Retinoid acid-induced microRNA-31-5p suppresses myogenic proliferation and differentiation by targeting CamkIIδ

MicroRNA-31-5p Exacerbates Lipopolysaccharide-Induced Acute Lung Injury via Inactivating Cab39/AMPKα Pathway

Acute lung injury (ALI) and the subsequent acute respiratory distress syndrome remain devastating diseases with high mortality rates and poor prognoses among patients in intensive care units. The present study is aimed at investigating the role and underlying mechanisms of microRNA-31-5p (miR-31-5p) on lipopolysaccharide- (LPS-) induced ALI. Mice were pretreated with miR-31-5p agomir, antagomir, and their negative controls at indicated doses for 3 consecutive days, and then they received a single intratracheal injection of LPS (5 mg/kg) for 12 h to induce ALI. MH-S murine alveolar macrophage cell lines were cultured to further verify the role of miR-31-5p in vitro. For AMP-activated protein kinase α (AMPKα) and calcium-binding protein 39 (Cab39) inhibition, compound C or lentiviral vectors were used in vivo and in vitro. We observed an upregulation of miR-31-5p in lung tissue upon LPS injection. miR-31-5p antagomir alleviated, while miR-31-5p agomir exacerbated LPS-induced inflammation, oxidative damage, and pulmonary dysfunction in vivo and in vitro. Mechanistically, miR-31-5p antagomir activated AMPKα to exert the protective effects that were abrogated by AMPKα inhibition. Further studies revealed that Cab39 was required for AMPKα activation and pulmonary protection by miR-31-5p antagomir. We provide the evidence that endogenous miR-31-5p is a key pathogenic factor for inflammation and oxidative damage during LPS-induced ALI, which is related to Cab39-dependent inhibition of AMPKα.

MicroRNA-219a-5p-mediated inhibition of CaMKIIγ facilitates vestibular compensation in acute vertigo by promoting protein kinase C expression

Vestibular compensation (VC) refers to a behavioral recovery process in which firing rates of bilateral vestibular nuclei neurons are rebalanced. Our study aimed to investigate the underlying mechanism by which miR-219a-5p regulates Ca²⁺ /calmodulin-dependent protein kinase II γ isoform (CaMKIIγ) and protein kinase C (PKC) in VC. A unilateral vestibular deafferentation rat model was established by unilateral labyrinthectomy (UL), after which VC was evaluated in rats with UL-induced vertigo-like behavior by measuring vestibular defect behavior and performing rotarod tests, as well as by BrdU immunohistochemistry on medial vestibular nuclei. We found that miR-219a-5p was increased while CaMKIIγ was decreased during VC in the medial vestibular nucleus of rats that had undergone UL. Next, gain- and loss-of-function assays were conducted to evaluate the effects of miR-219a-5p and CaMKIIγ on the vestibular defect behaviors and VC, the results of which suggested that in rats after UL overexpression of CaMKIIγ inhibited VC, while overexpression of miR-219a-5p facilitated VC. A dual-luciferase reporter gene assay identified that miR-219a-5p targeted CaMKIIγ. This led to additional experiments showing that miR-219a-5p aptomir expression downregulated CaMKIIγ in cortical cells with a concomitant increase in PKC expression, which were verified further in vivo. In summary, in rats with acute vertigo, miR-219a-5p overexpression inhibits CaMKIIγ and elevates PKC, thereby facilitating VC. Our study offers possible targets for further evaluation as treatment of acute vertigo in humans.

