Involvement of microRNA214 and transcriptional regulation in reductions in mevalonate pyrophosphate decarboxylase mRNA levels in stroke-prone spontaneously hypertensive rat livers

MicroRNA-214 protects L6 skeletal myoblasts against hydrogen peroxide-induced apoptosis

MicroRNAs (miRNAs) have been reported as key gene regulators, and they control many fundamental biological processes. Previously, we demonstrated that miR-214 had a protective effect against myocardial apoptosis and myocardial fibrosis. In this study, we sought to investigate the expression of miR-214 in L6 skeletal myoblast (SKM), the regulatory effect of miR-214 on hydrogen peroxide (H₂O₂) induced cell apoptosis and the underlying mechanisms of the antiapoptotic effect. MiR-214 expression was up-regulated by H₂O₂ in a dose and time-dependent manner in L6 SKMs. To investigate the regulatory effects of miR-214 on L6 SKM, both gain-of-function and loss-of-function approaches were applied. The results showed that miR-214 improved cell survival and inhibited cell apoptosis, and blockage of miR-214 abrogated the protective effect on cell survival and resistance to apoptosis. Phosphatase and tensin homolog (PTEN) was negatively regulated by miR-214, and PTEN inhibitor obviously reversed the effect of miR-214 blockage on enhancing cell apoptosis. In addition, miR-214 up-regulated antiapoptotic protein Bcl-2, down-regulated proapoptotic protein Bax, prevented release of cytochrome c and inhibited caspase-3 activation. In summary, H₂O₂-induced injury increases miR-214 expression in L6 SKM, and miR-214 contributes to the protection of L6 SKM against apoptosis via lowering PTEN and subsequently inhibiting the mitochondrial-mediated caspase-dependent apoptotic signaling pathway.

Stroke-prone spontaneously hypertensive rats have reduced hydroxysteroid 17-β dehydrogenase 7 levels for low cholesterol biosynthesis

Reduced serum cholesterol content was recently reported to be one of the factors responsible for cerebral haemorrhage. Stroke-prone spontaneously hypertensive rats (SHRSP) are known to have lower serum cholesterol content than normotensive Wistar-Kyoto rats (WKY). We previously reported that lower levels of mevalonate pyrophosphate decarboxylase (MPD) and squalene epoxidase (SQE), which are associated with cholesterol biosynthesis in the liver, are involved in the low serum cholesterol content in SHRSP. Here, we investigate the levels of sterol 14-demethylase (CYP51), methylsterol monooxygenase (SC4MOL), and hydroxysteroid 17-β dehydrogenase 7 (HSD17B7), which contribute to the cholesterol synthesis pathway in the conversion of lanosterol to zymosterol, in SHRSP and WKY. The HSD17B7 mRNA levels in the liver of SHRSP were markedly lower than those in WKY, whereas no significant differences were observed in CYP51 and SC4MOL levels in the two types of rats. The relative levels of protein, heteronuclear RNA, and mRNA of HSD17B7 were also significantly lower in SHRSP than in WKY. The degradation rates of HSD17B7 were the same in SHRSP and WKY. The protein levels of HSD17B7 were not significantly reduced in tissues other than the liver, including the brain, lung, heart, spleen, kidney, and testis, in SHRSP. Moreover, HSD17B7 activity was significantly lower in SHRSP than in WKY. Thus, our results indicated that low protein levels and activity of HSD17B7 are responsible for the reduced cholesterol content in SHRSP, indicating that HSD17B7, along with MPD and SQE, is involved in the decreased cholesterol synthesis in the liver of SHRSP.

Regulation of terpenoid biosynthesis by miRNA in Persicaria minor induced by Fusarium oxysporum

Background

Persicaria minor (kesum) is an herbaceous plant with a high level of secondary metabolite compounds, particularly terpenoids. These terpenoid compounds have well-established roles in the pharmaceutical and food industries. Although the terpenoids of P. minor have been studied thoroughly, the involvement of microRNA (miRNA) in terpenoid regulation remains poorly understood and needs to be explored. In this study, P. minor plants were inoculated with the pathogenic fungus Fusarium oxysporum for terpenoid induction.

