Porcine respiratory and reproductive syndrome (PRRS) is one of the most devastating infectious diseases of pigs, causing reproductive failures in sows and severe respiratory symptoms in piglets and growing pigs. MicroRNAs (miRNAs) are reported to play an essential role in virus-host interactions. In this study, we demonstrated that miR-451 enhanced type I interferon (IFN-I) production through targeting proteasome subunit β8 (PSMB8), therefore restricting PRRS virus (PRRSV) replication. We showed that the expression of PSMB8 was upregulated by PRRSV infection, and knockdown of PSMB8 inhibited PRRSV replication by promoting IFN-I production. Moreover, we demonstrated that PSMB8 interacted with the regulatory domain of IRF3 to mediate K48-linked polyubiquitination and degradation of IRF3. Also, importantly, we showed that PSMB8, as a target gene of miR-451, negatively regulated IFN-I production by promoting IRF3 degradation, which is a previously unknown mechanism for PSMB8 to modulate innate immune responses.
OBJECTIVE: Porcine respiratory and reproductive syndrome virus (PRRSV), as a huge threat to the swine industry, is a causative agent that urgently needs to be solved. The dissecting of PRRSV pathogenesis and understanding of the host-pathogen interaction will provide insights into developing effective anti-PRRSV strategies. In this study, we showed that miR-451 dramatically inhibited PRRSV replication by targeting proteasome subunit β8 (PSMB8), a subunit of the immunoproteasome. Mutation of PSMB8 is often related to autoinflammatory diseases due to the elevated IFN production. We revealed that PSMB8 downregulated IFN production by promoting IRF3 degradation. In addition, we showed that PRRSV infection upregulated PSMB8 expression. Taken together, our findings reveal that miR-451 is a negative regulator of PRRSV replication, and PSMB8, a target gene of miR-451, negatively regulates IFN-I production by promoting IRF3 degradation, which is a previously unknown mechanism for PSMB8 to regulate innate immune responses.

In 2005, Altuvia and colleagues were the first to identify the gene that encodes miR-451 in the human pituitary gland, located in chromosome region 17q11.2. Subsequent studies have confirmed that miR-451 regulates various immune cells, including T cells, B cells, microglia, macrophages, and neutrophils, thereby influencing disease progression. The range of immune-related diseases affected encompasses various cancers, lymphoblastic leukemia, and injuries to the lungs and spinal cord, among others. Moreover, miR-451 is produced by immune cells and can regulate both their own functions and those of other immune cells, thus creating a regulatory feedback loop. This article aims to comprehensively review the interactions between miR-451 and immune cells, clarify the regulatory roles of miR-451 within the immune system, and assess its potential as both a therapeutic target and a biomarker for immune-related diseases.

MicroRNAs (miRs) are non-coding small RNA containing 18 to 22 nucleotides, that post-transcriptionally regulates mRNA expression. Chronic injection of β stimulator is known to induce cardiac injury and change of miRs expression level in the heart with some pathological changes such as fibrosis, heart failure, myocardial infarction. We investigated the changes in the expression level of miRs in the rat heart one hour after isoproterenol (a β stimulator) injection. Male Sprague-Dawley rats were assigned into three groups and received subcutaneous injection of normal sarin (NS) or 0.1 mg/kg isoproterenol (ISO-0.1) or 10 mg/kg isoproterenol (ISO-10). After one hour, we collected their heart and plasma. Total RNA was extracted from the left ventricle and used for deep miRNA sequencing. Based on the results of miRNA sequencing, we performed real-time polymerase chain reaction (RT-PCR) using 8 miR primers. Cardiac injury was evaluated by hematoxylin and eosin, and phosphotungstic acid-hematoxylin staining and measuring troponin-I levels in plasma. Troponin-I was significantly increased in ISO-0.1 and ISO-10 groups, but histological observation did not show any cardiac necrosis. miRNA sequencing identified 14 upregulated miRs and 12 downregulated miRs. Of the 26 miRs, RT-PCR confirmed miR-144-3p/5p and miR-451-5p were decreased, and that 5 miRs (miR-27a-5p, miR-30b-3p, miR-92a-1-5p, miR-132-5p, miR-582-3p) were upregulated. This study showed that β stimulus causes downregulation of miR-144/451 cluster and increases expression of five 5 miRs in the heart, especially 6.5-fold upregulation of miR-27a-5p as early as one hour after isoproterenol injection. Therefore, these miRs might be good biomarkers for cardiac injury.

