Its8, a fission yeast homolog of Mcd4 and Pig-n, is involved in GPI anchor synthesis and shares an essential function with calcineurin in cytokinesis.
In fission yeast, calcineurin is required for cytokinesis and ion homeostasis; however, most of its physiological roles remain obscure. To identify genes that share an essential function with calcineurin, we screened for mutations that confer sensitivity to the calcineurin inhibitor FK506 and high temperature and isolated the mutant its8-1. its8(+) encodes a homolog of the budding yeast MCD4 and human Pig-n that are involved in glycosylphosphatidylinositol (GPI) anchor synthesis. Consistently, reduced inositol labeling of proteins suggested impaired GPI anchor synthesis in its8-1 mutants. The temperature upshift induced a further decrease in inositol labeling and caused dramatic increases in the frequency of septation in its8-1 mutants. BE49385A, an inhibitor of MCD4 and Pig-n, also increased the septation index of the wild-type cell. Osmotic stabilization suppressed these morphological defects, indicating that cell wall weakness caused by impaired GPI anchor synthesis resulted in abnormal cytokinesis. Furthermore, calcineurin-deleted cells exhibited hypersensitivity to BE49385A, and FK506 exacerbated the cytokinesis defects of the its8-1 mutant. Thus, calcineurin and Its8 may share an essential function in cytokinesis and cell viability through the regulation of cell wall integrity.
Yada
T
T
Department of Pharmacology, Kobe University School of Medicine, Kobe 650-0017, Japan.
Sugiura
R
R
Kita
A
A
Itoh
Y
Y
Lu
Y
Y
Hong
Y
Y
Kinoshita
T
T
Shuntoh
H
H
Kuno
T
T
D000595:Amino Acid Sequence; D019703:Calcineurin / Q000502:physiology*; D065095:Calcineurin Inhibitors; D002455:Cell Division; D002473:Cell Wall / Q000378:metabolism; D003001:Cloning, Molecular; D005656:Fungal Proteins / Q000737:chemistry* / Q000502:physiology*; D006023:Glycoproteins; D017261:Glycosylphosphatidylinositols / Q000737:chemistry*; D049452:Green Fluorescent Proteins; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology; D007294:Inositol / Q000378:metabolism; D008164:Luminescent Proteins / Q000378:metabolism; D008358:Mannose / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D008861:Microsomes / Q000378:metabolism; D008957:Models, Genetic; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009995:Osmosis; D010770:Phosphotransferases; D011506:Proteins / Q000737:chemistry*; D011995:Recombination, Genetic; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins; D017386:Sequence Homology, Amino Acid; D016559:Tacrolimus / Q000494:pharmacology; D013696:Temperature; D013997:Time Factors
D065095:Calcineurin Inhibitors; D005656:Fungal Proteins; D006023:Glycoproteins; D017261:Glycosylphosphatidylinositols; D007166:Immunosuppressive Agents; C427749:Its8 protein, S pombe; D008164:Luminescent Proteins; C118052:MCD4 protein, S cerevisiae; D008565:Membrane Proteins; D011506:Proteins; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D049452:Green Fluorescent Proteins; D007294:Inositol; D010770:Phosphotransferases; C403312:Pign protein, mouse; D019703:Calcineurin; D008358:Mannose; D016559:Tacrolimus