THE FUNCTIONAL ROLES OF TGF-BETA SIGNALING IN CARDIAC LYMPHANGIOGENESIS DURING MYOCARDIAL ISCHEMIA - SUMMARY HEART FAILURE CAUSED BY MYOCARDIAL INFARCTION (MI) AND ISCHEMIA REPERFUSION INJURY (IRI) REMAIN THE LEADING CAUSE OF DEATH WORLDWIDE. RECENT STUDIES SHOW THAT STIMULATION OF LYMPHATIC GROWTH (LYMPHANGIOGENESIS) AFTER ISCHEMIC HEART DISEASE IMPROVES CARDIAC FUNCTION AND ATTENUATES ADVERSE CARDIAC REMODELING, LINKING LYMPHANGIOGENESIS AS A NOVEL TARGET FOR THE TREATMENT OF CARDIOVASCULAR DISEASE. HOWEVER, POST-MI CARDIAC LYMPHATICS IN RODENT MODELS OR MI PATIENTS EXHIBIT ABNORMAL STRUCTURE, COMPROMISING CARDIAC LYMPHATIC FUNCTION WHICH GIVE RISE TO PROLONGED CARDIAC INFLAMMATION. HOWEVER, THE MOLECULAR MECHANISMS DURING MI THAT DRIVE CARDIAC LYMPHATIC DYSFUNCTION REMAIN UNKNOWN. MY LONG-TERM GOAL IS TO IDENTIFY THE MOLECULAR MECHANISMS REGULATING CARDIAC LYMPHANGIOGENESIS DURING THE PATHOGENESIS OF ISCHEMIC HEART DISEASE. TRANSFORMING GROWTH FACTOR BETA (TGFB), HAS BEEN IDENTIFIED AS A MAJOR PLAYER DRIVING ENDMT PROGRESSION FOR CARDIAC FIBROSIS. HOWEVER, WHETHER TGFB SIGNALING REGULATES POST-MI CARDIAC LYMPHANGIOGENESIS AND LYMPHATIC FUNCTION IS UNKNOWN. MY PRELIMINARY DATA SHOWED THAT LYMPHATIC ENDOTHELIAL CELL (LEC)-SPECIFIC TGFBR2 DEFICIENT MICE (TGFBR2DLEC/DLEC MICE) EXHIBITED IMPROVED POST-MI CARDIAC FUNCTION, REDUCED CARDIAC FIBROSIS WITH INCREASED CARDIAC LYMPHANGIOGENESIS, IMPROVED LYMPHATIC VESSEL INTEGRITY, AND REDUCED CARDIAC INFLAMMATION. THIS DATA STRONGLY SUGGESTS TGFB NEGATIVELY REGULATES POST-MI CARDIAC LYMPHANGIOGENESIS AND CARDIAC FUNCTION. IN VITRO TREATING LECS WITH TGFB LEAD TO SIGNIFICANTLY REDUCED PROLIFERATION, MIGRATION, INCREASED APOPTOSIS AND DISRUPTED CELL VE-CADHERIN JUNCTIONS. RNASEQ ANALYSIS SHOWED TGFB PROMOTED A METABOLIC SHIFT IN LECS, SIGNIFICANTLY DOWNREGULATING CPT1A AND ITS MEDIATED FATTY- ACID OXIDATION (FAO) IN TGFB TREATED LECS. CPT1A, THE RATE LIMITING ENZYME OF FAO HAS BEEN SHOWN TO BE ESSENTIAL FOR DEVELOPMENTAL LYMPHANGIOGENESIS. INTERESTINGLY, RESCUING CPT1A FUNCTION USING ACETYLCARNITINE RESCUED TGFB MEDIATED LEC ACTIVITIES INCLUDING PROLIFERATION, APOPTOSIS, MIGRATION, AND JUNCTION STABILITY IN VITRO. THESE DATA STRONGLY SUGGEST THAT TGFB NEGATIVELY REGULATES LEC ACTIVITIES BY DOWNREGULATING CPT1A AND CPT1A-MEDIATED FAO IN LECS. INTRIGUINGLY, TGFBR2DLEC/DLEC MICE DISPLAYED INCREASED CPT1A EXPRESSION IN CARDIAC LYMPHATICS AFTER MI. WHILE TARGETING CPT1A IN TGFBR2DLEC/DLEC MICE (TGFBR2DLEC/DLEC, CPT1A DLEC/+) REVERSED THE REDUCED CARDIAC FIBROSIS SEEN IN TGFBR2DLEC/DLEC MICE AFTER MI. THEREFORE, I PROPOSE THAT TARGETING LEC TGFB SIGNALING CAN PRESERVE LYMPHATIC CPT1A-MEDIATED FAO, IMPROVE LYMPHATIC VESSEL INTEGRITY AND FUNCTION, AND PROMOTE CARDIAC REPAIR DURING MI. IN AIM 1 OF THIS STUDY, I WILL UTILIZE MOUSE GENETIC TOOLS AND IN VIVO APPROACHES TO ELUCIDATE THE FUNCTIONAL ROLE OF TGFB SIGNALING IN CARDIAC LYMPHANGIOGENESIS DURING MI. IN AIM 2 OF THIS STUDY, I WILL INCORPORATE IN VITRO CELL CULTURE AND IN VIVO ANIMAL MODELS TO ASSESS THE MOLECULAR MECHANISMS OF HOW TGFB SIGNALING AFFECTS LEC ACTIVITIES. SUCCESS IN THESE AIMS WILL LEAD TO THE DEVELOPMENT OF NOVEL THERAPEUTIC APPROACHES FOR TREATMENT OF CARDIOVASCULAR DISEASE.