microRNA and NF-kappa B

The NF-κB/Relish Activates miR-308 to Negatively Regulate Imd Pathway Immune Signaling in Drosophila

The strength and duration of the NF-κB signaling response must be tightly modulated to avoid an inadequate or excessive immune response. Relish, a core NF-κB transcription factor of the Drosophila Imd pathway, can control the expression of antimicrobial peptides, including Dpt and AttA, to defend against Gram-negative bacterial infections, but whether Relish may regulate miRNA expression to participate in the immune response remains unclear. In this study, taking advantage of Drosophila S2 cells and different overexpression/knockout/knockdown flies, we first found that Relish could directly activate the expression of miR-308 to negatively regulate the immune response and promote the survival of Drosophila during Enterobacter cloacae infection. Second, our results demonstrated that Relish-mediated expression of miR-308 could suppress target gene Tab2 to attenuate the Drosophila Imd pathway signal during the middle and late stages of the immune response. Third, we detected the dynamic expression patterns of Dpt, AttA, Relish, miR-308, and Tab2 in wild-type flies after E. coli infection, which further revealed that the feedback regulatory loop of Relish-miR-308-Tab2 plays a crucial role in the immune response and homeostasis maintenance of the Drosophila Imd pathway. Overall, our present study not only illustrates an important mechanism by which this Relish-miR-308-Tab2 regulatory axis can negatively control the Drosophila immune response and participate in homeostasis maintenance but also provides new insights into the dynamic regulation of the NF-κB/miRNA expression network of animal innate immunity.

MicroRNAs in septic acute kidney injury

Sepsis is a potentially fatal complication of burns and trauma that can cause acute kidney injury (AKI) with substantial morbidity and mortality, but this disease is poorly understood. Despite medical advances, effective therapeutic regimens for septic AKI remain uncommon. MicroRNAs (miRNAs) are endogenous non-coding RNAs that influence the translation of target messenger RNAs in a variety of biological processes. Emerging evidence has shown that miRNAs are intimately associated with septic AKI. The goal of this review was to summarize recent advances in the profound understanding of the functional role of miRNAs in septic AKI, as well as to provide new insights into miRNAs as feasible biomarkers and therapeutic targets for septic AKI.

Drosophila Relish-mediated miR-317 expression facilitates immune homeostasis restoration via inhibiting PGRP-LC

Innate immunity is the first and essential line for resisting pathogens, and the immune intensity and duration need to be strictly regulated to balance excessive or insufficient immune response. MicroRNAs (miRNAs) are crucial regulators of immune response in Drosophila, yet how immune-related miRNAs are regulated remains poorly understood. Herein, we elucidated that the involvement of miR-317 in NF-κB transcription factor Relish mediated Drosophila Imd pathway in response to Gram-negative (G-) bacteria stimulation. Remarkably, the dynamic expression profiling for immune response indicated that Relish simultaneously enhances the expression of the effector antimicrobial peptide Dpt as well as miR-317 post-infection. Upregulation of miR-317 could further down-regulate the expression of PGRP-LC, thereby forming a feedback in Drosophila Imd pathway to prevent over-activation and restore immune homeostasis. Taken together, our study not only uncovers a novel Relish/miR-317/PGRP-LC regulatory axis to attenuate Drosophila Imd immune response and facilitate immune homeostasis restoration, but also provides vital insights into the complex mechanisms of animal innate immune regulation.

