Abstract P1146: Global Analysis Of Murine Cardiac Gene Program Regulated By Thyroid Hormone And Transcriptional Repressor Rest

Abstract

Background: During adult heart failure, transcriptional reprogramming of fetal cardiac genes coincides with dysregulated heart functions. However, the underlying mechanisms remain incompletely understood. Thyroid hormone and RE1 silencing transcription factor (REST) are known regulators of cardiac gene reprogramming. Here, we report a global analysis of their co-regulatory functions. Methods: We generated a dual Myh6 and Myh7 mouse reporter line. This line was crossed with a conditional Rest allele to generate myocardial Rest knockout mice. Control and Rest null mice were treated with propylthiouracil (PTU) to inhibit thyroid hormone synthesis. PTU treatment induced heart failure and adult-to-fetal cardiac gene remodeling. Single nuclei multiomic profiling was performed, linking gene expression and gene regulatory network information from each nuclei to elucidate the impact of PTU or REST or both on cardiac gene reprogramming. Samples were collected to validate the newly identified factors involved in reprogramming. Results: Data analysis showed that PTU treatment upregulates transcription factor binding involving circadian gene expression ( Cry2 , Per2 , Per3 ). Downregulated genes are related to voltage-gated channel activity and BMP/TGFB activities involving heart development ( Myh6 , Nrg1 , Bmpr1a ) and SA node action potential ( Scn5a , Hcn2 , Ryr2 ). In contrast, Rest knockout upregulated genes are associated with arrhythmia, i.e. , cAMP catabolism ( Pde4d , Pde7a , Pde7b ), heart conduction ( Cacna1c , Gja1 , Pln ), and ion transport ( Kcnip2 , Pde4d, Esr1 ). Downregulated genes are involved in protein functions involving integrin-mediated signaling ( Itgal , Itga4 , Itga5 ), cytoskeleton organization ( Ctnna2 , Actb , Xirp1 ), and fiber organization ( Tgfb3 , Smad3 , Ptk2b ). Furthermore, a subset of genes was found to be co-regulated by thyroid hormone and REST, including Ccn2 , Myh9 , Nmrk2 , Fgr , Itga4 , Prkcb , Cspg4 which are involved in integrin signaling pathway, immune activation, and angiogenesis. Conclusion: Thyroid hormone and REST have shared function in cardiac gene reprogramming involving cardiac conduction and fibrosis as well as their own newly discovered, unique roles regulating circadian genes and cAMP catabolism, respectively.