Genetic Analysis of Hypoxic Stress Resistance - PROJECT SUMMARY Hypoxia (O2 deprivation) plays a central role in diverse human diseases, including ischemic stroke, myocardial infarction, pulmonary hypertension, traumatic brain injury, spinal cord injury, COPD, Cerebral Palsy, COVID- 19, and cancer. In diseases involving acute hypoxia, tissue is damaged through energy deprivation and oxidative stress. Metazoans respond to hypoxia by employing the conserved hypoxia response pathway (HRP), which can reduce hypoxic damage by reprogramming gene expression and metabolism. In disorders involving chronic hypoxia, the long-term adaptations and metabolic remodeling triggered by the HRP itself often cause tissue damage. The overall premise is that the HRP protects against hypoxic damage by (1) removing mitochondria through mitophagy, which eliminates mitochondria as a source of reactive oxygen species (ROS) within hypoxic cells, and by (2) regulating gene expression at multiple levels to mobilize antioxidant metabolism, which detoxifies ROS during hypoxia and reoxygenation. There is strong interest in targeting HRP components as pharmaceutical treatments; a better understanding of the pathway response will provide therapeutic targets for the diverse diseases associated with hypoxia (i.e., general medicine). The Rongo lab is tackling 3 major knowledge gaps in the basic science of hypoxia and the HRP: (1) how is the hypoxia response modulated by other environmental conditions and/or changes in internal physiology, (2) how does hypoxia and HRP activation regulate gene expression, and (3) how does hypoxia and the HRP induce mitophagy? Our research takes advantage of genetics and an intact, isogenic model organism (C. elegans) that can thrive under hypoxia, whose environment and genetics can be controlled with fidelity and reproducibility, and which possesses single conserved genes for the core components of the HRP. The lab’s goals over the next five years are to understand how hypoxia and the HRP (1) can be modulated by other pathways, including Protein Kinase G (PKG) signaling; (2) can regulate chromatin remodeling, transcription, and translation; and (3) can induce mitophagy in a tissue-specific manner over time. At its completion, their proposed research will have identified the in vivo substrates of PKG and revealed how it reprograms gene expression and physiology. It will have demonstrated how hypoxia and the HRP remodel the chromatin landscape, regulate gene transcription, and regulate translation over time during a hypoxic event. Finally, it will have identified the mitophagy receptors that mediate hypoxia-induced mitophagy in different tissues and at different time points, as well as how different aspects of HRP activation and mitochondrial quality control pathways co-regulate and crosstalk with one another. Their research employs multiple technical approaches, including molecular genetics, genomics, gene editing, and physiology. Its comprehensive approach should yield conserved insights into how tissues respond to hypoxic stress and pathology in vivo.
