Project Grant F31AI202524

LIPID-COPPER CROSSTALK AS A DETERMINANT OF FUNGAL ADAPTATION TO METAL STRESS - PROJECT SUMMARY/ABSTRACT FUNGAL PATHOGENS LIKE ASPERGILLUS FUMIGATUS KILL MILLIONS OF PEOPLE ANNUALLY WORLDWIDE, AND IMPACT MILLIONS MORE. THE COMBINATION OF CRITICALLY FEW ANTIFUNGAL DRUG CLASSES AND EMERGING RESISTANCE HAS CREATED A CRISIS REQUIRING IDENTIFICATION OF NOVEL THERAPEUTIC TARGETS. ONE POTENTIAL ACHILLES' HEEL LIES IN COPPER HOMEOSTASIS, AS MAINTENANCE OF COPPER HOMEOSTASIS IS CRITICAL FOR FUNGI TO COMBAT THE HOST IMMUNE SYSTEM. WITHIN THE PHAGOLYSOSOME, FUNGI EXPERIENCE COPPER INTOXICATION, RESULTING IN REACTIVE OXYGEN SPECIES (ROS) ACCUMULATION AND CELL DEATH. ELSEWHERE IN INFECTED TISSUES, FUNGI ENCOUNTER COPPER DEPRIVATION, CAUSING VITAL ENZYMES TO BE INACTIVATED DUE TO LOSS OF THEIR COFACTOR. EMERGING EVIDENCE SUGGESTS THAT CELLULAR LIPIDS ACTIVELY PARTICIPATE IN COPPER STRESS RESPONSES, CHALLENGING THE PROTEIN-CENTRIC TRANSPORTER PARADIGM. ALTHOUGH EXTENSIVE WORK IN THE KELLER LAB HAS CHARACTERIZED COPPER IMPORT AND EXPORT PATHWAYS IN A. FUMIGATUS, THE METABOLIC PROGRAMS ENABLING GROWTH UNDER COPPER STRESS REMAIN UNKNOWN. PRELIMINARY EVIDENCE DEMONSTRATES THAT LIPID-RICH FUNGAL STRAINS ARE SIGNIFICANTLY MORE RESISTANT TO COPPER STARVATION AND TOXICITY. ADDITIONALLY, THIS LIPOGENIC STATE IS INDUCIBLE BY OVEREXPRESSION OF THE UNCHARACTERIZED TRANSCRIPTION FACTOR HBXH OR BY EXOGENOUS ADDITION OF THE OXYLIPIN SIGNALING MOLECULE 5,8-DIHODE. THEREFORE, THE HYPOTHESIS FOR THE PROPOSED RESEARCH IS THAT FUNGAL GROWTH UNDER COPPER STRESS IS SUSTAINED BY LIPID-COPPER CROSSTALK, IN WHICH OXYLIPIN-DIRECTED LIPID DROPLET BIOGENESIS CREATES SPECIALIZED COMPARTMENTS FOR COPPER SEQUESTRATION AND ROS BUFFERING. THE RESEARCH STRATEGY PROPOSES TO ESTABLISH THAT LIPID DROPLETS SEQUESTER AND BUFFER COPPER AND ROS THROUGH AN INTEGRATED APPROACH COMBINING CELLULAR LOCALIZATION STUDIES WITH GENETIC DISSECTION OF LIPID BIOSYNTHETIC PATHWAYS AND HOST-PATHOGEN INTERACTION MODELS. THE SPECIFIC AIMS OF THIS PROPOSAL ARE: 1) DETERMINE WHETHER LIPID-RICH FUNGAL STRAINS LOCALIZE COPPER AND ROS TO LIPID DROPLETS AND ARE MORE RESISTANT TO HOST IMMUNE MECHANISMS, AND 2) IDENTIFY MECHANISMS LINKING LIPID SYNTHESIS TO COPPER STRESS TOLERANCE. THE RESEARCH AND TRAINING BY HARRISON ESTES WILL BE CONDUCTED UNDER THE MENTORSHIP OF DR. NANCY KELLER AT THE UNIVERSITY OF WISCONSIN- MADISON, WHO IS A LEADER IN FUNGAL COPPER BIOLOGY AND HAS PIONEERED THE INTEGRATION OF MULTI-OMICS ANALYSES, GENETIC TOOLS, AND HOST-PATHOGEN INTERACTION MODELS IN A. FUMIGATUS AND OTHER FUNGAL PATHOGENS. THE SUCCESS OF THIS PROPOSAL WILL REDEFINE COPPER TOLERANCE AS A SIGNAL-DIRECTED, PROGRAMMABLE METABOLIC STATE, REVEALING CONSERVED METABOLIC VULNERABILITIES ACROSS FUNGAL PATHOGENS THAT CAN BE TARGETED FOR BROAD-SPECTRUM ANTIFUNGAL DEVELOPMENT. ADDITIONALLY, THIS TRAINING WILL PROVIDE A CRITICAL FOUNDATION FOR HARRISON ESTES TO ESTABLISH AN INDEPENDENT RESEARCH PROGRAM INVESTIGATING METABOLIC VULNERABILITIES AS ANTIFUNGAL THERAPEUTIC TARGETS.