MicroRNA miR-24-3p promotes porcine reproductive and respiratory syndrome virus replication through suppression of heme oxygenase-1 expression

Host cells reprogram lipid droplet synthesis through YY1 to resist PRRSV infection

Metabolism in host cells can be modulated after viral infection, favoring viral survival or clearance. Here, we report that lipid droplet (LD) synthesis in host cells can be modulated by yin yang 1 (YY1) after porcine reproductive and respiratory syndrome virus (PRRSV) infection, resulting in active antiviral activity. As a ubiquitously distributed transcription factor, there was increased expression of YY1 upon PRRSV infection both in vitro and in vivo. YY1 silencing promoted the replication of PRRSV, whereas YY1 overexpression inhibited PRRSV replication. PRRSV infection led to a marked increase in LDs, while YY1 knockout inhibited LD synthesis, and YY1 overexpression enhanced LD accumulation, indicating that YY1 reprograms PRRSV infection-induced intracellular LD synthesis. We also showed that the viral components do not colocalize with LDs during PRRSV infection, and the effect of exogenously induced LD synthesis on PRRSV replication is nearly lethal. Moreover, we demonstrated that YY1 affects the synthesis of LDs by regulating the expression of lipid metabolism genes. YY1 negatively regulates the expression of fatty acid synthase (FASN) to weaken the fatty acid synthesis pathway and positively regulates the expression of peroxisome proliferator-activated receptor gamma (PPARγ) to promote the synthesis of LDs, thus inhibiting PRRSV replication. These novel findings indicate that YY1 plays a crucial role in regulating PRRSV replication by reprogramming LD synthesis. Therefore, our study provides a novel mechanism of host resistance to PRRSV and suggests potential new antiviral strategies against PRRSV infection.IMPORTANCEPorcine reproductive and respiratory virus (PRRSV) has caused incalculable economic damage to the global pig industry since it was first discovered in the 1980s. However, conventional vaccines do not provide satisfactory protection. It is well known that viruses are parasitic pathogens, and the completion of their replication life cycle is highly dependent on host cells. A better understanding of host resistance to PRRSV infection is essential for developing safe and effective strategies to control PRRSV. Here, we report a crucial host antiviral molecule, yin yang 1 (YY1), which is induced to be expressed upon PRRSV infection and subsequently inhibits virus replication by reprogramming lipid droplet (LD) synthesis through transcriptional regulation. Our work provides a novel antiviral mechanism against PRRSV infection and suggests that targeting YY1 could be a new strategy for controlling PRRSV.

Porcine reproductive and respiratory syndrome virus infection induces microRNA novel-216 production to facilitate viral-replication by targeting MAVS 3´UTR

Porcine reproductive and respiratory syndrome virus (PRRSV) has caused significant economic losses in the swine industry. In this study, the high-throughput sequencing, microRNAs (miRNAs) mimic, and lentivirus were used to screen for potential miRNAs that can promote PRRSV infection in porcine alveolar macrophages or Marc-145 cells. It was observed that novel-216, a previously unidentified miRNA, was upregulated through the p38 signaling pathway during PRRSV infection, and its overexpression significantly increased PRRSV replication. Further analysis revealed that novel-216 regulated PRRSV replication by directly targeting mitochondrial antiviral signaling protein (MAVS), an upstream molecule of type Ⅰ IFN that mediates the production and response of type Ⅰ IFN. The proviral function of novel-216 on PRRSV replication was abolished by MAVS overexpression, and this effect was reversed by the 3'UTR of MAVS, which served as the target site of novel-216. In conclusion, this study demonstrated that PRRSV-induced upregulation of novel-216 served to inhibit the production and response of typeⅠ IFN and facilitate viral replication, providing new insights into viral immune evasion and persistent infection.

Role of microRNAs in host defense against porcine reproductive and respiratory syndrome virus infection: a hidden front line

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most globally devastating viruses threatening the swine industry worldwide. Substantial advancements have been achieved in recent years towards comprehending the pathogenesis of PRRSV infection and the host response, involving both innate and adaptive immune responses. Not only a multitude of host proteins actively participate in intricate interactions with viral proteins, but microRNAs (miRNAs) also play a pivotal role in the host response to PRRSV infection. If a PRRSV-host interaction at the protein level is conceptualized as the front line of the battle between pathogens and host cells, then their fight at the RNA level resembles the hidden front line. miRNAs are endogenous small non-coding RNAs of approximately 20-25 nucleotides (nt) that primarily regulate the degradation or translation inhibition of target genes by binding to the 3'-untranslated regions (UTRs). Insights into the roles played by viral proteins and miRNAs in the host response can enhance our comprehensive understanding of the pathogenesis of PRRSV infection. The intricate interplay between viral proteins and cellular targets during PRRSV infection has been extensively explored. This review predominantly centers on the contemporary understanding of the host response to PRRSV infection at the RNA level, in particular, focusing on the twenty-six miRNAs that affect viral replication and the innate immune response.

Action mechanisms and characteristics of miRNAs to regulate virus replication

MicroRNAs (miRNAs) have the potential to be explored as antiviral products. It is known that miRNAs have different kinds of target mRNAs and different target sites in mRNAs, and that the action-modes of miRNAs at different target sites may be different. But there is no evidence demonstrating the significance of the differences for the regulation of viruses by miRNAs, which might be crucial for the exploration of miRNA-based antiviral products. Here the experimental studies about the antiviral effects of miRNAs, with validated target mRNAs and target sites in the mRNAs, were systematically collected, based on which the mechanisms whereby miRNAs regulated virus replication were systematically reviewed. And miRNAs' down-regulation rates on target mRNAs and antiviral rates were compared among the miRNAs with different target sites, to analyze the characteristics of action-modes of miRNAs at different target sites during virus replication.