TNF-α and NF-κB signaling play a critical role in cigarette smoke-induced epithelial-mesenchymal transition of retinal pigment epithelial cells in proliferative vitreoretinopathy

Proliferative vitreoretinopathy (PVR) is characterized by the growth and contraction of cellular membranes within the vitreous cavity and on both surfaces of the retina, resulting in recurrent retinal detachments and poor visual outcomes. Proinflammatory cytokines like tumor necrosis factor alpha (TNFα) have been associated with PVR and the epithelial-mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells. Cigarette smoke is the only known modifiable risk factor for PVR, but the mechanisms are unclear. The purpose of this study was to examine the impact of cigarette smoke on the proinflammatory TNFα/NF-κB/Snail pathway in RPE cells to better understand the mechanisms through which cigarette smoke increases the risk of PVR. Human ARPE-19 cells were exposed to cigarette smoke extract (CSE), for 4 to 24-hours and TNFα, Snail, IL-6, IL-8, and α-SMA levels were analyzed by qPCR and/or Western blot. The severity of PVR formation was assessed in a murine model of PVR after intravitreal injection of ARPE-19 cells pre-treated with CSE or not. Fundus imaging, OCT imaging, and histologic analysis 4 weeks after injection were used to examine PVR severity. ARPE-19 cells exposed to CSE expressed higher levels of TNFα, SNAIL, IL6 and IL8 mRNA as well as SNAIL, Vimentin and α-SMA protein. Inhibition of TNFα and NF-κB pathways blocked the effect of CSE. In vivo, intravitreal injection of ARPE-19 cells treated with CSE resulted in more severe PVR compared to mice injected with untreated RPE cells. These studies suggest that the TNFα pathway is involved in the mechanism whereby cigarette smoke increases PVR. Further investigation into the role of TNFα/NF-κB/Snail in driving PVR and pharmacological targeting of these pathways in disease are warranted.

The miR-26a-5p/IL-6 axis alleviates sepsis-induced acute kidney injury by inhibiting renal inflammation

Sepsis-induced acute kidney injury (AKI) is a common and life-threatening complication in hospitalized and critically ill patients and has unacceptable morbidity and mortality rates. However, effective approaches for the diagnosis and treatment of septic AKI are still lacking. Here, we demonstrated significant increases in the miR-26a-5p levels in renal tubular cells of LPS-induced septic AKI models both in vivo and in vitro. Mechanistically, we provided evidence of the involvement of NF-κB in miR-26a-5p induction. LPS treatment of renal tubular cells led to the activation of NF-κB, and inhibition of NF-κB by TPCA-1 prevented the induction of miR-26a-5p. These results indicated that NF-κB was a key upstream factor for the induction of miR-26a-5p in septic AKI. Anti-miR-26a-5p enhanced the expression of IL-6 at both the protein and mRNA levels following LPS treatment. Furthermore, our luciferase microRNA target reporter assay verified that IL-6 is a direct target of miR-26a-5p. Blocking miR-26a-5p promoted renal inflammation and worsened kidney injury. Thus, our study indicated that the miR-26a-5p/IL-6 axis can alleviate sepsis-induced acute kidney injury by inhibiting renal inflammation. This mechanism may represent a therapeutic target for septic AKI.

MicroRNAs as crucial mediators in the pharmacological activities of triptolide (Review)

Triptolide is the main bioactive constituent isolated from the Chinese herb Tripterygium wilfordii Hook F., which possesses a variety of pharmacological properties. MicroRNAs (miRNAs/miRs) are short non-coding RNAs that regulate gene expression post-transcriptionally. miRNAs are implicated in several intracellular processes, whereby their dysregulation contributes to pathogenesis of various diseases. Thus, miRNAs have great potential as biomarkers and therapeutic targets for diseases, and are implicated in drug treatment. Previous studies have reported that specific miRNAs are targeted, and their expression levels can be altered following exposure to triptolide. Thus, miRNAs are emerging as crucial mediators in the pharmacological activities of triptolide. The present review summarizes current literature on miRNAs as target molecules in the pharmacological activities of triptolide, including antitumor, anti-inflammatory, immunosuppressive, renal protective, cardioprotective, antiangiogenesis activities and multiorgan toxicity effects. In addition, the diverse signaling pathways involved are discussed to provide a comprehensive understanding of the underlying molecular mechanisms of triptolide in the regulation of target miRNAs.

