A role for the RASSF1A tumor suppressor in the regulation of tubulin polymerization and genomic stability.
The high frequency with which the novel tumor suppressor RASSF1A is inactivated by promoter methylation suggests that it plays a key role in the development of many primary human tumors. Yet the mechanism of RASSF1A action remains unknown. We now show that RASSF1A associates with microtubules and that this association is essential for RASSF1A to mediate its growth inhibitory effects. Overexpression of RASSF1A promotes the formation of stable microtubules, whereas a dominant-negative fragment of RASSF1A destabilizes microtubule networks. The RASSF1 protein is expressed as two main isoforms, 1A and 1C. The smaller 1C isoform also associates with microtubules but is less effective at stabilizing them. Because RASSF1A and RASSF1C localize to the mitotic spindle, we examined their effects upon genomic instability. RASSF1A and RASSF1C block activated Ras-induced genomic instability. However, a point mutant of RASSF1C, identified in human tumors, was severely defective for stabilizing tubulin and was unable to block the genomic destabilizing effects of Ras. Thus, we identify a role for RASSF1A/C in the control of microtubule polymerization and potentially in the maintenance of genomic stability.
Vos
Michele D
MD
Department of Cell and Cancer Biology, National Cancer Institute, National Institutes of Health, Rockville, Maryland 20850, USA.
Martinez
Alfredo
A
Elam
Candice
C
Dallol
Ashraf
A
Taylor
Barbara J
BJ
Latif
Farida
F
Clark
Geoffrey J
GJ
D000818:Animals; D019556:COS Cells; D002460:Cell Line; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D042822:Genomic Instability / Q000502:physiology*; D006801:Humans; D008870:Microtubules / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D014162:Transfection; D014404:Tubulin / Q000235:genetics / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000502:physiology*; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism
C411762:RASSF1 protein, human; D014404:Tubulin; D025521:Tumor Suppressor Proteins; D018631:ras Proteins