NEK2A Interacts with MAD1 and Possibly Functions as a Novel Integrator of the Spindle Checkpoint Signaling

Abstract

Chromosome segregation in mitosis is orchestrated by protein kinase signaling cascades. A biochemical cascade named spindle checkpoint ensures the spatial and temporal order of chromosome segregation during mitosis. Here we report that spindle checkpoint protein MAD1 interacts with NEK2A, a human orthologue of the Aspergillus nidulans NIMA kinase. MAD1 interacts with NEK2A in vitro and in vivo via a leucine zipper-containing domain located at the C terminus of MAD1. Like MAD1, NEK2A is localized to HeLa cell kinetochore of mitotic cells. Elimination of NEK2A by small interfering RNA does not arrest cells in mitosis but causes aberrant premature chromosome segregation. NEK2A is required for MAD2 but not MAD1, BUB1, and HEC1 to associate with kinetochores. These NEK2A-eliminated or -suppressed cells display a chromosome bridge phenotype with sister chromatid inter-connected. Moreover, loss of NEK2A impairs mitotic checkpoint signaling in response to spindle damage by nocodazole, which affected mitotic escape and led to generation of cells with multiple nuclei. Our data demonstrate that NEK2A is a kinetochore-associated protein kinase essential for faithful chromosome segregation. We hypothesize that NEK2A links MAD2 molecular dynamics to spindle checkpoint signaling. Chromosome segregation in mitosis is orchestrated by protein kinase signaling cascades. A biochemical cascade named spindle checkpoint ensures the spatial and temporal order of chromosome segregation during mitosis. Here we report that spindle checkpoint protein MAD1 interacts with NEK2A, a human orthologue of the Aspergillus nidulans NIMA kinase. MAD1 interacts with NEK2A in vitro and in vivo via a leucine zipper-containing domain located at the C terminus of MAD1. Like MAD1, NEK2A is localized to HeLa cell kinetochore of mitotic cells. Elimination of NEK2A by small interfering RNA does not arrest cells in mitosis but causes aberrant premature chromosome segregation. NEK2A is required for MAD2 but not MAD1, BUB1, and HEC1 to associate with kinetochores. These NEK2A-eliminated or -suppressed cells display a chromosome bridge phenotype with sister chromatid inter-connected. Moreover, loss of NEK2A impairs mitotic checkpoint signaling in response to spindle damage by nocodazole, which affected mitotic escape and led to generation of cells with multiple nuclei. Our data demonstrate that NEK2A is a kinetochore-associated protein kinase essential for faithful chromosome segregation. We hypothesize that NEK2A links MAD2 molecular dynamics to spindle checkpoint signaling. Chromosome movements during mitosis are governed by the interaction of spindle microtubules with a specialized chromosome domain located within the centromere. This specialized region, called the kinetochore (1Brinkley B.R. Stubblefield E. Chromosoma. 1966; 19: 28-43Crossref PubMed Scopus (146) Google Scholar, 2Roos U.-P. J. Cell Biol. 1976; 54: 363-385Google Scholar), is the site for spindle microtubule-centromere association. In addition to providing a physical link between chromosomes and spindle microtubules, the kinetochore has an active function in chromosomal segregation through microtubule motors and spindle checkpoint sensors located at or near it (3Nicklas R.B. J. Cell Biol. 1989; 109: 2245-2255Crossref PubMed Scopus (147) Google Scholar, 4Rieder C.L. Alexander S.P. J. Cell Biol. 1990; 110: 81-95Crossref PubMed Scopus (360) Google Scholar, 5Yao X. Abrieu A. Zheng Y. Sullivan K.F. Cleveland D.W. Nat. Cell Biol. 2000; 2: 484-491Crossref PubMed Scopus (307) Google Scholar, 6Li R. Murray A.W. Cell. 1991; 66: 519-531Abstract Full Text PDF PubMed Scopus (933) Google