Upregulation of miR-382 contributes to renal fibrosis secondary to aristolochic acid-induced kidney injury via PTEN signaling pathway

Acute kidney injury (AKI) has a critical role in the development of chronic kidney disease (CKD). Building on our previous findings, we explored the role of miR-382 in facilitating the transition of AKI to CKD using the Aristolochic acid (AA) nephropathy model, which was induced by intraperitoneal injection of aristolochic acid I salt (10 or 20 mg/kg). The effects of genetic depletion, pharmacologic inhibition, or overexpression of miR-382 on the PTEN/AKT signaling pathway were examined in vivo and in vitro. Changes in renal pathology and renal epithelial polarity were evaluated. A luciferase reporter assay was performed to investigate the reciprocal suppression relationship between miR-382 and PTEN. Renal fibrosis developed 14 d after AA exposure in a dose- and time-dependent manner. Renal abundance of miR-382 was upregulated following AA treatment, while genetic depletion or pharmacological inhibition of miR-382 partially reversed renal tubulointerstitial fibrosis. Expression of PTEN, a target of miR-382, was downregulated and subsequently its downstream AKT signaling pathway was activated during AKI to CKD transition induced by AA. Inhibition of PTEN in vitro resulted in the acquisition of the EMT phenotypes. Furthermore, upregulation of miR-382 in renal epithelial cells was partially mediated by the activation of NF-kB signaling, with a substantial elevation of proinflammatory cytokines. An in vivo study revealed that either miR-382 knockdown or miR-382 knockout was pivotal for inflammatory suppression, while an in vitro experiment confirmed that upregulation of miR-382 in cultured MTEC cells under AA exposure was remarkably reversed by NF-kB siRNA. These data indicated a novel role for the NF-κB/miR-382/PTEN/AKT axis in the pathogenesis of tubulointerstitial fibrosis following AA-induced acute renal tubular epithelial injury. Targeting miR-382 may lead to a potential novel therapeutic approach for retarding the AKT to CKD transition.

NF-κB promotes osteoclast differentiation by overexpressing MITF via down regulating microRNA-1276 expression

BACKGROUND

Nuclear factor-kappa B (NF-κB) is an important nuclear transcription factor in cells, involving in a series of processes such as cell proliferation, apoptosis, and differentiation. In this study, we explored the specific mechanism of NF-κB on the differentiation of osteoclasts.

METHODS

MicroRNAs (miRNAs) expression microarray data GSE105027 related to osteoarthritis was obtained to screen out the differentially expressed miRNA. Phorbol-12-myristate-13-acetate (PMA) was used to induce THP-1 cells to differentiate into macrophages, followed by induction to osteoclasts using macrophage colony-stimulating factor (M-CSF) and receptor activator of NF-κB ligand (RANKL). ELISA and RT-qPCR were conducted to examine IL-6 and IL-1β expression. The binding of NF-κB to the miR-1276 promoter region was demonstrated by ChIP assay, and targeting relationship between miR-1276 and MITF was verified by dual luciferase reporter assay. KK, iKBα, NF-kB, p-IKK, p-iKBα, p-NF-kB expression was analyzed by western blot. NF-κB and miR-1276 expression in osteoclasts was examined later. After gain- and less-of-function study, the effects on osteoclast differentiation were detected by TRAP-positive osteoclasts, TRAP activity, TRAP-5b content, F-Actin expression, as well as osteoclast differentiation marker genes expression.

RESULTS

NF-κB was activated in osteoclasts, and down-regulation of NF-κB inhibited osteoclast differentiation. Next, miR-1276 was downregulated in osteoclasts after differentiation from monocytes. Meanwhile, NF-κB decreased the expression of miR-1276 by binding to the miR-1276 promoter, thereby elevating MITF expression, thereby promoting osteoclast differentiation.

CONCLUSION

In summary, NF-κB promoted osteoclast differentiation through downregulating miR-1276 to upregulate MITF.

Oxidative Stress-Responsive MicroRNAs in Heart Injury

Reactive oxygen species (ROS) are important molecules in the living organisms as a part of many signaling pathways. However, if overproduced, they also play a significant role in the development of cardiovascular diseases, such as arrhythmia, cardiomyopathy, ischemia/reperfusion injury (e.g., myocardial infarction and heart transplantation), and heart failure. As a result of oxidative stress action, apoptosis, hypertrophy, and fibrosis may occur. MicroRNAs (miRNAs) represent important endogenous nucleotides that regulate many biological processes, including those involved in heart damage caused by oxidative stress. Oxidative stress can alter the expression level of many miRNAs. These changes in miRNA expression occur mainly via modulation of nuclear factor erythroid 2-related factor 2 (Nrf2), sirtuins, calcineurin/nuclear factor of activated T cell (NFAT), or nuclear factor kappa B (NF-κB) pathways. Up until now, several circulating miRNAs have been reported to be potential biomarkers of ROS-related cardiac diseases, including myocardial infarction, hypertrophy, ischemia/reperfusion, and heart failure, such as miRNA-499, miRNA-199, miRNA-21, miRNA-144, miRNA-208a, miRNA-34a, etc. On the other hand, a lot of studies are aimed at using miRNAs for therapeutic purposes. This review points to the need for studying the role of redox-sensitive miRNAs, to identify more effective biomarkers and develop better therapeutic targets for oxidative-stress-related heart diseases.

MicroRNA-150 restores endothelial cell function and attenuates vascular remodeling by targeting PTX3 through the NF-κB signaling pathway in mice with acute coronary syndrome

MicroRNAs (miRNAs) have been known to function as important regulators in the vascular system, with various physiopathological effects such as vascular remodeling and hypertension modulation. We aimed to explore whether microRNA-150 (miR-150) regulates endothelial cell function and vascular remodeling in acute coronary syndrome (ACS), and the involvement of PTX3 and NF-κB signaling pathway. Ten normal mice and sixty ApoE^-/- mice were chosen, and their coronary artery tissues and endothelial cells were extracted. ApoE^-/- mice were injected with a series of inhibitor or mimic for miR-150, or siRNA against PTX3. The miR-150 expression, NF-κB1, RELA, and PTX3 mRNA expression were assessed by reverse transcription quantitative polymerase chain reaction, and pentraxin-3, p-P50, and p-P65 protein expression by Western blot analysis. Cell viability and migration were assessed by MTT assay and scratch test. Matrigel tube formation assay was employed to determine vascular remodeling of endothelial cells. The dual-luciferase reporter assay verified that PTX3 was a target of miR-150. Mice with ACS presented with decreased miR-150 but increased PTX3. It was observed that the miR-150 mimic and siRNA against PTX3 reduced levels of PTX3, NF-κB1, and RELA in mice, and the miR-150 inhibitor reversed the tendency. The in vitro cell experimentation proved that miR-150 might facilitate endothelial cell proliferation, migration, and restrain vascular remodeling via inhibiting PTX3 expression. On the basis of the results of this study, it was hypothesized that miR-150 could possibly maintain endothelial cell function and suppress vascular remodeling by inhibiting PTX3 through the NF-κB signaling pathway in mice with ACS.

PIAS3-mediated feedback loops promote chronic colitis-associated malignant transformation

