A single Glu(62)-to-Lys(62) mutation in the Mos residues of the R7Delta447Gag-tMos protein causes the mutant virus to induce brain lesions.
We previously reported that R7Delta447, a 2954-base-pair (bp) laboratory-generated Moloney murine sarcoma virus, induced subcutaneous tumors in about 14% of infected mice but did not induce brain lesions. We now report that R7Delta447K, a spontaneous mutant of R7Delta447, induced brain lesions as well as subcutaneous tumors in all injected mice. The genomes of the two viruses differ in a single base pair: the deduced Glu(62) of the Mos residue of the R7Delta447 Gag-tMos protein is changed to Lys(62). More R7Delta447 than R7Delta447K focus-forming units were detected in both NIH3T3 and mouse cerebral vascular endothelial (MCVE) cells. However, R7Delta447K transformed NIH3T3 and MCVE cells more acutely than did R7Delta447. A distinctive feature that distinguished the morphologic transformation of R7Delta447- and R7Delta447K-infected MCVE cells is the markedly prolonged spindle-shaped phase exhibited by R7Delta447-infected MCVE cells. In addition, R7Delta447K was more efficient in inducing the phosphorylation of ERK1/2 than R7Delta447 in both MCVE and NIH3T3 cells. Moreover morphologic transformation was inhibited, and levels of phosphorylated ERK1/2 were reduced when R7Delta447- or R7Delta447K-infected NIH3T3 or MCVE cells were grown in the presence of the MEK1/2-specific inhibitor PD98095. Thus, we have identified a key residue in the Gag-tMos protein that profoundly affects activation of the Mos/MEK/ERK pathway, virus and cell replication, morphologic transformation in vitro and pathogenicity in vivo.
Yuen
P H
PH
Department of Carcinogenesis, Science Park-Research Division, The University of Texas M.D. Anderson Cancer Center, Smithville, TX 78957, USA.
Ryan
E A
EA
Devroe
E
E
Wong
P K
PK
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001932:Brain Neoplasms / Q000235:genetics*; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D008980:Moloney murine sarcoma virus / Q000235:genetics* / Q000472:pathogenicity*; D009154:Mutation; D017232:Oncogene Proteins v-mos / Q000235:genetics*; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D010766:Phosphorylation; D012878:Skin Neoplasms / Q000235:genetics
D017232:Oncogene Proteins v-mos; D015514:Oncogene Proteins, Fusion; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases