Nucleoporin translocated promoter region (Tpr) associates with dynein complex, preventing chromosome lagging formation during mitosis.
Gain or loss of whole chromosomes is often observed in cancer cells and is thought to be due to aberrant chromosome segregation during mitosis. Proper chromosome segregation depends on a faithful interaction between spindle microtubules and kinetochores. Several components of the nuclear pore complex/nucleoporins play critical roles in orchestrating the rapid remodeling events that occur during mitosis. Our recent studies revealed that the nucleoporin, Rae1, plays critical roles in maintaining spindle bipolarity. Here, we show association of another nucleoporin, termed Tpr (translocated promoter region), with the molecular motors dynein and dynactin, which both orchestrate with the spindle checkpoints Mad1 and Mad2 during cell division. Overexpression of Tpr enhanced multinucleated cell formation. RNA interference-mediated knockdown of Tpr caused a severe lagging chromosome phenotype and disrupted spindle checkpoint proteins expression and localization. Next, we performed a series of rescue and dominant negative experiments to confirm that Tpr orchestrates proper chromosome segregation through interaction with dynein light chain. Our data indicate that Tpr functions as a spatial and temporal regulator of spindle checkpoints, ensuring the efficient recruitment of checkpoint proteins to the molecular motor dynein to promote proper anaphase formation.
Frontier Science Organization and Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan.
Hiroshi
H
Nakano
Tatsuyoshi
T
Funasaka
Chieko
C
Hashizume
Richard W
RW
Wong
D000705:Anaphase / Q000502:physiology*; D000818:Animals; D015153:Blotting, Western; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D020090:Chromosome Segregation; D056445:Cytoplasmic Dyneins / Q000235:genetics / Q000378:metabolism; D004398:Dyneins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007124:Immunoenzyme Techniques; D018386:Kinetochores; D064246:Mad2 Proteins; D008677:Metaphase / Q000502:physiology*; D051379:Mice; D041681:NIH 3T3 Cells; D028861:Nuclear Pore Complex Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D008941:Spindle Apparatus
D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; C501384:MAD1L1 protein, human; C577697:MAD2L1 protein, human; D064246:Mad2 Proteins; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D012097:Repressor Proteins; C073597:TPR protein, human; C427758:DYNLL1 protein, human; D056445:Cytoplasmic Dyneins; D004398:Dyneins