Genes encoding microRNAs—already thought to be involved in the control of developmental events—have now found their way into the heart, according to a study in a recent issue of Nature (advanced online publication 12 June 2005; 10.1038/nature03817).
Yong Zhao et al. focused on two related microRNAs expressed in the heart. Shown is the expression pattern of one of these microRNAs, miR-1-1, in the mouse embryo. miR-1-1 is found in the developing heart (dark blue) and in the somites, embryonic structures that give rise to muscle.
The researchers next devised a new algorithm to search for microRNA target sequences in mRNA. Both microRNAs, they found, negatively regulate Hand2, a transcription factor that promotes expansion of ventricular heart muscle precursor cells. In line with that finding, overexpression of the microRNAs in the heart decreased the pool of proliferating precursor cells.
The authors also identified transcriptional regulators that control expression of the microRNAs. These included MyoD and other regulators of muscle differentiation. The data suggest that these heart microRNAs control the balance between differentiation and proliferation during heart development.
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Schubert, C. microRNAs manage the heart. Nat Med 11, 714 (2005). https://doi.org/10.1038/nm0705-714
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DOI: https://doi.org/10.1038/nm0705-714