Regulatory Non-Coding RNAs during Porcine Viral Infections: Potential Targets for Antiviral Therapy

Pigs play important roles in agriculture and bio-medicine; however, porcine viral infections have caused huge losses to the pig industry and severely affected the animal welfare and social public safety. During viral infections, many non-coding RNAs are induced or repressed by viruses and regulate viral infection. Many viruses have, therefore, developed a number of mechanisms that use ncRNAs to evade the host immune system. Understanding how ncRNAs regulate host immunity during porcine viral infections is critical for the development of antiviral therapies. In this review, we provide a summary of the classification, production and function of ncRNAs involved in regulating porcine viral infections. Additionally, we outline pathways and modes of action by which ncRNAs regulate viral infections and highlight the therapeutic potential of artificial microRNA. Our hope is that this information will aid in the development of antiviral therapies based on ncRNAs for the pig industry.

Deletion of a 7-amino-acid region in the porcine epidemic diarrhea virus envelope protein induces higher type I and III interferon responses and results in attenuation in vivo

Porcine epidemic diarrhea virus (PEDV) leads to enormous economic losses for the pork industry. However, the commercial vaccines failed to fully protect against the epidemic strains. Previously, the rCH/SX/2016-SHNXP strain with the entire E protein and the rCH/SX/2015 strain with the deletion of 7-amino-acid (7-aa) at positions 23-29 in E protein were constructed and rescued. The pathogenicity assay indicated that rCH/SX/2015 is an attenuated strain, but rCH/SX/2016-SHNXP belongs to the virulent strains. Then, the recombination PEDV (rPEDV-EΔaa23-aa29)strain with a 7-aa deletion in the E protein was generated, using the highly virulent rCH/SX/2016-SHNXP strain (rPEDV-Ewt) as the backbone. Compared with the rPEDV-Ewt strain, the release and infectivity of the rPEDV-EΔaa23-aa29 strain were significantly reduced in vitro, but stronger interferon (IFN) responses were triggered both in vitro and in vivo. The pathogenicity assay showed that the parental strain resulted in severe diarrhea (100%) and death (100%) in all piglets. Compared with the parental strain group, rPEDV-EΔaa23-aa29 caused lower mortality (33%) and diminished fecal PEDV RNA shedding. At 21 days, all surviving pigs were challenged orally with rPEDV-Ewt. No pigs died in the two groups. Compared with the mock group, significantly delayed and milder diarrhea and reduced fecal PEDV RNA shedding were detected in the rPEDV-EΔaa23-aa29 group. In conclusion, the deletion of a 7-aa fragment in the E protein (EΔaa23-aa29) attenuated PEDV but retained its immunogenicity, which can offer new ideas for the design of live attenuated vaccines and provide new insights into the attenuated mechanism of PEDV. IMPORTANCE Porcine epidemic diarrhea virus (PEDV) causes high mortality in neonatal piglets and remains a large challenge to the pork industry. Unfortunately, no safe and effective vaccines are available yet. The pathogenesis and molecular basis of the attenuation of PEDV remain unclear, which seriously hinders the development of PEDV vaccines. This study found that the rPEDV carrying EΔaa23-aa29 mutation in the E protein induced significantly higher IFN responses than the parental virus, partially attenuated, and remained immunogenic in piglets. For the first time, PEDV E was verified as an IFN antagonist in the infection context and identified as a virulence factor of PEDV. Our data also suggested that EΔaa23-aa29 mutation can be a good target for the development of live attenuated vaccines for PEDV and also provide new perspectives for the attenuated mechanism of PEDV.

Evasion strategies of porcine reproductive and respiratory syndrome virus

During the co-evolution of viruses and their hosts, viruses have developed various strategies for overcoming host immunological defenses so that they can proliferate efficiently. Porcine reproductive and respiratory syndrome virus (PRRSV), a significant virus to the swine industry across the world, typically establishes prolonged infection via diverse and complicated mechanisms, which is one of the biggest obstacles for controlling the associated disease, porcine reproductive and respiratory syndrome (PRRS). In this review, we summarize the latest research on how PRRSV circumvents host antiviral responses from both the innate and adaptive immune systems and how this virus utilizes other evasion mechanisms, such as the manipulation of host apoptosis and microRNA. A thorough understanding of the exact mechanisms of PRRSV immune evasion will help with the development of novel antiviral strategies against PRRSV.

Systematic Identification and Comparison of the Expressed Profiles of Exosomal MiRNAs in Pigs Infected with NADC30-like PRRSV Strain

