon 4A中。其中一个片段中的sarc序列与病毒序列完全共线，并且显然共享所有的限制性内切酶位点。第二个片段中的sarc序列有几组间隔序列，并且缺少病毒转化区中发现的一些限制性内切酶位点。尽管第二个sarc片段中存在这些间隔序列，但我们已能够将该sarc片段连接到HaMuSV的长末端重复序列上，并在将该DNA转染到NIH 3T3小鼠细胞后诱导细胞转化和高水平的p21表达。这些结果表明，通常在多种细胞中低水平表达的p21水平升高可诱导细胞转化。
