Abstract 12259: Gas6 Binding With Sav1 to Restore Yap Transcriptional Activity in a Specialized Cardiomyocytes Population Contributes to Heart Regeneration

Abstract

Introduction: The neonatal mammalian heart possesses transient regeneration capacity following injury, during which certain cardiomyocytes (CMs) undergo self-proliferation and establish specific communication networks within the microenvironment. However, the characteristic of these CMs has not been elucidated. Hypothesis: Analyzing communication networks of CMs involved in the microenvironment of neonatal heart regeneration will help identify heterogeneous populations of CMs and functional genes for regenerative treatment of adult myocardial infarction. Methods: CellChat was used to analyze communication networks in sc(n)RNA-seq datasets of postnatal mouse heart development and post-injury regeneration processes. Transcriptomic analysis was performed on Gas6-enriched CMs. Single-type cell isolation was used to assess Gas6 expression. CM-specific Gas6 loss- or gain-mice were generated using Cre-loxP system and Adeno-associated virus system. Adenoviral gene transfection, mass spectrometry, co-immunoprecipitation, domain truncation constructs, and dual-luciferase reporter gene assay were used to investigate the effect and mechanism of Gas6 in vitro. Results: The Gas pathway was identified among 2021 cell-cell pathways as contributing to the development and regeneration of CMs, with Gas6 being the functional gene involved. Gas6-enriched CMs exhibit heterogeneity in relation to proliferation and are abundant in neonatal hearts but disappear in adult hearts. CM-specific Gas6 gene knockout hindered myocardial proliferation in neonatal mice after apex resection. CM-specific Gas6 gene overexpression increased CM proliferation and protected cardiac function during postnatal heart growth and in injured adult hearts. In vitro studies revealed that the α-helical domain of Gas6 interacted with Sav1, inhibiting its recruitment to MST and subsequent phosphorylation cascade. Overexpression of Gas6 promoted Yap translocation into the nucleus and restored the transcription of genes involved proliferation and regeneration. Conclusions: Gas6-enriched CMs constitute a specialized population necessary for heart regeneration, in which Gas6 acts as a promoter of Yap transcriptional activity to enhance CM proliferation.