Exosomes are biological vesicles secreted and released by cells that act as mediators of intercellular communication and play a unique role in virus infection, antigen presentation, and suppression/promotion of body immunity. Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most damaging pathogens in the pig industry and can cause reproductive disorders in sows, respiratory diseases in pigs, reduced growth performance, and other diseases leading to pig mortality. In this study, we used the PRRSV NADC30-like CHsx1401 strain to artificially infect 42-day-old pigs and isolate serum exosomes. Based on high-throughput sequencing technology, 305 miRNAs were identified in serum exosomes before and after infection, among which 33 miRNAs were significantly differentially expressed between groups (13 relatively upregulated and 20 relatively downregulated). Sequence conservation analysis of the CHsx1401 genome identified 8 conserved regions, of which a total of 16 differentially expressed (DE) miRNAs were predicted to bind to the conserved region closest to the 3' UTR of the CHsx1401 genome, including 5 DE miRNAs capable of binding to the CHsx1401 3' UTR (ssc-miR-34c, ssc-miR-375, ssc-miR-378, ssc-miR-486, ssc-miR-6529). Further analysis revealed that the target genes of differentially expressed miRNAs were widely involved in exosomal function-related and innate immunity-related signaling pathways, and 18 DE miRNAs (ssc-miR-4331-3p, ssc-miR-744, ssc-miR-320, ssc-miR-10b, ssc-miR-124a, ssc-miR-128, etc.) associated with PRRSV infection and immunity were screened as potential functional molecules involved in the regulation of PRRSV virus infection by exosomes.

Small RNA sequencing and profiling of serum-derived exosomes from African swine fever virus-infected pigs

African swine fever (ASF) virus (ASFV) is responsible for one of the most severe swine diseases worldwide, with a morbidity rate of up to 100%; no vaccines or antiviral medicines are available against the virus. Exosomal miRNAs from individual cells can regulate the immune response to infectious diseases. In this study, pigs were infected with an ASFV Pig/HN/07 strain that was classified as acute form, and exosomal miRNA expression in the serum of infected pigs was analyzed using small RNA sequencing (small RNA-seq). Twenty-seven differentially expressed (DE) miRNAs were identified in the ASFV-infected pigs compared to that in the uninfected controls. Of these, 10 were upregulated and 17 were downregulated in the infected pigs. All DE miRNAs were analyzed using gene ontology (GO) terms and the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, and the DE miRNAs were found to be highly involved in T-cell receptor signaling, cGMP-PKG signaling, Toll-like receptor, MAPK signaling, and mTOR signaling pathways. Furthermore, the Cytoscape network analysis identified the network of interactions between DE miRNAs and target genes. Finally, the transcription levels of four miRNA genes (ssc-miR-24-3p, ssc-miR-130b-3p, ssc-let-7a, and ssc-let-7c) were examined using quantitative real-time PCR (qRT-PCR) and were found to be consistent with the small RNA-seq data. These DE miRNAs were associated with cellular genes involved in the pathways related to immune response, virus-host interactions, and several viral genes. Overall, our findings provide an important reference and improve our understanding of ASF pathogenesis and the immune or protective responses during an acute infection in the host.

Comparative transcriptomics reveals small RNA composition and differential microRNA responses underlying interferon-mediated antiviral regulation in porcine alveolar macrophages

Previous studies have shown that interferon-mediated antiviral activity is subtype-dependent. Using a whole transcriptome procedure, we aimed to characterize the small RNA transcriptome (sRNA-Seq) and specifically the differential microRNA (miRNA) responses in porcine alveolar macrophages (PAMs) upon antiviral activation during viral infection and interferon (IFN) stimulation. Data showed that near 90% of the qualified reads of sRNA were miRNAs, and about 10% of the other sRNAs included rRNA, snoRNA, snRNA, and tRNA in order of enrichment. As the majority of sRNA (>98%) were commonly detected in all PAM samples under different treatments, about 2% sRNA were differentially expressed between the different antiviral treatments. Focusing on miRNA, 386 miRNA were profiled, including 331 known and 55 novel miRNA sequences, of which most were ascribed to miRNA families conserved among vertebrates, particularly mammalian species. Of the miRNA profiles comparably generated across the different treatments, in general, significantly differentially expressed miRNA (SEM) demonstrated that: (1) the wild-type and vaccine strains of a porcine arterivirus (a.k.a., PRRSV) induced nearly reversed patterns of up- or down-regulated SEMs; (2) similar SEM patterns were found among the treatments by the vaccine strain and antiviral IFN-α1/-ω5 subtypes; and (3) the weak antiviral IFN-ω1, however, remarked a suppressive SEM pattern as to SEMs upregulated in the antiviral treatments by the vaccine and IFN-α1/-ω5 subtypes. Further articulation identified SEMs commonly or uniquely expressed in different treatments, and experimentally validated that some SEMs including miR-10b and particularly miR-9-1 acted significantly in regulation of differential antiviral reactions stimulated by different IFN subtypes. Therefore, this study provides a general picture of porcine sRNA composition and pinpoints key SEMs underlying antiviral regulation in PAMs correlated to a typical respiratory RNA virus in pigs.

Analysis of miRNA Expression Profiling of RIP2 Knockdown in Chicken HD11 Cells When Infected with Avian Pathogenic E. coli (APEC)

Colibacillosis is an acute and chronic avian disease caused by avian pathogenic E. coli (APEC). Previous studies have demonstrated that RIP2 plays a significant role in APEC infection. Moreover, increasing evidence indicates that microRNAs (miRNAs) are involved in host–pathogen interactions and the immune response. However, the role of miRNAs in the host against APEC infection remains unclear. Herein, we attempted to reveal new miRNAs potentially involved in the regulation of the immune and inflammatory response against APEC infection, with a particular focus on those possibly correlated with RIP2 expression, via miRNA-seq, RT-qPCR, Western blotting, dual-luciferase reporter assay, and CCK-8. The results showed that a total of 93 and 148 differentially expressed (DE) miRNAs were identified in the knockdown of RIP2 cells following APEC infection (shRIP2+APEC) vs. knockdown of RIP2 cells (shRIP2) and shRIP2 vs. wild-type cells (WT), respectively. Among those identified DE miRNAs, the biological function of gga-miR-455-5p was investigated. It was found that gga-miR-455-5p regulated by RIP2 was involved in the immune and inflammatory response against APEC infection via targeting of IRF2 to modulate the expression of type I interferons. Additionally, RIP2 could directly regulate the production of the type I interferons. Altogether, these findings highlighted the crucial role of miRNAs, especially gga-miR-455-5p, in host defense against APEC infection.

Mycobacterium avium subsp. paratuberculosis exploits miRNA expression to modulate lipid metabolism and macrophage polarisation pathways during infection

Pathogenic mycobacteria including Mycobacterium avium subsp. paratuberculosis (MAP), the causative agent of Johne's disease, manipulate host macrophages to persist and cause disease. In mycobacterial infection, highly plastic macrophages, shift between inflammatory M1 and permissive M2 phenotypes which alter the disease outcome and allow bacteria to survive intracellularly. Here we examine the impact of MAP infection on polarised macrophages and how increased lipid availability alters macrophage phenotype and bacterial persistence. Further, we assess if host microRNA (miRNA) are sensitive to macrophage polarisation state and how MAP can drive their expression to overcome innate responses. Using in vitro MAP infection, we find that increasing lipid availability through supplementing culture media with exogenous lipid increases cellular nitric oxide production. Lipid-associated miRs -19a, -129, -24, and -24-3p are differentially expressed following macrophage polarisation and lipid supplementation and are further regulated during MAP infection. Collectively, our results highlight the importance of host lipid metabolism in MAP infection and demonstrate control of miRNA expression by MAP to favour intracellular persistence.

Roles of Heme Oxygenase-1 in Neuroinflammation and Brain Disorders

The heme oxygenase (HO) system is believed to be a crucial mechanism for the nervous system under stress conditions. HO degrades heme to carbon monoxide, iron, and biliverdin. These heme degradation products are involved in modulating cellular redox homeostasis. The first identified isoform of the HO system, HO-1, is an inducible protein that is highly expressed in peripheral organs and barely detectable in the brain under normal conditions, whereas HO-2 is a constitutive protein that is highly expressed in the brain. Several lines of evidence indicate that HO-1 dysregulation is associated with brain inflammation and neurodegeneration, including Parkinson’s and Alzheimer’s diseases. In this review, we summarize the essential roles that the HO system plays in ensuring brain health and the molecular mechanism through which HO-1 dysfunction leads to neurodegenerative diseases and disruption of nervous system homeostasis. We also provide a summary of the herbal medicines involved in the regulation of HO-1 expression and explore the current situation regarding herbal remedies and brain disorders.

Molecular Mechanism of Porcine Epidemic Diarrhea Virus Cell Tropism

In the 21st century, several human and swine coronaviruses (CoVs) have emerged suddenly and caused great damage to people's lives and property. The porcine epidemic diarrhea virus (PEDV), leading to enormous economic losses to the pork industry and remains a large challenge. PEDV showed extensive cell tropism, and we cannot ignore the potential risk of cross-species transmission. However, the mechanism of adaptation and cell tropism of PEDV remains largely unknown and in vitro isolation of PEDV remains a huge challenge, which seriously impedes the development of vaccines. In this study, we confirmed that the spike (S) protein determines the adaptability of PEDV to monkey Vero cells and LLC-PK1 porcine cells, and isolated exchange of S1 and S2 subunits of adaptive strains did not make PEDV adapt to cells. Further, we found that the cellular adaptability of rCH/SX/2016-S_HNXP depends on S1 and the first half of S2 (S3), and the 803L and 976H of the S2 subunit are critical for rCH/SX/2016-S1_HNXP+S3_HNXP adaptation to Vero cells. These findings highlight the decisive role of PEDV S protein in cell tropism and the potential role of coronaviruses S protein in cross-species transmissibility. Besides, our work also provides some different insight into finding PEDV receptors and developing PEDV and other coronaviruses vaccines. IMPORTANCE CoVs can spill from an animal reservoir into a naive host to cause diseases in humans or domestic animals. PEDV results in high mortality in piglets, which has caused immense economic losses in the pork industry. Virus isolation is the first step in studying viral pathogenesis and developing effective vaccines. However, the molecular mechanism of PEDV cell tropism is largely unknown, and isolation of endemic PEDV strains remains a major challenge. This study confirmed that the S gene is the decisive gene of PEDV adaptability to monkey Vero cells and porcine LLC-PK1 cells by the PEDV reverse genetics system. Isolated exchange of S1 and S2 of adaptive strains did not make PEDV adapt to cells, and the 803L and 976H of S2 subunit are critical for rCH/SX/2016-S1_HNXP+S3_HNXP adaptation to Vero cells. These results illustrate the decisive role of PEDV S protein in cell tropism and highlight the potential role of coronaviruses S protein in cross-species transmissibility. Besides, our finding also provides some unique insight into identifying PEDV functional receptors and has guiding significance for developing PEDV and other coronavirus vaccines.

