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Boosting Cardiac Differentiation of ESCs via miR‐184/Wnt3 Pathway Modulation

The differentiation of pluripotent stem cells into cardiac mesoderm has allowed the definition of the mechanisms controlling normal heart development and pathogenesis of congenital heart diseases. While Wnt signaling represents a central regulator of cardiac mesoderm differentiation [1-3], we still lack a complete understanding of this process – for example, the exact regulatory function of Wnt3 during embryonic stem cell (ESC) differentiation into cardiac mesoderm remains unresolved.

Researchers from the laboratories of Guiying Wang, Jiuhong Kang (Tongji University, Shanghai, China), and Chenqi Lu (Fudan University, Shanghai, China) set out to explore the potential role of micro(mi)RNA mediated control of Wnt3 signaling during ESC differentiation into cardiac mesoderm and cardiomyocytes and identified miR‐184 [4-6] as a potential miRNA targeting Wnt3 mRNA. Liu et al. now report on their subsequent evaluation of the miR‐184/Wnt3 pathway in differentiating ESCs in a STEM CELLS article that fosters a new understanding of normal cardiac development and cardiac disease and may provide a means to develop efficient cell therapies for the damaged heart [7].

While studying the transcriptional dynamics of miR‐184, the authors discovered decreased expression during cardiac mesoderm differentiation of ESCs as embryoid bodies and increased expression during subsequent differentiation into cardiomyocytes. The suppression of cardiac mesoderm differentiation, associated gene expression (GATA4 and EOMES), and cardiomyocyte formation following miR‐184 overexpression during early-stage ESC differentiation further highlighted the general importance of this miRNA species. Finally, the lentiviral expression of a miR‐184-specific “sponge” [8], which dampens activity during early-stage ESC differentiation, also inhibited cardiac mesoderm differentiation and cardiomyocyte formation. Overall, these studies underscored the general importance of miR‐184 in the regulation of cardiac mesoderm differentiation, but what mechanism is involved?

Subsequent bioinformatic prediction of miR‐184 targets highlighted Wnt3, which the authors found to display an expression profile that negatively correlated to that of miR‐184 during ESC differentiation in cardiac mesoderm. Mechanistic studies using reporter constructs and overexpression confirmed that miR‐184 could directly bind to Wnt3 mRNA and inhibit its expression. Providing support to this claim, the authors finally demonstrated that Wnt3 knockout induced the same effect as miR‐184 overexpression during ESC differentiation and that Wnt3 overexpression rescued the inhibitory impact of miR‐184 overexpression.

Overall, the authors describe the general importance of the miR‐184/Wnt3 pathway as a regulator of cardiac mesoderm differentiation of ESCs. While these findings enhance our knowledge regarding normal cardiac development and the pathogenesis of cardiac disease, they may also foster the more efficient generation of cardiomyocytes from pluripotent stem cell sources and thereby enhance stem cell-based therapies in the damaged heart.

For more on microRNAs, the Wnt pathway, ESC differentiation, and stem cell therapies, stay tuned to the Stem Cells Portal!


References

  1. Lindsley RC, Gill JG, Kyba M, et al., Canonical Wnt signaling is required for development of embryonic stem cell-derived mesoderm. Development 2006;133:3787.
  2. Barrow JR, Howell WD, Rule M, et al., Wnt3 signaling in the epiblast is required for proper orientation of the anteroposterior axis. Developmental Biology 2007;312:312-320.
  3. Liu P, Wakamiya M, Shea MJ, et al., Requirement for Wnt3 in vertebrate axis formation. Nature Genetics 1999;22:361-365.
  4. Liu C, Teng Z-Q, Santistevan NJ, et al., Epigenetic Regulation of miR-184 by MBD1 Governs Neural Stem Cell Proliferation and Differentiation. Cell Stem Cell 2010;6:433-444.
  5. Yu J, Ryan DG, Getsios S, et al., MicroRNA-184 antagonizes microRNA-205 to maintain SHIP2 levels in epithelia. Proceedings of the National Academy of Sciences 2008;105:19300.
  6. Nagosa S, Leesch F, Putin D, et al., microRNA-184 Induces a Commitment Switch to Epidermal Differentiation. Stem Cell Reports 2017;9:1991-2004.
  7. Liu X, Yang Y, Wang X, et al., MiR-184 directly targets Wnt3 in cardiac mesoderm differentiation of embryonic stem cells. STEM CELLS 2020;38:1568-1577.
  8. Ebert MS, Neilson JR, and Sharp PA, MicroRNA sponges: competitive inhibitors of small RNAs in mammalian cells. Nature Methods 2007;4:721-726.