miR‐98 acts as an inhibitor in chronic constriction injury‐induced neuropathic pain via downregulation of high‐mobility group AT‐hook 2

Vitamins A and D Enhance the Expression of Ror-γ-Targeting miRNAs in a Mouse Model of Multiple Sclerosis

Autoreactive T cells, particularly those characterized by a Th17 phenotype, exert significant influence on the pathogenesis of multiple sclerosis (MS). The present study aimed to elucidate the impact of individual and combined administration of vitamin A and D on neuroinflammation, and microRNAs (miRNAs) involved in T helper (Th)17 development, utilizing a murine model of experimental autoimmune encephalomyelitis (EAE). EAE was induced in C57BL/6 mice, and 3 days prior to immunization, intraperitoneal injections of vitamins A and D or their combination were administered. Th17 cell percentages were determined in splenocytes utilizing intracellular staining and flow cytometry. Furthermore, the expression of Ror γ-t, miR-98-5p and Let-7a-5p, was measured in both splenocytes and spinal cord tissues using RT-PCR. Treatment with vitamin A and D resulted in a reduction in both disease severity in EAE mice. Treated mice showed a decreased frequency of Th17 cells and lower expression levels of IL17 and Ror γ-t in splenocytes and spinal cord. The spinal cord tissues and splenocytes of mice treated with vitamins A, D, and combined A+D showed a significant upregulation of miR-98-5p and Let-7a-5p compared to the EAE group. Statistical analysis indicated a strong negative correlation between miR-98-5p and Let-7a-5p levels in splenocytes and Ror-t expression. Our findings indicate that the administration of vitamins A and D exerts a suppressive effect on neuroinflammation in EAE that is associated with a reduction in the differentiation of T cells into the Th17 phenotype and is mediated by the upregulation of miR-98-5p and Let-7a-5p, which target the Ror γ-t.

MiR-30b-5p attenuates neuropathic pain by the CYP24A1-Wnt/β-catenin signaling in CCI rats

MicroRNAs (miRNAs) has been reported to act as key regulators of neuronal function. Increasing evidence has showed that miRNAs exert significant effects in neuropathic pain. We explored the role of miR-30b-5p in neuropathic pain by establishing a rat model of chronic constrictive injury (CCI). The sciatic nerve of CCI rats was used to induce chronic neuropathic pain. The expression and cellular distribution of miR-30b-5p were determined by RT-qPCR and FISH. The mRNA level, protein level, and cellular distribution of CYP24A1 were detected by RT-qPCR, western blot, and immunofluorescence staining assays, respectively. The interaction between miR-30b-5p and CYP24A1 was examined by a luciferase reporter assay. The behavioral effects of miR-30b-5p were assessed after intrathecal administration. Mechanical stimuli and radiant heat were applied to assess mechanical allodynia and thermal hyperalgesia of rats. ELISA was performed to measure the concentration of inflammatory cytokines. MiR-30b-5p expression was significantly downregulated in the spinal cord tissues and of CCI rats. Overexpression of miR-30b-5p attenuated symptoms of neuropathic pain, including mechanical allodynia and thermal hyperalgesia. Additionally, miR-30b-5p overexpression suppressed neuroinflammation by reducing the levels of IL-6, TNF-α and COX2 and elevating the levels of IL-10 in CCI rats. Mechanistically, CYP24A1 was a target of miR-30b-5p, and its expression was negatively regulated by miR-30b-5p. Moreover, CYP24A1 expression was upregulated in CCI rats and knockdown of CYP24A1 attenuated neuropathic pain and neuroinflammation. Furthermore, miR-30b-5p reduced the levels of the Wnt pathway-related genes in CCI rats by downregulating CYP24A1. Rescue assays showed that overexpression of CYP24A1 or activation of Wnt pathway reduced the alleviative effects of miR-30b-5p overexpression on neuropathic pain in CCI rats. Overall, miR-30b-5p inhibits neuropathic pain progression in CCI rats by inhibiting the CYP24A1-Wnt/β-catenin pathway.