Result

SPME GC-MS analysis showed the highest terpenoid accumulation on the 6th day post-inoculation (dpi) compared to the other treatment time points (0 dpi, 3 dpi, and 9 dpi). Among the increased terpenoid compounds, α-cedrene, valencene and β-bisabolene were prominent. P. minor inoculated for 6 days was selected for miRNA library construction using next generation sequencing. Differential gene expression analysis showed that 58 miRNAs belonging to 30 families had significantly altered regulation. Among these 58 differentially expressed genes (DEGs), 33 miRNAs were upregulated, whereas 25 miRNAs were downregulated. Two putative novel pre-miRNAs were identified and validated through reverse transcriptase PCR. Prediction of target transcripts potentially involved in the mevalonate pathway (MVA) was carried out by psRobot software, resulting in four miRNAs: pmi-miR530, pmi-miR6173, pmi-miR6300 and a novel miRNA, pmi-Nov_13. In addition, two miRNAs, miR396a and miR398f/g, were predicted to have their target transcripts in the non-mevalonate pathway (MEP). In addition, a novel miRNA, pmi-Nov_12, was identified to have a target gene involved in green leaf volatile (GLV) biosynthesis. RT-qPCR analysis showed that pmi-miR6173, pmi-miR6300 and pmi-nov_13 were downregulated, while miR396a and miR398f/g were upregulated. Pmi-miR530 showed upregulation at 9 dpi, and dynamic expression was observed for pmi-nov_12. Pmi-6300 and pmi-miR396a cleavage sites were detected through degradome sequence analysis. Furthermore, the relationship between miRNA metabolites and mRNA metabolites was validated using correlation analysis.

Conclusion

Our findings suggest that six studied miRNAs post-transcriptionally regulate terpenoid biosynthesis in P. minor. This regulatory behaviour of miRNAs has potential as a genetic tool to regulate terpenoid biosynthesis in P. minor.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5954-0) contains supplementary material, which is available to authorized users.

Levels of tight junction protein CLDND1 are regulated by microRNA-124 in the cerebellum of stroke-prone spontaneously hypertensive rats

The claudin family shows organ- and tissue-specific expression of individual members. Deficiency or aberrant expression of distinct claudins has been reported to be associated with severe pathophysiological consequences. Claudin domain-containing 1 (CLDND1), also known as claudin-25, shows homology to this family of proteins. Furthermore, serum CLDND1-derived peptide antibody levels are elevated in patients with cerebral infarction, as compared with healthy controls. We previously reported that, in the adult murine brain, CLDND1 is abundantly expressed in the cerebellum in common sites of intracerebral hemorrhage, and CLDND1 levels are transiently decreased after hemorrhagic insult. However, regulation of CLDND1 expression levels in cerebrovascular disease is poorly studied, and most regulatory microRNAs remain to be defined. We assessed its expression level, according to the presence of early signs of cerebrovascular disease, in the brain of stroke-prone spontaneously hypertensive rats (SHRSPs) and investigated the microRNA regulation of Cldnd1 mRNA. We investigated the post-transcriptional regulation of Cldnd1 by examining the subcellular distribution of its mRNA and evaluating its translational regulation by microRNA in human brain endothelial cells (HBECs) and in the brain of SHRSPs. Using bioinformatics, we identified a conserved microRNA-124 (miR-124)-binding site in the 3'-untranslated region of Cldnd1 and demonstrated that miR-124 regulates the translation of Cldnd1 mRNA reporters in a sequence-specific manner in luciferase assays. HBECs transfected with an miR-124 mimic showed decreased levels of CLDND1 mRNA in reverse transcription quantitative PCR. miR-124 levels were markedly lower in SHRSP than in Wister Kyoto rat brains, whereas Cldnd1 mRNA and protein levels were significantly higher. In SHRSP brains, Cldnd1 mRNA levels increased with a decrease in miR-124. Therefore, by interacting with Cldnd1 mRNA, miR-124 influences CLDNL1 levels in the brain, thus playing a role in the development of cerebrovascular disease in SHRSPs.