Host Cells Actively Resist Porcine Reproductive and Respiratory Syndrome Virus Infection via the IRF8-MicroRNA-10a-SRP14 Regulatory Pathway

MicroRNAs (miRNAs) play an important role in the virus-host interaction. Our previous work has indicated that the expression level of miR-10a increased in porcine alveolar macrophages (PAMs) during porcine reproductive and respiratory syndrome virus (PRRSV) infection and further inhibited viral replication through downregulates the expression of host molecule signal-recognition particle 14 (SRP14) protein. However, the molecular mechanism of miR-10a increased after PRRSV infection remains unknown. In the present study, transcription factor interferon regulatory factor 8 (IRF8) was identified as a negative regulator of miR-10a. PRRSV infection decreases the expression level of IRF8 in PAMs, leading to upregulating miR-10a expression to play an anti-PRRSV role. Meanwhile, this work first proved that IRF8 promoted PRRSV replication in an miR-10a-dependent manner. Further, we explained that SRP14, the target gene of miR-10a, promotes the synthesis of the PRRSV genome by interacting with the viral components Nsp2, thus facilitating PRRSV replication. In conclusion, we identified a novel IRF8-miR-10a-SRP14 regulatory pathway against PRRSV infection, which provides new insights into virus-host interactions and suggests potential new antiviral strategies to control PRRSV. IMPORTANCE Porcine reproductive and respiratory syndrome virus (PRRSV) has rapidly spread to the global pig industry and caused incalculable economic damage since first discovered in the 1980s. However, conventional vaccines do not provide satisfactory protection. Understanding the molecular mechanisms of host resistance to PRRSV infection is necessary to develop safe and effective strategies to control PRRSV. During viral infection, miRNAs play vital roles in regulating the expression of viral or host genes at the posttranscriptional level. The significance of our study is that we revealed the transcriptional regulation mechanism of the antiviral molecule miR-10a after PRRSV infection. Moreover, our research also explained the mechanism of host molecule SRP14, the target gene of miR-10a regulating PRRSV replication. Thus, we report a novel regulatory pathway of IRF8-miR-10a-SRP14 against PRRSV infection, which provides new insights into virus-host interactions and suggests potential new control measures for future PRRSV outbreaks.

The long non-coding RNA LNC_000397 negatively regulates PRRSV replication through induction of interferon-stimulated genes

Background

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most significant threats to the global swine industry. It is of great importance to understand viral-host interactions to develop novel antiviral strategies. Long non-coding RNAs (lncRNAs) have emerged as critical factors regulating host antiviral immune responses. However, lncRNAs participating in virus-host interactions during PRRSV infection remain largely unexplored.

Method

RNA transcripts of porcine alveolar macrophages (PAMs) infected with two different PRRSV strains, GSWW/2015 and VR2332, at 24 h post-infection were sequenced by high-throughput sequencing. Four programs namely, CNCI, CPC, PFAM, and phyloCSF, were utilized to predict the coding potential of transcripts. mRNAs co-localized or co-expressed with differentially expressed lncRNAs were considered as their targets. Fuction of lncRNAs was predicted by GO and KEGG analysis of their target mRNAs. The effect of LNC_000397 on PRRSV replication was validated by knockdown its expression using siRNA. Target genes of LNC_000397 were identified by RNA-Sequencing and validated by RT-qPCR.

Result

In this study, we analyzed lncRNA and mRNA expression profiles of PRRSV GSWW/2015 and VR2332 infected porcine alveolar macrophages. A total of 1,147 novel lncRNAs were characterized, and 293 lncRNAs were differentially expressed. mRNAs co-localized and co-expressed with lncRNAs were enriched in pathogen-infection-related biological processes such as Influenza A and Herpes simplex infection. Functional analysis revealed the lncRNA, LNC_000397, which was up-regulated by PRRSV infection, negatively regulated PRRSV replication. Knockdown of LNC_000397 significantly impaired expression of antiviral ISGs such as MX dynamin-like GTPase 1 (MX1), ISG15 Ubiquitin-like modifier (ISG15), and radical S-adenosyl methionine domain containing 2 (RSAD2).

Conclusions

LNC_000397 negatively regulated PRRSV replication by inducing interferon-stimulated genes (ISGs) expression. Our study is the first report unveiling the role of host lncRNA in regulating PRRSV replication, which might be beneficial for the development of novel antiviral therapeutics.

Versatile role of miR-24/24-1*/24-2* expression in cancer and other human diseases

MiRNAs (miRs) have been proven to be well-validated therapeutic targets. Emerging evidence has demonstrated that intricate, intrinsic and paradoxical functions of miRs are context-dependent because of their multiple upstream regulators, broad spectrum of downstream molecular targets and distinct expression in various tissues, organs and disease states. Targeted therapy has become an emerging field of research. One key for the development of successful miR-based/targeted therapy is to acquire integrated knowledge of its regulatory network and its association with disease phenotypes to identify critical nodes of the underlying pathogenesis. Herein, we systematically summarized the comprehensive role of miR-24-3p (miR-24), along with its passenger strands miR-24-1-5p* (miR-24-1) and miR-24-2-5p* (miR-24-2), emphasizing their microenvironment, intracellular targets, and associated gene networks and regulatory phenotypes in 18 different cancer types and 13 types of other disorders. MiR-24 targets and regulates numerous genes in various cancer types and enhances the expression of several oncogenes (e.g., cMyc, BCL2 and HIF1), which are challenging in terms of druggability. In contrast, several tumor suppressor proteins (p21 and p53) have been reported to be downregulated by miR-24. MiR-24 also regulates the cell cycle and is associated with numerous cancer hallmarks such as apoptosis, proliferation, metastasis, invasion, angiogenesis, autophagy, drug resistance and other diseases pathogenesis. Overall, miR-24 plays an emerging role in the diagnosis, prognosis and pathobiology of various diseases. MiR-24 is a potential target for targeted therapy in the era of precision medicine, which expands the landscape of targetable macromolecules, including undruggable proteins.