BACKGROUND: The miR-451 has been reported to play an important role in colorectal cancer (CRC) pathogenesis and can be a pivotal diagnosis biomarker of CRC. Given the contradictions in the diagnosis value of the miR-451 in patients with CRC, deciphering the diagnostic/prognostic role of this miRNA in CRC will support the identification of a novel therapeutic target for CRC. Therefore, in the present meta-analysis, we evaluated the diagnostic value of miR-451 in CRC patients.
METHODS: The electronic databases of Embase, PubMed, ISI Web of Science, and Scopus systematically searched for relevant studies. The odds ratio (OR) with a 95% confidence interval (CI) was calculated to evaluate the association between miR-451 family expression and diagnosis of colorectal cancer. The parameters including sensitivity, specificity, and area under the curve (AUC) were obtained. The quality of evidence was evaluated using the Newcastle-Ottava Scale (NOS).
RESULTS: This study involved 510 patients (45% female and 55% male) with CRC. The pooled analysis of the studies showed a significant association between low expression levels of miR-451 in patients with CRC (OR = 7.59; 95% CI 2.39 - 24.07; p = 0.001). The overall sensitivity and specificity were 0.95 (0.61 - 1) and 0.83 (0.43 - 0.99), respectively. The pooled AUC was 0.97 (0.88 - 1; p < 0.006). Results showed if the pre-test probability is 50% for a patient, the post-test probability will be 85%. The indices demonstrated the high potency of miR-451 as a diagnostic biomarker in patients with CRC. No publication bias was observed using the Begg\'s (p=0.85) and Egger\'s tests (p=0.45).
CONCLUSIONS: A strong relationship between the low expression levels of miR-451 and CRC progression was observed. This finding suggests the miR-451 family may be helpful as a potential biomarker for the earlier diagnosis of colorectal cancer.

BACKGROUND: Type 2 cardiorenal syndrome (CRS) is a progressive renal insufficiency in patients with chronic heart failure, but its pathophysiology is still unclear. The Chinese medicine Zhenwu Decoction plays an important role in the prevention and treatment of 2-CRS, however, its mechanism of action remains unknown.
OBJECTIVE: The aim of this study was to investigate whether the ameliorative effect of ZWD on 2-CRS renal fibrosis is related to the modulation of miR-451 expression and thus mediating the TLR4/NF-κB/HIF-1α loop.
METHODS: A type 2 CRS rat model was constructed using ligation of the left anterior descending branch of the coronary artery + 3/4 nephrectomy, and randomly divided into Control, Sham, Model, Captopril, ZWD-L, ZWD-M and ZWD-H groups.After 4 weeks of ZWD intervention, its effects on cardiac and renal functions of type 2 CRS rats were observed by hematuria and cardiac ultrasonography. Changes in kidney tissue morphology were observed by HE, Masson and PASM staining. The protein and mRNA expression of TLR4, NF-κB, HIF-1α and IκBα in kidney tissues were detected by immunohistochemistry and qPCR. Immunofluorescence was used to detect the protein expression of NF-κB and HIF-1α in renal tissues. Western blot and qPCR were used to detect the protein expression of MCP-1, ICAM-1, IL-1β, IL-6, TGF-β, α-SMA, FN, Smad2, Smad3, and E-cadherin in renal tissues. PCR was used to detect the protein expression of miR-451mRNA expression level in kidney tissues.
RESULTS: In this study, we found that ZWD was able to reduce the expression of Scr, BUN, NT-proBNP, and 24-hour quantitative urine protein, elevate LVEF, FS, CO, and reduce the level of LVIDS in type 2 CRS rats, as well as attenuate renal interstitial fibrosis and improve tubular swelling. In addition, Zhenwu Decoction up-regulated the expression of miR-451 in renal tissues and inhibited the expression of TLR4, NF-κB, and HIF-1α proteins and genes, which in turn inhibited the expression of inflammatory factors and fibrosis-related factors.
CONCLUSIONS: ZWD was able to up-regulate the expression of miR-451 in renal tissues, inhibit the TLR4/NF-κB/HIF-1α response loop, and then inhibit the expression of inflammatory factors and fibrosis-related factors, improve renal fibrosis, and delay the pathological process of type 2 CRS.

