Epigenetic Regulation of Cardiomyocyte Maturation by Arginine Methyltransferase CARM1.

Background: During the neonatal stage, the cardiomyocyte undergoes a constellation of molecular, cytoarchitectural, and functional changes known collectively as cardiomyocyte maturation to increase myocardial contractility and cardiac output. Despite the importance of cardiomyocyte maturation, the molecular mechanisms governing this critical process remain largely unexplored.

Methods: We leveraged an in vivo mosaic knockout system to characterize the role of , the founding member of protein arginine methyltransferase, in cardiomyocyte maturation.

Functional coordination of non-myocytes plays a key role in adult zebrafish heart regeneration.

Cardiac regeneration occurs primarily through proliferation of existing cardiomyocytes, but also involves complex interactions between distinct cardiac cell types including non-cardiomyocytes (non-CMs). However, the subpopulations, distinguishing molecular features, cellular functions, and intercellular interactions of non-CMs in heart regeneration remain largely unexplored. Using the LIGER algorithm, we assemble an atlas of cell states from 61,977 individual non-CM scRNA-seq profiles isolated at multiple time points during regeneration.

Derivation of stable embryonic stem cell-like, but transcriptionally heterogenous, induced pluripotent stem cells from non-permissive mouse strains.

Genetic background is known to play a role in the ability to derive pluripotent, embryonic stem cells (ESC), a trait referred to as permissiveness. Previously we demonstrated that induced pluripotent stem cells (iPSC) can be readily derived from non-permissive mouse strains by addition of serum-based media supplemented with GSK3B and MEK inhibitors, termed 2iS media, 3 days into reprogramming. Here, we describe the derivation of second type of iPSC colony from non-permissive mouse strains that can be stably maintained independently of 2iS media.

An Optimized Protocol for Human Direct Cardiac Reprogramming.

Direct cardiac reprogramming, the conversion of fibroblasts into cardiomyocyte-like cells (iCMs), is an attractive approach to heal the injured heart. Here we present a new approach to human cardiac reprogramming that utilizes a polycistronic three-factor reprogramming cocktail and one microRNA. Our protocol produces cardiac Troponin T positive human iCMs (hiCMs) at an efficiency of 40%-60%, approximately double that of previous protocols, within just 2 weeks.

Permissiveness to form pluripotent stem cells may be an evolutionarily derived characteristic in Mus musculus.

Mus musculus is the only known species from which embryonic stem cells (ESC) can be isolated under conditions requiring only leukemia inhibitory factor (LIF). Other species are non-permissive in LIF media, and form developmentally primed epiblast stem cells (EpiSC) similar to cells derived from post-implantation, egg cylinders. To evaluate whether non-permissiveness extends to induced pluripotent stem cells (iPSC), we derived iPSC from the eight founder strains of the mouse Collaborative Cross.