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Cdk8 Kinase Module: A Mediator of Life and Death Decisions in Times of Stress

The Cdk8 kinase module (CKM) of the multi-subunit mediator complex plays an essential role in cell fate decisions in response to different environmental cues. In the budding yeast S. cerevisiae, the CKM consists of four conserved subunits (cyclin C and its cognate cyclin-dependent kinase Cdk8, Med13...

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Autores principales: Friedson, Brittany, Cooper, Katrina F.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8540245/
https://www.ncbi.nlm.nih.gov/pubmed/34683473
http://dx.doi.org/10.3390/microorganisms9102152
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author Friedson, Brittany
Cooper, Katrina F.
author_facet Friedson, Brittany
Cooper, Katrina F.
author_sort Friedson, Brittany
collection PubMed
description The Cdk8 kinase module (CKM) of the multi-subunit mediator complex plays an essential role in cell fate decisions in response to different environmental cues. In the budding yeast S. cerevisiae, the CKM consists of four conserved subunits (cyclin C and its cognate cyclin-dependent kinase Cdk8, Med13, and Med12) and predominantly negatively regulates a subset of stress responsive genes (SRG’s). Derepression of these SRG’s is accomplished by disassociating the CKM from the mediator, thus allowing RNA polymerase II-directed transcription. In response to cell death stimuli, cyclin C translocates to the mitochondria where it induces mitochondrial hyper-fission and promotes regulated cell death (RCD). The nuclear release of cyclin C requires Med13 destruction by the ubiquitin-proteasome system (UPS). In contrast, to protect the cell from RCD following SRG induction induced by nutrient deprivation, cyclin C is rapidly destroyed by the UPS before it reaches the cytoplasm. This enables a survival response by two mechanisms: increased ATP production by retaining reticular mitochondrial morphology and relieving CKM-mediated repression on autophagy genes. Intriguingly, nitrogen starvation also stimulates Med13 destruction but through a different mechanism. Rather than destruction via the UPS, Med13 proteolysis occurs in the vacuole (yeast lysosome) via a newly identified Snx4-assisted autophagy pathway. Taken together, these findings reveal that the CKM regulates cell fate decisions by both transcriptional and non-transcriptional mechanisms, placing it at a convergence point between cell death and cell survival pathways.
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spelling pubmed-85402452021-10-24 Cdk8 Kinase Module: A Mediator of Life and Death Decisions in Times of Stress Friedson, Brittany Cooper, Katrina F. Microorganisms Review The Cdk8 kinase module (CKM) of the multi-subunit mediator complex plays an essential role in cell fate decisions in response to different environmental cues. In the budding yeast S. cerevisiae, the CKM consists of four conserved subunits (cyclin C and its cognate cyclin-dependent kinase Cdk8, Med13, and Med12) and predominantly negatively regulates a subset of stress responsive genes (SRG’s). Derepression of these SRG’s is accomplished by disassociating the CKM from the mediator, thus allowing RNA polymerase II-directed transcription. In response to cell death stimuli, cyclin C translocates to the mitochondria where it induces mitochondrial hyper-fission and promotes regulated cell death (RCD). The nuclear release of cyclin C requires Med13 destruction by the ubiquitin-proteasome system (UPS). In contrast, to protect the cell from RCD following SRG induction induced by nutrient deprivation, cyclin C is rapidly destroyed by the UPS before it reaches the cytoplasm. This enables a survival response by two mechanisms: increased ATP production by retaining reticular mitochondrial morphology and relieving CKM-mediated repression on autophagy genes. Intriguingly, nitrogen starvation also stimulates Med13 destruction but through a different mechanism. Rather than destruction via the UPS, Med13 proteolysis occurs in the vacuole (yeast lysosome) via a newly identified Snx4-assisted autophagy pathway. Taken together, these findings reveal that the CKM regulates cell fate decisions by both transcriptional and non-transcriptional mechanisms, placing it at a convergence point between cell death and cell survival pathways. MDPI 2021-10-15 /pmc/articles/PMC8540245/ /pubmed/34683473 http://dx.doi.org/10.3390/microorganisms9102152 Text en © 2021 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Review
Friedson, Brittany
Cooper, Katrina F.
Cdk8 Kinase Module: A Mediator of Life and Death Decisions in Times of Stress
title Cdk8 Kinase Module: A Mediator of Life and Death Decisions in Times of Stress
title_full Cdk8 Kinase Module: A Mediator of Life and Death Decisions in Times of Stress
title_fullStr Cdk8 Kinase Module: A Mediator of Life and Death Decisions in Times of Stress
title_full_unstemmed Cdk8 Kinase Module: A Mediator of Life and Death Decisions in Times of Stress
title_short Cdk8 Kinase Module: A Mediator of Life and Death Decisions in Times of Stress
title_sort cdk8 kinase module: a mediator of life and death decisions in times of stress
topic Review
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8540245/
https://www.ncbi.nlm.nih.gov/pubmed/34683473
http://dx.doi.org/10.3390/microorganisms9102152
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