Abstract 209: Downregulation of KLF2 in the Endothelium Contributes to the Pathogenesis in LMNA-related Dilated Cardiomyopathy

Background: Mutations in the gene that encodes the nuclear envelope proteins lamin A and C (LMNA) accounts for 6% of all cases of Dilated Cardiomyopathy (DCM). However, the molecular mechanisms that underlie “cardiolaminopathy” remain elusive, and it is unknown why mutations in this ubiquitously expressed gene have such a disproportionate effect on the heart. Hypothesis: Despite the fact that LMNA is abundantly expressed in endothelial cells (ECs) and mutations in LMNA are known to induce EC dysfunction, little is known about the EC-specific phenotype of LMNA-related DCM. As EC dysfunction has been known to contribute to DCM, we hypothesize that EC dysfunction due to LMNA mutation has a significant impact on the pathogenesis and disease progression of DCM. Results: Intriguingly, our preliminary data showed that iPSC-ECs derived from patients (n=5) harboring the LMNA-mutation exhibit decrease functionality as seen by impaired angiogenesis and decreased NO production (control iPSC-ECs vs LMNA iPSC-ECs; p<0.05). Similarly, genome editing of isogenic iPSC lines enabled us to recapitulate the EC disease phenotype further allowing us to dissect the effects of LMNA mutations on EC function. LMNA corrected iPSC-ECs (via use of CRISPR/Cas9 genome editing tool to correct the single mutated copy in heterozygous patient’s iPSCs) showed restoration of EC function. Whole genome RNA-sequencing identified Krüppel-like Factor 2 (KLF2) as a potential transcript responsible for EC dysfunction in LMNA-mutated patients. Importantly, treatment of LMNA-mutated ECs with KLF2 agonists showed rescue of EC dysfunction. Furthermore, iPSC-derived cardiomyocytes (iPSC-CMs) from LMNA-mutated patients that exhibited DCM phenotype, showed improvement in CM physiology when co-cultured with iPSC-ECs treated with KLF2 agonists. Conclusion: This study is a first step towards understanding the molecular mechanisms of cardiolaminopathy by modeling endothelial dysfunction using patient-specific iPSCs. Moreover, our results suggest that improving EC function in cardiolaminopathy patients could have a significant impact on the pathogenesis of DCM. Results from this work could potentially lead to new strategies that could improve the management of DCM patients.