TY - JOUR
T1 - RAN GTPase Is a RASSF1 A Effector Involved in Controlling Microtubule Organization
AU - Dallol, Ashraf
AU - Hesson, LB
AU - Matallanas, D
AU - Cooper, WN
AU - O'Neill, E
AU - Maher, Eamonn
AU - Koich, W
AU - Latif, Farida
PY - 2009/7/1
Y1 - 2009/7/1
N2 - RASSF1A is a tumor suppressor gene that is inactivated by hypermethylation of its promoter region in most types of human cancers [1-3]. The incidence of spontaneous or induced tumors is significantly higher in Rassf1a(-/-) mice than in wild-type mice, confirming the tumor suppressor function of RASSF1A [4, 5]. RASSF1A promotes apoptosis mainly through its interaction with the proapoptotic serine/threonine STE20-like kinases MST1 and 2 [6, 7]. However, Rassf1a(-/-) mice do not show overt signs of deregulated apoptosis [4, 5], suggesting that other RASSF1A effectors are also critical for tumor suppression. In a proteomics screen, we identified RAN GTPase, MST1 and 2 kinases, and alpha- and gamma-tubulin as RASSF1A-interacting proteins. We show that RASSF1A-induced microtubule hyperstability, a hallmark of RASSF1A expression [8, 9], is RAN-GTP dependent. RASSF1A promotes the accumulation of the GTP-bound form of RAN via the MST2-induced phosphorylation of RCC1. Depletion of RASSF1A results in mislocalization of RCC1 to the mitotic spindle and spindle poles, leading to mitotic spindle abnormalities and prometaphase block. A similar mitotic delay is also observed with MST2 depletion. These findings reveal a mechanism for how RASSF1A controls microtubule stability and for how its loss compromises the integrity of the mitotic spindle, leading to aneuploidy and tumorigenesis.
AB - RASSF1A is a tumor suppressor gene that is inactivated by hypermethylation of its promoter region in most types of human cancers [1-3]. The incidence of spontaneous or induced tumors is significantly higher in Rassf1a(-/-) mice than in wild-type mice, confirming the tumor suppressor function of RASSF1A [4, 5]. RASSF1A promotes apoptosis mainly through its interaction with the proapoptotic serine/threonine STE20-like kinases MST1 and 2 [6, 7]. However, Rassf1a(-/-) mice do not show overt signs of deregulated apoptosis [4, 5], suggesting that other RASSF1A effectors are also critical for tumor suppression. In a proteomics screen, we identified RAN GTPase, MST1 and 2 kinases, and alpha- and gamma-tubulin as RASSF1A-interacting proteins. We show that RASSF1A-induced microtubule hyperstability, a hallmark of RASSF1A expression [8, 9], is RAN-GTP dependent. RASSF1A promotes the accumulation of the GTP-bound form of RAN via the MST2-induced phosphorylation of RCC1. Depletion of RASSF1A results in mislocalization of RCC1 to the mitotic spindle and spindle poles, leading to mitotic spindle abnormalities and prometaphase block. A similar mitotic delay is also observed with MST2 depletion. These findings reveal a mechanism for how RASSF1A controls microtubule stability and for how its loss compromises the integrity of the mitotic spindle, leading to aneuploidy and tumorigenesis.
U2 - 10.1016/j.cub.2009.05.064
DO - 10.1016/j.cub.2009.05.064
M3 - Article
C2 - 19559616
SN - 1879-0445
VL - 19
SP - 1227
EP - 1232
JO - Current Biology
JF - Current Biology
IS - 14
ER -