Abstract Wed009: Zeb1 Is a Key Regulator of Cardiomyocyte Structure and Function

Introduction: Cardiomyocytes (CMs) are crucial for maintaining cardiac contractility, and disruptions in gene regulatory networks contribute to cardiac dysfunction. Our prior work identified Zeb1 as a key downstream target of Cpeb4, an RNA-binding protein dynamically regulated in cardiac hypertrophy. While Zeb1 is well-studied in cancer metastasis and epithelial-to-mesenchymal transition, its role in CMs remains largely unexplored. Given its function in skeletal muscle regeneration, we hypothesize that Zeb1 regulates CM maturation, structural integrity, and contractility. Hypothesis: Zeb1 is essential for CM structure and function. Its deletion leads to sarcomeric disorganization and cardiac impairment, while its overexpression promotes pathological hypertrophy. Methods: A CM-specific Zeb1 conditional knockout (Zeb1 cKO) mouse model was generated. Echocardiography at 12 weeks revealed early systolic dysfunction, which worsened over time. Histological analysis of 25-week-old Zeb1 cKO hearts showed sarcomeric disarray and fibrosis, while electron microscopy confirmed sarcomere disruption. Female mice were more susceptible to the Zeb1KO than male mice, with higher sarcomere damage and a dilated CM phenotype. Zeb1 has been deleted since birth in the Zeb1cKO model, we checked the CM structure and function in an inducible MerCreMer mice model, confirming its role in CM homeostasis. To investigate Zeb1-dependent transcriptional changes, we performed bulk RNA sequencing on left ventricular tissue, revealing a shift toward epithelial-like gene expression. We are conducting ChIP-seq analysis on purified neonatal rat CMs (NRCMs) to identify Zeb1’s direct transcriptional targets post-hypertrophic stimulation. We observed increased protein levels of Zeb1 after pressure overload surgery (TAC). We overexpressed (OE) Zeb1 using adenovirus in NRCMs, which increased hypertrophic gene markers Nppa and Nppb. Zeb1 OE also increases CM size. We also induced CM-specific Zeb1 OE in 8-week-old mice using AAV9 and saw increased left ventricular wall thickness. Conclusion: Our findings establish Zeb1 as a crucial regulator of cardiomyocyte structure and function. Loss of Zeb1 disrupts sarcomere integrity, impairs contractility, and drives early cardiac dysfunction, potentially through epithelial reprogramming of CMs. Future studies will define Zeb1 transcriptional targets and their role in cardiac remodeling, providing potential therapeutic insights for treating cardiac dysfunction.