Changes in cell morphology and cytoskeletal organization are induced by human mitotic checkpoint gene, Bub1.
The mitotic spindle checkpoint prevents the onset of anaphase and subsequent cell division until chromosomes are properly aligned on a bipolar spindle. Thus, it regulates the cell division cycle by keeping cells with defective spindles from leaving mitosis. The budding uninhibited by benzimidazole (Bub1) is a key component of mitotic checkpoint. Bub1 encodes a serine/threonine kinase required for mitotic spindle checkpoint function. The regulation of cell morphology in eukaryotic cells is a complex process involving major components of the cytoskeleton including actin microfilaments, microtubules, and intermediate filaments (IFs). Here we show that Bub1 directly affects the structural integrity of IFs. Constitutive expression of Bub1 caused disappearance of filamentous vimentin, a type III IF, and consequently changed cell morphology. Expression of kinase domain-deleted Bub1 induced neither morphological change nor disappearance of vimentin. These observations suggest that Bub1 not only regulates the cell cycle, but also may be involved in the cytoskeletal control in interphase cells.
Division of Haematology, Department of Internal Medicine, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, 113-8421 Tokyo, Japan.
Jun
J
Ando
Koichi
K
Sugimoto
Kenji
K
Tamayose
Makoto
M
Sasaki
Miki
M
Ando
Kazuo
K
Oshimi
D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D048429:Cell Size; D003599:Cytoskeleton / Q000378:metabolism* / Q000648:ultrastructure*; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism* / Q000648:ultrastructure*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*
D018797:Cell Cycle Proteins; C584277:BUB1 protein, human; C090464:Bub1 spindle checkpoint protein; D017346:Protein Serine-Threonine Kinases