Dysregulation of miR-381-3p and miR-23b-3p in skeletal muscle could be a possible estimator of early post-mortem interval in rats

Abstract

Background The post-mortem interval (PMI) is the time elapsed since the dead of an individual until the body is found, which is relevant for forensic purposes. The miRNAs regulate the expression of some genes; and due to their small size, they can better support degradation, which makes them suitable for forensic analysis. In the present work, we evaluated the gene expression of miR-381-3p, miR-23b-3p, and miR-144-3p in skeletal muscle in a murine model at the early PMI. Methods We designed a rat model to evaluate the early PMI under controlled conditions. This model consisted in 25 rats divided into five groups of rats, that correspond to the 0, 3, 6, 12 and 24 hours of PMI. The 0 h-PMI was considered as the control group. Muscle samples were taken from each rat to analyze the expression of miR-381-3p, miR-23b-3p, and miR-144-3p by quantitative RT-PCR. The gene expression of each miRNA was expressed as Fold Change (FC) and compared among groups. To find the targets of these miRNAs and the pathways where they participate, we performed an in-silico analysis. From the gene targets of miR-381-3p identified in the silico analysis, the EPC1 gene was selected for gene expression analysis by quantitative RT-PCR in these samples. Also, to evaluate if miR-381-3p could predict the early PMI, a mixed effects model was calculated using its gene expression. Results An upregulation of miR-381-3p was found at 24 h-PMI compared with the control group of 0 h-PMI and (FC = 1.02 vs. FC = 1.96; p = 0.0079). This was the opposite for miR-23b-3p, which had a down-regulation at 24 h-PMI compared to 0 h-PMI (FC = 1.22 vs. FC = 0.13; p = 0.0079). Moreover, the gene expression of miR-381-3p increased throughout the first 24 h of PMI, contrary to miR-23b-3p. The targets of these two miRNAs, participate in biological pathways related to hypoxia, apoptosis, and RNA metabolism. The gene expression of EPC1 was found downregulated at 3 and 12 h of PMI, whereas it remained unchanged at 6 h and 24 h of PMI. Using a multivariate analysis, it was possible to predict the FC of miR-381-3p of all but 6 h-PMI analyzed PMIs. Discussion The present results suggest that miR-23b-3p and miR-381-3p participate at the early PMI, probably regulating the expression of some genes related to the autolysis process as EPC1 gene. Although the miR-381-3p gene expression is a potential estimator of PMI, further studies will be required to obtain better estimates.

MiR-29a Family as a Key Regulator of Skeletal Muscle Dysplasia in a Porcine Model of Intrauterine Growth Retardation

“…The expression of miR-381-3p was the highest in IUGR pig skeletal muscle, accounting for 21.17% (normal: 9.86%), while the expression of miR-206 in normal pig skeletal muscle was the highest, accounting for 15.45% (IUGR: 10.13%). Previous studies have reported that miR-381-3p may be involved in the autolysis of skeletal muscle in the early stage of death [ 38 ]; these results suggest that miR-381 may play an important role in regulating skeletal muscle homeostasis in IUGR animals.…”

A miRNome analysis at the early postmortem interval

“…Although it is expected that the expression of some of these miRNAs decays as the PMI increases, there are miRNAs whose expression increases at PMI, such as MiR195 and MiR122 ( Wang et al, 2013a ). In fact, in our lab we found an increase in the expression of miR-381-3p in rats’ skeletal muscle at the 24 h of PMI ( Martínez-Rivera et al, 2021 ). This suggests that just as with some mRNAs, there is an upregulation of miRNAs which are needed for the body decomposition process.…”

“…A total of five rat skeletal muscle samples were obtained from a postmortem interval rat model which was previously established in our laboratory ( Martínez-Rivera et al, 2021 ). In brief, nine adult male Wistar rats were selected for the study; all with an average weight of 200 gr.…”

“…The 0 h-PMI was considered the control group. The procedures to obtain the muscle samples of rats at 24 h of PMI and controls were performed as previously described ( Martínez-Rivera et al, 2021 ). All procedures of the PMI rat model reported in this study were approved by the local ethic and scientific committees ( Martínez-Rivera et al, 2021 ).…”

“…The RNAs from each rat skeletal muscle sample were obtained using glass beads and Trizol™ Reagent as previously described ( Martínez-Rivera et al, 2021 ). The integrity of the obtained RNAs was evaluated in agarose gels ( Fig.…”