Scholar). Several lines of evidence have implicated the kinetochore in generation of a diffusible checkpoint signal that can block cell cycle progression into anaphase until all kinetochores have successfully attached to spindle microtubules. Delayed attachment of one or more chromosomes to the spindle is correlated with a corresponding delay in the onset of anaphase. For mutants that fail to arrest the cell cycle in mitosis after disassembly of microtubules in budding yeast, genetic screen has identified three MAD (mitotic arrest deficiency) and three BUB (budding uninhibited by benomyl) genes (7Hoyt M.A. Totis L. Roberts B.T.S. Cell. 1990; 66: 507-517Abstract Full Text PDF Scopus (899) Google Scholar). Vertebrate homologues of MAD1 (8Jin D.Y. Spencer F. Jeang K.T. Cell. 1998; 93: 81-91Abstract Full Text Full Text PDF PubMed Scopus (459) Google Scholar), MAD2 (9Chen R.H. Waters J.C. Salmon E.D. Murray A.W. Science. 1996; 274: 242-246Crossref PubMed Scopus (379) Google Scholar, 10Li Y. Benezra R. Science. 1996; 274: 246-248Crossref PubMed Scopus (521) Google Scholar), BUB3 (11Taylor S.S. Ha E. McKeon F. J. Cell Biol. 1998; 142: 1-11Crossref PubMed Scopus (361) Google Scholar, 12Martinez-Exposito M.J. Kaplan K.B. Copeland J. Sorger P.K. Proc. Natl. Acad. Sci. U. S. A. 1999; 96: 8493-8498Crossref PubMed Scopus (83) Google Scholar), BUB1, and BUBR1 (13Taylor S.S. McKeon F. Cell. 1997; 89: 727-735Abstract Full Text Full Text PDF PubMed Scopus (477) Google Scholar, 14Cahill D.P. Lengauer C. Yu J. Riggins G.J. Willson J.K. Markowitz S.D. Kinzler K.W. Vogelstein B. Nature. 1998; 392: 300-303Crossref PubMed Scopus (1314) Google Scholar, 15Chan G.K. Jablonski S.A. Sudakin V. Hittle J.C. Yen T.J. J. Cell Biol. 1999; 146: 941-954Crossref PubMed Scopus (312) Google Scholar) are spindle checkpoint components transiently associated with kinetochore. Expression of the kinetochore binding domain of murine BUB1 (13Taylor S.S. McKeon F. Cell. 1997; 89: 727-735Abstract Full Text Full Text PDF PubMed Scopus (477) Google Scholar) or injection of antibodies against BUBR1 (15Chan G.K. Jablonski S.A. Sudakin V. Hittle J.C. Yen T.J. J. Cell Biol. 1999; 146: 941-954Crossref PubMed Scopus (312) Google Scholar) results in premature onset of anaphase, presumably by replacement of the endogenous proteins at kinetochores. Collectively, these data indicate that binding of these spindle checkpoint components at the kinetochores may generate a signal in response to spindle defects and/or aberrant kinetochore protein-protein interactions. Mitosis is orchestrated by signaling cascades that coordinate mitotic processes and ensure accurate chromosome segregation. The key switch for the onset of mitosis is the archetypal cyclin-dependent kinase Cdc2. Besides the master mitotic kinase Cdc2, there are three protein serine/threonine kinase families as follows: the Polo kinases, Aurora kinases, and the NEK (NIMA-related kinases) (16Nigg E.A. Nat. Rev. Mol. Cell. Biol. 2001; 2: 21-32Crossref PubMed Scopus (1252) Google Scholar, 17O'Connell M.J. Krien M.J. Hunter T. Trends Cell Biol. 2003; 13: 221-228Abstract Full Text Full Text PDF PubMed Scopus (188) Google Scholar). The latter family has proven the most enigmatic in function, although recent advances from several sources are beginning to reveal a common functional theme. NIMA (never in mitosis A) is vital in Aspergillus nidulans for entry into mitosis (17O'Connell M.J. Krien M.J. Hunter T. Trends Cell Biol. 2003; 13: 221-228Abstract Full Text Full Text PDF PubMed Scopus (188) Google Scholar, 18Oakley B.R. Morris N.R. J. Cell Biol. 1983; 96: 1155-1158Crossref PubMed Scopus (93) Google Scholar). Mutation of NIMA arrests cells in G2 without interfering with p34cdc2 activation, suggesting that the