Int J Med Sci 2014; 11(8):824-833. doi:10.7150/ijms.8358
Frequent Co-Expression of miRNA-5p and -3p Species and Cross-Targeting in Induced Pluripotent Stem Cells
1. Department of Animal Science & Graduate Institute of Biotechnology, Chinese Culture University, Taipei, Taiwan;
2. Centre for Stem Cell Research, Universiti Tunku Abdul Rahman, Faculty of Medicine and Health Sciences, Kajang, Selangor, Malaysia;
3. Department of Preclinical Sciences, Universiti Tunku Abdul Rahman, Faculty of Medicine and Health Sciences, Kajang, Selangor, Malaysia;
4. Singapore BioImaging Consortium, Singapore;
5. Duke-NUS Graduate Medical School, Singapore;
6. Dean's Office, Universiti Tunku Abdul Rahman, Faculty of Medicine and Health Sciences, Kajang, Selangor, Malaysia;
7. Tissue Engineering Group, National Orthopaedic Centre of Excellence for Research and Learning, Department of Orthopaedic Surgery, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.
Huang CJ, Nguyen PNN, Choo KB, Sugii S, Wee K, Cheong SK, Kamarul T. Frequent Co-Expression of miRNA-5p and -3p Species and Cross-Targeting in Induced Pluripotent Stem Cells. Int J Med Sci 2014; 11(8):824-833. doi:10.7150/ijms.8358. Available from http://www.medsci.org/v11p0824.htm
Background: A miRNA precursor generally gives rise to one major miRNA species derived from the 5' arm, and are called miRNA-5p. However, more recent studies have shown co-expression of miRNA-5p and -3p, albeit in different concentrations, in cancer cells targeting different sets of transcripts. Co-expression and regulation of the -5p and -3p miRNA species in stem cells, particularly in the reprogramming process, have not been studied.
Methods: In this work, we investigated co-expression and regulation of miRNA-5p and -3p species in human induced pluripotent stem cells (iPSCs), mesenchymal stem cells (MSCs) and embryonic stem cells (ESC) using a nanoliter-scale real-time PCR microarray platform that included 1,036 miRNAs.
Results: In comparing iPSC and ESC, only 32 miRNAs were found to be differentially expressed, in agreement of the ESC-like nature of iPSC. In the analysis of reprogramming process in iPSCs, 261 miRNAs were found to be differentially expressed compared with the parental MSC and pre-adipose tissue, indicating significant miRNA alternations in the reprogramming process. In iPSC reprogrammed from MSC, there were 88 miRNAs (33.7%), or 44 co-expressed 5p/3p pairs, clearly indicating frequent co-expression of both miRNA species on reprogramming. Of these, 40 pairs were either co-up- or co-downregulated indicating concerted 5p/3p regulation. The 5p/3p species of only 4 pairs were regulated in reverse directions. Furthermore, some 5p/3p species of the same miRNAs were found to target the same transcript and the same miRNA may cross-target different transcripts of proteins of the G1/S transition of the cell cycle; 5p/3p co-targeting was confirmed in stem-loop RT-PCR.
Conclusion: The observed cross- and co-regulation by paired miRNA species suggests a fail-proof scheme of miRNA regulation in iPSC, which may be important to iPSC pluripotency.
Keywords: Induced pluripotent stem cells, reprogramming, miRNA-5p/3p species, cell cycle control