Project Grant F32AI202938

DISSECTING THE ROLE OF IKK-EPSILON IN TICK IMMUNITY AND VECTOR COMPETENCE - PROJECT SUMMARY TICK SPECIES SUCH AS IXODES SCAPULARIS ARE MAJOR VECTORS OF BACTERIAL PATHOGENS, INCLUDING LYME DISEASE AND GRANULOCYTIC ANAPLASMOSIS. NEVERTHELESS, STRATEGIES FOR CONTROLLING TICK-BORNE DISEASE ARE EXTREMELY LIMITED AND DO NOT ADDRESS VECTOR COMPETENCE, OR THE ABILITY FOR TICKS TO HARBOR AND TRANSMIT THESE PATHOGENS. ONE MAJOR FACTOR CONTROLLING VECTOR COMPETENCE IS THE TICK IMMUNE RESPONSE TO INFECTION, OF WHICH MECHANISTIC KNOWLEDGE IS PROFOUNDLY LACKING. TO DEVELOP EFFECTIVE, TARGETED METHODS TO PREVENT TICK-BORNE DISEASE BEFORE PATIENTS BECOME SICK, A FAR GREATER UNDERSTANDING OF TICK IMMUNE PATHWAYS IS NECESSARY. WE RECENTLY DISCOVERED THAT THE NON-CANONICAL IKB KINASE IKKE RESTRICTS TICK BACTERIAL BURDEN BY STIMULATING THE IMD PATHWAY, A VITAL ARTHROPOD INNATE IMMUNE RESPONSE ORTHOLOGOUS TO MAMMALIAN TNFR-NF-KB SIGNALING. FURTHERMORE, PHOSPHOPROTEOMIC ANALYSIS INDICATES THAT IKKE REGULATES NUMEROUS SIGNALING PATHWAYS RELEVANT TO TICK IMMUNITY. THE CENTRAL HYPOTHESIS OF THIS STUDY IS THAT TICK IKKE FUNCTIONS AS A CENTRAL POINT OF IMMUNE REGULATION, INTERACTING WITH MULTIPLE SIGNALING NETWORKS, INCLUDING THE IMD PATHWAY, WHICH IMPACT VECTOR COMPETENCE. PRELIMINARY DATA INDICATE THAT IKKE PHOSPHORYLATES THE IMD PATHWAY CORE REGULATOR XIAP. IN AIM 1, IMD-ACTIVATING INTERACTIONS BETWEEN IKKE AND XIAP WILL BE CHARACTERIZED BY PERFORMING MOLECULAR AND BIOCHEMICAL INTERACTION ASSAYS AND BY APPLYING CAS9-MEDIATED GENE EDITING AND TARGETED MUTAGENESIS TECHNIQUES. IN AIM 2, THE TICK IKKE SIGNALING NETWORK WILL BE MAPPED THROUGH COMPLEMENTARY UNBIASED METHODS INCLUDING PROXIMITY-BASED PROTEIN LABELING, PROTEOMICS, AND TRANSCRIPTOMICS. MANY TICK ORTHOLOGS OF CANONICAL PHOSPHORYLATION TARGETS OF IKKE ARE LACKING CONSERVED MOTIFS, RENDERING THE MECHANISMS OF IKKE IMMUNE INDUCTION UNCLEAR. THESE SCREENS WILL REVEAL MOLECULAR TARGETS WHICH IKKE SIGNALS THROUGH TO RESTRICT TICK PATHOGEN BURDEN. THE RESULTS OF THIS STUDY WILL LEAD TO NEW AVENUES OF INVESTIGATION FOR TARGETED CONTROL OF TICK-BORNE DISEASE AT THE VECTOR LEVEL. THIS PROJECT IS CONDUCTED AT WASHINGTON STATE UNIVERSITY, WHICH HAS LONG-STANDING PROMINENCE IN THE FIELD OF TICK-BORNE DISEASE AND WHOSE INVESTIGATORS FOSTER A HIGHLY COLLABORATIVE RESEARCH COMMUNITY. THE TRAINING PLAN ASSOCIATED WITH THIS PROJECT IS FACILITATED BY THE JOINT MENTORSHIP OF DR. DANA SHAW (PRIMARY SPONSOR) AND DR. EROL FIKRIG (CO-SPONSOR). AT THE CONCLUSION OF THIS FELLOWSHIP, DR. OSBRON WILL TRANSITION INTO A POSITION AS AN INDEPENDENT INVESTIGATOR.