Abstract
Perturbations during the cell DNA-Damage Response (DDR) can originate from alteration in the functionality of the microRNA-mediated gene regulation, being microRNAs (miRNAs), small non-coding RNAs that act as post-transcriptional regulators of gene expression. The oncogenic miR-27a is over-expressed in several tumors and, in the present study, we investigated its interaction with ATM, the gene coding for the main kinase of DDR pathway. Experimental validation to confirm miR-27a as a direct regulator of ATM was performed by site-direct mutagenesis of the luciferase reporter vector containing the 3′UTR of ATM gene, and by miRNA oligonucleotide mimics. We then explored the functional miR-27a/ATM interaction under biological conditions, i.e., during the response of A549 cells to ionizing radiation (IR) exposure. To evaluate if miR-27a over-expression affects IR-induced DDR activation in A549 cells we determined cell survival, cell cycle progression and DNA double-strand break (DSB) repair. Our results show that up-regulation of miR-27a promotes cell proliferation of non-irradiated and irradiated cells. Moreover, increased expression of endogenous mature miR-27a in A549 cells affects DBS rejoining kinetics early after irradiation.
Highlights
To maintain the integrity of genome, eukaryotic cells rely on a highly regulated system pathway of response to DNA damage—the DNA-Damage Response (DDR)—which encompasses damage sensors, mediators, signal transducers and effectors
We recently demonstrated that miR-27a and ATM are differentially expressed and anti-correlated in γ-irradiated human lymphocytes incubated in microgravity and that miR-27a could interact with ATM-3'-untranslated region (3'untranslated region (UTR)) [14]
We examined the role of miR-27a during the DNA-Damage Response (DDR)
Summary
To maintain the integrity of genome, eukaryotic cells rely on a highly regulated system pathway of response to DNA damage—the DNA-Damage Response (DDR)—which encompasses damage sensors, mediators, signal transducers and effectors. DDR pathway is post-transcriptionally regulated through selective mRNA stabilization or decay and regulation of translation [3] In this context, non-coding RNAs, such as microRNAs (miRNAs), have emerged as important regulators of gene expression of key components of DDR pathway. MiRNAs are natural single-stranded, small RNA molecules (18–22 nt) that regulate gene expression by binding to target mRNAs and suppress their translation or promote their cleavage [4]. Accumulating evidences have shown that miRNAs are altered following genotoxic and cytotoxic stress, and several studies suggested that miRNA expression is regulated in DDR at the transcriptional level, in a p53-dependent manner [11] and through modulation of miRNAs’ processing and maturation steps [12]. We analyzed the biological effects of miR-27a over-expression on the DNA damage response to γ-rays in A549 cells by using miRNA mimics which are chemically synthesized double stranded RNAs that, when introduced into cells, efficiently mimic specific endogenous miRNAs
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
