Project Grant R01DK135999

KIBRA-INDUCED BIOMECHANICAL CHANGES AND THERAPEUTIC TARGETING IN PODOCYTES - DESPITE RECENT PROGRESS IN THE IDENTIFICATION OF MEDIATORS OF PODOCYTE INJURY, MECHANISMS UNDERLYING PODOCYTE LOSS REMAIN POORLY UNDERSTOOD, AND CELL-SPECIFIC THERAPY IS LACKING. OUR LONG-TERM GOAL IS TO ELUCIDATE CRITICAL SIGNALING PATHWAYS THAT DISRUPT PODOCYTE CYTOARCHITECTURE IN ORDER TO IDENTIFY TARGETS FOR THERAPEUTIC INTERVENTION FOR GLOMERULAR DISEASES. OUR WORK HAS IDENTIFIED KIBRA (ENCODED BY WWC1) AS A KEY REGULATOR OF GLOMERULAR DISEASE PROGRESSION, PODOCYTE CYTOSTRUCTURE, AND PODOCYTE INJURY VIA DOWNSTREAM LATS KINASE ACTIVATION AND YAP INHIBITION IN THE CANONICAL HIPPO SIGNALING PATHWAY. HOWEVER, LITTLE IS KNOWN ABOUT THE REGULATION OF WWC1/KIBRA EXPRESSION, AND THERAPEUTIC IMPLICATIONS FOR KIBRA UPREGULATION IN FSGS AND DIABETIC NEPHROPATHY REMAIN UNCLEAR. ADDITIONALLY, OUR PRELIMINARY DATA SUPPORT NON-CANONICAL DIRECT KIBRA DOWNSTREAM REGULATION OF TRANSCRIPTION FACTORS TEAD 1-4. THE OVERALL OBJECTIVES OF THIS APPLICATION ARE TO DEFINE THE REGULATORS OF WWC1/KIBRA EXPRESSION AND FUNCTION IN PODOCYTES, TEST NON-CANONICAL KIBRA-TEAD SIGNALING, AND TO TARGET LATS AND TEAD AS NOVEL THERAPEUTIC STRATEGIES FOR KIBRA-MEDIATED AND DIABETIC PODOCYTE INJURY. BASED ON OUR PRELIMINARY RNA-SEQ ANALYSIS, OUR CENTRAL HYPOTHESIS IS THAT WWC1/KIBRA FUNCTION IN PODOCYTES IS REPRESSED BY THE MICRO-RNA 200 FAMILY AND REGULATED BY TRANSCRIPTION FACTORS SUCH AS SOX4. IN ADDITION TO CANONICAL KIBRA REGULATION OF LATS/YAP, KIBRA NON-CANONICALLY DIRECTLY SUPPRESSES TEAD 1-4 EXPRESSION. TOGETHER, THESE DOWNSTREAM SIGNALING EVENTS DISRUPT PODOCYTE STRUCTURAL INTEGRITY AND PODOCYTE-GLOMERULAR BASEMENT MEMBRANE (GBM) ADHESION, THEREBY PROMOTING GLOMERULAR DISEASE PROGRESSION. THE RATIONALE FOR THE PROPOSED RESEARCH IS THAT TESTING NOVEL REGULATORS OF KIBRA, NON-CANONICAL KIBRA SIGNALING, AND BOTH NOVEL CANONICAL AND NON- CANONICAL THERAPEUTIC APPROACHES WILL SIGNIFICANTLY INCREASE UNDERSTANDING OF THE MECHANISMS UNDERLYING GLOMERULAR DISEASE PROGRESSION AND ADVANCE THE QUEST FOR NEW SELECTIVE TREATMENTS. OUR HYPOTHESIS WILL BE TESTED BY PURSUING THREE SPECIFIC AIMS: AIM 1 WILL TEST NOVEL MICRO-RNA AND TRANSCRIPTIONAL REGULATION OF WWC1/KIBRA EXPRESSION AND FUNCTION AND WILL DEFINE THE BIOMECHANICAL SEQUELAE OF KIBRA-MEDIATED PODOCYTE STRUCTURAL DISRUPTION. AIM 2 WILL TEST DOWNSTREAM KIBRA NON-CANONICAL REGULATION OF TEAD 1-4 AND THE EFFECTS OF LATS KINASE DEPLETION AND INHIBITION IN VITRO AND IN VIVO. AIM 3 WILL TEST THE THERAPEUTIC EFFICACY OF PHARMACOLOGIC TEAD AGONISTS AND LATS INHIBITORS INDIVIDUALLY AND COMBINED AS MULTI-TARGETED THERAPY FOR KIBRA-MEDIATED AND DIABETIC DISEASE MODELS IN VITRO AND IN VIVO. THE WORK PROPOSED HERE IS EXPECTED TO DEFINE DISEASE RELEVANT REGULATORS OF PODOCYTE KIBRA EXPRESSION AND ELUCIDATE NOVEL TARGETS AND TREATMENT STRATEGIES FOR GLOMERULAR DISEASES.