Investigation of microRNA expression and DNA repair gene transcripts in human oocytes and blastocysts

Abstract

Purpose The aim of the study is to investigate the regulation of DNA repair genes by microRNAs (miRNAs). miRNAs are short non-coding RNAs that regulate transcriptional and post-transcriptional gene silencing. Several miRNAs that are expressed during preimplantation embryo development have been shown or are predicted to target genes that regulate cell cycle checkpoints and DNA repair in response to DNA damage. Methods This study compares the expression level of 20 miRNAs and 9 target transcripts involved in DNA repair. The statistical significance of differential miRNA expression between oocytes and blastocysts was determined by t test analysis using the GraphPad Prism v6 software. The possible regulatory roles of miRNAs on their target messenger RNAs (mRNAs) were analysed using a Pearson correlation test. Results This study shows for the first time that several miRNAs are expressed in human oocytes and blastocysts that target key genes involved in DNA repair and cell cycle checkpoints. Blastocysts exhibited statistically significant lower expression levels for the majority of miRNAs compared to oocytes (p<0.05). Correlation analyses showed that there was both inverse and direct association between miRNAs and their target mRNAs. Conclusions miRNAs target many mRNAs including ones involved in DNA repair mechanisms. This study suggests that miRNAs and their target mRNAs involved in DNA repair are expressed in preimplantation embryos. Similar to the miRNAs expressed in adult tissues, these miRNAs seem to have regulatory roles on their target DNA repair mRNAs during preimplantation embryo development.

Human alpha defensin 5 is a candidate biomarker to delineate inflammatory bowel disease

“…All other statistical analyses were performed using GraphPad Prism v6 software [ 26 ]. qRT-PCR and IHC HD5 counts were examined by applying an unpaired two-tailed Student’s t -test with the Welch correction, respectively.…”

Mãe, obrigada pelos microRNAs

“…Os microRNAs são expressos nos mais diversos organismos eucariotos, inclusive em humanos. Foi verificado que há a expressão de miRNAs tanto em células germinativas quanto em embriões humanos 23 . Desde o final da década de 1970, quando ocorreu o nascimento do primeiro "bebê de proveta", já é discutida a utilização de embriões remanescentes de técnicas de fertilização in vitro, e até então, esta prática é vetada.…”

Roles of microRNAs in mammalian reproduction: from the commitment of germ cells to peri‐implantation embryos

“…By contrast, most zygotic miRNAs are derived from maternal oocytes (Tang et al, ). Altered miRNA expression in cumulus cells could result in a poor ovarian response in women undergoing in vitro fertilization (Karakaya et al, ), and some miRNAs are highly specific to the blastocyst and are not expressed in the oocytes (Tulay et al, ). In addition, sperm‐borne miR‐34c‐5p is thought to initiate the first cleavage divisions in the mouse (Liu et al, ), and is positively correlated with intracytoplasmic sperm injection outcomes, as well as high‐quality embryos, implantation, pregnancy and live birth in humans (Cui et al, ), and the presence of miR‐34c‐5p indicates viability and high‐quality spermatozoa in humans (Abu‐Halima et al, ).…”