Oncogenic Adenomatous polyposis coli mutants impair the mitotic checkpoint through direct interaction with Mad2.
The majority of colorectal tumors are aneuploid because of the underlying chromosome instability (CIN) phenotype, in which a defective mitotic checkpoint is implicated. Adenomatous polyposis coli (APC), a tumor suppressor gene that is commonly mutated in colon cancers, has been suggested in causing CIN; however, the molecular mechanism remains unresolved. In this study, we report an interaction of tumor-associated N-terminal APC fragments (N-APC) with Mad2, an essential mitotic checkpoint protein, providing a direct molecular support for linking APC mutations to the generation of CIN. N-APC interacts with Mad2 in Xenopus egg extracts, colon cancer cells, and in vitro with purified components. The interaction between N-APC and Mad2 decreases the soluble pool of Mad2, which is essential for Mad2 cycling and releasing from unattached kinetochores to produce a diffusible |P;wait anaphase|P' signal. Addition of such an N-APC mutant of egg extracts inactivates the mitotic checkpoint. Expressing a tumor-associated N-APC mutant in mammalian cells with an intact mitotic checkpoint produces premature anaphase onset with missegregated chromosomes.
Zhang
Jiayin
J
Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
Neisa
Roberto
R
Mao
Yinghui
Y
D025601:Adenomatous Polyposis Coli Protein / Q000378:metabolism*; D000705:Anaphase; D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002457:Cell Extracts; D045744:Cell Line, Tumor; D002877:Chromosomes, Human / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D064246:Mad2 Proteins; D008938:Mitosis; D008954:Models, Biological; D009154:Mutation / Q000235:genetics*; D009857:Oncogenes; D010063:Ovum / Q000378:metabolism; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014981:Xenopus; D029867:Xenopus Proteins / Q000378:metabolism*
D025601:Adenomatous Polyposis Coli Protein; D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D002457:Cell Extracts; D004268:DNA-Binding Proteins; C577697:MAD2L1 protein, human; D064246:Mad2 Proteins; C499480:Mad2 protein, Xenopus; D011994:Recombinant Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D029867:Xenopus Proteins