Rationale: Colitis-associated colorectal cancer (CAC) usually exhibits an accelerated disease progression, an increased resistance to therapeutic drugs and a higher mortality rate than sporadic colorectal cancer (CRC). PIAS3 is a member of the protein inhibitor of activated STAT (PIAS) family; however, little is known about the expression and biological functions of PIAS3 in CAC. The aim of our study was to investigate the biological mechanisms of PIAS3 in CAC. Methods: PIAS3 expression was examined in colon tissues of CAC/CRC patients and azoxymethane-dextran sulfate sodium (AOM-DSS)-induced mice. The role of PIAS3 was studied using a series of in vitro, in vivo and clinical approaches. Results: Downregulated PIAS3 expression, upregulated miR-18a expression and highly activated NF-κB and STAT3 were observed in colon tissues of CAC/CRC patients and AOM-DSS-induced mice. In vitro experiments revealed that PIAS3 significantly inhibited the activation of NF-κB and STAT3 and demonstrated that activated NF-κB and STAT3 transcriptionally regulated miR-18a level, and up-regulation of miR-18a expression led to defective PIAS3 expression. Moreover, PIAS3-mediated autoregulatory feedback loops (PIAS3/NF-κB/miR-18a and PIAS3/STAT3/miR-18a) were verified in vitro and were found to regulate cell proliferation. Additionally, modulation of the feedback loops via overexpression of PIAS3 or knockdown of miR-18a significantly inhibited cell proliferation in a mouse CRC xenograft model. Furthermore, upregulation of PIAS3 by intracolonic administration of PIAS3 lentivirus or anti-miR-18a lentivirus in AOM-DSS-induced mice led to dramatically reduced tumor sizes/numbers, whereas knockdown of PIAS3 in CAC mice significantly promoted tumor growth. Conclusion: Our data clearly show that PIAS3-mediated feedback loops control cell proliferation and function as robust driving forces for CAC progression. Targeting these highly activated feedback loops might offer promising therapeutic strategies for CAC.

Up-regulated Pro-inflammatory MicroRNAs (miRNAs) in Alzheimer's disease (AD) and Age-Related Macular Degeneration (AMD)

Alzheimer's disease (AD) of the brain neocortex and age-related macular degeneration (AMD) of the retina are two complex neurodegenerative disorders, which (i) involve the progressive dysregulation and deterioration of multiple neurobiological signaling pathways, (ii) exhibit the temporal accumulation of pro-inflammatory lesions including the amyloid beta (Aβ) peptide-containing senile plaques of AD and the drusen of AMD, and (iii) culminate in an insidious inflammatory neurodegeneration ending, respectively, in neural cell atrophy and death and progressive loss of cognition and central visual function. Recent independent research studies have indicated that AD and AMD share common, pathological signaling defects and disease mechanisms at the molecular genetic level. Using high-integrity total RNA samples pooled from AD brain and AMD retina, microfluidic hybridization miRNA arrays, and bioinformatics, the current study was undertaken to quantify microRNA (miRNA) speciation and complexity common to both AD and AMD. These small non-coding (sncRNAs) are known to post-transcriptionally regulate multiple neurobiological pathways and an abundance of research information has already been generated on the roles of these miRNAs in pathological situations involving inflammatory neuropathology and neural cell decline. Here, for the first time, we report the sequence and abundance of a septet of sncRNAs including miRNA-7, miRNA-9-1, miRNA-23a/miRNA-27a, miRNA-34a, miRNA-125b-1, miRNA-146a, and miRNA-155 that are significantly increased in abundance and common to both AD-affected superior temporal lobe neocortex (Brodmann A22) and the AMD-affected macular region of the retina. Bioinformatics, miRNA-mRNA complementarity, next-gen RNA sequencing, and feature alignment analysis further indicate that these 7 up-regulated miRNAs have the potential to interact with and down-regulate ~ 9460 target messenger RNAs (mRNAs; about 3.5% of the genome) involved in the synchronization of amyloid production and clearance, phagocytosis, innate-immune, pro-inflammatory, and neurotrophic signaling and/or synaptogenesis in diseased tissues.