Intracerebral hemorrhage (ICH) is a subtype of stroke with the highest fatality and disability rate. Up to now, commonly used first-line therapies have limited value in improving prognosis. Angiogenesis is essential to neurological recovery after ICH. Recent studies have shown that microRNA-451(miR-451) plays an important role in angiogenesis by regulating the function of vascular endothelial cells. We found miR-451 was significantly decreased in the peripheral blood of ICH patients in the acute stage. Based on the clinical findings, we conducted this study to investigate the potential regulatory effect of miR-451 on angiogenesis after ICH. The expression of miR-451 in ICH mouse model and in a hemin toxicity model of human brain microvascular endothelial cells (hBMECs) was decreased the same as in ICH patients. MiR-451 negatively regulated the proliferation, migration, and tube formation of hBMECs in vitro. MiR-451 negatively regulated the microvessel density in the perihematoma tissue and affected neural functional recovery of ICH mouse model. Knockdown of miR-451 could recovered tight junction and protect the integrity of blood-brain barrier after ICH. Based on bioinformatic programs, macrophage migration inhibitory factor (MIF) was predicted to be the target gene and identified to be regulated by miR-451 inhibiting the protein translation. And p-AKT and p-ERK were verified to be downstream of MIF in angiogenesis. These results all suggest that miR-451 will be a potential target for regulating angiogenesis in ICH.

microRNAs are a class of small RNAs that have been extensively studied, which are involved in many biological processes and disease occurrence. The incidence of intrauterine growth restriction is higher in mammals, especially multiparous mammals. In this study, we found that the weight of the longissimus dorsi of intrauterine growth-restricted pigs was significantly lower than that of normal pigs. Then, intrauterine growth-restricted pig longissimus dorsi were used to characterize miRNA expression profiles by RNA sequencing. A total of 333 miRNAs were identified, of which 26 were differentially expressed. Functional enrichment analysis showed that these differentially expressed miRNAs regulate the expression of their target genes (such as PIK3R1, CCND2, AKT3, and MAP3K7), and these target genes play an important role in the proliferation and differentiation of skeletal muscle through signaling pathways such as the PI3K-Akt, MAPK, and FoxO signaling pathways. Furthermore, miRNA-451 was significantly upregulated in IUGR pig skeletal muscle. Overexpression of miR-451 in C2C12 cells significantly promoted the expression of Mb, Myod, Myog, Myh1, and Myh7, suggesting that miR-451 may be involved in the regulation of the myoblastic differentiation of C2C12 cells. Our results reveal the role of miRNA-451 in regulating myogenic differentiation of skeletal muscle in pigs with intrauterine growth restriction.

BACKGROUND: Lung cancer is a leading cause of cancer mortality. It is one of the most abundant cancer types clinically, with 2 million new cases diagnosed yearly.
OBJECTIVE: Using clinically collected non-small cell lung cancer (NSCLC) samples, we sought to hypothesize an innovative intact signaling cascade for the disorder.
METHODS: We dissected snap-frozen NSCLC tissues along with sibling-paired nearby non-tumorous tissues from 108 NSCLC patients. We measured the expression levels of miR-451/ETV4/MMP13 using qRT-PCR and did a thorough investigation of the molecular mechanism for the signaling axis in NSCLC cell line A549. We also studied the epithelial-mesenchymal transition (EMT) process.
RESULTS: The activity of miR-451 was significantly decreased in NSCLC tissues, while the expression levels of ETV4 and MMP13 were remarkably increased. At the same time, miR-451 levels maintained a declining trend across TNM stage I-III. Inversely, ETV4 and MMP13 increased as the TNM stage increased. The miR-451/ETV4/MMP13 signaling axis was closely associated with prognosis in NSCLC patients. Based on in vitro experiments, ETV4 was a direct targeting factor for miRNA-451. Meanwhile, ETV4 promoted the tumor properties of NSCLC cells by directly activating MMP13. Silencing MMP13 blocked the EMT progress of NSCLC cells.
CONCLUSIONS: Overall, we hypothesized an impeccable signaling pathway for NSCLC from a new aspect, and this can offer alternative insights for a better understanding of the disorder.