NIMA protein has a central role in the G2/M transition. Moreover, if the G2 arrest of nimA mutants is bypassed by additional mutations, the resulting mitotic cells show aberrant spindle and nuclear envelope organization (17O'Connell M.J. Krien M.J. Hunter T. Trends Cell Biol. 2003; 13: 221-228Abstract Full Text Full Text PDF PubMed Scopus (188) Google Scholar, 18Oakley B.R. Morris N.R. J. Cell Biol. 1983; 96: 1155-1158Crossref PubMed Scopus (93) Google Scholar, 19Lu K.P. Hunter T. Cell. 1995; 81: 413-424Abstract Full Text PDF PubMed Scopus (141) Google Scholar), pointing to functions of NIMA beyond the control of mitotic entry. NEK2A, the homologue in human cells with the greatest structural similarity to NIMA within the catalytic domain, is regulated in yeast in a manner similar to regulation of NIMA in A. nidulans; its expression and serine/threonine kinase activity is highest during late G2 phase, when NEK2A is expected to function critically (20Fry A.M. Meraldi P. Nigg E.A. EMBO J. 1998; 17: 470-481Crossref PubMed Scopus (343) Google Scholar). Furthermore, a portion of NEK2A localizes to centrosomes and in mammalian cells appears to a role similar to NIMA in entry into mitosis (16Nigg E.A. Nat. Rev. Mol. Cell. Biol. 2001; 2: 21-32Crossref PubMed Scopus (1252) Google Scholar, 17O'Connell M.J. Krien M.J. Hunter T. Trends Cell Biol. 2003; 13: 221-228Abstract Full Text Full Text PDF PubMed Scopus (188) Google Scholar). NEK2A may have more during several of the cell from to multiple of its expression and in and chromosome the (16Nigg E.A. Nat. Rev. Mol. Cell. Biol. 2001; 2: 21-32Crossref PubMed Scopus (1252) Google Scholar, 17O'Connell M.J. Krien M.J. Hunter T. Trends Cell Biol. 2003; 13: 221-228Abstract Full Text Full Text PDF PubMed Scopus (188) Google Scholar, Y. Zheng L. J. Biol. Full Text Full Text PDF PubMed Scopus Google Scholar). it has that NEK2A is associated with (17O'Connell M.J. Krien M.J. Hunter T. Trends Cell Biol. 2003; 13: 221-228Abstract Full Text Full Text PDF PubMed Scopus (188) Google Scholar), it not NEK2A is localized to the kinetochore and NEK2A functions during chromosome movements in mitosis. The mitotic spindle checkpoint is a chromosome segregation that chromosome from premature segregation in the of This is as a chromosome or of kinetochore protein is to block the of cells from to anaphase X. R.B. J. Cell Sci. 1997; 110: Google Scholar). The of the mitotic checkpoint in yeast a in response to spindle in the checkpoint has into an essential of and Cleveland D.W. Cell. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar). of antibodies to MAD2 into cells premature anaphase onset and chromosome G.J. R.H. Murray A.W. J. Cell Biol. 1998; PubMed Scopus Google Scholar). In budding yeast, the spindle checkpoint a between the MAD1 and MAD2 proteins R.H. Murray A.W. Mol. Biol. Cell. 1999; PubMed Scopus Google Scholar). MAD1 is required for MAD2 to the kinetochore R.H. Murray A.W. Mol. Biol. Cell. 1999; PubMed Scopus Google Scholar), it is MAD1 function is into the mitotic the of MAD1 function in mitotic spindle checkpoint we yeast genetic and identified the Our show that NEK2A interacts with MAD1 via the leucine the MAD1 In we show that NEK2A and MAD1 are to the kinetochore of mitotic cells. the of MAD1 in spindle checkpoint and function of NEK2A in we that NEK2A links mitotic checkpoint signaling to chromosome segregation human MAD1 a from of to screen a HeLa in with the domain in the by yeast the genes and for the genes the with the of MAD1, which with NEK2A, mutants of MAD1 the MAD1 and by of the with and by of and into In mutants of NEK2A to the between NEK2A and MAD1. NEK2A by the with and by the of and into from HeLa cells by with for at addition of and to for to the at for and murine as with The resulting into and For mammalian expression of the NEK2A, NEK2A with and and into the of MAD1 with and and into MAD1, and in as the of MAD1 into a into The of NEK2A from yeast with and it with at the C terminus and RNA small interfering at the terminus of proteins as R. X. C. Y. X. J. Biol. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar). of with with NEK2A or MAD1. The expression of protein by addition of by after the in and and for of by a The by for at The to a with by with of MAD1 and cell as a of NEK2A The protein to with and with of The in the and for and the The with of and the with and and as and by and cells to in with at in and with and by to the after and proteins in and by at for at proteins with to with and in protein for proteins to The into three and with antibodies against the MAD1, and with and by and for for of NEK2A to the to the a a or X. Abrieu A. Zheng Y. Sullivan K.F. Cleveland D.W. Nat. Cell Biol. 2000; 2: 484-491Crossref PubMed Scopus (307) Google Scholar). The RNA by In the of for of as X. Abrieu A. Zheng Y. Sullivan K.F. Cleveland D.W. Nat. Cell Biol. 2000; 2: 484-491Crossref PubMed Scopus (307) Google Scholar). In HeLa cells and with or control the of the NEK2A protein by X. Abrieu A. Zheng Y. Sullivan K.F. Cleveland D.W. Nat. Cell Biol. 2000; 2: 484-491Crossref PubMed Scopus (307) Google Scholar). cells in and HeLa cells with with as In after with or HeLa cells for with and and for with as X. Abrieu A. Zheng Y. Sullivan K.F. Cleveland D.W. Nat. Cell Biol. 2000; 2: 484-491Crossref PubMed Scopus (307) Google Scholar, X. Cleveland D.W. J. Cell Biol. 1997; PubMed Scopus Google Scholar). cells in in and three in the with in with These cells with antibodies in a for and three in antibodies to MAD1, and NEK2A binding of with and MAD2 with an as X. Abrieu A. Zheng Y. Sullivan K.F. Cleveland D.W. Nat. Cell Biol. 2000; 2: 484-491Crossref PubMed Scopus (307) Google Scholar). with a and and with In of HeLa cells to for a of to of NEK2A the mitotic spindle These cells and with for the cell and The with in and with of as a and as a a the with and with for to and the an Cell and and from as in with and In and HeLa cells with with and as J. C. Y. X. Sci. Scholar). In after HeLa cells with by and as to and by and antibodies and The a NEK2A a for proteins that associate with MAD1, the of MAD1 as to screen a HeLa by yeast a with by of and we several of MAD1. that one of these the C terminus of NEK2A from to human NEK2A the of interaction between NEK2A and MAD1 and to the that the interaction between MAD1 and NEK2A, we of yeast and to additional yeast to the binding between NEK2A and MAD1. we to the of NEK2A from a HeLa cell and we it into the domain for the interaction between MAD1 and NEK2A, we a to for protein-protein interaction in the We that proteins a leucine The leucine of MAD1 is located between and and the leucine of NEK2A is located between and leucine protein-protein we to if leucine the between MAD1 and a of mutants as in The NEK2A with MAD1 into yeast We activity as a for protein-protein in yeast genetic MAD1 to NEK2A C terminus a to the leucine NEK2A does not with MAD1, suggesting that a of NEK2A, which its C may required for its MAD1 binding the NEK2A binding MAD1, of MAD1 with into yeast cells. in C and NEK2A to the MAD1 central which a leucine yeast genetic that the leucine of MAD1 to the of NEK2A a with the the interaction between MAD1 and NEK2A in yeast and if NEK2A a with MAD1, we in and cells in that NEK2A is by of MAD1 that MAD1 is by MAD1 with control and in of the we that the interaction between MAD1 and NEK2A is if NEK2A to MAD1 in vitro and to the binding from the yeast we as and of that in that the NEK2A to MAD1 via its C In the interaction of and