MicroRNA-375 Is Induced in Cisplatin Nephrotoxicity to Repress Hepatocyte Nuclear Factor 1-β

Nephrotoxicity is a major adverse effect of cisplatin-mediated chemotherapy in cancer patients. The pathogenesis of cisplatin-induced nephrotoxicity remains largely unclear, making it difficult to design effective renoprotective approaches. Here, we have examined the role of microRNAs (miRNAs) in cisplatin-induced nephrotoxicity. We show that cisplatin nephrotoxicity was not affected by overall depletion of both beneficial and detrimental miRNAs from kidney proximal tubular cells in mice in which the miRNA-generating enzyme Dicer had been conditionally knocked out. To identify miRNAs involved in cisplatin nephrotoxicity, we used microarray analysis to profile miRNA expression and identified 47 up-regulated microRNAs and 20 down-regulated microRNAs in kidney cortical tissues. One up-regulated miRNA was miR-375, whose expression was also induced in cisplatin-treated renal tubular cells. Interestingly, inhibition of miR-375 decreased cisplatin-induced apoptosis, suggesting that miR-375 is a cell-damaging or pro-apoptotic agent. Blockade of P53 or NF-κB attenuated cisplatin-induced miR-375 expression, supporting a role of P53 and NF-κB in miR-375 induction. We also identified hepatocyte nuclear factor 1 homeobox B (HNF-1β) as a key downstream target of miR-375. Of note, we further demonstrated that HNF-1β protected renal cells against cisplatin-induced apoptosis. Together, these results suggest that upon cisplatin exposure, P53 and NF-κB collaboratively induce miR-375 expression, which, in turn, represses HNF-1β activity, resulting in renal tubular cell apoptosis and nephrotoxicity.

Potential Role of microRNAs in Cardiovascular Disease: Are They up to Their Hype?

PURPOSE OF REVIEW

Cardiovascular diseases remain the foremost cause of mortality globally. As molecular medicine unravels the alterations in genomic expression and regulation of the underlying atherosclerotic process, it opens new vistas for discovering novel diagnostic biomarkers and therapeutics for limiting the disease process. miRNAs have emerged as powerful regulators of protein translation by regulating gene expression at the post-transcriptional level.

RECENT FINDINGS

Overexpression and under-expression of specific miRNAs are being evaluated as a novel approach to diagnosis and treatment of cardiovascular disease. This review sheds light on the current knowledge of the miRNA evaluated in cardiovascular disease.

CONCLUSION

In this review we summarize the data, including the more recent data, regarding miRNAs in cardiovascular disease and their potential role in future in diagnostic and therapeutic strategies.

Anti-microRNAs as Novel Therapeutic Agents in the Clinical Management of Alzheimer's Disease

Overview- One hundred and ten years since its first description Alzheimer's disease (AD) still retains its prominent status: (i) as the industrialized world's number one cause of age-related intellectual impairment and cognitive decline; (ii) as this country's most rapidly expanding socioeconomic and healthcare concern; and (iii) as an insidious, progressive and lethal neurological disorder of the human central nervous system (CNS) for which there is currently no adequate treatment or cure (Alzheimer, 1991; Alzheimer et al., 1991, 1995) [https://www.alz.org/facts/downloads/facts_figures_2015.pdf (2015)]. The concept of small non-coding RNAs (ncRNAs) as being involved in the etiopathogenesis of AD and age-related human neurodegenerative disease was first proposed about 25 years ago, however it was not until 2007 that specific microRNA (miRNA) abundance, speciation and localization to the hippocampal CA1 region (an anatomical area of the human CNS specifically targeted by the AD process) was shown to strongly associate with AD-type change when compared to age-matched controls (Lukiw et al., 1992; Lukiw, 2007; Schipper et al., 2007; Cogswell et al., 2008; Guerreiro et al., 2012). Currently about 400 reports address the potential link between disruptions in miRNA signaling and the development of various features associated with AD neuropathology (http://www.ncbi.nlm.nih.gov/pubmed/?term=micro+RNA+alzheimer's+disease). In this “Perspectives” paper we will highlight some of the most recent literature on anti-miRNA (AM; antagomir) therapeutic strategies and some very recent technological advances in the analysis and characterization of defective miRNA signaling pathways in AD compared to neurologically normal age-matched controls.