Porcine Reproductive and Respiratory Syndrome Virus Evades Antiviral Innate Immunity via MicroRNAs Regulation

Porcine reproductive and respiratory syndrome (PRRS) is one of the most important diseases in pigs, leading to significant economic losses in the swine industry worldwide. MicroRNAs (miRNAs) are small single-stranded non-coding RNAs involved in regulating gene expressions at the post-transcriptional levels. A variety of host miRNAs are dysregulated and exploited by PRRSV to escape host antiviral surveillance and help virus infection. In addition, PRRSV might encode miRNAs. In this review, we will summarize current progress on how PRRSV utilizes miRNAs for immune evasions. Increasing knowledge of the role of miRNAs in immune evasion will improve our understanding of PRRSV pathogenesis and help us develop new treatments for PRRSV-associated diseases.

Induction of HOXA3 by PRRSV inhibits IFN-I response through negatively regulation of HO-1 transcription

Type I interferons (IFN-I) play a key role in the host defense against virus infection, but porcine reproductive and respiratory syndrome virus (PRRSV) infection does not effectively activate IFN-I response, and the underlying molecular mechanisms are poorly characterized. In this study, a novel transcription factor of the heme oxygenase-1 (HO-1) gene, homeobox A3 (HOXA3), was screened and identified. Here, we found that HOXA3 was significantly increased during PRRSV infection. We demonstrated that HOXA3 promotes PRRSV replication by negatively regulating the HO-1 gene transcription, which is achieved by regulating type I interferons (IFN-I) production. A detailed analysis showed that PRRSV exploits HOXA3 to suppress beta interferon (IFN-β) and IFN-stimulated gene (ISG) expression in host cells. We also provide direct evidence that the activation of IFN-I by HO-1 depends on its interaction with IRF3. Then we further proved that deficiency of HOXA3 promoted the HO-1-IRF3 interaction, and subsequently enhanced IRF3 phosphorylation and nuclear translocation in PRRSV-infected cells. These data suggest that PRRSV uses HOXA3 to negatively regulate the transcription of the HO-1 gene to suppress the IFN-I response for immune evasion. IMPORTANCE Porcine reproductive and respiratory syndrome (PRRS), caused by PRRSV, leads the pork industry worldwide to significant economic losses. HOXA3 is generally considered to be an important molecule in the process of body development and cell differentiation. Here, we found a novel transcription factor of the HO-1 gene, HOXA3, can negatively regulate the transcription of the HO-1 gene and play an important role in the suppression of IFN-I response by PRRSV. PRRSV induces the upregulation of HOXA3, which can negatively regulate HO-1 gene transcription, thereby weakening the interaction between HO-1 and IRF3 for inhibiting the type I IFN response. This study extends the function of HOXA3 to the virus field for the first time and provides new insights into PRRSV immune evasion mechanism.

MicroRNA-376b-3p Promotes Porcine Reproductive and Respiratory Syndrome Virus Replication by Targeting Viral Restriction Factor TRIM22

Porcine reproductive and respiratory syndrome virus is a major economically significant pathogen and has evolved several strategies to evade host's antiviral response and provide favorable conditions for survival. In the present study, we demonstrated that a host microRNA, miR-376b-3p, was upregulated by PRRSV infection through the viral components, nsp4 and nsp11, and miR-376b-3p can directly target tripartite motif-containing 22 (TRIM22) to impair its anti-PRRSV activity, thus facilitating the replication of PRRSV. Meanwhile, we found that TRIM22 induced degradation of the nucleocapsid protein (N) of PRRSV by interacting with N protein to inhibit PRRSV replication, and further study indicated that TRIM22 could enhance the activation of lysosomal pathway by interacting with LC3 to induce lysosomal degradation of N protein. In conclusion, PRRSV increased miR-376b-3p expression and hijacked the host miR-376b-3p to promote PRRSV replication by impairing the antiviral effect of TRIM22. Therefore, our finding outlines a novel strategy of immune evasion exerted by PRRSV, which is helpful for better understanding the pathogenesis of PRRSV. IMPORTANCE Porcine reproductive and respiratory syndrome virus (PRRSV) causes enormous economic losses each year in the swine industry worldwide. MicroRNAs (miRNAs) play important roles during viral infections via modulating the expression of viral or host genes at post-transcriptional level. TRIM22 has recently been identified as a key restriction factor that inhibited the replication of a number of human virus such as HIV, ECMV, HCV, HBV, IAV, and RSV. Here we showed that host miR-376b-3p could be up-regulated by PRRSV and functioned to impair the anti-PRRSV role of TRIM22 to facilitate PRRSV replication. Meanwhile, we found that TRIM22 inhibited the replication of PRRSV by interacting with viral N protein and accelerating its degradation through the lysosomal pathway. Collectively, the paper described a novel mechanism that PRRSV exploited the host miR-376b-3p to evade antiviral responses and provided a new insight into the study of virus-host interactions.

