Over the past half century scientists have learned much about how cells detect physical and chemical cues in their environment. Typically, cell signaling requires a plasma membrane receptor, an intracellular transducer and a downstream effector such as a protein kinase. Protein kinases are well known to phosphorylate downstream targets such as transcription factors, which drive new gene transcription. Most kinases also phosphorylate upstream components leading to positive or negative feedback. In this way, some signals become amplified while others become diminished. Familiar examples of negative feedback include desensitization to odors, light, and many pharmaceuticals. Whereas past work has focused on feedback inhibition leading to desensitization, our proposed work will focus on three additional and important consequences of feedback regulation: I: Signal coordination; for example to limit inappropriate activation of a competing kinase pathway. II: Signal tuning; for example to convert a graded input to a switch-like output, or vice versa. III: Signal tracking; for example to allow cell growth or migration towards a gradient stimulus. Our investigation will center on the mitogen activated protein kinases (MAPKs), which are activated in response to diverse (and often competing) stimuli including hormones, stresses and cytokines. Among the best- characterized MAPK pathways are those found in yeast Saccharomyces cerevisiae, where they contribute to cell mating and the osmotic stress response. Our approach will capitalize on recent breakthroughs, including newer fluorescent sensors capable of tracking biological responses, as well as new microfluidics devices capable of tracking pathway activity in single cells. Comprehensive identification of MAPK substrates, and establishing the consequences of those phosphorylation events, will inform new predictive computational models. Our investigations will require multiple rounds of data collection, model building, model testing, and model refinement, and would therefore benefit greatly from the flexibility and stability provided by the R35 grant mechanism.

Public Health Relevance

Most drugs (or hormones or neurotransmitters) are not delivered in a continuous fashion, in the absence of other inputs or in unchanging physiological conditions. The objective of this project is to determine how molecular feedback mechanisms contribute to the coordination, tuning and spatial tracking of cell stimuli. The results of this work could reveal new drug targets and drug combinations to treat stress-related pathologies.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Unknown (R35)
Project #
5R35GM118105-04
Application #
9690122
Study Section
Special Emphasis Panel (ZGM1)
Program Officer
Dunsmore, Sarah
Project Start
2016-05-01
Project End
2021-04-30
Budget Start
2019-05-01
Budget End
2020-04-30
Support Year
4
Fiscal Year
2019
Total Cost
Indirect Cost
Name
University of North Carolina Chapel Hill
Department
Biochemistry
Type
Schools of Medicine
DUNS #
608195277
City
Chapel Hill
State
NC
Country
United States
Zip Code
27599
Isom, Daniel G; Page, Stephani C; Collins, Leonard B et al. (2018) Coordinated regulation of intracellular pH by two glucose-sensing pathways in yeast. J Biol Chem 293:2318-2329
Shellhammer, James P; Morin-Kensicki, Elizabeth; Matson, Jacob P et al. (2017) Amino acid metabolites that regulate G protein signaling during osmotic stress. PLoS Genet 13:e1006829