Inhibition of Smurf2 translation by miR-322/503 modulates TGF-β/Smad2 signaling and intestinal epithelial homeostasis

Posttranscriptional Regulation of Intestinal Mucosal Growth and Adaptation by Noncoding RNAs in Critical Surgical Disorders

The human intestinal epithelium has an impressive ability to respond to insults and its homeostasis is maintained by well-regulated mechanisms under various pathophysiological conditions. Nonetheless, acute injury and inhibited regeneration of the intestinal epithelium occur commonly in critically ill surgical patients, leading to the translocation of luminal toxic substances and bacteria to the bloodstream. Effective therapies for the preservation of intestinal epithelial integrity and for the prevention of mucosal hemorrhage and gut barrier dysfunction are limited, primarily because of a poor understanding of the mechanisms underlying mucosal disruption. Noncoding RNAs (ncRNAs), which include microRNAs (miRNAs), long ncRNAs (lncRNAs), circular RNAs (circRNAs), and small vault RNAs (vtRNAs), modulate a wide array of biological functions and have been identified as orchestrators of intestinal epithelial homeostasis. Here, we feature the roles of many important ncRNAs in controlling intestinal mucosal growth, barrier function, and repair after injury-particularly in the context of postoperative recovery from bowel surgery. We review recent literature surrounding the relationships between lncRNAs, microRNAs, and RNA-binding proteins and how their interactions impact cell survival, proliferation, migration, and cell-to-cell interactions in the intestinal epithelium. With advancing knowledge of ncRNA biology and growing recognition of the importance of ncRNAs in maintaining the intestinal epithelial integrity, ncRNAs provide novel therapeutic targets for treatments to preserve the gut epithelium in individuals suffering from critical surgical disorders.

Non-coding RNAs and angiogenesis in cardiovascular diseases: a comprehensive review

Non-coding RNAs (ncRNAs) have key roles in the etiology of many illnesses, including heart failure, myocardial infarction, stroke, and in physiological processes like angiogenesis. In transcriptional regulatory circuits that control heart growth, signaling, and stress response, as well as remodeling in cardiac disease, ncRNAs have become important players. Studies on ncRNAs and cardiovascular disease have made great progress recently. Here, we go through the functions of non-coding RNAs (ncRNAs) like circular RNAs (circRNAs), and microRNAs (miRNAs) as well as long non-coding RNAs (lncRNAs) in modulating cardiovascular disorders.

MicroRNA-322-5p targeting Smurf2 regulates the TGF-β/Smad pathway to protect cardiac function and inhibit myocardial infarction

Acute coronary artery blockage leads to acute myocardial infarction (AMI). Cardiomyocytes are terminally differentiated cells that rarely divide. Treatments preventing cardiomyocyte loss during AMI have a high therapeutic benefit. Accumulating evidence shows that microRNAs (miRNAs) may play an essential role in cardiovascular diseases. This study aims to explore the biological function and underlying regulatory molecular mechanism of miR-322-5p on myocardial infarction (MI). This study's miR-322-5p is downregulated in MI-injured hearts according to integrative bioinformatics and experimental analyses. In the MI rat model, miR-322-5p overexpression partially eliminated MI-induced changes in myocardial enzymes and oxidative stress markers, improved MI-caused impairment on cardiac functions, inhibited myocardial apoptosis, attenuated MI-caused alterations in TGF-β, p-Smad2, p-Smad4, and Smad7 protein levels. In oxygen-glucose deprivation (OGD)-injured H9c2 cells, miR-322-5p overexpression partially rescued OGD-inhibited cell viability and attenuated OGD-caused alterations in the TGF-β/Smad signaling. miR-322-5p directly targeted Smurf2 and inhibited Smurf2 expression. In OGD-injured H9c2 cells, Smurf2 knockdown exerted similar effects to miR-322-5p overexpression upon cell viability and TGF-β/Smad signaling; moreover, Smurf2 knockdown partially attenuated miR-322-5p inhibition effects on OGD-injured H9c2 cells. In conclusion, miR-322-5p is downregulated in MI rat heart and OGD-stimulated rat cardiomyocytes; the miR-322-5p/Smurf2 axis improves OGD-inhibited cardiomyocyte cell viability and MI-induced cardiac injuries and dysfunction through the TGF-β/Smad signaling.

Curcumin promotes renewal of intestinal epithelium by miR-195-3p

ETHNOPHARMACOLOGICAL RELEVANCE

Turmeric (Curcuma longa) has been used to treat gastrointestinal disorders in the Indian Ayurvedic medical system. According to the theory behind traditional Chinese medicine, turmeric can be distributed in the spleen meridian, for which it has been used as a digestive aid. Curcumin (Cur), a natural polyphenol compound originally derived from turmeric, has anti-inflammatory activity and can assist in treating inflammatory bowel disease.

AIMS OF THE STUDY

To investigate curcumin's protective effects on intestinal epithelium and explore the underlying miR-195-3p-related mechanisms.

MATERIALS AND METHODS

The miR-195-3p mimics were used to over-express miR-195-3p. The in vitro effects of Cur and miR-195-3p on the intestine were shown utilizing intestinal cryptlike epithelial cell line-6 (IEC-6) cells. By fasting for 48 h, an intestinal mucosal atrophy model of SD rats was created in vivo. Cur (25 or 50 mg/kg) was assessed for its protective effect on intestinal epithelium. Glycyrrhetinic acid (GA) with an intestinal protective effect reported in our previous research was adopted as a positive drug for the in vivo and in vitro bioactivity evaluation since there is no universally positive drug for either intestinal mucosal restitution or miR-195-3p modulation.

RESULTS

Cur protects the intestinal epithelium and promotes its repair after injury via down-regulating miR-195-3p. In vitro experiments showed that Cur inhibited the apoptosis of IEC-6 cells, stimulated their growth, and down-regulated the level of miR-195-3p in cells. When miR-195-3p was overexpressed, the viability of IEC-6 cells decreased while the apoptosis rate increased. All the above detrimental effects were alleviated after curcumin intervention. Moreover, Cur reversed the effect of miR-195-3p on its downstream occludin. In vivo, results showed that 48-h fasting impaired the integrity of the small intestinal mucosa (abnormal crypt structure and reduced goblet cell number), which was ameliorated by Cur treatment. In addition, the Cur treatment reversed both the increased expression level of miR-195-3p and decreased levels of ki-67 and occludin caused by fasting.

CONCLUSIONS

Cur could promote the proliferation and repair after injury of the intestinal mucosa by down-regulating miR-195-3p.

CREB-binding protein and HIF-1α/β-catenin to upregulate miR-322 and alleviate myocardial ischemia-reperfusion injury

Myocardial ischemia/reperfusion injury (MIRI) is a prevalent condition associated with numerous critical clinical conditions. miR-322 has been implicated in MIRI through poorly understood mechanisms. Our preliminary analysis indicated potential interaction of CREB-binding protein (CBP), a transcriptional coactivator and acetyltransferase, with HIF-1α/β-catenin, which might regulate miR-322 expression. We, therefore, hypothesized that CBP/HIF-1α/β-catenin/miR-322 axis might play a role in MIRI. Rat cardiomyocytes subjected to oxygen-glucose deprivation /reperfusion (OGD/R) and Langendorff perfused heart model were used to model MIRI in vitro and in vivo, respectively. We used various techniques such as CCK-8 assay, transferase dUTP nick end labeling staining, western blotting, RT-qPCR, chromatin immunoprecipitation (ChIP), dual-luciferase assay, co-immunoprecipitation (Co-IP), hematoxylin and eosin staining, and TTC staining to assess cell viability, apoptosis, and the levels of CBP, HIF-1α, β-catenin, miR-322, and acetylation. Our results indicate that OGD/R in cardiomyocytes decreased CBP/HIF-1α/β-catenin/miR-322 expression, increased cell apoptosis and cytokines, and reduced cell viability. However, overexpression of CBP or miR-322 suppressed OGD/R-induced cell injury, while knockdown of HIF-1α/β-catenin further exacerbated the damage. HIF-1α/β-catenin bound to miR-322 promoter to promote its expression, while CBP acetylated HIF-1α/β-catenin for stabilization. Overexpression of CBP attenuated MIRI in rats by acetylating HIF-1α/β-catenin to stabilize their expression, resulting in stronger binding of HIF-1α/β-catenin with the miR-322 promoter and subsequent increased miR-322 levels. Therefore, activating CBP/HIF-1α/β-catenin/miR-322 signaling may be a potential approach to treat MIRI.

MIR503HG: A potential diagnostic and therapeutic target in human diseases

LncRNAs are involved in many physiological and pathological processes, including chromatin remodeling, transcription, posttranscriptional gene expression, mRNA stability, translation, and posttranslational modification, and their functions depend on subcellular localization. MIR503HG is a lncRNA as well as a host gene for the miRNAs miR-503 and miR-424. MIR503HG functions independently or synergistically with miR-503. MIR503HG affects cell proliferation, invasion, metastasis, apoptosis, angiogenesis, and other biological behaviors. The mechanism of MIR503HG in disease includes interaction with protein, sponging miRNA to regulate downstream target gene, and participation in NF-κB, TGF-β, ERK/MAPK, and PI3K/AKT signaling pathways. In this review, we summarize the molecular mechanisms of MIR503HG in disease and its potential applications in diagnosis, prognosis, and treatment. We also raise some unanswered questions in this area, providing insights for future research.

miR-322 promotes the differentiation of embryonic stem cells into cardiomyocytes

Previous studies have shown that miR-322 regulates the functions of various stem cells. However, the role and mechanism of embryonic stem cell (ESCs) differentiation into cardiomyocytes remains unknown. Celf1 plays a vital role in stem cell differentiation and may be a potential target of miR-322 in ESCs' differentiation. We studied the function of miR-322An using mESCs transfected with lentivirus-mediated miR-322. RT-PCR results indicated that miR-322 increased NKX-2.5, MLC2V, and α-MHC mRNA expression, signifying that miR-322 might promote the differentiation of ESCs toward cardiomyocytes in vitro. The western blotting and immunofluorescence results confirmed this conclusion. In addition, the knockdown of miR-322 expression inhibited ESCs' differentiation toward cardiomyocytes in cultured ESCs in vitro. Western blotting results showed that miR-322 suppressed celf1 protein expression. Furthermore, Western blotting, RT-PCR, and immunofluorescence results showed that celf1 may inhibit ESCs' differentiation toward cardiomyocytes in vitro. Overall, the results indicate that miR-322 might promote ESCs' differentiation toward cardiomyocytes by regulating celf1 expression.

Long non-coding RNA SENCR alleviates endothelial-to-mesenchymal transition via targeting miR-126a

INTRODUCTION

Long non-coding RNAs (lncRNAs) constitute a growing class of non-coding genes with diverse cellular function. Recent studies have reported that lncRNA smooth muscle and endothelial cell-enriched (SENCR) was associated with the phenotype switch of vascular smooth muscle cells and participated in vascular homeostasis. However, the potential role of SENCR in endothelial-to-mesenchymal transition (EndMT) and the underlying mechanism remain unknown.

MATERIAL AND METHODS

Human carotid plaque samples and human coronary endothelial cells (HACECs) were collected to examine the expression of SENCR. Quantitative PCR and immunoblots were performed to evaluate the expression of SENCR and miR-126a in HACECs in response to TGF-β1 and transfected with small interfering RNA.

RESULTS

We found that SENCR was significantly decreased in carotid plaques as compared to normal carotids. Knockdown of SENCR in HACECs aggravated the expression of smooth muscle markers α-SMA and calponin induced by TGF-β1 but repressed the expression of endothelial markers platelet/endothelial cell adhesion molecule 1 (PECAM1) and VE-cadherin down-regulated by TGF-β1. Through bioinformatic analysis and Luciferase assay, miR-126a was identified as the direct target of SENCR. Further mechanistic experiments revealed that overexpression of miR-126a bound to the 3'UTR region of SMURF2 and inhibited the expression of SMURF2, which was considered as the negative regulator of TGF-β/Smad signaling. Finally, overexpression of miR-126a did not restore the decreased expression of the smooth muscle markers α-SMA and calponin under the condition of SMURF2 depletion, suggesting that the effect of miR-126a on EndMT progression is SMURF2 dependent.

CONCLUSIONS

SENCR alleviates TGF-β-induced EndMT and sponges miR-126a expression via direct inhibition of the negative regulator of TGF-β/Smad signaling SMURF2.

Upregulated miR-322-5p regulates cell cycle and promotes cell proliferation and apoptosis by directly targeting Wee1 in mice liver injury

Liver injury from any number of causes (e.g. chemical material, drugs and diet, viral infection) is a global health problem, and its mechanism is not clearly understood. MicroRNAs (miRNAs) expression profiling is gaining popularity because miRNAs, as key regulators in gene expression networks, can influence many biological processes and have also shown promise as biomarkers for disease. Previous studies reported the regulation effects of miRNAs in liver injury, whereas function and molecular mechanisms of miR-322-5p were still unclear. Therefore, our study focused on the biological role of miR-322-5p in carbon tetrachloride (CCl4)-induced liver injury proliferation, apoptosis, and cell cycle. A mouse model of CCl4-induced liver injury was established, and the transcriptomes and miRNAs transcriptomes of 2d and 5d liver tissues after injury were sequenced. The expression of miR-322-5p and the cell cycle genes were detected in liver tissues and Hepa1-6 cell line by miRNA RT-PCR, qRT-PCR. The effects of miR-322-5p on liver cell proliferation, cell cycle and apoptosis were evaluated using MTS assays and flow cytometry analysis. The relationship between miR-322-5p and Wee1 was predicted and confirmed by bioinformatics analysis and a dual luciferase reporter assay. Functional experiments, including an MTS assay and flow cytometric analysis, were performed to study the effects of Wee1. MiR-322-5p was upregulated in injury liver tissues, and downregulated miR-322-5p was proved to inhibit proliferation, apoptosis and arrest cell cycle at G2/M in vitro. The dual-luciferase reporter assay results indicated that miR-322-5p has a binding site at position 285 in the Wee1 3´UTR. The effects of miR-322-5p in proliferation and cell cycle regulation can be abolished by Wee1 through rescue experiments. By directly targeting Wee1 influenced the expression of several cell cycle factors, including Cyclin dependent kinase 1 (Cdk1), cyclin B1 (Ccnb1) and Cell division cyclin 25C (Cdc25C). MiR-322-5p may function as a suppressive factor by negatively controlling Wee1, thus, highlighting the potential role of miR-322-5p as a therapeutic target for liver injury.Abbreviations: ALT: Alanine aminotransferase; AST: Aspartate aminotransferase; GSH: Glutathione, γ-glutamyl cysteinel + glycine; CCl4: Carbon tetrachloride; HE: Haematoxylin and eosin; KEGG: Kyoto Encyclopedia of Genes and Genomes.

MicroRNAs involved in the TGF-β signaling pathway in atherosclerosis

Atherosclerosis (AS) is a chronic inflammatory vascular disease with a multifactorial pathogenesis. It becomes a global health concern, especially causing an array of fatal consequences among the elderly. However, the mechanisms of AS remain unexplained. The transforming growth factor-β (TGF-β) signaling pathway is widely involved in the inflammation, immune function, proliferation, differentiation，and apoptosis in vivo. Based on previous researches, it has not been confirmed whether the TGF-β pathway promotes or inhibits atherosclerosis. Furthermore, more and more studies have found that microRNAs can regulate atherosclerosis through the TGF-β signaling pathway. In this review, we summarize and discuss the role of microRNAs in the pathogenesis of atherosclerosis via the TGF-β signaling pathway.

MicroRNA-411-3p inhibits bleomycin-induced skin fibrosis by regulating transforming growth factor-β/Smad ubiquitin regulatory factor-2 signalling

Skin fibrosis, which is characterized by fibroblast proliferation and increased extracellular matrix, has no effective treatment. An increasing number of studies have shown that microRNAs (miRNAs/miRs) participate in the mechanism of skin fibrosis, such as in limited cutaneous systemic sclerosis and pathological scarring. The objective of the present study was to determine the role of miR‐411‐3p in bleomycin (BLM)‐induced skin fibrosis and skin fibroblast transformation. Using Western blot analysis and real‐time quantitative polymerase chain reaction assess the expression levels of miR‐411‐3p, collagen (COLI) and transforming growth factor (TGF)‐β/Smad ubiquitin regulatory factor (Smurf)‐2/Smad signalling factors both in vitro and in vivo with or without BLM. To explore the regulatory relationship between miR‐411‐3p and Smurf2, we used the luciferase reporter assay. Furthermore, miR‐411‐3p overexpression was identified in vitro and in vivo via transfection with Lipofectamine 2000 reagent and injection. Finally, we tested the dermal layer of the skin using haematoxylin and eosin and Van Gieson's staining. We found that miR‐411‐3p expression was decreased in bleomycin (BLM)‐induced skin fibrosis and fibroblasts. However, BLM accelerated transforming growth factor (TGF)‐β signalling and collagen production. Overexpression of miR‐411‐3p inhibited the expression of collagen, F‐actin and the TGF‐β/Smad signalling pathway factors in BLM‐induced skin fibrosis and fibroblasts. In addition, miR‐411‐3p inhibited the target Smad ubiquitin regulatory factor (Smurf)‐2. Furthermore, Smurf2 was silenced, which attenuated the expression of collagen via suppression of the TGF‐β/Smad signalling pathway. We demonstrated that miR‐411‐3p exerts antifibrotic effects by inhibiting the TGF‐β/Smad signalling pathway via targeting of Smurf2 in skin fibrosis.

Surface-Displayed Amuc_1100 From Akkermansia muciniphila on Lactococcus lactis ZHY1 Improves Hepatic Steatosis and Intestinal Health in High-Fat-Fed Zebrafish

Fatty liver and intestinal barrier damage were widespread in most farmed fish, which severely restrict the development of aquaculture. Therefore, there was an urgent need to develop green feed additives to maintain host liver and intestinal health. In this study, a probiotic pili-like protein, Amuc_1100 (AM protein), was anchored to the surface of Lactococcus lactis ZHY1, and the effects of the recombinant bacteria AM-ZHY1 on liver fat accumulation and intestinal health were evaluated. Zebrafish were fed a basal diet, high-fat diet, and high-fat diet with AM-ZHY1 (10⁸ cfu/g) or control bacteria ZHY1 for 4 weeks. Treatment with AM-ZHY1 significantly reduced hepatic steatosis in zebrafish. Quantitative PCR (qPCR) detection showed that the expression of the lipogenesis [peroxisome-proliferator-activated receptors (PPARγ), sterol regulatory element-binding proteins-1c (SREBP-1c), fatty acid synthase (FAS), and acetyl-CoA carboxylase 1 (ACC1)] and lipid transport genes (CD36 and FABP6) in the liver were significantly downregulated (p < 0.05), indicating that AM-ZHY1 could reduce liver fat accumulation by inhibiting lipid synthesis and absorption. Moreover, supplementing AM-ZHY1 to a high-fat diet could significantly reduce serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, indicating that liver injury caused by high-fat diets was improved. The expression of tumor necrosis factor (TNF)-a and interleukin (IL)-6 in the liver decreased significantly (p < 0.05), while IL-1β and IL-10 did not change significantly in the AM-ZHY1 group. Compared to the high-fat diet-fed group, the AM-ZHY1 group, but not the ZHY1 group, significantly increased the expression of intestinal tight junction (TJ) proteins (TJP1a, claudina, claudin7, claudin7b, claudin11a, claudin12, and claudin15a; p < 0.05). Compared to the high-fat diet group, the Proteobacteria and Fusobacteria were significantly reduced and increased in the AM-ZHY1 group, respectively. In conclusion, the recombinant bacteria AM-ZHY1 has the capacity to maintain intestinal health by protecting intestinal integrity and improving intestinal flora structure and improving fatty liver disease by inhibiting lipid synthesis and absorption. This study will lay a foundation for the application of AM protein in improving abnormal fat deposition and restoring the intestinal barrier in fish.

MicroRNA-18a-5p represses scar fibroblast proliferation and extracellular matrix deposition through regulating Smad2 expression

The aim of the present study was to investigate the expression and role of microRNA-18a-5p (miR-18a-5p) during the formation of hypertrophic scar (HS), and to further explore the molecular mechanisms involved. Downregulation of miR-18a-5p in HS tissues and human HS fibroblasts (hHSFs) was detected by reverse transcription-quantitative polymerase chain reaction. The binding sites between miR-18a-5p and the 3'-untranslated region of SMAD family member 2 (Smad2) were predicted by TargetScan and confirmed by dual-luciferase reporter assay. To investigate the role of miR-18a-5p in HS formation, the effects of miR-18a-5p downregulation or upregulation on hHSFs were subsequently determined. Cell proliferation was detected by an MTT assay, while cell apoptosis was measured by flow cytometry. In addition, the protein expression levels of Smad2, Collagen I (Col I) and Col III were examined by western blot assay. The findings indicated that miR-18a-5p downregulation in hHSFs significantly promoted the cell proliferation, decreased cell apoptosis and enhanced the expression levels of Smad2, Col I and Col III protein and mRNA, whereas miR-18a-5p upregulation in hHSFs exerted opposite effects. Notably, the effects of miR-18a-5p upregulation on hHSFs were eliminated by Smad2 upregulation. In conclusion, the data indicated that miR-18a-5p was downregulated during HS formation, and its upregulation repressed scar fibroblast proliferation and extracellular matrix deposition by targeting Smad2. Therefore, miR-18a-5p may serve as a novel therapeutic target for the treatment of HS.

Noncoding RNAs as Promising Diagnostic Biomarkers and Therapeutic Targets in Intestinal Fibrosis of Crohn's Disease: The Path From Bench to Bedside

Fibrosis is a major pathway to organ injury and failure, accounting for more than one-third of deaths worldwide. Intestinal fibrosis causes irreversible and serious clinical complications, such as strictures and obstruction, secondary to a complex pathogenesis. Under the stimulation of profibrotic soluble factors, excessive activation of mesenchymal cells causes extracellular matrix deposition via canonical transforming growth factor-β/Smads signaling or other pathways (eg, epithelial-to-mesenchymal transition and endothelial-to-mesenchymal transition) in intestinal fibrogenesis. In recent studies, the importance of noncoding RNAs (ncRNAs) stands out in fibrotic diseases in that ncRNAs exhibit a remarkable variety of biological functions in modulating the aforementioned fibrogenic responses. In this review, we summarize the role of ncRNAs, including the emerging long ncRNAs and circular RNAs, in intestinal fibrogenesis. Notably, the translational potential of ncRNAs as diagnostic biomarkers and therapeutic targets in the management of intestinal fibrosis is discussed based on clinical trials from fibrotic diseases in other organs. The main points of this review include the following: • Characteristics of ncRNAs and mechanisms of intestinal fibrogenesis • Wide participation of ncRNAs (especially the emerging long ncRNAs and circular RNAs) in intestinal fibrosis, including transforming growth factor-β signaling, epithelial-to-mesenchymal transition/endothelial-to-mesenchymal transition, and extracellular matrix remodeling • Translational potential of ncRNAs in the diagnosis and treatment of intestinal fibrosis based on clinical trials from fibrotic diseases in other organs.

Extracellular-vesicle containing miRNA-503-5p released by macrophages contributes to atherosclerosis

Endothelial dysfunction, and the differentiation of smooth muscle cells (SMCs) into proliferative, secretory phenotypes, are two major pathophysiological processes in atherosclerosis. SMCs have the potential to recruit macrophages in atherosclerotic plaques, in which macrophages drive inflammatory responses. In this study, we found that microRNA-503-5p (miR-503-5p) was enriched in either extracellular vesicles (EVs), secreted by oxidized low-density lipoprotein-treated macrophages, or the EVs from peripheral blood mononuclear cells of atherosclerosis patients. miR-503-5p was transferred intercellularly from macrophages to the co-cultured human coronary artery endothelial cells (HCAECs) and HCASMCs via EVs, thus reducing the proliferative and angiogenic abilities of HCAECs and accelerating the proliferative and migrating abilities of HCASMCs. Smad family members 1, 2 and 7 were negatively regulated by miR-503-5p in HCAECs and HCASMCs. miR-503-5p was verified as an enhancer of inflammatory cytokines and adhesion molecules released by macrophages, in part via the down-regulation of smad family members 1, 2 and 7. The inhibition of miR-503-5p by lentivirus reduced atherosclerotic lesion formations in the aorta of atherosclerotic mice. Our work demonstrated a miR-503-5p- and EV-mediated mechanism for macrophage communication with HCAECs and HCASMCs in atherosclerosis. miR-503-5p is pro-atherosclerotic stimuli that may be a therapeutic target for atherosclerosis treatment.

The RNA-binding protein HuR regulates intestinal epithelial restitution by modulating Caveolin-1 gene expression

The integrity of the intestinal mucosal barrier protects hosts against pathological conditions. Early mucosal restitution after wounding refers to epithelial cell migration into a defect. The RNA-binding protein HuR plays an important role in the posttranscriptional regulation of gene expression and is involved in many aspects of cellular physiology. In the present study, we investigated the role of HuR in the regulation of cell migration through the posttranscriptional regulation of Caveolin-1 (Cav-1). Online software was used to identify Cav-1 mRNA as a potential target of HuR. The interaction of HuR with Cav-1 mRNA was investigated via ribonucleoprotein immunoprecipitation (RNP IP) assays and biotin pulldown analysis. HuR was found to bind specifically to the Cav-1 3'-UTR rather than the coding region or 5'-UTR. Transfection of cells with siHuR decreased both HuR protein levels and Cav-1 protein levels; conversely, ectopic overexpression of HuR via infection of cells with an adenoviral vector containing HuR cDNA (AdHuR) increased Cav-1 protein levels without disturbing Cav-1 mRNA levels. Thus, HuR enhanced Cav-1 expression in vitro by stimulating Cav-1 translation. Intestinal epithelium-specific HuR knockout in mice decreased Cav-1 protein levels without changing Cav-1 mRNA levels, consistent with the in vitro results. Decreasing the levels of HuR via siHuR transfection inhibited early epithelial repair, but this effect was reversed by ectopic overexpression of GFP-tagged Cav-1. These results indicate that posttranscriptional regulation of Cav-1 gene expression by HuR plays a critical role in the regulation of rapid epithelial repair after wounding.

SMAD-specific E3 ubiquitin ligase 2 promotes angiogenesis by facilitating PTX3 degradation in MSCs from patients with ankylosing spondylitis

Dysregulated angiogenesis of mesenchymal stem cells (MSCs) is closely related to inflammation and disrupted bone metabolism in patients with various autoimmune diseases. However, the role of MSCs in the development of abnormal angiogenesis in patients with ankylosing spondylitis (AS) remains unclear. In this study, we cultured human umbilical vein endothelial cells (HUVECs) with bone marrow-derived MSCs from patients with AS (ASMSCs) or healthy donors (HDMSCs) in vitro. Then, the cocultured HUVECs were assayed using a cell counting kit-8 (CCK-8) to evaluate the cell proliferation. A wound healing assay was performed to investigate cell migration, and a tube formation assay was conducted to determine the angiogenesis efficiency. ASMSCs exhibited increased angiogenesis, and increased expression of SMAD-specific E3 ubiquitin ligase 2 (Smurf2) in MSCs was the main cause of abnormal angiogenesis in patients with AS. Downregulation of Smurf2 in ASMSCs blocked angiogenesis, whereas overexpression of Smurf2 in HDMSCs promoted angiogenesis. The pro-angiogenic effect of Smurf2 was confirmed by the results of a Matrigel plug assay in vivo. By functioning as an E3 ubiquitin ligase in MSCs, Smurf2 regulated the levels of pentraxin 3 (PTX3), which has been shown to suppress angiogenesis through the PTX3-fibroblast growth factor 2 pathway. Moreover, Smurf2 transcription was regulated by activating transcription factor 4-induced endoplasmic reticulum stress. In conclusion, these results identify novel roles of Smurf2 in negatively regulating PTX3 stability and promoting angiogenesis in ASMSCs.

Long noncoding RNA SMUL suppresses SMURF2 production-mediated muscle atrophy via nonsense-mediated mRNA decay

As the world population grows, muscle atrophy leading to muscle wasting could become a bigger risk. Long noncoding RNAs (lncRNAs) are known to play important roles in muscle growth and muscle atrophy. Meanwhile, it has recently come to light that many putative small open reading frames (sORFs) are hidden in lncRNAs; however, their translational capabilities and functions remain unclear. In this study, we uncovered 104 myogenic-associated lncRNAs translated, in at least a small peptide, by integrated transcriptome and proteomic analyses. Furthermore, an upstream ORF (uORF) regulatory network was constructed, and a novel muscle atrophy-associated lncRNA named SMUL (Smad ubiquitin regulatory factor 2 [SMURF2] upstream lncRNA) was identified. SMUL was highly expressed in skeletal muscle, and its expression level was downregulated during myoblast differentiation. SMUL promoted myoblast proliferation and suppressed differentiation in vitro. In vivo, SMUL induced skeletal muscle atrophy and promoted a switch from slow-twitch to fast-twitch fibers. In the meantime, translation of the SMUL sORF disrupted the stability of SMURF2 mRNA. Mechanistically, SMUL restrained SMURF2 production via nonsense-mediated mRNA decay (NMD), participating in the regulation of the transforming growth factor β (TGF-β)/SMAD pathway and further regulating myogenesis and muscle atrophy. Taken together, these results suggest that SMUL could be a novel therapeutic target for muscle atrophy.

miR-19b targets pulmonary endothelial syndecan-1 following hemorrhagic shock

Hemorrhagic shock results in systemic injury to the endothelium contributing to post-shock morbidity and mortality. The mechanism involves syndecan-1, the backbone of the endothelial glycocalyx. We have shown in a rodent model that lung syndecan-1 mRNA is reduced following hemorrhage, whereas the molecular mechanism underlying the mRNA reduction is not clear. In this study, we present evidence that miR-19b targets syndecan-1 mRNA to downregulate its expression. Our results demonstrate that miR-19b was increased in hemorrhagic shock patients and in-vitro specifically bound to syndecan-1 mRNA and caused its degradation. Further, hypoxia/reoxygenation (H/R), our in vitro hemorrhage model, increased miR-19b expression in human lung microvascular endothelial cells, leading to a decrease in syndecan-1 mRNA and protein. H/R insult and miR-19b mimic overexpression comparably exaggerated permeability and enhanced endothelial barrier breakdown. The detrimental role of miR-19b in inducing endothelial dysfunction was confirmed in vivo. Lungs from mice undergoing hemorrhagic shock exhibited a significant increase in miR-19b and a concomitant decrease in syndecan-1 mRNA. Pretreatment with miR-19b oligo inhibitor significantly decreased lung injury, inflammation, and permeability and improved hemodynamics. These findings suggest that inhibition of miR-19b may be a putative therapeutic avenue for mitigating post shock pulmonary endothelial dysfunction in hemorrhage shock.

HDAC3 Silencing Enhances Acute B Lymphoblastic Leukaemia Cells Sensitivity to MG-132 by Inhibiting the JAK/Signal Transducer and Activator of Transcription 3 Signaling Pathway

PURPOSE

HDAC3, which is associated with smurf2, has been shown to be associated with poor prognosis in B-ALL. This study examined the efficacy of targeting HDAC3 combined with MG-132 as a possible therapeutic strategy for B-ALL patients.

METHODS

Real-time PCR and western blot were used to measure the expression of smurf2 and HDAC3 from B-ALL patients bone marrow samples. Sup-B15 and CCRF-SB cells were treated with MG-132, small interfering RNA of smurf2 or HDAC3. A plasmid designed to up-regulate smurf2 expression was transfected into B-ALL cells. Flow cytometry and western blot were used to measure variation due to these treatments in terms of apoptosis and cell cycle arrest.

RESULTS

Expression of Smurf2 and HDAC3 mRNA were inversely related in B-ALL patients. Up-regulation of smurf2 or MG-132 influenced HDAC3, further inhibiting the JAK/signal transducer and activator of transcription 3 (STAT3) signal pathway and inducing apoptosis in B-ALL cells. When we treated Sup-B15 and CCRF-SB cells with siHDAC3 and MG-132 for 24 h, silencing HDAC3 enhanced the apoptosis rate induced by MG-132 in B-ALL cells and further inhibited the JAK/STAT3 pathway. Furthermore, MG-132 was observed to cause G2/M phase arrest in B-ALL cells and inhibited the JAK/STAT3 pathway, leading to apoptosis.

CONCLUSIONS

Silencing of HDAC3 enhanced the sensitivity of B-ALL cells to MG-132. The combination of targeting HDAC3 and MG-132 may provide a new avenue for clinical treatment of acute B lymphocytic leukaemia and improve the poor survival of leukaemia patients.

MicroRNA-674-5p induced by HIF-1α targets XBP-1 in intestinal epithelial cell injury during endotoxemia

Intestinal mucosal integrity dysfunction during endotoxemia can contribute to translocation of intestinal bacteria and a persistent systemic inflammatory response, which both fuel the pathophysiological development of sepsis or endotoxemia. The pathogenesis of intestinal damage induced by endotoxemia remains poorly understood. Here, we identified the microRNA (miR)-674-5p/X-box binding protein 1 (XBP-1) axis as a critical regulator and therapeutic target in preventing intestinal crypt cell proliferation during endotoxemia. MiR-674-5p was markedly increased in intestinal epithelial cells (IECs) during endotoxemia and its induction depended on hypoxia-inducible factor-1α (HIF-1α). Intriguingly, gene expression microanalysis revealed that expression of XBP-1 was down-regulated in IECs with over-expression of miR-674-5p. miR-674-5p was found to directly target XBP-1 protein expression. Upon in vitro, anti-miR-674-5p enhanced sXBP-1 expression and facilitated intestinal crypt cell proliferation. Blockade of miR-674-5p promoted XBP-1 activity, attenuated intestinal inflammation, and expedited intestinal regeneration, resulting in protection against endotoxemia-induced intestinal injury in mice. More importantly, the survival in endotoxemia mice was significantly improved by inhibiting intestinal miR-674-5p. Collectively, these data indicate that control of a novel miR-674-5p/XBP-1 signaling axis may mitigate endotoxemia -induced intestinal injury.

MiR-411-3p alleviates Silica-induced pulmonary fibrosis by regulating Smurf2/TGF-β signaling

Occupational exposure to silica dust particles was the major cause of pulmonary fibrosis, and many miRNAs have been demonstrated to regulate target mRNAs in silicosis. In the present study, we found that a decreasing level of miR-411-3p in silicosis rats and lung fibroblasts induced by TGF-β1. Enlargement of miR-411-3p could inhibit the cell proliferation and migration in lung fibroblasts with TGF-β1 treatment and attenuate lung fibrosis in silicotic mice. In addition, a mechanistic study showed that miR-411-3p exert its inhibitory effect on Smad ubiquitination regulatory factor 2 (Smurf2) expression and decrease ubiquitination degradation of Smad7 regulated by smurf2, result in blocking of TGF-β/Smad signaling. We proposed that increased expression of miR-411-3p abrogates silicosis by blocking activation of TGF-β/Smad signaling through decreasing ubiquitination degradation effect of smurf2 on Smad7.

Potential microRNA-related targets in clearance pathways of amyloid-β: novel therapeutic approach for the treatment of Alzheimer's disease

Imbalance between amyloid-beta (Aβ) peptide synthesis and clearance results in Aβ deregulation. Failure to clear these peptides appears to cause the development of Alzheimer's disease (AD). In recent years, microRNAs have become established key regulators of biological processes that relate among others to the development and progression of neurodegenerative diseases, such as AD. This review article gives an overview on microRNAs that are involved in the Aβ cascade and discusses their inhibitory impact on their target mRNAs whose products participate in Aβ clearance. Understanding of the mechanism of microRNA in the associated signal pathways could identify novel therapeutic targets for the treatment of AD.

MiR-195 and miR-497 suppress tumorigenesis in lung cancer by inhibiting SMURF2-induced TGF-β receptor I ubiquitination

SMURF2 is a member of the HECT family of E3 ubiquitin ligases that have important roles as a negative regulator of transforming growth factor‐β (TGF‐β) signaling through ubiquitin‐mediated degradation of TGF‐β receptor I. However, the regulatory mechanism of SMURF2 is largely unknown. In this study, we identified that micro(mi)R‐195 and miR‐497 putatively target SMURF2 using several target prediction databases. Both miR‐195 and miR‐497 bind to the 3′‐UTR of the SMURF2 mRNA and inhibit SMURF2 expression. Furthermore, miR‐195 and miR‐497 regulate SMURF2‐dependent TβRI ubiquitination and cause the activation of the TGF‐β signaling pathway in lung cancer cells. Upregulation of miR‐195 and miR‐497 significantly reduced cell viability and colony formation through the activation of TGF‐β signaling. Interestingly, miR‐195 and miR‐497 also reduced the invasion ability of lung cancer cells when cells were treated with TGF‐β1. Subsequent in vivo studies in xenograft nude mice model revealed that miR‐195 and miR‐497 repress tumor growth. These findings demonstrate that miR‐195 and miR‐497 act as a tumor suppressor by suppressing ubiquitination‐mediated degradation of TGF‐β receptors through SMURF2, and suggest that miR‐195 and miR‐497 are potential therapeutic targets for lung cancer.

H19X-encoded miR-424(322)/-503 cluster: emerging roles in cell differentiation, proliferation, plasticity and metabolism

miR-424(322)/-503 are mammal-specific members of the extended miR-15/107 microRNA family. They form a co-expression network with the imprinted lncRNA H19 in tetrapods. miR-424(322)/-503 regulate fundamental cellular processes including cell cycle, epithelial-to-mesenchymal transition, hypoxia and other stress response. They control tissue differentiation (cardiomyocyte, skeletal muscle, monocyte) and remodeling (mammary gland involution), and paradoxically participate in tumor initiation and progression. Expression of miR-424(322)/-503 is governed by unique mechanisms involving sex hormones. Here, we summarize current literature and provide a primer for future endeavors.

Inhibition of Smurf2 translation by miR-322/503 protects from ischemia-reperfusion injury by modulating EZH2/Akt/GSK3β signaling

Myocardial ischemia-reperfusion (I/R) is a common and lethal disease that threatens people's life worldwide. The underlying mechanisms are under intensive study and yet remain unclear. Here, we explored the function of miR-322/503 in myocardial I/R injury. We used isolated rat perfused heart as an in vivo model and H9c2 cells subjected with the oxygen and glucose deprivation followed by reperfusion as in vitro model to study myocardial I/R injury. 2,3,5-Triphenyltetrazolium chloride (TTC) staining was used to measure the infarct size, and terminal deoxynucleotidyl transferase dUTP-mediated nick-end label (TUNEL) staining was used to examine apoptosis. Quantitative RT-PCR and Western blot were used to determine expression levels of miR-322/503, Smad ubiquitin regulatory factor 2 (Smurf2), enhancer of zeste homolog 2 (EZH2), p-Akt, and p-GSK3β. Overexpression of miR-322/503 decreased infarct size, inhibited cell apoptosis, and promoted cell proliferation through upregualtion of p-Akt and p-GSK3β. Thus the expression of miR-322/503 was reduced during I/R process. On the molecular level, miR-322/503 directly bound Smurf2 mRNA and suppressed its translation. Smurf2 ubiquitinated EZH2 and degraded EZH2, which could activate Akt/GSK3β signaling. Our study demonstrates that miR-322/503 plays a beneficial role in myocardial I/R injury. By inhibition of Smurf2 translation, miR-322/503 induces EZH2 expression and activates Akt/GSK3β pathway, thereby protecting cells from ischemia reperfusion injury.

miR-222 represses expression of zipcode binding protein-1 and phospholipase C-γ1 in intestinal epithelial cells

Both zipcode binding protein-1 (ZBP1) and phospholipase C-γ1 (PLCγ1) are intimately involved in many aspects of early intestinal mucosal repair after acute injury, but the exact mechanisms that control their cellular abundances remain largely unknown. The present study shows that microRNA-222 (miR-222) interacts with the mRNAs encoding ZBP1 and PLCγ1 and regulates ZBP1 and PLCγ1 expression in intestinal epithelial cells (IECs). The biotinylated miR-222 bound specifically to the ZBP1 and PLCγ1 mRNAs in IECs. Ectopically expressed miR-222 precursor destabilized the ZBP1 and PLCγ1 mRNAs and consequently lowered the levels of cellular ZBP1 and PLCγ1 proteins. Conversely, decreasing the levels of cellular miR-222 by transfection with its antagonism increased the stability of the ZBP1 and PLCγ1 mRNAs and increased the levels of ZBP1 and PLCγ1 proteins. Overexpression of miR-222 also inhibited cell migration over the wounded area, which was partially abolished by overexpressing ZBP1 and PLCγ1. Furthermore, prevention of the increased levels of ZBP1 and PLCγ1 in the miR-222-silenced cells by transfection with specific small interfering RNAs targeting ZBP1 or PLCγ1 mRNA inhibited cell migration after wounding. These findings indicate that induced miR-222 represses expression of ZBP1 and PLCγ1 at the posttranscriptional level, thus inhibiting IEC migration during intestinal epithelial restitution after wounding.

Notoginsenoside R1 Protects Against Diabetic Cardiomyopathy Through Activating Estrogen Receptor α and Its Downstream Signaling

Diabetic cardiomyopathy (DCM) leads to heart failure and death in diabetic patients, no effective treatment is available. Notoginsenoside R1 (NGR1) is a novel saponin that is derived from Panax notoginseng and our previous studies have showed cardioprotective and neuroprotective effects of NGR1. However, its role in protecting against DCM remains unexplored. Herein, we examine potential effects of NGR1 on cardiac function of diabetic db/db mice and H9c2 cardiomyocytes treated by advanced glycation end products (AGEs). In vitro experiments revealed that pretreatment with NGR1 significantly decreased AGEs-induced mitochondria injury, limited an increase in ROS, and reduced apoptosis in H9c2 cells. NGR1 eliminated ROS by promoting estrogen receptor α expression, which subsequently activated Akt and Nrf2-mediated anti-oxidant enzymes. In vivo investigation demonstrated that NGR1 significantly reduced serum lipid levels, insulin resistance, the expression of enzymes related to cardiomyopathy, and the expression of apoptotic proteins. Finally, NGR1 improved cardiac dysfunction and attenuated histological abnormalities, as evidenced by elevating ejection fraction and fractional shortening, and reducing cardiac fibrosis. Mechanistically, NGR1 promoted ERα expression, which led to the activation of Akt-Nrf2 signaling and the inhibition of the TGFβ pathway. Collectively, these results strongly indicate that NGR1 exerts cardioprotective effects against DCM through its inhibition of oxidative stress and apoptosis, and eventually suppresses cardiac fibrosis and hypertrophy, which suggests that NGR1 is a potential therapeutic medicine for the treatment of DCM.

USF2 inhibits the transcriptional activity of Smurf1 and Smurf2 to promote breast cancer tumorigenesis

Smurf1 (Smad ubiquitylation regulatory factor 1) and Smurf2 are negative regulators of the TGF-β (transforming growth factor-β) pathway. The protein stability and ubiquitin E3 activity regulation of Smurfs have been well studied. However, the mechanism of Smurfs expression at the transcriptional level remains uncharacterized. Here, we reported that USF2 (upstream stimulatory factor 2), a basic helix-loop-helix-leucine-zip transcription factor, is necessary for the transcriptional activity of Smurf1 and Smurf2. The 5'-flanking sequences of the Smurfs gene have more than one E-box motifs, and USF2 bounds the Smurfs promoter in vitro and in vivo. Over-expression USF2 inhibited the transcriptional activity of the Smurfs, and Smurfs mRNA was markedly decreased. Therefore, the activity of TGF-β was distinctly enhanced. Furthermore, in human breast cancers, USF2 was abnormally high expressed and correlated with cancer progression. USF2 was specifically inversely correlated with Smurfs in Luminal A subtype breast cancer patients. These findings suggest the mechanism regulation of Smurfs transcriptional activity, and shed new light on the cancer-promoting role of USF2.