The study aimed to determine the expression of miR451 in colorectal cancer (CRC) subjects with CRC cells, and the role of miR451 in colorectal cancer cells. In October 2020, ATC purchased CRC and normal mucosal cell lines of CRC and implanted them in DMEM with 10% fetal serum. The suitability of the HT29 cell line is verified using the STR profile. In an incubator with 5% CO2, enlarged cells were placed at 37 °C. TCGA data was used to select the top 120 patients with a high voice and the lowest 120 patients with a low voice. Cells were collected and coated with Annexin V and PE according to the manufacturer\'s instructions after 24.0 h. After that, the cells were separated. Cells were also tested using flow cytometry. HCT-120 cells were transplanted into a concentration of 5×105/ml cells in 6-source plates. HCT120 cells in the experimental group were combined with miR451 mimics, miR451 inhibitors, or miR451 miR + SMAD4B for 12 h at 37 °C, and cells were collected 24 h later at 37 °C. The sample was injected with 5 ml of Annexin VFITC and PE. Compared with normal colorectal mucosal cells, CRC cell lines decreased miR451 expression levels (fetal human cells (FHC) and HCoEpiC). Then, the HCT120 cells were transfected with miR451 inhibitors, and 72 h after transfection, say of miR451 was normal. There was a significant decrease in cell function in the miR451mimic groups, but an increase when the miR451 was blocked. The proliferation of cancer cells was prevented and chemotherapy was effective when miR451 was overexpressed. The SMAD4 gene provides instructions for making a protein involved in transmitting chemical signals from the cell surface to the nucleus. The SMAD4B expression was tested by RT-qPCR and Western blotting after 72.0 h of transmission. The mRNA and protein expression of SMAD4B decreased significantly when miR451 was significantly higher than when inhibited, as revealed in the results of this study. Seventy-two hours after transplantation, mRNA levels and SMAD4B proteins were measured in HCT120 cells. In addition, the researchers in this study investigated whether miR451 was associated with SMAD4B-directed control of CRC growth and migration. It was found that SMAD4B is highly expressed in both CRC and para-cancer tissues while using the TCGA database to detect SMAD4B expression. Patients with CRC with SMAD4B have a severe prognosis. MiR451 is sensitive to depressive disorders by targeting SMAD4B, according to these studies. We found that miR451 inhibited cell growth and migration, made CRC cells more readily available in chemotherapy, and did so by targeting SMAD4B. The findings suggest that miR451 and its genetic predisposition, SMAD4B, may help predict the prognosis and course of cancer patients. Treatments that target the miR451/SMAD4B axis may be helpful to people with CRC.

BACKGROUND: Cholangiocarcinoma is a kind of invasive malignant tumor followed by hepatocellular carcinoma. miR-451 was suggested to function as regulator in various human tumors, but its role in mediating tumor progression and predicting the prognosis of cholangiocarcinoma remains unknown. The clinical significance and biological function of miR-451 in cholangiocarcinoma were assessed in this study.
RESULTS: The tissue and serum expression of miR-451 was decreased in cholangiocarcinoma compared with corresponding normal samples. The downregulation of miR-451 was associated with the progressive TNM stage and positive lymph node metastasis of patients. miR-451 was identified to be an indicator of the diagnosis and prognosis of cholangiocarcinoma distinguishing cholangiocarcinoma patients from healthy volunteers and predicting the poor outcome of patients. miR-451 also served as a tumor suppressor negatively regulating the cellular processes of cholangiocarcinoma.
CONCLUSIONS: miR-451 played a vital role in the early detection and risk prediction of cholangiocarcinoma. miR-451 also suppressed the progression of cholangiocarcinoma, which provides a potential therapeutical target for cholangiocarcinoma treatment.