MAPK Mediates RAS-induced Chromosome Instability

• Published in: The Journal of biological chemistry 1999-12, Vol.274 (53), p.38083-38090
• Main Authors: Saavedra, H I, Fukasawa, K, Conn, C W, Stambrook, P J
• Format: Article
• Language: English
• Subjects: 1-phosphatidylinositol 3-kinase; 3T3 Cells; Animals; Cell Transformation, Viral; centrosomes; Chromosome Deletion; Enzyme Activation; Enzyme Inhibitors - pharmacology; Leukemia Virus, Murine - physiology; MAP Kinase Signaling System; Mice; Micronuclei, Chromosome-Defective; Mitogen-Activated Protein Kinases - antagonists & inhibitors; Mitogen-Activated Protein Kinases - metabolism; Mitosis - genetics; Oncogene Protein p21(ras) - physiology; Oncogene Proteins v-mos - genetics; PD98059; Phosphorylation; Ras protein; U0126; v-mos gene; v-Ras gene
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.274.53.38083

The generation of micronuclei is a reflection of DNA damage, defective mitosis, and loss of genetic material. The involvement of the MAPK pathway in mediating v- ras -induced micronuclei in NIH 3T3 cells was examined by inhibiting MAPK activation. Conversely, the MAPK pathway was constitutively activated by infecting cells with a v -mos retrovirus. Micronucleus formation was inhibited by the MAPK kinase inhibitors PD98059 and U0126, but not by wortmannin, an inhibitor of the Ras/phosphatidylinositol 3-kinase pathway. Transduction of cells with v -mos resulted in an increase in micronucleus formation, also consistent with the involvement of the MAPK pathway. Staining with the anti-centromeric CREST antibody revealed that instability induced by constitutive activation of MAPK is due predominantly to aberrant mitotic segregation, since most of the micronuclei were CREST-positive, reflective of lost chromosomes. A significant fraction of the micronuclei were CREST-negative, reflective of lost acentric chromosome fragments. Some of the instability observed was due to mitotic events, consistent with the increased formation of bi-nucleated cells, which result from perturbations of the mitotic spindle and failure to undergo cytokinesis. This chromosome instability, therefore, is a consequence of mitotic aberrations, mediated by the MAPK pathway, including centrosome amplification and formation of mitotic chromosome bridges.