Induction of diverse cardiac cell types by reprogramming fibroblasts with cardiac transcription factors.

Nam YJ, Lubczyk C, Bhakta M, Zang T, Fernandez-Perez A, McAnally J, Bassel-Duby R, Olson EN, Munshi NV
Development. 2014 141 (22): 4267-78

PMID: 25344074 · PMCID: PMC4302916 · DOI:10.1242/dev.114025

Various combinations of cardiogenic transcription factors, including Gata4 (G), Hand2 (H), Mef2c (M) and Tbx5 (T), can reprogram fibroblasts into induced cardiac-like myocytes (iCLMs) in vitro and in vivo. Given that optimal cardiac function relies on distinct yet functionally interconnected atrial, ventricular and pacemaker (PM) cardiomyocytes (CMs), it remains to be seen which subtypes are generated by direct reprogramming and whether this process can be harnessed to produce a specific CM of interest. Here, we employ a PM-specific Hcn4-GFP reporter mouse and a spectrum of CM subtype-specific markers to investigate the range of cellular phenotypes generated by reprogramming of primary fibroblasts. Unexpectedly, we find that a combination of four transcription factors (4F) optimized for Hcn4-GFP expression does not generate beating PM cells due to inadequate sarcomeric protein expression and organization. However, applying strict single-cell criteria to GHMT-reprogrammed cells, we observe induction of diverse cellular phenotypes, including those resembling immature forms of all three major cardiac subtypes (i.e. atrial, ventricular and pacemaker). In addition, we demonstrate that cells induced by GHMT are directly reprogrammed and do not arise from an Nxk2.5(+) progenitor cell intermediate. Taken together, our results suggest a remarkable degree of plasticity inherent to GHMT reprogramming and provide a starting point for optimization of CM subtype-specific reprogramming protocols.

© 2014. Published by The Company of Biologists Ltd.

MeSH Terms (19)

Action Potentials Analysis of Variance Animals Basic Helix-Loop-Helix Transcription Factors Cell Differentiation DNA Primers Embryonic Induction Fibroblasts GATA4 Transcription Factor Green Fluorescent Proteins Heart Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels Immunohistochemistry MEF2 Transcription Factors Mice Myocytes, Cardiac Real-Time Polymerase Chain Reaction T-Box Domain Proteins Transcription Factors

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