Cbk1 kinase and Bck2 control MAP kinase activation and inactivation during heat shock.
Saccharomyces cerevisiae Cbk1 kinase is a LATS/NDR tumor suppressor orthologue and component of the Regulation of Ace2 and Morphogenesis signaling network. Cbk1 was previously implicated in regulating polarized morphogenesis, gene expression, and cell integrity. Here we establish that Cbk1 is critical for heat shock and cell wall stress signaling via Bck2, a protein associated with the Pkc1-Mpk1 cell integrity pathway. We demonstrate that cbk1 and bck2 loss-of-function mutations prevent Mpk1 kinase activation and Mpk1-dependent gene expression but do not disrupt Mpk1 Thr-190/Tyr-192 phosphorylation. Bck2 overexpression partially restores Mpk1-dependent Rlm1 transcription factor activity in cbk1 mutants, suggesting that Bck2 functions downstream of Cbk1. We demonstrate that Bck2 precisely colocalizes with the mitogen-activated protein kinase (MAPK) phosphatase Sdp1. During heat shock, Bck2 and Sdp1 transiently redistribute from nuclei and the cytosol to mitochondria and other cytoplasmic puncta before returning to their pre-stressed localization patterns. Significantly, Cbk1 inhibition delays the return of Bck2 and Sdp1 to their pre-stressed localization patterns and delays Mpk1 Thr-190/Tyr-192 dephosphorylation upon heat shock adaptation. We conclude that Cbk1 and Bck2 are required for Mpk1 activation during heat shock and cell wall stress and for Mpk1 dephosphorylation during heat shock adaptation. These data provide the first evidence that Cbk1 kinase regulates MAPK-dependent stress signaling and provide mechanistic insight into Sdp1 phosphatase regulation.
Department of Animal Biology and Mari Lowe Center for Comparative Oncology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
Venkata K
VK
Kuravi
Cornelia
C
Kurischko
Manasi
M
Puri
Francis C
FC
Luca
D054637:Dual-Specificity Phosphatases / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D015966:Gene Expression Regulation, Fungal / Q000502:physiology; D018869:Heat-Shock Response / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000096:biosynthesis* / Q000235:genetics; D010766:Phosphorylation / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*
C082733:BCK2 protein, S cerevisiae; D047908:Intracellular Signaling Peptides and Proteins; D029701:Saccharomyces cerevisiae Proteins; C423362:CBK1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; D020928:Mitogen-Activated Protein Kinases; C072724:SLT2 protein, S cerevisiae; D054637:Dual-Specificity Phosphatases; C467054:SDP1 protein, S cerevisiae