Fibroblasts can be reprogrammed into induced cardiomyocyte-like cells (iCMs) by forced expression of cardiogenic transcription factors. However, it remains unknown how fibroblasts adopt a cardiomyocyte (CM) fate during their spontaneous ongoing transdifferentiation toward myofibroblasts (MFs). By tracing fibroblast lineages following cardiac reprogramming in vitro, we found that most mature iCMs are derived directly from fibroblasts without transition through the MF state. This direct conversion is attributable to mutually exclusive induction of cardiac sarcomeres and MF cytoskeletal structures in the cytoplasm of fibroblasts during reprogramming. For direct fate switch from fibroblasts to iCMs, significant remodeling of actin isoforms occurs in fibroblasts, including induction of α-cardiac actin and decrease of the actin isoforms predominant in MFs. Accordingly, genetic or pharmacological ablation of MF-enriched actin isoforms significantly enhances cardiac reprogramming. Our results demonstrate that remodeling of actin isoforms is required for fibroblast to CM fate conversion by cardiac reprogramming.
Bibliographical noteFunding Information:
High-content imaging analysis was performed in the Vanderbilt High-Throughput Screening (HTS) Core Facility. The HTS Core receives support from the Vanderbilt Institute of Chemical Biology and the Vanderbilt-Ingram Cancer Center ( P30 CA68485 ). We appreciate the technical assistance by Dr. Boris Hinz. We thank Dr. Russell Addis for the TroponinT-GCaMP5-Zeo reporter construct. This work was supported by Gilead Sciences Research Scholars Program and NIH ( R01 HL146524 ) to Y.-J.N., NIH ( R01 AR049899 ) to J.M.E., and AHA ( 20POST35210170 ) to Z.Z.
© 2022 The Author(s)
- stress fiber
PubMed: MeSH publication types
- Journal Article
- Research Support, N.I.H., Extramural
- Research Support, Non-U.S. Gov't