Cardiomyocyte Krüppel‐like Factor 5 Regulates Ceramide Biosynthesis and miR‐30 Suppression in Ischemic Cardiomyopathy and Promotes Systolic Dysfunction

Abstract

Our lab previously identified Krϋppel‐like factor (KLF) 5 as a regulator of fatty acid oxidation in the heart during diabetes‐associated cardiac dysfunction. The regulation of cardiomyocyte KLF5 and its significance during ischemic heart failure has not been studied. Therefore, we assessed KLF5 expression in human ischemic heart failure samples and in rodent models 2‐ and 4‐weeks post‐permanent LAD ligation. In human and mouse heart failure samples KLF5 levels were increased. We therefore hypothesized that aberrant regulation of cardiac KLF5 contributes to disease progression in ischemic heart failure. To address our hypothesis, we generated a novel mouse model of inducible (Dox‐ON), cardiomyocyte specific expression of KLF5 and assessed cardiac function using echocardiography. We further characterized the response of our previously described αMHC‐Klf5−/− mice and mice treated with pharmacological KLF5 inhibitor ML264 (10 mg/kg 2xper day) to MI. KLF5 overexpression resulted in systolic dysfunction beginning 2‐weeks after induction. Conversely, αMHC‐Klf5−/− mice and mice treated with ML264 subjected to LAD ligation had increased ejection fraction, lower end‐diastolic volume, and reduced heart weights compared to control mice after MI. To identify lipid metabolism‐related processes affected by KLF5 in the heart, we performed lipidomic analysis by LC‐MS/MS, which showed that KLF5 transgenic heart tissue had increased levels of ceramides and ceramide‐derived lipids. Among the three pathways that contribute in ceramide biosynthesis, KLF5 altered expression of the de novo biosynthesis pathway by increasing SPTLC1 and SPTLC2. After MI, αMHC‐Klf5−/− had lower cardiac SPTLC1 and SPTLC2 expression compared with control mice. To pursue potential post‐transcriptional mechanisms that are triggered by KLF5, we performed cardiac miR array analysis and gene expression analysis in primary cardiomyocytes of αMHC‐Klf5−/− hearts. We found increased levels of all 5 miR‐30 family members, which have been associated with better prognosis in heart failure patients. Conversely, cardiac miR‐30s were decreased in KLF5 transgenic mice and in human heart failure samples. After MI, miR‐30 levels were partially restored in αMHC‐Klf5−/− hearts compared to controls. We suggest that MI upregulates KLF5, which stimulates ceramide biosynthesis and suppresses miR‐30, both of which have been attributed causality for cardiac dysfunction in heart failure.Support or Funding InformationNational Heart Lung and Blood Institute of the National Institutes of Health HL130218 (KD); American Heart Association predoctoral fellowship 18PRE34060115 (MH); Ruth L. Kirschstein National Research Service Award (NRSA) F30 predoctoral fellowship F30HL146007 (MH); American Heart Association and the Kahn Family Post‐Doctoral Fellowship in Cardiovascular Research 18POST34060150 (IDK)