The mitotic arrest deficient protein MAD2B interacts with the small GTPase RAN throughout the cell cycle.
BACKGROUND
Previously, we identified the mitotic arrest deficient protein MAD2B (MAD2L2) as a bona fide interactor of the renal cell carcinoma (RCC)-associated protein PRCC. In addition, we found that fusion of PRCC with the transcription factor TFE3 in t(X;1)(p11;q21)-positive RCCs results in an impairment of this interaction and, concomitantly, an abrogation of cell cycle progression. Although MAD2B is thought to inhibit the anaphase promoting complex (APC) by binding to CDC20 and/or CDH1(FZR1), its exact role in cell cycle control still remains to be established.


RESULTS
Using a yeast two-hybrid interaction trap we identified the small GTPase RAN, a well-known cell cycle regulator, as a novel MAD2B binding protein. Endogenous interaction was established in mammalian cells via co-localization and co-immunoprecipitation of the respective proteins. The interaction domain of RAN could be assigned to a C-terminal moiety of 60 amino acids, whereas MAD2B had to be present in its full-length conformation. The MAD2B-RAN interaction was found to persist throughout the cell cycle. During mitosis, co-localization at the spindle was observed.


CONCLUSIONS
The small GTPase RAN is a novel MAD2B binding protein. This novel protein-protein interaction may play a role in (i) the control over the spindle checkpoint during mitosis and (ii) the regulation of nucleocytoplasmic trafficking during interphase.
Medendorp
Klaas
K
Department of Human Genetics, Radboud University Nijmegen Medical Centre, Nijmegen Centre for Molecular Life Sciences, Nijmegen, The Netherlands.
van Groningen
Jan J M
JJ
Vreede
Lilian
L
Hetterschijt
Lisette
L
van den Hurk
Wilhelmina H
WH
de Bruijn
Diederik R H
DR
Brugmans
Linda
L
van Kessel
Ad Geurts
AG
D000818:Animals; D019556:COS Cells; D064199:Cdc20 Proteins; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D002522:Chlorocebus aethiops; D006801:Humans; D064246:Mad2 Proteins; D008938:Mitosis; D008954:Models, Biological; D025941:Protein Interaction Mapping; D011506:Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D020931:ran GTP-Binding Protein / Q000737:chemistry*
D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins; C120552:MAD2L2 protein, human; D064246:Mad2 Proteins; D011506:Proteins; C577488:CDC20 protein, human; D020931:ran GTP-Binding Protein