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Updated: Aug 18, 2026
Derivation of Cardiac Progenitor Cells from Embryonic Stem Cells
Published on: January 12, 2015
Interplay between the retinoblastoma protein and LEK1 specifies stem cells toward the cardiac lineage
Evangelia Papadimou1, Claudine Ménard, Corinne Grey
1CRBM, CNRS FRE 2593, Montpellier, France.
Abstract:
The molecular mechanisms governing early cardiogenesis are still largely unknown. Interestingly, the retinoblastoma protein (Rb), a regulator of cell cycle, has recently emerged as a new candidate regulating cell differentiation. Rb-/- mice die at midgestation and mice lacking E2f1/E2f3, downstream components of the Rb-dependent transcriptional pathway, die of heart failure. To gain insight into the function of Rb pathway in early cardiogenesis, we used Rb-/- embryonic stem (ES) cells differentiating into cardiomyocytes. Rb-/- cells displayed a dramatic delay in expression of cardiac-specific transcription factors and in turn in the whole process of cardiac differentiation. The phenotype of Rb-/- ES cell-derived cardiomyocytes was rescued by reintroducing Rb in cardiac progenitors, by stimulating the BMP-dependent cardiogenic pathway or by overexpression of Nkx2.5. ES cells deficient in the recently identified factor LEK1, a murine homolog of the cardiomyogenic factor 1, or specific disruption of Rb-LEK1 interaction into the nucleus of differentiating ES cells recapitulated the delay in cardiac differentiation of Rb-/- ES cells. Thus, we provide evidence for a novel Rb/LEK1-dependent and BMP-independent transcriptional program, which plays a pivotal role in priming ES cells toward a cardiac fate.
Insights
The retinoblastoma protein (Rb) is crucial for early heart development. Its absence delays cardiac differentiation in stem cells, highlighting a novel Rb/LEK1 pathway essential for forming cardiomyocytes.
Area of Science:
- Developmental Biology
- Stem Cell Biology
- Molecular Cardiology
Background:
- Early cardiogenesis mechanisms remain largely unknown.
- The retinoblastoma protein (Rb), a cell cycle regulator, is implicated in cell differentiation.
- Rb-deficient mice and those lacking downstream E2f1/E2f3 factors exhibit embryonic lethality due to heart failure.
Purpose of the Study:
- To investigate the role of the Rb pathway in early cardiogenesis using embryonic stem (ES) cells.
- To elucidate the molecular mechanisms underlying Rb's function in cardiac differentiation.
Main Methods:
- Utilized Rb-/- embryonic stem (ES) cells undergoing differentiation into cardiomyocytes.
- Assessed the expression of cardiac-specific transcription factors.
- Investigated rescue strategies including Rb reintroduction, BMP pathway stimulation, Nkx2.5 overexpression, and LEK1 disruption.
- Examined the impact of Rb-LEK1 interaction disruption.
Main Results:
- Rb-/- ES cells showed a significant delay in cardiac differentiation and expression of cardiac-specific genes.
- Reintroduction of Rb, BMP pathway stimulation, or Nkx2.5 overexpression rescued the differentiation defect.
- LEK1 deficiency or disrupted Rb-LEK1 nuclear interaction mimicked the delayed cardiac differentiation phenotype.
- Identified a novel Rb/LEK1-dependent, BMP-independent transcriptional program.
Conclusions:
- The retinoblastoma protein (Rb) plays a critical role in regulating the timing and efficiency of early cardiac differentiation.
- A novel transcriptional program involving Rb and LEK1 is essential for priming ES cells towards a cardiac fate.
- This pathway operates independently of the BMP signaling pathway.
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