Dietary amino acid insufficiency (AAI) can yield a wide variety of outcomes that can be either adverse orbeneficial to health. A clearer understanding of the molecular factors and processes guiding homeostaticcontrol of the proteome (proteostasis) during AAI is essential to identify novel causes of improved stressresistance and nutritional health. Collectively protein synthesis, proteolysis, and targeting are central toproteostasis and AAI triggers stress signaling pathways that are central for cell adaptation. The overarchinghypothesis of this proposal is that the outcome of these key signaling networks that respond to AAI are vital tocontrolling proteostasis and disease resistance. Cellular sensing of AAI involves overlapping signaltransduction mechanisms that are largely conserved from yeast to humans. Our published and preliminarydata demonstrate that key among these networks is the multi-part Integrated Stress Response (ISR), whichfeatures translational and transcriptional gene expression networks directed by phosphorylation of eukaryoticinitiation factor 2. In the ISR network, the transcription factor ATF4 is central to directing the gene expressionprograms that help ameliorate AAI. The objective of this application is to define the contribution of the ISR tothe early molecular and physiological responses that function to maintain proteostasis during dietary AAI. Toachieve the objective of this application we propose three Specific Aims: 1) Define how variations in AAIactivate the ISR; 2) Determine the role of ATF4 in the transcriptional networks and proteostatic responses toAAI; and 3) Assess novel control of proteolysis by the ISR during AAI. To accomplish these aims, time coursestudies will be conducted in cell lines and genetic strains of mice with targeted deficiencies in the ISR.Analyses will utilize a combination of sophisticated molecular biology and stable isotope techniques to assessand compare the mechanism of ISR activation and propagation in cell lysates and in the liver and skeletalmuscle of mice during AAI. The proposal is innovative in that it will reveal for the first time how thetranscriptome and translatome are guided by the ISR during AAI in vivo and provide insight into how the ISRcoordinates with other nutrient sensing networks to regulate protein balance. The work proposed is significantbecause a greater understanding of the mechanisms activated by AAI will lead to new molecular targets andapproaches to better prevent or treat human diseases.
|Effective start/end date||9/20/16 → 6/30/21|
- National Institutes of Health (NIH)