is and can of a in that MAD1 domain to the leucine zipper-containing of we that NEK2A interacts with MAD1. NEK2A to the of (20Fry A.M. Meraldi P. Nigg E.A. EMBO J. 1998; 17: 470-481Crossref PubMed Scopus (343) Google Scholar) of NEK2A that NEK2A is at centrosomes and is in A recent report (17O'Connell M.J. Krien M.J. Hunter T. Trends Cell Biol. 2003; 13: 221-228Abstract Full Text Full Text PDF PubMed Scopus (188) Google Scholar) that NEK2A is associated with the kinetochore of mitotic cells. MAD1 is a kinetochore protein from yeast to biochemical interaction between MAD1 and NEK2A to NEK2A is a we a NEK2A against human protein to if NEK2A protein is in HeLa cell chromosome in that the NEK2A a protein of in mitotic HeLa cell which the molecular of NEK2A if NEK2A is a we NEK2A protein in the and mitotic cell with that of chromosome by in the NEK2A signal is in chromosome with that of mitotic cell a similar to that NEK2A is in the chromosome if NEK2A is a kinetochore we a that of kinetochore protein of mitotic cells X. Abrieu A. Zheng Y. Sullivan K.F. Cleveland D.W. Nat. Cell Biol. 2000; 2: 484-491Crossref PubMed Scopus (307) Google Scholar, X. Cleveland D.W. J. Cell Biol. 1997; PubMed Scopus Google Scholar). in HeLa cells the NEK2A and a a human that with by a to the In the in NEK2A appears as of are as of The from three that NEK2A is located at the domain to in MAD1 to similar to that of NEK2A, which is with of human MAD1 (8Jin D.Y. Spencer F. Jeang K.T. Cell. 1998; 93: 81-91Abstract Full Text Full Text PDF PubMed Scopus (459) Google Scholar, G.K. Yen T.J. J. Cell Sci. 2001; PubMed Google Scholar). NEK2A can to we HeLa cells with and for its by in NEK2A protein a similar to that of endogenous which is with in the These results indicate that a similar to endogenous the that NEK2A is located at the and is with MAD1, we that NEK2A interacts with MAD1 at the kinetochore. NEK2A in the the of NEK2A the of MAD1 to the kinetochore and the of we RNA to NEK2A by into HeLa cells. the for NEK2A protein by we HeLa cells with and cells at of in with a NEK2A that the of NEK2A protein at control cells with an NEK2A This is as it not the of proteins as an of the for NEK2A we HeLa cells with a of of and we cells with a NEK2A that NEK2A a of NEK2A protein without the of proteins as of the not the of NEK2A NEK2A in the of cells with or to the at of NEK2A in of successfully cells. We of NEK2A protein of MAD1 to the and we HeLa cells with and or a control after the cells and for MAD1, and in MAD1 a MAD1 localized to the kinetochore of the cells with NEK2A suggesting that NEK2A is not required for of MAD1 to the kinetochore. the of these cells to arrest in mitosis. NEK2A to we if NEK2A is essential for the of HEC1 to the kinetochore. in HEC1 a kinetochore in control and suggesting that HEC1 to kinetochore is of NEK2A for Chromosome of NEK2A causes cell defects in HeLa we control and with and MAD1. anaphase cells with a of of sister cells with NEK2A display a chromosome bridge in which the of sister are with one or more sister a phenotype A.M. Mol. Biol. Cell. 2003; PubMed Scopus Google Scholar) in cells of these cells that sister to as the by MAD1 and a and The in sister to entry into anaphase in of which to We mitotic in which of sister in the from NEK2A and control cells. We the of cells chromosome bridge and we it as the of the cell that is in mitosis. in a from three show that the of NEK2A in in cells chromosomes and chromosome These data demonstrate that loss of NEK2A is for defects of chromosome segregation associated with premature entry into anaphase. if NEK2A kinase is essential for of spindle checkpoint and for mitotic we of NEK2A, and we for its in chromosome segregation. cells that proteins and kinase three the of