Effects of IC50 dose of retinol on metabolomics of RAW264.7 cells

Vitamin A is one of the most multifunctional vitamins in normal human physiology and is involved in several basic physiological processes from embryonic development to adulthood, such as embryogenesis, vision, immunity, cell differentiation, and proliferation. In this study, we conducted ¹ H- NMR to evaluate the metabolomic changes in RAW264.7 cells after treatment with retinol at an IC₅₀ dose to identify its effects on the differential metabolites and main metabolic pathways. Our results showed that the IC₅₀ dose (140 μM) of retinol affected the metabolism of RAW264.7 cells, with a total of 22 differential metabolites identified via ¹ H-NMR, including amino acids, sugars, organic acids, glutathione, glycerin, and creatine. Additionally, multiple metabolic pathways were affected by retinol treatment, including downregulation of amino acid biosynthesis, protein synthesis, and pyruvate metabolism. We speculate that the cytotoxicity of retinol at the IC₅₀ dose is attributed to mitochondrial dysfunction as a result of oxidative stress or lipid peroxidation. PRACTICAL APPLICATIONS: With the general improvement of people's living standards, people use dietary supplements to improve the level of retinol to prevent non-specific diseases. But there are more and more cases of acute or chronic poisoning caused by excessive intake of vitamin A. Therefore, it is necessary to study the toxicity of vitamin A, and more attention should be paid to the excessive intake of vitamin A. From the perspective of metabolomics, this experiment studies the adverse effects of high dose retinol through the changes of metabolites and metabolic pathways at the cellular level. This study will assist further analyses of the toxic mechanism of excessive retinol as fortified foods and nutrient supplementation.

Retinoic acid and microRNA

Retinoic acid (RA), the biologically active metabolite of vitamin A, regulates a vast spectrum of biological processes, such as cell differentiation, proliferation, apoptosis, and morphogenesis. microRNAs (miRNAs) play a crucial role in regulating gene expression by binding to messenger RNA (mRNA) which leads to mRNA degradation and/or translational repression. Like RA, miRNAs regulate multiple biological processes, including proliferation, differentiation, apoptosis, neurogenesis, tumorigenesis, and immunity. In fact, RA regulates the expression of many miRNAs to exert its biological functions. miRNA and RA regulatory networks have been studied in recent years. In this manuscript, we summarize literature that highlights the impact of miRNAs in RA-regulated molecular networks included in the PubMed.

Nutritive vitamins as epidrugs

Epigenetic modifications play an important role in disease pathogenesis and therefore are a focus of intense investigation. Epigenetic changes include DNA, RNA, and histone modifications along with expression of non-coding RNAs. Various factors such as environment, diet, and lifestyle can influence the epigenome. Dietary nutrients like vitamins can regulate both physiological and pathological processes through their direct impact on epigenome. Vitamin A acts as a major regulator of above-mentioned epigenetic mechanisms. B group vitamins including biotin, niacin, and pantothenic acid also participate in modulation of various epigenome. Further, vitamin C has shown to modulate both DNA methylation and histone modifications while few reports have also supported its role in miRNA-mediated pathways. Similarly, vitamin D also influences various epigenetic modifications of both DNA and histone by controlling the regulatory mechanisms. Despite the information that vitamins can modulate the epigenome, the detailed mechanisms of vitamin-mediated epigenetic regulations have not been explored fully and hence further detailed studies are required to decipher their role at epigenome level in both normal and disease pathogenesis. The current review summarizes the available literature on the role of vitamins as epigenetic modifier and highlights the key evidences for developing vitamins as potential epidrugs.

MicroRNA and retinoic acid

BACKGROUND AND OBJECTIVE

Retinoic acid is a metabolite of vitamin A that is necessary to maintain health in human and most of the other vertebrates. MicroRNAs (miR or miRNAs) are small, non-coding RNA particles that diminish mRNA translation of various genes and so can regulate critical cell processes including cell death, proliferation, development, etc. The aim of this review is to study interrelations between retinoic acid with miRNAs.

METHODS

We reviewed and summarized all published articles in PubMed, Europe PMC, and Embase databases with any relationship between retinoic acid and miRNAs from Jun 2003 to Dec 2018 that includes 126 articles.

RESULTS

Results showed direct and indirect relationships between retinoic acid and miRNAs in various levels including effects of retinoic acid on expression of various miRNAs and miRNA-biogenesis enzymes, and effect of miRNAs on metabolism of retinoic acid.

DISCUTION AND CONCLUSION

This review indicates that retinoic acid has inter-correlations with various miRNA members and their metabolism in health and disease may require implications of the other.