DF-1 cells prevent MG-HS infection through gga-miR-24-3p/RAP1B mediated decreased proliferation and increased apoptosis

Mycoplasma gallisepticum (MG) is a major poultry pathogen that can induce Chronic Respiratory Disease (CRD) in chickens, causing serious economic losses in the poultry industry worldwide. Increasing evidence suggests that microRNAs (miRNAs) act as a vital role in resisting microbial pathogenesis and maintaining cellular mechanism. Our previous miRNAs sequencing data showed gga-miR-24-3p expression level was significantly increased in MG-infected chicken lungs. The aim of this study is to reveal the cellular mechanism behind the MG-HS infection. We found that gga-miR-24-3p was significantly upregulated and Ras-related protein-B (RAP1B) was downregulated in chicken fibroblast cells (DF-1) with MG infection. Dual luciferase reporting assay and rescue assay confirmed that RAP1B was the target gene of gga-miR-24-3p. Meanwhile, overexpressed gga-miR-24-3p increased the levels of tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β), and significantly inhibited cell proliferation as well as promoted MG-infected DF-1 cell apoptosis, whereas inhibition of gga-miR-24-3p had the opposite effect. More importantly, the results of overexpression and knockdown of target gene RAP1B demonstrated that the presence of RAP1B promoted cell proliferation and it saved the reduced or increased cell proliferation caused by overexpression or inhibition of gga-miR-24-3p. Furthermore, the overexpression of gga-miR-24-3p could significantly inhibit the expression of MG-HS adhesion protein. Taken together, these findings demonstrate that DF-1 cells can resist MG-HS infection through gga-miR-24-3p/RAP1B mediated decreased proliferation and increased apoptosis, which provides a new mechanism of resistance to MG infection in vitro.

MicroRNAs based regulation of cytokine regulating immune expressed genes and their transcription factors in COVID-19

Background

Coronavirus disease 2019 is characterized by the elevation of a broad spectrum of inflammatory mediators associated with poor disease outcomes. We aimed at an in-silico analysis of regulatory microRNA and their transcription factors (TF) for these inflammatory genes that may help to devise potential therapeutic strategies in the future.

Methods

The cytokine regulating immune-expressed genes (CRIEG) were sorted from literature and the GEO microarray dataset. Their co-differentially expressed miRNA and transcription factors were predicted from publicly available databases. Enrichment analysis was done through mienturnet, MiEAA, Gene Ontology, and pathways predicted by KEGG and Reactome pathways. Finally, the functional and regulatory features were analyzed and visualized through Cytoscape.

Results

Sixteen CRIEG were observed to have a significant protein-protein interaction network. The ontological analysis revealed significantly enriched pathways for biological processes, molecular functions, and cellular components. The search performed in the miRNA database yielded ten miRNAs that are significantly involved in regulating these genes and their transcription factors.

Conclusion

An in-silico representation of a network involving miRNAs, CRIEGs, and TF, which take part in the inflammatory response in COVID-19, has been elucidated. Thus, these regulatory factors may have potentially critical roles in the inflammatory response in COVID-19 and may be explored further to develop targeted therapeutic strategies and mechanistic validation.

MicroRNA ssc-miR-124a exhibits antiviral activity against porcine reproductive and respiratory syndrome virus via suppression of host genes CD163

Porcine reproductive and respiratory syndrome (PRRS) is a serious infectious disease in the swine industry, which causes severe economic losses to current swine production worldwide. There are no effective antiviral strategies for preventing this disease. Previous studies showed that microRNAs (miRNAs) play important role in virus-host interactions. In this study, we demonstrated that the expression level of ssc-miR-124a was significantly downregulated during both high and low pathogenic PRRSV infection. Overexpression of ssc-miR-124a markedly inhibits PRRSV replication in PAMs. Luciferase reporter experiments and RISC immunoprecipitation assay were used to identify the ssc-miR-124a could directly target the 3'UTR of pig CD163 mRNA in a sequence-specific manner and that CD163 mRNA and protein levels were reduced in PAMs overexpressing ssc-miR-124a. These data not only provide new insights into virus-host interactions during PRRSV infection, but also suggest potential new antiviral strategies against PRRSV infection in the future.

Structural comparison of CD163 SRCR5 from different species sheds some light on its involvement in porcine reproductive and respiratory syndrome virus-2 infection in vitro

Porcine reproductive and respiratory syndrome (PRRS) is a serious disease burdening global swine industry. Infection by its etiological agent, PRRS virus (PRRSV), shows a highly restricted tropism of host cells and has been demonstrated to be mediated by an essential scavenger receptor (SR) CD163. CD163 fifth SR cysteine-rich domain (SRCR5) is further proven to play a crucial role during viral infection. Despite intense research, the involvement of CD163 SRCR5 in PRRSV infection remains to be elucidated. In the current study, we prepared recombinant monkey CD163 (moCD163) SRCR5 and human CD163-like homolog (hCD163L1) SRCR8, and determined their crystal structures. After comparison with the previously reported crystal structure of porcine CD163 (pCD163) SRCR5, these structures showed almost identical structural folds but significantly different surface electrostatic potentials. Based on these differences, we carried out mutational research to identify that the charged residue at position 534 in association with the one at position 561 were important for PRRSV-2 infection in vitro. Altogether the current work sheds some light on CD163-mediated PRRSV-2 infection and deepens our understanding of the viral pathogenesis, which will provide clues for prevention and control of PRRS.