Regulation of Intestinal Epithelial Barrier Function by Long Noncoding RNA uc.173 through Interaction with MicroRNA 29b

The mammalian intestinal epithelium establishes a selectively permeable barrier that supports nutrient absorption and prevents intrusion by noxious luminal substances and microbiota. The effectiveness and integrity of the barrier function are tightly regulated via well-controlled mechanisms. Long noncoding RNAs transcribed from ultraconserved regions (T-UCRs) control diverse cellular processes, but their roles in the regulation of gut permeability remain largely unknown. Here we report that the T-UCR uc.173 enhances intestinal epithelial barrier function by antagonizing microRNA 29b (miR-29b). Decreasing the levels of uc.173 by gene silencing led to dysfunction of the intestinal epithelial barrier in cultured cells and increased the vulnerability of the gut barrier to septic stress in mice. uc.173 specifically stimulated translation of the tight junction (TJ) claudin-1 (CLDN1) by associating with miR-29b rather than by binding directly to CLDN1 mRNA. uc.173 acted as a natural decoy RNA for miR-29b, which interacts with CLDN1 mRNA via the 3' untranslated region and represses its translation. Ectopically expressed uc.173 abolished the association of miR-29b with CLDN1 mRNA and restored claudin-1 expression to normal levels in cells overexpressing miR-29b, thus rescuing the barrier function. These results highlight a novel function of uc.173 in controlling gut permeability and define a mechanism by which uc.173 stimulates claudin-1 translation, by decreasing the availability of miR-29b to CLDN1 mRNA.

α4 Coordinates Small Intestinal Epithelium Homeostasis by Regulating Stability of HuR

The mammalian intestinal epithelium is a rapidly self-renewing tissue in the body, and its homeostasis depends on a dynamic balance among proliferation, migration, apoptosis, and differentiation of intestinal epithelial cells (IECs). The protein phosphatase 2A (PP2A)-associated protein α4 controls the activity and specificity of serine/threonine phosphatases and is thus implicated in many cellular processes. Here, using a genetic approach, we investigated the mechanisms whereby α4 controls the homeostasis of the intestinal epithelium. In mice with ablated α4, the small intestinal mucosa exhibited crypt hyperplasia, villus shrinkage, defective differentiation of Paneth cells, and reduced IEC migration along the crypt-villus axis. The α4-deficient intestinal epithelium also displayed decreased expression of different intercellular junction proteins and abnormal epithelial permeability. In addition, α4 deficiency decreased the levels of the RNA-binding protein HuR in the mucosal tissue. In cultured IECs, ectopic overexpression of HuR in α4-deficient cells rescued the production of these intercellular junction proteins and restored the epithelial barrier function to a nearly normal level. Mechanistically, α4 silencing destabilized HuR through a process involving HuR phosphorylation by IκB kinase α, leading to ubiquitin-mediated proteolysis of HuR. These findings indicate that the critical impact of α4 upon the barrier function and homeostasis of the intestinal epithelium depends largely on its ability to regulate the stability of HuR.

The Long Non-Coding RNA MIR503HG Enhances Proliferation of Human ALK-Negative Anaplastic Large-Cell Lymphoma

Anaplastic lymphoma kinase (ALK)-negative anaplastic large-cell lymphoma (ALCL) is a rare type of highly malignant, non-Hodgkin lymphoma. Currently, only a few gene rearrangements have been linked to ALK-negative ALCL progression. However, the specific molecular mechanisms underlying the growth of ALK-negative ALCL tumors remain unclear. Here, we investigated aberrantly expressed, long non-coding RNAs (lncRNAs) in ALK-negative ALCL and assessed their potential biological function. MIR503HG (miR-503 host gene) was highly expressed in ALK-negative cell lines and was significantly upregulated in tumors in mice formed from ALK-negative ALCL cell lines. Depletion of MIR503HG suppressed tumor cell proliferation in vivo and in vitro; conversely, its overexpression enhanced tumor cell growth. MIR503HG-induced proliferation was mediated by the induction of microRNA-503 (miR-503) and suppression of Smurf2, resulting in stabilization of the tumor growth factor-β receptor (TGFBR) and enhanced tumor cell growth. Collectively, these findings support a potential role for MIR503HG in cancer cell proliferation through the miR-503/Smurf2/TGFBR axis and indicate that MIR503HG is a potential marker in ALK-negative ALCL.

MicroRNA-26a inhibits hyperplastic scar formation by targeting Smad2

Hypertrophic scar (HS) is a fibrotic disease in which excessive extracellular matrix forms due to the response of fibroblasts to tissue damage. Novel evidence suggests that microRNAs (miRNAs or miRs) may contribute to hypertrophic scarring; however, the role of miRNAs in HS formation remains unclear. In the present study, miR-26a was significantly downregulated in HS tissues and human HS fibroblasts (hHSFs) was detected by reverse transcription-quantitative analysis. TargetScan was used to predict that mothers against decapentaplegic homolog 2 (Smad2) is a potential target gene of miR-26a and a dual-luciferase reporter assay confirmed that Smad2 was a target gene of miR-26a. The expression of Smad2 was upregulated in HS tissues and hHSFs. Cell Counting Kit-8 and flow cytometry analyses demonstrated that the overexpression of miR-26a significantly suppressed the proliferation ability of hHSFs and the apoptotic rate of hHSFs was significantly upregulated in response to miR-26a mimic transfection. Furthermore, the expression of B-cell lymphoma-2 (Bcl-2)-associated X protein was increased and Bcl-2 expression was decreased following miR-26a mimic transfection. The expression of collagens I and III was significantly inhibited following treatment with miR-26a mimics in hHSF cells. Conversely, miR-26a inhibitors served an opposing role in hHSFs. Furthermore, Smad2 overexpression enhanced the expression of collagens I and c III; however, Smad2 silencing inhibited the expression of collagens I and c III. In conclusion, the results of the present study indicate that miR-26a inhibits HS formation by modulating proliferation and apoptosis ad well as inhibiting the expression of extracellular matrix-associated proteins by targeting Smad2.

MicroRNA regulatory networks reflective of polyhexamethylene guanidine phosphate-induced fibrosis in A549 human alveolar adenocarcinoma cells

Polyhexamethylene guanidine phosphate (PHMG-phosphate), an active component of humidifier disinfectant, is suspected to be a major cause of pulmonary fibrosis. Fibrosis, induced by recurrent epithelial damage, is significantly affected by epigenetic regulation, including microRNAs (miRNAs). The aim of this study was to investigate the fibrogenic mechanisms of PHMG-phosphate through the profiling of miRNAs and their target genes. A549 cells were treated with 0.75 μg/mL PHMG-phosphate for 24 and 48 h and miRNA microarray expression analysis was conducted. The putative mRNA targets of the miRNAs were identified and subjected to Gene Ontology analysis. After exposure to PHMG-phosphate for 24 and 48 h, 46 and 33 miRNAs, respectively, showed a significant change in expression over 1.5-fold compared with the control. The integrated analysis of miRNA and mRNA microarray results revealed the putative targets that were prominently enriched were associated with the epithelial-mesenchymal transition (EMT), cell cycle changes, and apoptosis. The dose-dependent induction of EMT by PHMG-phosphate exposure was confirmed by western blot. We identified 13 putative EMT-related targets that may play a role in PHMG-phosphate-induced fibrosis according to the Comparative Toxicogenomic Database. Our findings contribute to the comprehension of the fibrogenic mechanism of PHMG-phosphate and will aid further study on PHMG-phosphate-induced toxicity.

Cooperative Repression of Insulin-Like Growth Factor Type 2 Receptor Translation by MicroRNA 195 and RNA-Binding Protein CUGBP1

Insulin-like growth factor type 2 (IGF2) receptor (IGF2R) recognizes mannose 6-phosphate-containing molecules and IGF2 and plays an important role in many pathophysiological processes, including gut mucosal adaptation. However, the mechanisms that control cellular IGF2R abundance are poorly known. MicroRNAs (miRNAs) and RNA-binding proteins (RBPs) critically regulate gene expression programs in mammalian cells by modulating the stability and translation of target mRNAs. Here we report that miRNA 195 (miR-195) and RBP CUG-binding protein 1 (CUGBP1) jointly regulate IGF2R expression at the posttranscriptional level in intestinal epithelial cells. Both miR-195 and CUGBP1 interacted with the 3' untranslated region (3'-UTR) of Igf2r mRNA, and the association of CUGBP1 with Igf2r mRNA enhanced miR-195 binding to Igf2r mRNA. Ectopically expressed CUGBP1 and miR-195 repressed IGF2R translation cooperatively without altering the stability of Igf2r mRNA. Importantly, the miR-195- and CUGBP1-repressed levels of cellular IGF2R led to a disruption in the structure of the trans-Golgi network. These findings indicate that IGF2R expression is controlled posttranscriptionally by two factors that associate with Igf2r mRNA and suggest that miR-195 and CUGBP1 dampen IGF signaling by inhibiting IGF2R translation.

MicroRNA-322 attenuates aluminum maltolate-induced apoptosis in the human SH-SY5Y neuroblastoma cell line

Aluminum-maltolate (Al‑Malt) is a potent apoptosis inductor, which has been widely reported as an etiologic factor in Alzheimer's disease (AD). MicroRNA-322 (miR‑322) is a vital regulator in various biological processes. The aim of the current study was to identify the role and possible underlying mechanism of miR‑322 in Al‑Malt‑induced apoptosis. Eight concentrations of Al‑Malt were prepared and used for treating the human neuroblastoma cell line, SH‑SY5Y. Subsequent to treatment with Al‑Malt for 3 days, cell viability, apoptosis and the expression levels of apoptosis‑associated factors were measured. In addition, the mRNA expression level of miR‑322 was monitored. Furthermore, cells were transfected with an miR‑322 mimic and/or treated with Al‑Malt, and cell viability, apoptosis and the expression levels of apoptosis‑associated factors were measured again. Al‑Malt significantly inhibited cell viability, but promoted apoptosis. The apoptosis‑associated factors, V‑Myc avian myelocytomatosis viral oncogene homolog (c‑Myc), Bcl-2-associated X protein, caspase‑3 and cleaved caspase‑3 were markedly upregulated by Al‑Malt. The mRNA expression level of miR‑322 was negatively regulated by Al‑Malt. Furthermore, miR‑322 attenuated the apoptosis induced by Al‑Malt and recovered the expression changes of these four factors. Thus, miR‑322 may attenuate Al‑Malt‑induced apoptosis by recovering the expression change of c‑Myc. Furthermore, miR‑322 may be involved in the pathogenesis of Al‑Malt‑associated AD.

HuR Enhances Early Restitution of the Intestinal Epithelium by Increasing Cdc42 Translation

The mammalian intestinal mucosa exhibits a spectrum of responses after acute injury and repairs itself rapidly to restore the epithelial integrity. The RNA-binding protein HuR regulates the stability and translation of target mRNAs and is involved in many aspects of gut epithelium homeostasis, but its exact role in the regulation of mucosal repair after injury remains unknown. We show here that HuR is essential for early intestinal epithelial restitution by increasing the expression of cell division control protein 42 (Cdc42) at the posttranscriptional level. HuR bound to the Cdc42 mRNA via its 3' untranslated region, and this association specifically enhanced Cdc42 translation without an effect on the Cdc42 mRNA level. Intestinal epithelium-specific HuR knockout not only decreased Cdc42 levels in mucosal tissues, but it also inhibited repair of damaged mucosa induced by mesenteric ischemia/reperfusion in the small intestine and by dextran sulfate sodium in the colon. Furthermore, Cdc42 silencing prevented HuR-mediated stimulation of cell migration over the wounded area by altering the subcellular distribution of F-actin. These results indicate that HuR promotes early intestinal mucosal repair after injury by increasing Cdc42 translation and demonstrate the importance of HuR deficiency in the pathogenesis of delayed mucosal healing in certain pathological conditions.

Transcriptional regulation of importin-α1 by JunD modulates subcellular localization of RNA-binding protein HuR in intestinal epithelial cells

The RNA-binding protein HuR is crucial for normal intestinal mucosal regeneration by modulating the stability and translation of target mRNAs, but the exact mechanism underlying HuR trafficking between the cytoplasm and nucleus remains largely unknown. Here we report a novel function of transcription factor JunD in the regulation of HuR subcellular localization through the control of importin-α₁ expression in intestinal epithelial cells (IECs). Ectopically expressed JunD specifically inhibited importin-α₁ at the transcription level, and this repression is mediated via interaction with CREB-binding site that was located at the proximal region of importin-α₁ promoter. Reduction in the levels of importin-α₁ by JunD increased cytoplasmic levels of HuR, although it failed to alter whole cell HuR levels. Increased levels of endogenous JunD by depleting cellular polyamines also inhibited importin-α₁ expression and increased cytoplasmic HuR levels, whereas JunD silencing rescued importin-α₁ expression and enhanced HuR nuclear translocation in polyamine-deficient cells. Moreover, importin-α₁ silencing protected IECs against apoptosis, which was prevented by HuR silencing. These results indicate that JunD regulates HuR subcellular distribution by downregulating importin-α₁, thus contributing to the maintenance of gut epithelium homeostasis.

Posttranscriptional regulation of intestinal epithelial integrity by noncoding RNAs

Maintenance of the gut epithelial integrity under stressful environments requires epithelial cells to rapidly elicit changes in gene expression patterns to regulate their survival, adapt to stress, and keep epithelial homeostasis. Disruption of the intestinal epithelial integrity occurs commonly in patients with various critical illnesses, leading to the translocation of luminal toxic substances and bacteria to the blood stream. Recently, noncoding RNAs (ncRNAs) have emerged as a novel class of master regulators of gene expression and are fundamentally involved in many aspects of gut mucosal regeneration, protection, and epithelial barrier function. Here, we highlight the roles of several intestinal epithelial tissue-specific microRNAs, including miR-222, miR-29b, miR-503, and miR-195, and long ncRNAs such as H19 and SPRY4-IT1 in the regulation of cell proliferation, apoptosis, migration, and cell-to-cell interactions and also further analyze the mechanisms through which ncRNAs and their interactions with RNA-binding proteins modulate the stability and translation of target mRNAs. WIREs RNA 2017, 8:e1399. doi: 10.1002/wrna.1399 For further resources related to this article, please visit the WIREs website.

E3 ubiquitin ligase: A potential regulator in fibrosis and systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune disease characterized by fibrosis in the skin and internal organs. The pathogenesis of SSc is not completely understood until now. Recently, many studies have focused on the role of E3 ubiquitin ligases in organ fibrosis. However, the possible regulatory mechanisms of E3 ubiquitin ligases in fibrosis and SSc are not well documented. In this review, we summarized that E3 ubiquitin ligases regulated fibrosis through ubiquitin-mediated degradation of TGF-β/Smad signaling pathway. Moreover, E3 ubiquitin ligases participated in regulating fibrosis by other methods, such as inducing epithelial transition to mesenchymal cell, enhancing the production of TGF-β and protecting activated hepatic stellate cells from apoptosis. However, the specific regulatory mechanisms of E3 ubiquitin ligases in scleroderma is still not fully understood. There are more works to be done to specify the mechanism of E3 ubiquitin ligases in regulation of fibrosis in SSc.

Mouse oocytes suppress miR-322-5p expression in ovarian granulosa cells

This study tested the hypothesis that oocyte-derived paracrine factors (ODPFs) regulate miRNA expression in mouse granulosa cells. Expression of mmu-miR-322-5p (miR-322) was higher in mural granulosa cells (MGCs) than in cumulus cells of the Graafian follicles. The expression levels of miR-322 decreased when cumulus cells or MGCs were co-cultured with oocytes denuded of their cumulus cells. Inhibition of SMAD2/3 signaling by SB431542 increased miR-322 expression by cumulus-oocyte complexes (COCs). Moreover, the cumulus cells but not the MGCs in Bmp15^–/–/Gdf9^+/– (double-mutant) mice exhibited higher miR-322 expression than those of wild-type mice. Taken together, these results show that ODPFs suppress the expression of miR-322 in cumulus cells. Gene ontology analysis of putative miR-322 targets whose expression was detected in MGCs with RNA-sequencing suggested that multiple biological processes are affected by miR-322 in MGCs. These results demonstrate that ODPFs regulate miRNA expression in granulosa cells and that this regulation may participate in the differential control of cumulus cell versus MGC functions. Therefore, the ODPF-mediated regulation of cumulus cells takes place at both transcriptional and post-transcriptional levels.

Post-transcriptional regulation of Wnt co-receptor LRP6 and RNA-binding protein HuR by miR-29b in intestinal epithelial cells

MicroRNAs (miRNAs) control gene expression by binding to their target mRNAs for degradation and/or translation repression and are implicated in many aspects of cellular physiology. Our previous study shows that miR-29b acts as a biological repressor of intestinal mucosal growth, but its exact downstream targets remain largely unknown. In the present study, we found that mRNAs, encoding Wnt co-receptor LRP6 (low-density lipoprotein-receptor-related protein 6) and RNA-binding protein (RBP) HuR, are novel targets of miR-29b in intestinal epithelial cells (IECs) and that expression of LRP6 and HuR is tightly regulated by miR-29b at the post-transcriptional level. miR-29b interacted with both Lrp6 and HuR mRNAs via their 3′-UTRs and inhibited LRP6 and HuR expression by destabilizing Lrp6 and HuR mRNAs and repressing their translation. Studies using heterologous reporter constructs revealed a greater repressive effect of miR-29b through a single binding site in the Lrp6 or HuR 3′-UTR, whereas deletion mutation of this site prevented miR-29b-induced repression of LRP6 and HuR expression. Repression of HuR by miR-29b in turn also contributed to miR-29b-induced LRP6 inhibition, since ectopic overexpression of HuR in cells overexpressing miR-29b restored LRP6 expression to near normal levels. Taken together, our results suggest that miR-29b inhibits expression of LRP6 and HuR post-transcriptionally, thus playing a role in the regulation of IEC proliferation and intestinal epithelial homoeostasis.

