Biochemistry, Biophysics, and Structural Biology Commons^™

Med13 Degradation Defines A New Receptor-Mediated Autophagy Pathway Activated By Nutrient Deprivation, Sara E. Hanley

Graduate School of Biomedical Sciences Theses and Dissertations

Cells are exposed to an enormous amount of diverse extracellular cues but have a limited arsenal of weapons for protecting and maintaining homeostasis. To overcome these restrictions, nature has engineered proteins that have multiple functions. The pleiotropy of using one protein to carry out a variety of functions allows cells to rapidly execute tailored responses to a diverse set of signals. The Cdk8 kinase module (CKM) is a conserved detachable unit of the Mediator complex predominantly known for its role in transcriptional regulation. The CKM is composed of four proteins, the scaffolding proteins Med13 and Med12, as well as the …

Modeling The Tripartite Role Of Cyclin C In Cellular Stress Response Coordination, Steven J. Doyle

Graduate School of Biomedical Sciences Theses and Dissertations

For normal cellular function, exogenous signals must be interpreted and careful coordination must take place to ensure desired fates are achieved. Mitochondria are key regulatory nodes of cellular fate, undergoing fission/fusion cycles depending on the needs of the cell, and help mediate cell death fates. The CKM or Cdk8 kinase module, is composed of cyclin C (CC), Cdk8, Med12/12L, and Med13/13L. The CKM controls RNA polymerase II, acting as a regulator of stress-response and growth-control genes. Following stress, CC translocates to the mitochondria and interacts with both fission and iRCD apoptotic mediators. We hypothesize that CC represents a key mediator, …

Snf1 Cooperates With The Cwi Mapk Pathway To Mediate The Degradation Of Med13 Following Oxidative Stress, Stephen D Willis, David C Stieg, Kai Li Ong, Ravina Shah, Alexandra K. Strich, Julianne H Grose, Katrina F Cooper

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

Eukaryotic cells, when faced with unfavorable environmental conditions, mount either pro-survival or pro-death programs. The conserved cyclin C-Cdk8 kinase plays a key role in this decision. Both are members of the Cdk8 kinase module that, along with Med12 and Med13, associate with the core Mediator complex of RNA polymerase II. In Saccharomyces cerevisiae, oxidative stress triggers Med13 destruction, which releases cyclin C into the cytoplasm to promote mitochondrial fission and programmed cell death. The SCFGrr1 ubiquitin ligase mediates Med13 degradation dependent on the cell wall integrity pathway, MAPK Slt2. Here we show that the AMP kinase Snf1 activates a second …

Mechanistic Insights Into The Regulation Of Mitochondrial Fission By Cyclin C, Vidyaramanan Ganesan, Katrina F Cooper, Randy Strich

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

Cyclin C is a component of the mediator complex of RNA polymerase II that localizes to the nucleus under normal conditions. In response to stress, cyclin C translocates to the cytosol and mitochondria and mediates stress‐induced mitochondrial fission and apoptosis. The molecular mechanisms by which cyclin C induces mitochondrial fission are unknown. Using in vitro experimental approaches, we sought to investigate the mechanistic basis of cyclin C mediated mitochondrial fission.

Med13p Prevents Stress-Independent Mitochondrial Hyperfragmentation And Aberrant Apoptosis Activation In Saccharomyces Cerevisiae By Controlling Cyclin C Nuclear Localization, Svetlana Khakhina

Graduate School of Biomedical Sciences Theses and Dissertations

During aging, and as a result of environmental changes, cells are exposed to elevated levels of reactive oxygen species (ROS). High ROS levels induce lipid oxidation, protein aggregation, mitochondrial hyperfragmentation, DNA damage and programmed cell death (PCD), also called apoptosis. PCD is a highly regulated process and its misregulation has been linked to neurodegenerative diseases and cancer development.

Our hypothesis is that cyclin C plays a role in the initiation of apoptosis. During normal conditions, cyclin C represses the transcription of stress response genes (SRG). In response to stress, cyclin C translocates to the cytoplasm where it facilitates mitochondrial hyperfragmentation …