MAPK mediates RAS-induced chromosome instability.
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.
Saavedra
H I
HI
Department of Cell Biology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0521, USA.
Fukasawa
K
K
Conn
C W
CW
Stambrook
P J
PJ
D016475:3T3 Cells; D000818:Animals; D002472:Cell Transformation, Viral; D002872:Chromosome Deletion; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D009052:Leukemia Virus, Murine / Q000502:physiology; D020935:MAP Kinase Signaling System; D051379:Mice; D048629:Micronuclei, Chromosome-Defective; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008938:Mitosis / Q000235:genetics; D015689:Oncogene Protein p21(ras) / Q000502:physiology*; D017232:Oncogene Proteins v-mos / Q000235:genetics; D010766:Phosphorylation
D004791:Enzyme Inhibitors; D017232:Oncogene Proteins v-mos; D020928:Mitogen-Activated Protein Kinases; D015689:Oncogene Protein p21(ras)