Dynamic MicroRNA Expression Programs during Cardiac Differentiation of Human Embryonic Stem Cells: Role for miR-499

Abstract

Background—MicroRNAs (miRNAs) are a newly discovered endogenous class of small noncoding RNAs that play important posttranscriptional regulatory roles by targeting messenger RNAs (mRNAs) for cleavage or translational repression. Human embryonic stem cells (hESCs) are known to express miRNAs that are often undetectable in adult organs, and a growing body of evidence has implicated miRNAs as important arbiters of heart development and disease.

Methods and Results—To better understand the transition between the human embryonic and cardiac "miRNA-omes", we report here the first miRNA profiling study of cardiomyocytes derived from hESCs (hESC-CMs). Analyzing 711 unique miRNAs, we then identify several interesting miRNAs, including miR-1, miR-133, and miR-208, that have been previously reported to be involved in cardiac development and disease and that show surprising patterns of expression across our samples. We also identify novel miRNAs such as miR-499 that are strongly associated with cardiac differentiation, and which shares many predicted targets with miR-208. Over-expression of miR-499 and miR-1 resulted in upregulation of important cardiac myosin heavy chain genes in embryoid bodies; miR-499 over-expression also caused upregulation of the cardiac transcription factor MEF2C.

Conclusions—Taken together, our data give significant insight into the regulatory networks that govern hESC differentiation, and highlights the ability of miRNAs to perturb, and even control, the genes that are involved in cardiac specification of hESCs.