Targeted localization of Inn1, Cyk3 and Chs2 by the mitotic-exit network regulates cytokinesis in budding yeast.
The mitotic-exit network (MEN) is a signaling pathway that is essential for the coordination of mitotic exit and cytokinesis. Whereas the role of the MEN in mitotic exit is well established, the molecular mechanisms by which MEN components regulate cytokinesis remain poorly understood. Here, we show that the MEN controls components involved in septum formation, including Inn1, Cyk3 and Chs2. MEN-deficient mutants, forced to exit mitosis as a result of Cdk1 inactivation, show defects in targeting Cyk3 and Inn1 to the bud-neck region. In addition, we found that the chitin synthase Chs2 did not efficiently localize at the bud neck in the absence of MEN activity. Ultrastructural analysis of the bud neck revealed that low MEN activity led to unilateral, uncoordinated extension of the primary and secondary septa. This defect was partially suppressed by increased levels of Cyk3. We therefore propose that the MEN directly controls cytokinesis via targeting of Inn1, Cyk3 and Chs2 to the bud neck.
Meitinger
Franz
F
German Cancer Research Centre, DKFZ-ZMBH Alliance, Molecular Biology of Centrosomes and Cilia Unit, Im Neuenheimer Feld 581, 69120 Heidelberg, Germany.
Petrova
Boryana
B
Lombardi
Ilde Mancini
IM
Bertazzi
Daniela Trinca
DT
Hub
Birgit
B
Zentgraf
Hanswalter
H
Pereira
Gislene
G
D016203:CDC2 Protein Kinase / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002687:Chitin Synthase / Q000378:metabolism*; D003001:Cloning, Molecular; D048749:Cytokinesis / Q000235:genetics; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000172:deficiency*; D008938:Mitosis / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D018995:Myosin Heavy Chains / Q000172:deficiency; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D004718:Saccharomycetales / Q000502:physiology*; D017384:Sequence Deletion / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics
D018797:Cell Cycle Proteins; C418803:Cyk3 protein, S cerevisiae; C116847:HOF1 protein, S cerevisiae; C528682:Inn1 protein, S cerevisiae; C112936:MYO1 protein, S cerevisiae; D008869:Microtubule-Associated Proteins; D029701:Saccharomyces cerevisiae Proteins; C069390:CHS3 protein, S cerevisiae; D002687:Chitin Synthase; D016203:CDC2 Protein Kinase; D018995:Myosin Heavy Chains