endogenous NEK2A not that the is to the of HeLa suggesting the kinase activity is not required for its with kinetochore. of these cells the of chromosome and chromosome between sister in premature anaphase similar to in cells Moreover, sister to in cells a and We mitotic cells of from three in which of sister in the We the of or chromosome bridge phenotype and the of mitotic cells. in expression of the NEK2A in in cells with chromosomes with of and chromosome with of the from NEK2A which is with the phenotype by a recent A.M. Mol. Biol. Cell. 2003; PubMed Scopus Google Scholar). we that NEK2A kinase is essential for faithful chromosome segregation during transition. NEK2A kinase is essential for spindle checkpoint in the of spindle we HeLa cells with by for in there a in the of mitotic cells that with cells with there an in the of cells with multiple which a of checkpoint the in protein expression we that the of cells protein to for endogenous NEK2A kinase and to spindle checkpoint by endogenous NEK2A for MAD2 to with the of NEK2A by not the of MAD1 and HEC1 to kinetochores C and the between MAD1 and spindle checkpoint proteins as MAD2 and BUB1, we to NEK2A We cells for MAD2 as spindle checkpoint proteins can at the kinetochore at of cell in MAD2 a kinetochore in control HeLa cells. MAD2 is from most kinetochores of suggesting that the NEK2A the between MAD2 and via interaction with MAD1. of spindle checkpoint protein in the cells in the of BUB1 kinetochores of cells or the disassembly of BUB1 from kinetochores of anaphase cells we that NEK2A is required for the of but not BUB1 and MAD1, to kinetochores. NEK2A a with We have identified and NEK2A as a NEK2A is localized to the kinetochore in addition to its (16Nigg E.A. Nat. Rev. Mol. Cell. Biol. 2001; 2: 21-32Crossref PubMed Scopus (1252) Google Scholar, A.M. Meraldi P. Nigg E.A. EMBO J. 1998; 17: 470-481Crossref PubMed Scopus (343) Google Scholar). These results are with the of mitotic as G.K. Hittle J.C. E. Yen T.J. Mol. Biol. Cell. 2003; PubMed Scopus Google Scholar, A. J. L. L. X. Cell 2003; 13: PubMed Scopus Google Scholar). of NEK2A has of kinetochore-associated NEK2A from (16Nigg E.A. Nat. Rev. Mol. Cell. Biol. 2001; 2: 21-32Crossref PubMed Scopus (1252) Google Scholar, A.M. Meraldi P. Nigg E.A. EMBO J. 1998; 17: 470-481Crossref PubMed Scopus (343) Google Scholar) that not reveal of NEK2A to kinetochore. We that is a of in of the antibodies that in the (16Nigg E.A. Nat. Rev. Mol. Cell. Biol. 2001; 2: 21-32Crossref PubMed Scopus (1252) Google Scholar, A.M. Meraldi P. Nigg E.A. EMBO J. 1998; 17: 470-481Crossref PubMed Scopus (343) Google Scholar). is that the by not at kinetochores. We that NEK2A a of NEK2A is not associated with kinetochore in the but associated with kinetochore the of the nuclear Our the interaction between MAD1 and NEK2A and to kinetochores of the mitotic cells. NEK2A is not required for MAD1 to the kinetochore and In of NEK2A not of HEC1 and BUB1, suggesting that kinetochore several but and NEK2A the of a of proteins to that NEK2A does not with MAD1 in yeast genetic the NEK2A interacts with MAD1, suggesting a interaction of NEK2A, which may the site The of NEK2A with MAD1 that these proteins are in a of to there are additional proteins in the protein from mammalian cells or the interaction is and regulated by cell cycle NEK2A an of the that NEK2A is an of the spindle for NEK2A function to arrest mitosis in the of the spindle damage by the microtubule In NEK2A is for mitotic progression as cells without NEK2A mitosis with chromosomes and sister which led to of cells and the of This is a of of mitotic checkpoint that cells to mitosis all the chromosomes are This phenotype when functions of spindle checkpoint proteins MAD1, BUB1, and Cleveland D.W. Cell. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar, S. Nigg E.A. Science. PubMed Scopus Google Scholar, Hittle J.C. Jablonski S.A. Yen T.J. Nat. Cell Biol. 2003; PubMed Scopus Google Scholar). A.M. Mol. Biol. Cell. 2003; PubMed Scopus Google Scholar) similar from expression of the kinase NEK2A in cells. these to link the chromosome segregation defects to the to the loss of NEK2A the in which NEK2A may as a mitotic checkpoint by MAD2 function at kinetochore to ensure of all sister anaphase MAD2 is a spindle checkpoint localized to the kinetochores in which the signal (9Chen R.H. Waters J.C. Salmon E.D. Murray A.W. Science. 1996; 274: 242-246Crossref PubMed Scopus (379) Google Scholar, Cleveland D.W. Cell. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar, G.J. R.H. Murray A.W. J. Cell Biol. 1998; PubMed Scopus Google Scholar). has that of MAD2 to kinetochores MAD1 R.H. A. Murray A.W. J. Cell Biol. 1998; PubMed Scopus Google Scholar, V. Benezra R. EMBO J. 2003; PubMed Scopus Google Scholar). In MAD2 is in mitosis by protein and its with MAD1 and V. A. R. B. Sorger P.K. Benezra R. Nature. 2001; PubMed Scopus Google Scholar). The to MAD2 protein kinetochores in cells as in that NEK2A kinase may a link between MAD2 protein and its role in spindle checkpoint signaling. In MAD2 the NEK2A 17O'Connell M.J. Krien M.J. Hunter T. Trends Cell Biol. 2003; 13: 221-228Abstract Full Text Full Text PDF PubMed Scopus (188) Google Scholar). to MAD2 protein in vitro by NEK2A kinase from by the of NEK2A protein to it of to MAD2 is a for NEK2A in vitro and in The of that MAD2 for a of the mitotic checkpoint cells are in mitotic block in response to microtubule as and which to of chromosomes and of Cleveland D.W. Cell. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar). has that of an of MAD2 protein in an aberrant mitotic checkpoint in and an to in V. A. R. B. Sorger P.K. Benezra R. Nature. 2001; PubMed Scopus Google Scholar). The to MAD2 kinetochores in cells and the of in the of the phenotype in the MAD2 in cells V. A. R. B. Sorger P.K. Benezra R. Nature. 2001; PubMed Scopus Google Scholar). aberrant NEK2A cascade signaling to of MAD2 to which to the mitotic spindle of to cells NEK2A Our of of NEK2A expression and activity may a to the signaling cascade the signaling which in the of chromosome and the components that are in mitotic checkpoint signaling. Y. Zheng L. J. Biol. Full Text Full Text PDF PubMed Scopus Google Scholar) that NEK2A interacts with a kinetochore protein a protein to the protein located at the budding yeast kinetochore during mitosis. Furthermore, these that NEK2A and is required for faithful chromosome in We the role of NEK2A in chromosome segregation of HeLa cells. In we that of NEK2A does not kinetochore of suggesting that protein of HEC1 at is not required for of HEC1 to the kinetochore. has that HEC1 S. Nigg E.A. Science. PubMed Scopus Google Scholar), G.K. Hittle J.C. E. Yen T.J. Mol. Biol. Cell. 2003; PubMed Scopus Google Scholar), and Hittle J.C. Jablonski S.A. Yen T.J. Nat. Cell Biol. 2003; PubMed Scopus Google Scholar) are in of MAD1 to the kinetochore of mammalian cells. it as to the molecular the of MAD1 with the and its dynamics are regulated by mitotic kinase cascades. Our that MAD1 interacts with NEK2A at the kinetochore an additional of the protein-protein interaction at the kinetochore. it of to the of the of in kinetochore dynamics and chromosome movements by of the interaction of NEK2A with MAD1 a role for NEK2A in kinetochore dynamics in addition to its function for The that of NEK2A of MAD2 to mitotic and chromosome in HeLa cells from anaphase the of NEK2A in faithful chromosome segregation. We for MAD1 and Yen and for MAD1 and HEC1 We of for during the of