Roles of Pdk1p, a fission yeast protein related to phosphoinositide-dependent protein kinase, in the regulation of mitosis and cytokinesis

• Published in: Molecular biology of the cell Vol. 16; no. 7; pp. 3162 - 3175
• Main Authors: Bimbó, Andrea, Liu, Jianhua, Balasubramanian, Mohan K
• Format: Journal Article
• Language: English
• Published: United States The American Society for Cell Biology 01.07.2005
• Subjects: 3-Phosphoinositide-Dependent Protein Kinases; Actomyosin - chemistry; Amino Acid Sequence; Animals; Cell Division; Cell Nucleus - metabolism; Cell Proliferation; Contractile Proteins - chemistry; Cytokinesis; Fluorescent Antibody Technique, Indirect; Gene Expression Regulation, Fungal; Genotype; Green Fluorescent Proteins - metabolism; Humans; Membrane Glycoproteins - metabolism; Metaphase; Metazoa; Mitosis; Molecular Sequence Data; Mutation; Phenotype; Phosphatidylinositol 3-Kinases - metabolism; Phylogeny; Protein Structure, Tertiary; Protein-Serine-Threonine Kinases - metabolism; Protein-Serine-Threonine Kinases - physiology; Saccharomyces cerevisiae Proteins - metabolism; Schizosaccharomyces - metabolism; Schizosaccharomyces pombe; Schizosaccharomyces pombe Proteins - metabolism; Sequence Homology, Amino Acid; Spindle Apparatus; Time Factors
• ISSN: 1059-1524; 1939-4586
• DOI: 10.1091/mbc.E04-09-0769

Proteins related to the phosphoinositide-dependent protein kinase family have been identified in the majority of eukaryotes. Although much is known about upstream mechanisms that regulate the PDK1-family of kinases in metazoans, how these kinases regulate cell growth and division remains unclear. Here, we characterize a fission yeast protein related to members of this family, which we have termed Pdk1p. Pdk1p localizes to the spindle pole body and the actomyosin ring in early mitotic cells. Cells deleted for pdk1 display multiple defects in mitosis and cytokinesis, all of which are exacerbated when the function of fission yeast polo kinase, Plo1p, is partially compromised. We conclude that Pdk1p functions in concert with Plo1p to regulate multiple processes such as the establishment of a bipolar mitotic spindle, transition to anaphase, placement of the actomyosin ring and proper execution of cytokinesis. We also present evidence that the effects of Pdk1p on cytokinesis are likely mediated via the fission yeast anillin-related protein, Mid1p, and the septation initiation network.