Interactions Among lncRNAs/circRNAs, miRNAs, and mRNAs in Neuropathic Pain

Neuropathic pain (NP) is directly caused by an injury or disease of the somatosensory nervous system. It is a serious type of chronic pain that is a burden to the economy and public health. Although recent studies have improved our understanding of NP, its pathogenesis has not been fully elucidated. Noncoding RNAs, including lncRNAs, circRNAs, and miRNAs, are involved in the pathological development of NP through many mechanisms. In addition, extensive evidence suggests that novel regulatory mechanisms among lncRNAs/circRNAs, miRNAs, and mRNAs play a crucial role in the pathophysiological process of NP. In this review, we comprehensively summarize the regulatory relationship among lncRNAs/circRNAs, miRNAs, and mRNAs and emphasize the important role of the lncRNA/circRNA-miRNA-mRNA axis in NP.

Non-coding RNA regulators of diabetic polyneuropathy

Diabetic polyneuropathy is a common and disturbing complication of diabetes mellitus, presenting patients and caregivers with a substantial disease burden. Emerging mechanisms which are underlying diabetes may provide novel pathways to understand diabetic polyneuropathy (DPN). Specifically, non-coding RNA molecules consisting of microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are implicated in the biological processes underlying DPN, and may link it to clinical spheres such as other metabolic and neural pathologies. Here, we elaborate on several candidate non-coding RNAs which may be associated with DPN via regulatory roles governing phenomena related to inflammatory, pain-provoking, and metabolic syndrome pathways. Specific examples include miRNAs such as miR-106a, -146a, -9, -29b, -466a, and -98; likewise, lncRNAs MIAT, PVT1, H19, MEG3, and MALAT1 are implicated, often co-affecting the involved pathways. Incorporating newly discovered regulators into what we know about specific clinical applications may highlight novel avenues for diagnosis, prevention, and intervention with DPN.

Loss of SNHG4 Attenuated Spinal Nerve Ligation-Triggered Neuropathic Pain through Sponging miR-423-5p

Neuropathic pain is an intractable comorbidity of spinal cord injury. Increasing noncoding RNAs have been implicated in neuropathic pain development. lncRNAs have been recognized as significant regulators of neuropathic pain. lncRNA Small Nucleolar RNA Host Gene 4 (SNHG4) is associated with several tumors. However, the molecular mechanisms of SNHG4 in neuropathic pain remain barely documented. Here, we evaluated the function of SNHG4 in spinal nerve ligation (SNL) rat models. We observed that SNHG4 was significantly upregulated in SNL rat. Knockdown of SNHG4 was able to attenuate neuropathic pain progression via regulating behaviors of neuropathic pain including mechanical and thermal hyperalgesia. Moreover, knockdown of SNHG4 could repress the neuroinflammation via inhibiting IL-6, IL-12, and TNF-α while inducing IL-10 levels. Additionally, miR-423-5p was predicted as the target of SNHG4 by employing bioinformatics analysis. miR-423-5p has been reported to exert significantly poorer in several diseases. However, the role of miR-423-5p in the development of neuropathic pain is needed to be clarified. Here, in our investigation, RIP assay confirmed the correlation between miR-423-5p and SNHG4. Meanwhile, we found that miR-423-5p was significantly decreased in SNL rat models. SNHG4 regulated miR-423-5p expression negatively. As exhibited, the loss of miR-423-5p contributed to neuropathic pain progression, which was rescued by the silence of SNHG4. Therefore, our study indicated SNHG4 as a novel therapeutic target for neuropathic pain via sponging miR-423-5p.

High Mobility Group A (HMGA): Chromatin Nodes Controlled by a Knotty miRNA Network

High mobility group A (HMGA) proteins are oncofoetal chromatin architectural factors that are widely involved in regulating gene expression. These proteins are unique, because they are highly expressed in embryonic and cancer cells, where they play a relevant role in cell proliferation, stemness, and the acquisition of aggressive tumour traits, i.e., motility, invasiveness, and metastatic properties. The HMGA protein expression levels and activities are controlled by a connected set of events at the transcriptional, post-transcriptional, and post-translational levels. In fact, microRNA (miRNA)-mediated RNA stability is the most-studied mechanism of HMGA protein expression modulation. In this review, we contribute to a comprehensive overview of HMGA-targeting miRNAs; we provide detailed information regarding HMGA gene structural organization and a comprehensive evaluation and description of HMGA-targeting miRNAs, while focusing on those that are widely involved in HMGA regulation; and, we aim to offer insights into HMGA-miRNA mutual cross-talk from a functional and cancer-related perspective, highlighting possible clinical implications.

