Behnam Kamalidehghan,1,* Mohsen Habibi,2,* Sara S Afjeh,1 Maryam Shoai,3 Saeideh Alidoost,4 Rouzbeh Almasi Ghale,4 Nahal Eshghifar,5 Farkhondeh Pouresmaeili1,6 1Department of Medical Genetics, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran; 2Central Laboratory, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran; 3Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK; 4Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran; 5Department of Cellular and Molecular Biology, Faculty of Advanced Science and Technology, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran and Men’s Health and Reproductive Health Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran; 6Men’s Health and Reproductive Health Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran*These authors contributed equally to this workCorrespondence: Farkhondeh PouresmaeiliMen’s Health and Reproductive Health Research Center, Shahid Beheshti University of Medical Sciences, Tehran, IranTel/Fax +98 21-23872572Email pouresfar@gmail.comBackground: MicroRNAs (miRNA) play a key role in the regulation of gene expression through the translational suppression and control of post-transcriptional modifications.Aim: Previous studies demonstrated that miRNAs conduct the pathways involved in human reproduction including maintenance of primordial germ cells (PGCs), spermatogenesis, oocyte maturation, folliculogenesis and corpus luteum function. The association of miRNA expression with infertility, polycystic ovary syndrome (PCOS), premature ovarian failure (POF), and repeated implantation failure (RIF) was previously revealed. Furthermore, there are evidences of the importance of miRNAs in embryonic development and implantation. Piwi-interacting RNAs (piRNAs) and miRNAs play an important role in the post-transcriptional regulatory processes of germ cells. Indeed, the investigation of small RNAs including miRNAs and piRNAs increase our understanding of the mechanisms involved in fertility. In this review, the current knowledge of microRNAs in embryogenesis and fertility is discussed.Conclusion: Further research is necessary to provide new insights into the application of small RNAs in the diagnosis and therapeutic approaches to infertility.Keywords: miRNA, female fertility, male fertility, piwi-interacting RNAs, piRNAs
