Nrf1/2 (human) and SKN-1 (Caenorhabditis elegans ortholog) are key infection-related transcription factors whose regulation is incompletely understood, representing a critical gap in knowledge. The long-term goal of this research is to understand how the host alleviates stress during exposure to pathogens. The objective of this application is to elucidate new mechanisms of SKN-1 regulation that contribute to its protective effects. The central hypothesis is that NIPI-3 and CDC-48.1/2 are amongst previously unknown factors that positively regulate SKN-1 to protect against immune associated stress. The rationale for this investigation is that the identification of new regulators which control a conserved stress response under pathogenic conditions may allow for their therapeutic modulation to alleviate infection induced pathology. The central hypothesis will be addressed by the following aims.
Specific Aim #1 will identify how NIPI-3 regulates SKN-1 activity. The working hypothesis, based on preliminary and published data, is that NIPI-3 regulates SKN-1 activity in the intestine via CEBP-1. Specifically, NIPI-3 is proposed to negatively regulate CEBP-1, to directly influence the amount and/or activity of SKN-1 available to carry out its protective transcriptional response.
Specific Aim #2 will elucidate the role of CDC-48.1/2 in influencing SKN-1 activity. CDC-48.1/2 is hypothesized to elicit its effects on SKN-1 by its role in the ER-associated degradation (ERAD) pathway. Specifically, it is proposed that CDC-48.1/2 shuttles SKN- 1A, the ER-tethered form of SKN-1, to the cytosolic side of the ER membrane, a process necessary for its activation. However, CDC-48.1/2 is additionally predicted to ensure the proper trafficking of BLI-3, a NADPH oxidase necessary for activating cytoplasmic SKN-1.
Specific Aim #3 will identify additional factors that regulate SKN-1 activity and pathogen resistance. In addition to CDC-48.1/2 and NIPI-3, other factors of in- terest were found, including two that only affect SKN-1 activity on pathogen. In this aim, the screen will be com- pleted and additional factors will be characterized. The approach is postulated to reveal further insights into the mechanisms of SKN-1 regulation. Because SKN-1 and human Nrf orthologs protect against infection-related stress, the research will have a significant impact on the understanding of the cytoprotective responses that occur during the immune response. Knowledge of the targets and mechanisms that drive anti-inflammatory re- sponses may allow for their eventual pharmacological targeting for the benefit of those suffering from damaging immune responses. The proposed research is innovative because it identifies SKN-1 regulators under infectious conditions, representing a substantive departure from previous studies.

Public Health Relevance

The research proposed in this application will lead to greater understanding of how stress and damage related to the immune response is mitigated. Such knowledge is relevant to public health because it will lead to the potential manipulation of this response to the patient?s advantage in the treatment of infections and autoimmune disorders.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Innate Immunity and Inflammation Study Section (III)
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Singleton, Kentner L
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University of Texas Health Science Center Houston
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