TRAMM/TrappC12 plays a role in chromosome congression, kinetochore stability, and CENP-E recruitment.
Chromosome congression requires the stable attachment of microtubules to chromosomes mediated by the kinetochore, a large proteinaceous structure whose mechanism of assembly is unknown. In this paper, we present the finding that a protein called TRAMM (formerly known as TrappC12) plays a role in mitosis. Depletion of TRAMM resulted in noncongressed chromosomes and arrested cells in mitosis. Small amounts of TRAMM associated with chromosomes, and its depletion affected the localization of some kinetochore proteins, the strongest effect being seen for CENP-E. TRAMM interacts with CENP-E, and depletion of TRAMM prevented the recruitment of CENP-E to the kinetochore. TRAMM is phosphorylated early in mitosis and dephosphorylated at the onset of anaphase. Interestingly, this phosphorylation/dephosphorylation cycle correlates with its association/disassociation with CENP-E. Finally, we demonstrate that a phosphomimetic form of TRAMM recruited CENP-E to kinetochores more efficiently than did the nonphosphorylatable mutant. Our study identifies a moonlighting function for TRAMM during mitosis and adds a new component that regulates kinetochore stability and CENP-E recruitment.
Department of Biology, Concordia University, Montreal, Quebec H4B 1R6, Canada.
Miroslav P
MP
Milev
Department of Biology, Concordia University, Montreal, Quebec H4B 1R6, Canada.
Benedeta
B
Hasaj
Department of Biology, Concordia University, Montreal, Quebec H4B 1R6, Canada.
Djenann
D
Saint-Dic
Department of Biology, Concordia University, Montreal, Quebec H4B 1R6, Canada.
Sary
S
Snounou
Department of Biology, Concordia University, Montreal, Quebec H4B 1R6, Canada.
Qingchuan
Q
Zhao
Department of Biology, Concordia University, Montreal, Quebec H4B 1R6, Canada Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec H3A 0C7, Canada michael.sacher@concordia.ca.
Michael
M
Sacher
D015153:Blotting, Western; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D045584:Chromosome Positioning; D020090:Chromosome Segregation; D002877:Chromosomes, Human; D006367:HeLa Cells; D006801:Humans; D018386:Kinetochores / Q000737:chemistry* / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D008938:Mitosis / Q000502:physiology*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D008941:Spindle Apparatus; D020798:Two-Hybrid System Techniques; D033921:Vesicular Transport Proteins / Q000378:metabolism*
D002868:Chromosomal Proteins, Non-Histone; D033921:Vesicular Transport Proteins; C068688:centromere protein E; C406327:transport protein particle, TRAPP