Germinal center-associated nuclear protein (GANP) is involved in mRNA export of Shugoshin-1 required for centromere cohesion and in sister-chromatid exchange.
Germinal center-associated nuclear protein (GANP) is a 210-kDa protein that is upregulated in rapidly proliferating B cells. GANP contains regions for RNA-primase and minichromosome maintenance 3 (MCM3)-associated activities, as well as a Sac3-homology region, which is associated with mRNA export in yeast. Here, we examined the role of GANP in mRNA export and cell proliferation in mammalian cells. The ganp small interfering RNA (siRNA) induced cell-cycle arrest at the G2/M-phase, but increased abnormal chromosome alignment of metaphase chromosomes and cell apoptosis in HeLa cells. These changes were not associated with either the abnormality of the spindle assembly checkpoint or the expression level of cohesin. ganp siRNA disrupted the assembly and localization of cohesin at the centromeres in metaphase cells, which is a quite similar phenotype caused by Shugoshin-1 (Sgo1) siRNA-treatment, which was reported previously. ganp siRNA did induce a selective decrease in Sgo1 transcript levels in the cytoplasm, resulting in a lack of cohesin at the centromeres in metaphase and premature separation of the sister chromatids at mitosis. GANP lacking the Sac3-homology region caused the dominant-negative effect with similar abnormalities and impaired mRNA export. Thus, human GANP is critically involved in cell proliferation at the mitotic phase through its selective support of Sgo1 mRNA export.
Okamoto
Nobukazu
N
Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1, Honjo, Kumamoto 860-8556, Japan.
Kuwahara
Kazuhiko
K
Ohta
Kazutaka
K
Kitabatake
Masahiro
M
Takagi
Katsumasa
K
Mizuta
Hiroshi
H
Kondo
Eisaku
E
Sakaguchi
Nobuo
N
D000123:Acetyltransferases / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D049109:Cell Proliferation; D002503:Centromere / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D012854:Sister Chromatid Exchange
D018797:Cell Cycle Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C496644:SGO1 protein, human; D000123:Acetyltransferases; C406825:MCM3AP protein, human