MicroRNA-144 relieves chronic constriction injury-induced neuropathic pain via targeting RASA1

MicroRNAs (miRNAs) have been shown to participate in development of neuropathic pain. However, the role of microRNA-144 (miR-144) in neuropathic pain remains unclear. In the present study, we established a neuropathic pain mouse model via chronic constriction injury (CCI)-induction. The successful establishment of this model was confirmed via evaluation of paw withdrawal threshold (PWT) and paw withdrawal latency (PWL). By using this model, we found that miR-144 was significantly downregulated in CCI-induced neuropathic pain mice. In addition, intrathecal injection of miR-144 agomiR alleviated mechanical and thermal hyperalgesia in neuropathic pain mice as shown by the increased of PWT and PWL. Moreover, miR-144 negatively regulated neuroinflammation by decreasing the expression of proinflammatory mediators, including TNF-α (tumor necrosis factor-α), IL (interleukin)-1β, and IL-6, thus facilitating the inhibition of neuropathic pain development. Mechanistically, RASA1 (RAS P21 Protein Activator 1) was downregulated following the injection of agomiR-144, and was verified to be a target of miR-144. Furthermore, overexpression of RASA1 reversed the inhibitory effect of miR-144 on neuropathic pain. Therefore, the present study suggested that miR-144 has the potential to be explored as therapeutic target for treatment of neuropathic pain.

MicroRNA-448 modulates the progression of neuropathic pain by targeting sirtuin 1

MicroRNAs (miRNAs) play crucial roles in the pathogenesis of neuropathic pain. The present study investigated the effects of miR-448 on the progression of neuropathic pain in a rat model of chronic constriction injury (CCI) of the sciatic nerve. Reverse-transcription quantitative polymerase chain reaction was conducted to detect the gene expression. The paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) were used to assess the pain threshold. The protein expression levels of interleukin (IL)-6, IL-1β and tumor necrosis factor-α (TNF-α) were detected by ELISA. The target of miR-448 was predicted by TargetScan software. The Student's t-test or one-way ANOVA were used to identify statistical differences among groups. miR-448 was persistently upregulated in CCI rats, and both mechanical allodynia and thermal hyperalgesia in CCI rats were decreased following miR-448 downregulation. The expression levels of IL-1β, IL-6 and TNF-α were significantly increased in CCI rats compared with controls, and these effects were reversed following treatment with a miR-448 inhibitor. A luciferase reporter assay revealed that sirtuin 1 (SIRT1) was a target gene of miR-448. SIRT1 was found to abrogate the effect of miR-448 on neuropathic pain development. Collectively, the results of the present study revealed that miR-448 promoted neuropathic pain in CCI rats by regulating neuroinflammation via SIRT1. Therefore, SIRT1 may be considered as a novel biomarker for neuropathic pain.

Effects of miR-150 on neuropathic pain process via targeting AKT3

MicroRNAs (miRNA) are reported to be a vital regulator of neuropathic pain. Even so, the molecular mechanisms of miRNA function on neuropathic pain development are known little. Our research was designed to investigate the role of miRNA in neuropathic pain development in rat modle set up by chronic sciatic nerve injury (CCI). Increasing miR-150 expression could significantly alleviate neuropathic pain in CCI rats. For farther researching the regulation mechanism of miR-150 on neuropathic pain, we screened AKT3 as a possible target of miR-150 by bioinformatic mechods and predicted a possible target of miR-150 in 3'-untranslated region (UTR) of AKT3 who serves as an oncogene. In rat model, the expression both of AKT3 mRNA and protein were significantly upregulated. The overexpressed miR-150 importantly repressed the level of AKT3 and simultaneously alleviate mechanical and thermal hyperalgesia in rat model. These suppressant impacts of miR-150 on neuropathic pain process can be reversed by the overexpression of AKT3. Considering all above results, our research declared that miR-150 can restrain neuropathic pain process though targeting AKT3 in vivo, suggesting that miR-150 could be the therapeutic target for neuropathic pain therapy by regulating AKT3.