H19 Long Noncoding RNA Regulates Intestinal Epithelial Barrier Function via MicroRNA 675 by Interacting with RNA-Binding Protein HuR

The disruption of the intestinal epithelial barrier function occurs commonly in various pathologies, but the exact mechanisms responsible are unclear. The H19 long noncoding RNA (lncRNA) regulates the expression of different genes and has been implicated in human genetic disorders and cancer. Here, we report that H19 plays an important role in controlling the intestinal epithelial barrier function by serving as a precursor for microRNA 675 (miR-675). H19 overexpression increased the cellular abundance of miR-675, which in turn destabilized and repressed the translation of mRNAs encoding tight junction protein ZO-1 and adherens junction E-cadherin, resulting in the dysfunction of the epithelial barrier. Increasing the level of the RNA-binding protein HuR in cells overexpressing H19 prevented the stimulation of miR-675 processing from H19, promoted ZO-1 and E-cadherin expression, and restored the epithelial barrier function to a nearly normal level. In contrast, the targeted deletion of HuR in intestinal epithelial cells enhanced miR-675 production in the mucosa and delayed the recovery of the gut barrier function after exposure to mesenteric ischemia/reperfusion. These results indicate that H19 interacts with HuR and regulates the intestinal epithelial barrier function via the H19-encoded miR-675 by altering ZO-1 and E-cadherin expression posttranscriptionally.

The ubiquitin ligase Smurf2 suppresses TGFβ-induced epithelial-mesenchymal transition in a sumoylation-regulated manner

Epithelial-mesenchymal transition (EMT) is a fundamental cellular process in epithelial tissue development, and can be reactivated in cancer contributing to tumor invasiveness and metastasis. The cytokine transforming growth factor-β (TGFβ) is a key inducer of EMT, but the mechanisms that regulate TGFβ-induced EMT remain incompletely understood. Here, we report that knockdown of the ubiquitin ligase Smurf2 promotes the ability of TGFβ to induce EMT in a three-dimensional cell culture model of NMuMG mammary epithelial cells. In other studies, we identify Smurf2 as a target of the small ubiquitin like modifier (SUMO) pathway. We find that the SUMO-E2 conjugating enzyme Ubc9 and the SUMO E3 ligase PIAS3 associate with Smurf2 and promote its sumoylation at the distinct sites of Lysines 26 and 369. The sumoylation of Smurf2 enhances its ability to induce the degradation of the TGFβ receptor and thereby suppresses EMT in NMuMG cells. Collectively, our data reveal that Smurf2 acts in a sumoylation-regulated manner to suppress TGFβ-induced EMT. These findings have significant implications for our understanding of epithelial tissue development and cancer.

Long noncoding RNA SPRY4-IT1 regulates intestinal epithelial barrier function by modulating the expression levels of tight junction proteins

Epithelial cells line the intestinal mucosa and form an important barrier to a wide array of noxious substances in the lumen. Disruption of the barrier integrity occurs commonly in various pathologies. Long noncoding RNAs (lncRNAs) control diverse biological processes, but little is known about the role of lncRNAs in regulation of the gut permeability. Here we show that the lncRNA SPRY4-IT1 regulates the intestinal epithelial barrier function by altering expression of tight junction (TJ) proteins. SPRY4-IT1 silencing led to dysfunction of the epithelial barrier in cultured cells by decreasing the stability of mRNAs encoding TJ proteins claudin-1, claudin-3, occludin, and JAM-1 and repressing their translation. In contrast, increasing the levels of SPRY4-IT1 in the intestinal mucosa protected the gut barrier in mice exposed to septic stress by increasing the abundance of TJ proteins. SPRY4-IT1 directly interacted with TJ mRNAs, and this process was enhanced through the association with the RNA-binding protein HuR. Of interest, the intestinal mucosa from patients with increased gut permeability exhibited a decrease in the levels of SPRY4-IT1. These findings highlight a novel role for SPRY4-IT1 in controlling the intestinal epithelial barrier and define a mechanism by which SPRY4-IT1 modulates TJ expression by altering the stability and translation of TJ mRNAs.

MicroRNA: master controllers of intracellular signaling pathways

Signaling pathways are essential intracellular networks that coordinate molecular outcomes to external stimuli. Tight regulation of these pathways is essential to ensure an appropriate response. MicroRNA (miRNA) is a class of small, non-coding RNA that regulates gene expression at a post-transcriptional level by binding to the complementary sequence on target mRNA, thus limiting protein translation. Intracellular pathways are controlled by protein regulators, such as suppressor of cytokine signaling and A20. Until recently, expression of these classical protein regulators was thought to be controlled solely by transcriptional induction and proteasomal degradation; however, there is a growing body of evidence describing their regulation by miRNA. This new information has transformed our understanding of cell signaling by adding a previously unknown layer of regulatory control. This review outlines the miRNA regulation of these classical protein regulators and describes their broad effects at both cellular and disease levels. We review the regulation of three important signaling pathways, including the JAK/STAT, NF-κB, and TGF-β pathways, and summarize an extensive catalog of their regulating miRNAs. This information highlights the importance of the miRNA regulon and reveals a previously unknown regulatory landscape that must be included in the identification and development of novel therapeutic targets for clinical disorders.

miR-195 plays a role in steroid resistance of ulcerative colitis by targeting Smad7

An imbalance in pro- and anti-inflammation is an important mechanism of steroid resistance in UC (ulcerative colitis), and miRNAs may participate in this process. The present study aimed to explore whether miRNAs play a role in the steroid resistance of UC by regulating gene expression of the inflammation signal pathway. SS (steroid-sensitive) patients, SR (steroid-resistant) patients and healthy individuals were recruited. In vivo miRNA profiles of serum samples showed that miR-195 was decreased significantly in the SR group compared with the SS group (P<0.05). This result was confirmed by qPCR (quantitative real-time PCR) and miRNA ISH (in situ hybridization) in serum and colon tissue samples. Online software was used to identify Smad7 mRNA as a potential target of miR-195. The direct interaction of miR-195 and Smad7 mRNA was investigated using a biotinylated miR-195 pull-down assay. Overexpression of a miR-195 precursor lowered cellular levels of Smad7 protein; conversely, antagonism of miR-195 enhanced Smad7 translation without disturbing Smad7 mRNA levels. A luciferase reporter assay revealed a repressive effect of miR-195 via a single Smad7 3'-UTR target site, and point mutation of this site prevented miR-195-induced repression of Smad7 translation. Furthermore, increased levels of miR-195 led to a decrease in c-Jun and p65 expression. In contrast, transfection with anti-miR-195 led to increased levels of c-Jun and p65 protein. The decrease in miR-195 led to an increase in Smad7 expression and corresponding up-regulation of p65 and the AP-1 (activator protein 1) pathway, which might explain the mechanism of steroid resistance in UC patients.

Transgenic Expression of miR-222 Disrupts Intestinal Epithelial Regeneration by Targeting Multiple Genes Including Frizzled-7

Defects in intestinal epithelial integrity occur commonly in various pathologies. miR-222 is implicated in many aspects of cellular function and plays an important role in several diseases, but its exact biological function in the intestinal epithelium is underexplored. We generated mice with intestinal epithelial tissue-specific overexpression of miR-222 to investigate the function of miR-222 in intestinal physiology and diseases in vivo. Transgenic expression of miR-222 inhibited mucosal growth and increased susceptibility to apoptosis in the small intestine, thus leading to mucosal atrophy. The miR-222-elevated intestinal epithelium was vulnerable to pathological stress, since local overexpression of miR-222 not only delayed mucosal repair after ischemia/reperfusion-induced injury, but also exacerbated gut barrier dysfunction induced by exposure to cecal ligation and puncture. miR-222 overexpression also decreased expression of the Wnt receptor Frizzled-7 (FZD7), cyclin-dependent kinase 4 and tight junctions in the mucosal tissue. Mechanistically, we identified the Fzd7 messenger ribonucleic acid (mRNA) as a novel target of miR-222 and found that [miR-222/Fzd7 mRNA] association repressed Fzd7 mRNA translation. These results implicate miR-222 as a negative regulator of normal intestinal epithelial regeneration and protection by downregulating expression of multiple genes including the Fzd7. Our findings also suggest a novel role of increased miR-222 in the pathogenesis of mucosal growth inhibition, delayed healing and barrier dysfunction.

MiR-497∼195 cluster microRNAs regulate osteoblast differentiation by targeting BMP signaling

MicroRNAs play important roles during cell reprogramming and differentiation. In this study, we identified the miR-497∼195 cluster, a member of the miR-15 family, as strongly upregulated with age of postnatal bone development in vivo and late differentiation stages of primary osteoblasts cultured in vitro. Early expression of miR-195-5p inhibits differentiation and mineralization. Microarray analyses along with quantitative PCR demonstrate that miR-195-5p alters the gene regulatory network of osteoblast differentiation and impairs the induction of bone morphogenetic protein (BMP) responsive genes. Applying reporter gene and Western blot assays, we show that miR-195-5p interferes with the BMP/Smad-pathway in a dose-dependent manner. Systematically comparing the changes in mRNA levels in response to miR-195-5p overexpression with the changes observed in the natural course of osteoblast differentiation, we demonstrate that microRNAs of the miR-15 family affect several target genes involved in BMP signaling. Predicted targets including Furin, a protease that cleaves pro-forms, genes encoding receptors such as Acvr2a, Bmp1a, Dies1, and Tgfbr3, molecules within the cascade like Smad5, transcriptional regulators like Ski and Zfp423 as well as Mapk3 and Smurf1 were validated by quantitative PCR. Taken together, our data strongly suggest that miR-497∼195 cluster microRNAs act as intracellular antagonists of BMP signaling in bone cells.