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Updated: May 4, 2026
Retroviral Infection of Murine Embryonic Stem Cell Derived Embryoid Body Cells for Analysis of Hematopoietic Differentiation
Published on: October 20, 2014
C/EBPa-mediated activation of microRNAs 34a and 223 inhibits Lef1 expression to achieve efficient reprogramming into
Javier Rodriguez-Ubreva1, Laura Ciudad, Chris van Oevelen
1Chromatin and Disease Group, Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.
Abstract:
MicroRNAs (miRNAs) exert negative effects on gene expression and influence cell lineage choice during hematopoiesis. C/EBPa-induced pre-B cell-to-macrophage transdifferentiation provides an excellent model to investigate the contribution of miRNAs to hematopoietic cell identity, especially because the two cell types involved fall into separate lymphoid and myeloid branches. In this process, efficient repression of the B cell-specific program is essential to ensure transdifferentation and macrophage function. miRNA profiling revealed that upregulation of miRNAs is highly predominant compared with downregulation and that C/EBPa directly regulates several upregulated miRNAs. We also determined that miRNA 34a (miR-34a) and miR-223 sharply accelerate C/EBPa-mediated transdifferentiation, whereas their depletion delays this process. These two miRNAs affect the transdifferentiation efficiency and activity of macrophages, including their lipopolysaccharide (LPS)-dependent inflammatory response. miR-34a and miR-223 directly target and downregulate the lymphoid transcription factor Lef1, whose ectopic expression delays transdifferentiation to an extent similar to that seen with miR-34a and miR-223 depletion. In addition, ectopic introduction of Lef1 in macrophages causes upregulation of B cell markers, including CD19, Pax5, and Ikzf3. Our report demonstrates the importance of these miRNAs in ensuring the erasure of key B cell transcription factors, such as Lef1, and reinforces the notion of their essential role in fine-tuning the control required for establishing cell identity.
Insights
MicroRNAs (miRNAs) are crucial for cell identity during hematopoiesis. Specific miRNAs, miR-34a and miR-223, accelerate the switch from B cells to macrophages by downregulating the Lef1 transcription factor.
Area of Science:
- * Hematopoiesis and cell lineage determination.
- * Molecular mechanisms of cell identity.
- * MicroRNA (miRNA) regulation of gene expression.
Background:
- * MicroRNAs (miRNAs) are key regulators of gene expression, influencing cell fate decisions in hematopoiesis.
- * The transdifferentiation of pre-B cells to macrophages, induced by C/EBPa, serves as a model to study miRNA roles in hematopoietic cell identity.
- * Efficient suppression of B cell-specific genes is vital for successful macrophage differentiation.
Purpose of the Study:
- * To investigate the role of miRNAs in C/EBPa-induced pre-B cell-to-macrophage transdifferentiation.
- * To identify specific miRNAs that modulate this transdifferentiation process and macrophage function.
- * To elucidate the molecular targets of these regulatory miRNAs.
Main Methods:
- * miRNA profiling to identify differentially expressed miRNAs during transdifferentiation.
- * Functional assays to assess the impact of miRNA modulation (upregulation/depletion) on transdifferentiation efficiency.
- * Analysis of miRNA targets, including the lymphoid transcription factor Lef1.
Main Results:
- * miRNA upregulation was predominant during transdifferentiation, with C/EBPa directly regulating several miRNAs.
- * MiRNA 34a (miR-34a) and miR-223 significantly accelerated transdifferentiation, while their depletion delayed it.
- * miR-34a and miR-223 directly target and downregulate Lef1, a key B cell transcription factor. Ectopic Lef1 expression in macrophages induced B cell markers.
Conclusions:
- * miR-34a and miR-223 are critical for efficient B cell-to-macrophage transdifferentiation.
- * These miRNAs ensure the erasure of B cell-specific transcription factors like Lef1, establishing macrophage identity.
- * miRNAs play an essential role in fine-tuning cellular identity during hematopoietic development.
