title: Induction of abnormal nuclear shapes in two distinct modes by overexpression of serine/threonine protein phosphatase 5 in Hela cells.
abstract: Okadaic acid-sensitve serine/threonine protein phosphatase 5 (PP5) is expressed ubiquitously in various tissues and is considered to participate in many cellular processes. PP5 has a catalytic domain in the C-terminal region and three tetratricopeptide repeat (TPR) motifs in the N-terminal region, which are suspected to function as a protein-protein interaction domain. Physiological roles of PP5 are still largely unknown, although several PP5-binding proteins were reported and a few in vivo functions of PP5 were suggested. In the present study, the effects of expression of the full-length wild-type PP5 fused with EGFP (EGFP-PP5(WT)) and its phosphatase-dead mutant EGFP-PP5(H304A) were investigated. Transient expression of either EGFP-PP5(WT) or EGFP-PP5(H304A) in HeLa cells induced deformed nuclei with a 10-fold frequency compared to that of EGFP. Abnormal-shaped nuclei were also substantially increased by induced moderate expression of PP5 in tet-on HeLa cells. Many HeLa cells expressing EGFP-PP5(WT) possessed multi-nuclei separated from each other by nuclear membrane, while expression of EGFP-PP5(H304A) induced deformed nuclei which were multiple-like in shape, but not separated completely and were surrounded by one nuclear membrane. These results suggest that PP5 plays important roles at the M-phase of the cell cycle, especially in separation of chromosomes and formation of nuclear membrane.
authors.affiliation: Biochemistry Division, National Cancer Center Research Institute, Tokyo, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Fukuda
authors.forename: Naoto
authors.initials: N
authors.lastname: Tsuchiya
authors.forename: Kaori
authors.initials: K
authors.lastname: Hara-Fujita
authors.forename: Sachiyo
authors.initials: S
authors.lastname: Takagi
authors.forename: Minako
authors.initials: M
authors.lastname: Nagao
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Nakagama
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D002467:Cell Nucleus / Q000648:ultrastructure*; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D010749:Phosphoprotein Phosphatases; C089641:protein phosphatase 5