The human Mis12 complex is required for kinetochore assembly and proper chromosome segregation.
During cell division, kinetochores form the primary chromosomal attachment sites for spindle microtubules. We previously identified a network of 10 interacting kinetochore proteins conserved between Caenorhabditis elegans and humans. In this study, we investigate three proteins in the human network (hDsn1Q9H410, hNnf1PMF1, and hNsl1DC31). Using coexpression in bacteria and fractionation of mitotic extracts, we demonstrate that these proteins form a stable complex with the conserved kinetochore component hMis12. Human or chicken cells depleted of Mis12 complex subunits are delayed in mitosis with misaligned chromosomes and defects in chromosome biorientation. Aligned chromosomes exhibited reduced centromere stretch and diminished kinetochore microtubule bundles. Consistent with this, localization of the outer plate constituent Ndc80HEC1 was severely reduced. The checkpoint protein BubR1, the fibrous corona component centromere protein (CENP) E, and the inner kinetochore proteins CENP-A and CENP-H also failed to accumulate to wild-type levels in depleted cells. These results indicate that a four-subunit Mis12 complex plays an essential role in chromosome segregation in vertebrates and contributes to mitotic kinetochore assembly.
Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093, USA.
Susan L
SL
Kline
Iain M
IM
Cheeseman
Tetsuya
T
Hori
Tatsuo
T
Fukagawa
Arshad
A
Desai
D000818:Animals; D001324:Autoantigens / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D000076247:Centromere Protein A; D002645:Chickens; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism; D020090:Chromosome Segregation / Q000235:genetics*; D017124:Conserved Sequence / Q000235:genetics; D003598:Cytoskeletal Proteins; D019143:Evolution, Molecular; D006367:HeLa Cells; D006801:Humans; D018386:Kinetochores / Q000378:metabolism*; D046911:Macromolecular Substances / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000235:genetics / Q000378:metabolism; D008938:Mitosis / Q000502:physiology*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D008941:Spindle Apparatus / Q000235:genetics / Q000378:metabolism*
D001324:Autoantigens; C000619700:CENPA protein, human; C121933:CENPH protein, human; D018797:Cell Cycle Proteins; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone; D003598:Cytoskeletal Proteins; C470829:Dsn1 protein, S cerevisiae; C492664:MIS12 protein, human; D046911:Macromolecular Substances; D008869:Microtubule-Associated Proteins; C120529:NDC80 protein, human; C108276:NNF1 protein, S cerevisiae; C470828:Nsl1 protein, S cerevisiae; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins; C068688:centromere protein E; D011494:Protein Kinases; C584277:BUB1 protein, human; C090464:Bub1 spindle checkpoint protein; D017346:Protein Serine-Threonine Kinases