Cbk1 regulation of the RNA-binding protein Ssd1 integrates cell fate with translational control.
Spatial control of gene expression, at the level of both transcription and translation, is critical for cellular differentiation [1-4]. In budding yeast, the conserved Ndr/warts kinase Cbk1 localizes to the new daughter cell, where it acts as a cell fate determinant. Cbk1 both induces a daughter-specific transcriptional program and promotes morphogenesis in a less well-defined role [5-8]. Cbk1 is essential in cells expressing functional Ssd1, an RNA-binding protein of unknown function [9-11]. We show here that Cbk1 inhibits Ssd1 in vivo. Loss of this regulation dramatically slows bud expansion, leading to highly aberrant cell wall organization at the site of cell growth. Ssd1 associates with specific mRNAs, a significant number of which encode cell wall remodeling proteins. Translation of these messages is rapidly and specifically suppressed when Cbk1 is inhibited; this suppression requires Ssd1. Transcription of several of these Ssd1-associated mRNAs is also regulated by Cbk1, indicating that the kinase controls both the transcription and translation of daughter-specific mRNAs. This work suggests a novel system by which cells coordinate localized expression of genes involved in processes critical for cell growth and division.
Jansen
Jaclyn M
JM
Department of Biochemistry, Molecular Biology, and Cell Biology, Northwestern University, Evanston, IL 60208, USA.
Wanless
Antony G
AG
Seidel
Christopher W
CW
Weiss
Eric L
EL
D015152:Blotting, Northern; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology*; D002473:Cell Wall / Q000235:genetics / Q000502:physiology; D017931:DNA Primers / Q000235:genetics; D036681:Fluorescence Recovery After Photobleaching; D040461:Gene Components; D015966:Gene Expression Regulation, Fungal / Q000235:genetics / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
D017931:DNA Primers; D047908:Intracellular Signaling Peptides and Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; C485219:Ssd1 protein, S cerevisiae; C423362:CBK1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases