Hepato-specific microRNA-122 facilitates accumulation of newly synthesized miRNA through regulating PRKRA

Exploring the roles of non-coding RNAs in liver regeneration

Liver regeneration (LR) is a complex process encompassing three distinct phases: priming, proliferation phase and restoration, all influenced by various regulatory factors. After liver damage or partial resection, the liver tissue demonstrates remarkable restorative capacity, driven by cellular proliferation and repair mechanisms. The essential roles of non-coding RNAs (ncRNAs), predominantly microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNA (circRNA), in regulating LR have been vastly studied. Additionally, the impact of ncRNAs on LR and their abnormal expression profiles during this process have been extensively documented. Mechanistic investigations have revealed that ncRNAs interact with genes involved in proliferation to regulate hepatocyte proliferation, apoptosis and differentiation, along with liver progenitor cell proliferation and migration. Given the significant role of ncRNAs in LR, an in-depth exploration of their involvement in the liver's self-repair capacity can reveal promising therapeutic strategies for LR and liver-related diseases. Moreover, understanding the unique regenerative potential of the adult liver and the mechanisms and regulatory factors of ncRNAs in LR are crucial for improving current treatment strategies and exploring new therapeutic approaches for various liver-related diseases. This review provides a brief overview of the LR process and the ncRNA expression profiles during this process. Furthermore, we also elaborate on the specific molecular mechanisms through which multiple key ncRNAs regulate the LR process. Finally, based on the expression characteristics of ncRNAs and their interactions with proliferation-associated genes, we explore their potential clinical application, such as developing predictive indicators reflecting liver regenerative activity and manipulating LR processes for therapeutic purposes.

Inhibiting the aberrant PACT-p53 axis activation ameliorates spinal cord ischaemia-reperfusion injury in rats

Spinal cord ischaemia-reperfusion injury (SCII) induces multiple molecular and cellular changes, resulting in dyskinesia. Recently, it is reported that the p53 network plays a vital role in SCII. However, the roles of the PACT/PRKRA (interferon-inducible double-stranded RNA-dependent protein kinase activator A)-p53 axis in SCII are still unclear. The aim of this study was to elucidate the roles of the PACT-p53 axis in SCII. A Sprague-Dawley rat model of SCII was established by subjecting rats to a 14-min occlusion of the aortic arch. The Tarlov criteria, Western blotting, double immunofluorescence staining, haematoxylin and eosin (HE) staining, and transferase dUTP nick end labelling (TUNEL) assay were performed after SCII. Here, spinal cord ischaemia-reperfusion (SCI) caused hindlimb motor functional deficits as assessed by the Tarlov criteria. The protein expression of PACT was substantially upregulated at 48 h after SCII. Increased PACT fluorescence was mainly localized to neurons. Si-PACT pretreatment improved hindlimb motor function, ameliorated histological changes, and attenuated cell apoptosis after SCII. Si-PACT pretreatment reduced the protein expression of PACT, p53, Caspase-8 and IL-1β and the number of double-labelled PACT and p53. Taken together, inhibiting the aberrant PACT-p53 axis activation by si-PACT pretreatment ameliorates SCI-induced neuroapoptosis and neuroinflammation in rats. Silencing PACT expression is promising new therapeutic strategy for SCII.

The MYEOV-MYC association promotes oncogenic miR-17/93-5p expression in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy worldwide. As metastasis and malignant progression are primarily responsible for the poor clinical outcomes of PDAC, identifying key genes involved in these processes and the underlying molecular mechanisms of PDAC is vital. In this study, by analyzing TCGA PDAC data and matched GTEx data, we found that MYEOV expression is associated with poor survival in PDAC patients and higher in carcinoma tissues than in healthy tissues. Elevated levels of MYEOV led to enhanced cell proliferation, invasion and migration in vitro and in vivo. Transcriptome analysis results revealed that MYEOV mediates global alterations in gene expression profiles in PDAC cells. MiRNA-seq analysis showed that MYEOV regulates the expression levels of miR-17-5p and miR-93-5p, and its depletion resulted in reduced cell proliferation, invasion and migration, as observed in MYEOV-knockdown PDAC cells. These effects are likely due to the ability of MYEOV to regulate enrichment of the transcription factor MYC at the gene promoter regions of the two miRNAs. Furthermore, we identified a complex containing MYEOV and MYC in the nucleus, providing additional evidence for the association of MYEOV with MYC. Taken together, our results suggest that MYEOV promotes oncogenic miR-17/93-5p expression by associating with MYC, contributing to PDAC progression.

Molecular switch in human diseases-disintegrin and metalloproteinases, ADAM17

The ADAMs (a disintegrin and metalloproteinase) are a family of cell surface proteins with crucial roles in the regulation of cell adhesion, cell proliferation to migration, proteolysis and cell signaling transduction pathways. Among these enzymes, the ADAM17 shows significant effects in the “ectodomain shedding” of its substrates such as cytokines (e.g., tumor necrosis factor α, TNFα), growth factors (e.g., epidermal growth factor, EGF), adhesion proteins (e.g., L-selectin), and their receptors (e.g., IL-6R and TNFα). Several studies focus on the underlying molecular mechanisms of ADAM17 in diseased conditions. Here, we took several different approaches to elucidate the function of ADAM17, the participation of ADAM17 in several human diseases, and the potential as targeted therapy reagents. As more and more studies verify the miRNA-mediated expression variation of ADAM17, the specific regulation network of miRNAs and ADAM17 was exploited in this review as well.

Arginine Metabolism and Its Potential in Treatment of Colorectal Cancer

Colorectal cancer is the leading cause of death from cancer globally. The current treatment protocol still heavily relies on early detection and surgery. The molecular mechanisms underlying development of colorectal cancer are clinically important and determine the prognosis and treatment response. The arginine metabolism pathway is hyperactive in colorectal cancer and several molecules involved in the pathway are potential targets for chemoprevention and targeted colorectal cancer therapy. Endothelial nitric oxide synthase (eNOS), argininosuccinate synthetase and ornithine decarboxylase (ODC) are the main enzymes for arginine metabolism. Limiting arginine-rich meat consumption and inhibiting ODC activity largely reduces polyamine synthesis and the incidence of colorectal cancer. Arginine transporter CAT-1 and Human member 14 of the solute carrier family 6 (SLC6A14) are overexpressed in colorectal cancer cells and contributes to intracellular arginine levels. Human member 9 of the solute carrier family 38 (SLC38A9) serves as a component of the lysosomal arginine-sensing machinery. Pharmaceutical inhibition of single enzyme or arginine transporter is hard to meet requirement of restoring of abnormal arginine metabolic network. Apart from application in early screening for colorectal cancer, microRNA-based therapeutic strategy that simultaneously manipulating multiple targets involved in arginine metabolism brings promising future in the treatment of colorectal cancer.

BCL-w: apoptotic and non-apoptotic role in health and disease

The BCL-2 family of proteins integrates signals that trigger either cell survival or apoptosis. The balance between pro-survival and pro-apoptotic proteins is important for tissue development and homeostasis, while impaired apoptosis contributes to several pathologies and can be a barrier against effective treatment. BCL-w is an anti-apoptotic protein that shares a sequence similarity with BCL-X_L, and exhibits a high conformational flexibility. BCL-w level is controlled by a number of signaling pathways, and the repertoire of transcriptional regulators largely depends on the cellular and developmental context. As only a few disease-relevant genetic alterations of BCL2L2 have been identified, increased levels of BCL-w might be a consequence of abnormal activation of signaling cascades involved in the regulation of BCL-w expression. In addition, BCL-w transcript is a target of a plethora of miRNAs. Besides its originally recognized pro-survival function during spermatogenesis, BCL-w has been envisaged in different types of normal and diseased cells as an anti-apoptotic protein. BCL-w contributes to survival of senescent and drug-resistant cells. Its non-apoptotic role in the promotion of cell migration and invasion has also been elucidated. Growing evidence indicates that a high BCL-w level can be therapeutically relevant in neurodegenerative disorders, neuron dysfunctions and after small intestinal resection, whereas BCL-w inhibition can be beneficial for cancer patients. Although several drugs and natural compounds can bi-directionally affect BCL-w level, agents that selectively target BCL-w are not yet available. This review discusses current knowledge on the role of BCL-w in health, non-cancerous diseases and cancer.

Expression of blood hepatocyte-derived microRNA-122 in canine multicentric lymphoma with hepatic involvement

This study was performed to evaluate the hepatocyte-derived microRNA (miR)-122 as novel diagnostic biomarker in canine lymphoma. Fifteen dogs were enrolled in this study. Dogs presented at Small Animal Teaching Hospital, Faculty of Veterinary Medicine, Cairo University. Dogs were divided into 8 clinically healthy dogs act as control and 7 clinically ill dogs. All dogs were subjected to clinical, ultrasonographic, hemato-biochemical and ultrasound-guided fine-needle biopsy for cytological and histopathological investigations. On the basis of these results, 7 dogs were found to be suffering from multicentric lymphoma involving liver. Serum hepatocyte-derived miRA-122 was determined by real-time quantitative polymerase chain reaction in all dogs. Multicentric lymphoma involving liver manifested by inappetance for several days, depression and peripheral lymphadenopathy. Hematological examination showed significant lymphocytosis. Serum biochemical analysis revealed significant increase in ALT, AST, ALP compared to control dogs. Ultrasonography revealed hypoechoic lymphoid aggregation at area of "porta hepatis" and circumscribed hypoechoic nodule interrupt liver parenchyma. Cytology revealed infiltration of liver tissue by lymphoblast cells and histopathology revealed diffuse infiltration of hepatic sinusoids and portal area by uniform population of small lymphocytes. Serum miRNA-122 analysis showed a significant increase represented as 9.00 fold in canine multicentric lymphoma involving liver. Serum hepatocyte-derived miRNA-122 is of diagnostic value, non invasive, stable and easily measurable blood biomarker for the detection of hepatocellular injury in dogs with multicentric lymphoma involving liver.

LncRNA KCNQ1OT1 promoted BMP2 expression to regulate osteogenic differentiation by sponging miRNA-214

BACKGROUND

Osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) is of much significance for bone formation, the imbalance of it would result in osteoporosis and other pathological bone defects. Increasing evidences showed that long non-coding RNAs (lncRNAs) and miRNAs played vital roles in the regulation of osteogenic differentiation. LncRNA KCNQ1OT1 was often regarded as an imprinted lncRNA and was related to tumor progression, while its function in osteogenic differentiation remained unclear.

METHOD

qRT-PCR was performed to detect the expression of KCNQ1OT1, miR-214 and osteogenesis-related genes BMP2, Runx2, OPN, and OCN. Western blotting was carried out to detect osteogenesis-related markers. The osteoblastic phenotype was evidenced by alkaline phosphatase (ALP) activity and Alizarin Red S accumulation detection. Bioinformatics and luciferase assays were used to predict and validate the interaction between KCNQ1OT1 and miR-214 as well as BMP2 and miR-214.

RESULTS

KCNQ1OT1 was significantly up-regulated during the process of osteogenic induction while miR-214 was contrarily down-regulated. Knockdown of KCNQ1OT1 inhibited osteogenic differentiation and down-regulated BMP2 and osteogenesis-related genes. It was also confirmed that KCNQ1OT1 directly interacted with miR-214. Meanwhile, miR-214 could bind to 3'UTR of BMP2 and therefore inhibited its expression. Furthermore, co-transfection of miR-214 inhibitor could rescue the down-regulation of BMP2 and osteogenesis-related genes and osteogenic differentiation suppression induced by KCNQ1OT1 knockdown. Moreover, miR-214 inhibitor significantly reversed the decreased protein levels of p-Smad1/5/8, Runx2 and Osterix induced by shKCNQ1OT1.

CONCLUSIONS

KCNQ1OT1 positively regulated osteogenic differentiation of BMSCs by acting as a ceRNA to regulate BMP2 expression through sponging miR-214.

Baseline Hepatic Levels of miR-29b and Claudin are Respectively Associated with the Stage of Fibrosis and HCV RNA in Hepatitis C

We sought to determine if the baseline hepatic levels of miR-122, miR-29b, Claudin, Occludin, Protein Kinase R (PKR) or PKR activator (PRKRA) were correlated with HCV RNA or stage of fibrosis in patients with chronic hepatitis C (CHC). A total of 25 CHC patients (genotype 1) who were treatment naive at the time of sample collection enrolled in this study. By multivariate analysis, CLDN RNA was found as the single independent factor positively correlated with HCV RNA levels (p=0.003), while hepatic miR-29b levels was found as the single independent factor for predicting advanced stage of fibrosis (p=0.028). Conclusion: Our results highlight miR-29b and CLDN as novel predictors of advanced stage of liver fibrosis and baseline HCV RNA in CHC.

MiR-122 marks the differences between subcutaneous and visceral adipose tissues and associates with the outcome of bariatric surgery

The physiological roles and clinical impacts of the differences between visceral fat (VF) and subcutaneous fat (SF) are unclear. The present study aimed to compare the miRNA signatures between visceral fat (VF) and subcutaneous fat (SF) and study their influences on outcomes of bariatric surgery. To study the microRNA signatures of the VF and SF in obesity, we performed paired microRNA arrays of the adipose tissues from 20 bariatric surgery patients. The microRNA analysis identified miR-122 as the most significant signature between VF and SF. The tissue distribution, functions, and influences on adipogensis of miR-122 were analysed by Northern blotting, microRNA mimics and inhibitors, and whole-genome microarray analysis. The outcomes of body weight changes after bariatric surgery were analysed and correlated with the miR-122 abundances. Northern blotting confirmed that miR-122 was highly expressed in VF and SF. Bioinformatics analysis of the microarray revealed that proliferator activator receptor-γ (PPAR-γ) signalling was critically affected by miR-122. The modulation of PPAR-γ by miR-122 was confirmed in murine adipocytes and human adipose tissues. Furthermore, the differentiation of preadipocytes was significantly influenced by miR-122. In obese patients receiving bariatric surgery, the ratio of VF and SF miR-122 abundance correlated with 6-month and 1-year % excess body weight loss. Our findings indicate that miR-122 is highly expressed in adipose tissue. The abundance of miR-122 affects PPAR-γ signalling and adipocytes differentiation in vitro and human adipose tissues. Higher miR-122 in VF may be associated with greater body weight loss after bariatric surgery.

Evaluation of hepatocyte-derived microRNA-122 for diagnosis of acute and chronic hepatitis of dogs

Aim:

This study was performed to evaluate the diagnostic value of hepatocyte-derived microRNA (miRNA)-122 in acute and chronic hepatitis of dogs.

Materials and Methods:

A total of 26 dogs presented at Veterinary Teaching Hospital, Faculty of Veterinary Medicine, Cairo University, 16 dogs out of 26 showing clinical signs of hepatic insufficiency were subjected to clinical, ultrasonographic, hematobiochemical and ultrasound-guided fine-needle biopsy for cytological and histopathological investigations. On the basis of these results, 7 dogs out of 16 dogs were found to be suffering from acute hepatitis and 9 dogs suffering from chronic hepatitis. 10 clinically healthy dogs were kept as control. Serum hepatocyte-derived miRNA-122 was analyzed by real-time quantitative polymerase chain reaction in all dogs.

Results:

The dogs suffering from acute hepatitis manifested jaundice, vomiting, and depression while dogs with chronic hepatitis manifested anorexia, abdominal distension, weight loss, and melena. Hematological parameters showed normocytic normochromic anemia and thrombocytopenia in both acute and chronic hepatitis groups. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and total bilirubin were significantly higher than control values in acute hepatitis. In chronic hepatitis, total protein and albumin were significantly lower than control values with normal ALT, AST, ALP, and gamma-glutamyltransferase values. Ultrasonography revealed a diffuse decrease in hepatic echogenicity in acute hepatitis while the increase in hepatic echogenicity and anechoic ascetic fluid in chronic hepatitis. Cytology revealed hepatic vacuolar degeneration and histopathology revealed necrosis and apoptosis of hepatocyte in acute hepatitis while revealed massive fibrous tissue proliferation in hepatic parenchyma in chronic hepatitis. Serum miRNA-122 analysis, normalized for glyceraldehyde-3-phosphate dehydrogenase expression revealed a significant increase in acute hepatitis accompanied with elevation in ALT and AST, while in chronic hepatitis, elevation of serum miRNA-122 was accompanied with ALT and AST of the normal range.

Conclusion:

Serum hepatocyte-derived miRNA-122 is of diagnostic value and highly stable blood indicator for the detection of hepatocellular injury in dogs than aminotransferases, especially in cases where aminotransferases do not exceed normal serum level.

Triple therapy of hepatocellular carcinoma with microRNA-122 and doxorubicin co-loaded functionalized gold nanocages

A combination of different therapy strategies has great potential to efficaciously treat malignant tumors, by virtue of their synergetic effects. Herein, a co-delivery system based on gold nanocages (AuNCs) was designed to deliver both doxorubicin (DOX) and microRNA-122 mimic (miR-122) for an enhanced cancer therapy. DOX was loaded into the AuNCs and miR-122 was condensed onto the surface of the functionalized AuNCs by an electrostatic interaction. Polyethyleneglycol (PEG) and hyaluronic acid (HA) were also introduced to the co-delivery system for targeted drug delivery. We evaluated the cellular uptake, biodistribution and anti-tumor effect in vitro and in vivo. Our results demonstrated an effective delivery of DOX and miR-122 into tumor cells and the tumor tissue. Importantly, the triple therapy, namely the combination of chemotherapy, gene therapy and photothermal therapy, mediated by this multifunctional drug delivery system, exhibited better anti-tumor effect than any single therapy, both in vitro and in vivo. Additionally, this drug delivery system caused insignificant toxicity to the major organs and had no obvious effect on the body weight of the mice. It could be concluded that multifunctional AuNCs are promising as a co-delivery vector for an enhanced anti-tumor effect.

miR2Pathway: A novel analytical method to discover MicroRNA-mediated dysregulated pathways involved in hepatocellular carcinoma

MicroRNAs (miRNAs) are small, non-coding RNAs involved in the regulation of gene expression at a post-transcriptional level. Recent studies have shown miRNAs as key regulators of a variety of biological processes, such as proliferation, differentiation, apoptosis, metabolism, etc. Aberrantly expressed miRNAs influence individual gene expression level, but rewired miRNA-mRNA connections can influence the activity of biological pathways. Here, we define rewired miRNA-mRNA connections as the differential (rewiring) effects on the activity of biological pathways between hepatocellular carcinoma (HCC) and normal phenotypes. Our work presented here uses a PageRank-based approach to measure the degree of miRNA-mediated dysregulation of biological pathways between HCC and normal samples based on rewired miRNA-mRNA connections. In our study, we regard the degree of miRNA-mediated dysregulation of biological pathways as disease risk of biological pathways. Therefore, we propose a new method, miR2Pathway, to measure and rank the degree of miRNA-mediated dysregulation of biological pathways by measuring the total differential influence of miRNAs on the activity of pathways between HCC and normal states. miR2Pathway proposed here systematically shows the first evidence for a mechanism of biological pathways being dysregulated by rewired miRNA-mRNA connections, and provides new insight into exploring mechanisms behind HCC. Thus, miR2Pathway is a novel method to identify and rank miRNA-dysregulated pathways in HCC.

A functional variant at miRNA-122 binding site in IL-1a 3' UTR predicts risk of recurrence in patients with oropharyngeal cancer

IL-1α, an important regulator of immune and inflammation responses, has been implicated in cancer development and prognosis. An insertion (Ins)/deletion (Del) polymorphism (IL-1α rs3783553) in the 3′ UTR of IL-1α may disrupt a binding site for miRNA-122 and may affect its transcription level. Thus, this polymorphism may cause interindividual variation in immune and inflammation responses and thus may lead to different susceptibility to treatment response and prognosis of such patients. We evaluated the association of IL-1α rs3783553 polymorphism with risk of recurrence of squamous cell carcinoma of the oropharynx (SCCOP) in a cohort of 1008 patients. Log-rank test and univariate and multivariable Cox models were used to evaluate associations. Compared with patients with Del/Del homozygous genotype, the patients with Ins/Del+Ins/Ins variant genotypes had worse disease-free survival (log-rank P < 0.0001) and increased risk of SCCOP recurrence (HR, 2.4, 95% CI, 1.7-3.3) after multivariable adjustment. Furthermore, among patients with HPV16-positive tumors, the patients with Ins/Del+Ins/Ins variant genotypes of the IL-1α polymorphism had worse disease-free survival (log-rank P < 0.0001) and much higher recurrence risk than those with Del/Del homozygous genotype of this polymorphism (HR, 16.3, 95% CI, 5.0-52.7). Our findings suggest that IL-1α rs3783553 polymorphism may modulate the risk of SCCOP recurrence in patients, particularly for patients with HPV16-positive tumors. However, larger studies are needed to validate these results.

miR-181a-2 downregulates the E3 ubiquitin ligase CUL4A transcript and promotes cell proliferation

MiR-181a-2 plays a major role in cell proliferation both positively and negatively depending on tissue type by targeting several regulators 3'UTR regions. We have predicted several targets for miR-181a-2 through computational approaches and characterized one its interesting target, CUL4A, an E3 ubiquitin ligase. CUL4A regulates diverse functions in the cells including DNA repair, DNA replication, cell cycle, genomic stability through polyubiquitination of target proteins. Deregulation of both miR-181a-2 and CUL4A are reported in many cancerous cells, but the functional link between them is unknown. We show that miR-181a-5p binds to 3'UTR of CUL4A and regulates its transcripts levels in HEK293 cells through overexpression studies. In addition, by using MTT and Neutral red assays, we showed that miR-181a-2 overexpression increased the proliferation in HEK293 cells. Moreover, cell cycle analysis using flow cytometer revealed that an increase in S-phase cells upon the overexpression of miR-181a-2. Though several miRNAs are known to downregulate the CUL4A levels, here we show that miR-181a-2 also participates in the downregulation of CUL4A. Taken together, our data demonstrated that miR-181a-2 increases the cell proliferation in HEK293 cells possibly through the downregulation of CUL4A.

Post-transcriptional regulation of ERBB2 by miR26a/b and HuR confers resistance to tamoxifen in estrogen receptor-positive breast cancer cells

Tamoxifen-resistant (TAMR) estrogen receptor-positive (ER+) breast cancer is characterized by elevated Erb-B2 receptor tyrosine kinase 2 (ERBB2) expression. However, the underlying mechanisms responsible for the increased ERBB2 expression in the TAMR cells remain poorly understood. Herein, we reported that the ERBB2 expression is regulated at the post-transcriptional level by miR26a/b and the RNA-binding protein human antigen R (HuR), both of which associate with the 3'-UTR of the ERBB2 transcripts. We demonstrated that miR26a/b inhibits the translation of ERBB2 mRNA, whereas HuR enhances the stability of the ERBB2 mRNA. In TAMR ER+ breast cancer cells with elevated ERBB2 expression, we observed a decrease in the level of miR26a/b and an increase in the level of HuR. The forced expression of miR26a/b or the depletion of HuR decreased ERBB2 expression in the TAMR cells, resulting in the reversal of tamoxifen resistance. In contrast, the inactivation of miR26a/b or forced expression of HuR decreased tamoxifen responsiveness of the parental ER+ breast cancer cells. We further showed that the increase in HuR expression in the TAMR ER+ breast cancer cells is attributable to an increase in the HuR mRNA isoform with shortened 3'-UTR, which exhibits increased translational activity. This shortening of the HuR mRNA 3'-UTR via alternative polyadenylation (APA) was observed to be dependent on cleavage stimulation factor subunit 2 (CSTF2/CstF-64), which is up-regulated in the TAMR breast cancer cells. Taken together, we have characterized a model in which the interplay between miR26a/b and HuR post-transcriptionally up-regulates ERBB2 expression in TAMR ER+ breast cancer cells.

The Hepatoprotective and MicroRNAs Downregulatory Effects of Crocin Following Hepatic Ischemia-Reperfusion Injury in Rats

Background. Liver ischemia-reperfusion (IR) injury is one of the chief etiologies of tissue damage during liver transplantation, hypovolemic shock, and so forth. This study aimed to evaluate hepatoprotective effect of crocin on IR injury and on microRNAs (miR-122 and miR-34a) expression. Materials and Methods. 32 rats were randomly divided into four groups: sham, IR, crocin pretreatment (Cr), and crocin pretreatment + IR (Cr + IR) groups. In sham and Cr groups, animals were given normal saline (N/S) and Cr (200 mg/Kg) for 7 consecutive days, respectively, and laparotomy without inducing IR was done. In IR and Cr + IR groups, N/S and Cr were given for 7 consecutive days and rats underwent a partial (70%) ischemia for 45 min/reperfusion for 60 min. Blood and tissue samples were taken for biochemical, molecular, and histopathological examinations. Results. The results showed decreased levels of antioxidants activity and increased levels of liver enzymes improved by crocin. The expression of miR-122, miR-34a, and p53 decreased, while Nrf2 increased by crocin. Crocin ameliorated histopathological changes. Conclusion. The results demonstrated that crocin protected the liver against IR injury through increasing the activity of antioxidant enzymes, improving serum levels of liver enzymes, downregulating miR-122, miR-34a, and p53, and upregulating Nrf2 expression.

Effect of TGF-β/smad signaling pathway blocking on expression profiles of miR-335, miR-150, miR-194, miR-27a, and miR-199a of hepatic stellate cells (HSCs)

AIM

The aim of this study was to determine the effect of inhibition of TGF-β/smad signaling on the expression profiles of miR-335, miR-150, miR-194, miR-27a, miR-199a of hepatic stellate cells (HSCs).

BACKGROUND

Liver fibrosis is excessive deposition of extracellular matrix proteins due to ongoing inflammation and HSC activation that occurs in most types of chronic liver diseases. Recent studies have shown the importance of microRNAs in the pathogenesis of chronic liver diseases.

METHODS

In this study, for inhibition of TGF-β smad-signaling pathway, expressing Smad4 shRNA plasmids were transfected into HSCs. Subsequently, using Real Time-PCR, we measured the expression levels of miR-335, miR-150, miR-194, miR-27a and miR-199a.

RESULTS

Gene expression analysis showed that downregulation of Smad4 by vector Smad4shRNA significantly increased the expression levels of miR-335 (P<0.01) and miR-150 (P<0.001) and decreased the expression level of miR-27a (P<0.05).

CONCLUSION

The results of this study suggest that blocking TGF-β smad-signaling can also differentially modulate microRNA expression in support of activation and fibrogenesis of HSCs.

MiR-122 targets VEGFC in bladder cancer to inhibit tumor growth and angiogenesis

Previous studies indicate that microRNA-122 (miR-122) is down-regulated in several cancer cells and regulates cell apoptosis, proliferation, metastasis, and tumor angiogenesis. However, the mount of miR-122 in bladder cancer and the pivotal molecular mechanisms of miR-122 used to regulate bladder carcinogenesis and angiogenesis remain to be clarified. Here, we reveal that miR-122 expression is down-regulated in human bladder cancer tissues and cell lines. MiR-122 represses vascular endothelial growth factor C (VEGFC) post-transcriptional expression by directly binding to its 3'-UTR. The protein kinase B (AKT) and mammalian target of rapamycin (mTOR), which are the most important downstream molecules of VEGFC, are also decreased in bladder cancer cell after miR-122 overexpression. Furthermore, miR-122 over-expression decreases bladder cancer cell migration, invasion, colony formation in vitro and slow bladder cancer growth and angiogenesis in vivo. Finally, miR-122 sensitizes bladder cancer cells to cisplatin-induced apoptosis. Taken together, these studies suggest that miR-122 serves as a tumor suppressor and down-regulating VEGFC expression, leading to the inhibition of bladder cancer growth and angiogenesis.

MicroRNAs in the Evaluation and Potential Treatment of Liver Diseases

Acute and chronic liver disease continue to result in significant morbidity and mortality of patients, along with increasing burden on their families, society and the health care system. This in part is due to increased incidence of liver disease associated factors such as metabolic syndrome; improved survival of patients with chronic predisposing conditions such as HIV; as well as advances in the field of transplantation and associated care leading to improved survival. The fact that one disease can result in different manifestations and outcomes highlights the need for improved understanding of not just genetic phenomenon predisposing to a condition, but additionally the role of epigenetic and environmental factors leading to the phenotype of the disease. It is not surprising that providers continue to face daily challenges pertaining to diagnostic accuracy, prognostication of disease severity, progression, and response to therapies. A number of these challenges can be addressed by incorporating a personalized approach of management to the current paradigm of care. Recent advances in the fields of molecular biology and genetics have paved the way to more accurate, individualized and precise approach to caring for liver disease. The study of microRNAs and their role in both healthy and diseased livers is one example of such advances. As these small, non-coding RNAs work on fine-tuning of cellular activities and organ function in a dynamic and precise fashion, they provide us a golden opportunity to advance the field of hepatology. The study of microRNAs in liver disease promises tremendous improvement in hepatology and is likely to lay the foundation towards a personalized approach in liver disease.

Tiny giants of gene regulation: experimental strategies for microRNA functional studies

The discovery over two decades ago of short regulatory microRNAs (miRNAs) has led to the inception of a vast biomedical research field dedicated to understanding these powerful orchestrators of gene expression. Here we aim to provide a comprehensive overview of the methods and techniques underpinning the experimental pipeline employed for exploratory miRNA studies in animals. Some of the greatest challenges in this field have been uncovering the identity of miRNA-target interactions and deciphering their significance with regard to particular physiological or pathological processes. These endeavors relied almost exclusively on the development of powerful research tools encompassing novel bioinformatics pipelines, high-throughput target identification platforms, and functional target validation methodologies. Thus, in an unparalleled manner, the biomedical technology revolution unceasingly enhanced and refined our ability to dissect miRNA regulatory networks and understand their roles in vivo in the context of cells and organisms. Recurring motifs of target recognition have led to the creation of a large number of multifactorial bioinformatics analysis platforms, which have proved instrumental in guiding experimental miRNA studies. Subsequently, the need for discovery of miRNA-target binding events in vivo drove the emergence of a slew of high-throughput multiplex strategies, which now provide a viable prospect for elucidating genome-wide miRNA-target binding maps in a variety of cell types and tissues. Finally, deciphering the functional relevance of miRNA post-transcriptional gene silencing under physiological conditions, prompted the evolution of a host of technologies enabling systemic manipulation of miRNA homeostasis as well as high-precision interference with their direct, endogenous targets. For further resources related to this article, please visit the WIREs website.

MicroRNA-122 Inhibits the Production of Inflammatory Cytokines by Targeting the PKR Activator PACT in Human Hepatic Stellate Cells

MicroRNA-122 (miR-122) is one of the most abundant miRs in the liver. Previous studies have demonstrated that miR-122 plays a role in inflammation in the liver and functions in hepatic stellate cells (HSCs), which reside in the space of Disse. Here, we showed that the transient inhibition of PKR-activating protein (PACT) expression, by miR-122 or siRNA targeting of PACT, suppressed the production of proinflammatory cytokines, such as interleukin (IL)-6, monocyte chemoattractant protein-1 (MCP-1) and IL-1β, in human HSC LX-2. Sequence and functional analyses confirmed that miR-122 directly targeted the 3′-untranslated region of PACT. Immunofluorescence analysis revealed that miR-122 blocked NF-κB-nuclear translocation in LX-2 cells. We also showed that conditioned medium from miR-122-transfected LX-2 cells suppressed human monocyte-derived THP-1 cell migration. Taken together, our study indicates that miR-122 may downregulate cytokine production in HSCs and macrophage chemotaxis and that the targeting of miR-122 may have therapeutic potential for preventing the progression of liver diseases.

A functional variant at miRNA-122 binding site in IL-1α 3' UTR predicts risk and HPV-positive tumours of oropharyngeal cancer

BACKGROUND

Genetic polymorphisms in the 3' untranslated regions (3' UTRs) targeted by miRNAs alter the strength of miRNA binding in a manner that affects the behaviour of individual miRNAs. An insertion (Ins)/deletion (Del) polymorphism (rs3783553) in the 3' UTR of IL-1α may disrupt a binding site for miRNA-122. IL-1α plays an important role in inflammation, immunity and defense against infection. Thus, we hypothesised that the rs3783553 polymorphism affects individual susceptibility to human papillomavirus (HPV)-associated oral squamous cell carcinoma (OSCC).

METHODS

We genotyped the rs3783553 polymorphism; and determined HPV16 L1 serology, tumour HPV16 DNA and serum IL-1α expression. Univariate/multivariable logistic regression models were used to calculate associations.

RESULTS

We found that HPV16 L1 seropositivity alone was associated with an increased risk of OSCC (Odds ratio (OR), 3.1; 95% confidence interval (CI), 2.1-4.6), and the risk of HPV16-associated OSCC was modified by the rs3783553 polymorphism. Patients with both HPV16 L1 seropositivity and Del/Del genotype for the rs3783553 had the highest risk of OSCC when using patients with HPV16 L1 seronegativity and Ins/Del+Ins/Ins genotypes as a comparison group. Notably, that effect modification was particularly pronounced in several subgroups (e.g. SCCOP, never-smokers and never-drinkers). The patients with Del/Del genotype were approximately 3.0 times more likely to have HPV16-positive squamous cell carcinoma of the oropharynx (SCCOP) tumours compared to those patients with Ins/Del+Ins/Ins genotypes. Additionally, functional relevance of this variant was characterised to explore the genotype-phenotype correlation.

CONCLUSION

These results suggest that IL-1α 3' UTR rs3783553 polymorphism may be functional and influence susceptibility to HPV16-associated OSCC, particularly for SCCOP. Validation of our findings is warranted.

MicroRNA Screening and the Quest for Biologically Relevant Targets

MicroRNAs (miRNAs) are a class of genome-encoded small RNAs that post-transcriptionally regulate gene expression by repressing target transcripts containing partially or fully complementary binding sites.

Despite their relatively low number, miRNAs have been shown to directly regulate a large fraction of the transcriptome. In agreement with their pervasive role in the regulation of eukaryotic gene expression, miRNAs have been implicated in virtually all biological processes, including different pathologies.

The use of screening technologies to systematically analyze miRNA function in cell-based assays offers a unique opportunity to gain new insights into complex biological and disease-relevant processes. Given the low complexity of the miRNome and the similarities to small interfering RNA (siRNA) screening experimental approaches, phenotypic screening using genome-wide libraries of miRNA mimics or inhibitors is not, per se, technically challenging. The identification of miRNA targets and, more importantly, the characterization of their mechanisms of action through the identification of the key targets underlying observed phenotypes remain the major challenges of this approach.

This article provides an overview of cell-based screenings for miRNA function that were performed in different biological contexts. The advantages and limitations of computational and experimental approaches commonly used to identify miRNA targets are also discussed.

Imperfect centered miRNA binding sites are common and can mediate repression of target mRNAs

Background

MicroRNAs (miRNAs) bind to mRNAs and target them for translational inhibition or transcriptional degradation. It is thought that most miRNA-mRNA interactions involve the seed region at the 5′ end of the miRNA. The importance of seed sites is supported by experimental evidence, although there is growing interest in interactions mediated by the central region of the miRNA, termed centered sites. To investigate the prevalence of these interactions, we apply a biotin pull-down method to determine the direct targets of ten human miRNAs, including four isomiRs that share centered sites, but not seeds, with their canonical partner miRNAs.

Results

We confirm that miRNAs and their isomiRs can interact with hundreds of mRNAs, and that imperfect centered sites are common mediators of miRNA-mRNA interactions. We experimentally demonstrate that these sites can repress mRNA activity, typically through translational repression, and are enriched in regions of the transcriptome bound by AGO. Finally, we show that the identification of imperfect centered sites is unlikely to be an artifact of our protocol caused by the biotinylation of the miRNA. However, the fact that there was a slight bias against seed sites in our protocol may have inflated the apparent prevalence of centered site-mediated interactions.

Conclusions

Our results suggest that centered site-mediated interactions are much more frequent than previously thought. This may explain the evolutionary conservation of the central region of miRNAs, and has significant implications for decoding miRNA-regulated genetic networks, and for predicting the functional effect of variants that do not alter protein sequence.

MicroRNAs in the onset and development of cardiovascular disease

Physiological and pathological roles for small non-encoding miRNAs (microRNAs) in the cardiovascular system have recently emerged and are now widely studied. The discovery of widespread functions of miRNAs has increased the complexity of gene-regulatory processes and networks in both the cardiovascular system and cardiovascular diseases. Indeed, it has recently been shown that miRNAs are implicated in the regulation of many of the steps leading to the development of cardiovascular disease. These findings represent novel aspects in miRNA biology and, therefore, our understanding of the role of these miRNAs during the pathogenesis of cardiovascular disease is critical for the development of novel therapies and diagnostic interventions. The present review will focus on understanding how miRNAs are involved in the onset and development of cardiovascular diseases.

MiR-10a* up-regulates coxsackievirus B3 biosynthesis by targeting the 3D-coding sequence

MicroRNAs (miRNAs) are small non-coding RNAs that can posttranscriptionally regulate gene expression by targeting messenger RNAs. During miRNA biogenesis, the star strand (miRNA*) is generally degraded to a low level in the cells. However, certain miRNA* express abundantly and can be recruited into the silencing complex to regulate gene expression. Most miRNAs function as suppressive regulators on gene expression. Group B coxsackieviruses (CVB) are the major pathogens of human viral myocarditis and dilated cardiomyopathy. CVB genome is a positive-sense, single-stranded RNA. Our previous study shows that miR-342-5p can suppress CVB biogenesis by targeting its 2C-coding sequence. In this study, we found that the miR-10a duplex could significantly up-regulate the biosynthesis of CVB type 3 (CVB3). Further study showed that it was the miR-10a star strand (miR-10a*) that augmented CVB3 biosynthesis. Site-directed mutagenesis showed that the miR-10a* target was located in the nt6818–nt6941 sequence of the viral 3D-coding region. MiR-10a* was detectable in the cardiac tissues of suckling Balb/c mice, suggesting that miR-10a* may impact CVB3 replication during its cardiac infection. Taken together, these data for the first time show that miRNA* can positively modulate gene expression. MiR-10a* might be involved in the CVB3 cardiac pathogenesis.

The hunting of targets: challenge in miRNA research

MicroRNAs (miRNAs) are small noncoding RNAs that control the expression of around 60% of the human protein-coding genes. In the past decade, deregulation of miRNAs (by expression and/or function) has been associated with the pathogenesis, progression and prognosis of different diseases, including leukemia. The number of discovered genes encoding miRNAs has risen exponentially in this period, but the numbers of miRNA-target genes discovered and validated lag far behind. Scientists have gained more in-depth knowledge of the basic mechanism of action of miRNAs, but the main challenge still remaining is the identification of direct targets of these important 'micro-players', to understand how they fine-tune so many biological processes in both healthy and diseased tissue. Many technologies have been developed in the past few years, some with more potential than others, but all with their own pros and cons. Here, we review the most common and most potent computational and experimental approaches for miRNA-target gene discovery and discuss how the hunting of targets is challenging but possible by taking the experimental limitations in consideration and choosing the correct cellular context for identifying relevant target genes.