HO-1: A new potential therapeutic target to combat osteoporosis

Heme oxygenase-1 (HO-1) exerts a protective effect against cell damage and induces the activity of many enzymes involved in the treatment of many human diseases, including osteoporosis. The increasing prevalence of osteoporosis and the limitations of the current treatments available led to a continuous occurrence of bone loss and osteoporotic fractures, highlighting the need of a better understanding of the mechanism and function of HO-1. Many factors cause osteoporosis, including lack of estrogen, aging, and iron overload, and they either cause the increase in inflammatory factors or the increase in reactive oxygen species to break bone reconstruction balance. Therefore, regulating the production of inflammatory factors and reactive oxygen species may become a strategy for the treatment of osteoporosis. Solid evidence showed that the overexpression of HO-1 compensates high oxidation levels by increasing intracellular antioxidant levels and reduces inflammation by suppressing pro-inflammatory factors. Some extracts can target HO-1 and ameliorate osteoporosis. However, no systematic report is available on therapies targeting HO-1 to combat osteoporosis. Therefore, this review summarizes the biological characteristics of HO-1, and the relationship between inflammatory response and reactive oxygen species production regulated by HO-1 and osteoporosis. The understanding of the role of HO-1 in osteoporosis may provide ideas for a potential clinical treatment and new drugs targeting HO-1.

Highly fluorescent morpholine naphthalimide deoxyuridine nucleotide for the detection of miRNA 24-3P through rolling circle amplification

In this study we synthesized the nucleotide dUrkTP, a highly fluorescent naphthalimide deoxyuridine triphosphate that undergoes aggregation-induced emission (AIE). We incorporated and extended dUrkTP during the primer extension of DNA mediated by DNA polymerase, and also in the rolling circle amplification of DNA mediated by Phi29 polymerase. Accordingly, we could use this fluorescent nucleotide for the detection of microRNA 24-3P, a biomarker of porcine reproductive and respiratory syndrome virus. The direct labeling system obtained during rolling circle DNA amplification exhibited increased fluorescence, due to AIE of the dUrkTP residue upon gel formation, thereby allowing the detection of miRNA 24-3P. This direct labeling system facilitated the simple and inexpensive detection of miRNA 24-3P with high sensitivity (limit of detection: 3.58 fM) and selectivity.

Heme Oxgenase-1, a Cardinal Modulator of Regulated Cell Death and Inflammation

Heme oxygenase catalyzes the rate-limiting step in heme degradation in order to generate biliverdin, carbon monoxide (CO), and iron. The inducible form of the enzyme, heme oxygenase-1 (HO-1), exerts a central role in cellular protection. The substrate, heme, is a potent pro-oxidant that can accelerate inflammatory injury and promote cell death. HO-1 has been implicated as a key mediator of inflammatory cell and tissue injury, as validated in preclinical models of acute lung injury and sepsis. A large body of work has also implicated HO-1 as a cytoprotective molecule against various forms of cell death, including necrosis, apoptosis and newly recognized regulated cell death (RCD) programs such as necroptosis, pyroptosis, and ferroptosis. While the antiapoptotic potential of HO-1 and its reaction product CO in apoptosis regulation has been extensively characterized, relatively fewer studies have explored the regulatory role of HO-1 in other forms of necrotic and inflammatory RCD (i.e., pyroptosis, necroptosis and ferroptosis). HO-1 may provide anti-inflammatory protection in necroptosis or pyroptosis. In contrast, in ferroptosis, HO-1 may play a pro-death role via enhancing iron release. HO-1 has also been implicated in co-regulation of autophagy, a cellular homeostatic program for catabolic recycling of proteins and organelles. While autophagy is primarily associated with cell survival, its occurrence can coincide with RCD programs. This review will summarize the roles of HO-1 and its reaction products in co-regulating RCD and autophagy programs, with its implication for both protective and detrimental tissue responses, with emphasis on how these impact HO-1 as a candidate therapeutic target in disease.

MiR-140 inhibits classical swine fever virus replication by targeting Rab25 in swine umbilical vein endothelial cells

Classical swine fever virus (CSFV) is one of the most important viral pathogens leading worldwide threats to pig industry. MicroRNAs (miRNAs) play important roles in regulating virus replication, but whether miRNAs affect CSFV infection is still poorly understood. In previous study, we identified four miRNAs that were down-regulated by CSFV in swine umbilical vein endothelial cells (SUVEC). In this study, miR-140, one of the most potently down-regulated genes was investigated. We found that the miRNA expression was significantly inhibited by CSFV infection. Subsequent studies revealed that miR-140 mimics significantly inhibited CSFV replication, while the inhibition of endogenous miR-140 enhanced CSFV replication. By using bioinformatics prediction, luciferase reporter system, real-time fluorescence quantitative PCR (RT-qPCR) and Western blot assays, we further demonstrated that miR-140 bind to the 3' UTR of Rab25 mRNA to regulate its expression. We also analyzed the expression pattern of Rab25 in SUVECs after CSFV infection. The results showed that CSFV infection induced Rab25 expression. Finally, Rab25 was found to promote CSFV replication. In conclusion, this study demonstrated that CSFV inhibits miR-140 expression and miR-140 inhibits replication by binding to host factor Rab25.

Natural Antioxidant and Anti-Inflammatory Compounds in Foodstuff or Medicinal Herbs Inducing Heme Oxygenase-1 Expression

Heme oxygenase-1 (HO-1) is an inducible antioxidant enzyme that catalyzes heme group degradation. Decreased level of HO-1 is correlated with disease progression, and HO-1 induction suppresses development of metabolic and neurological disorders. Natural compounds with antioxidant activities have emerged as a rich source of HO-1 inducers with marginal toxicity. Here we discuss the therapeutic role of HO-1 in obesity, hypertension, atherosclerosis, Parkinson's disease and hepatic fibrosis, and present important signaling pathway components that lead to HO-1 expression. We provide an updated, comprehensive list of natural HO-1 inducers in foodstuff and medicinal herbs categorized by their chemical structures. Based on the continued research in HO-1 signaling pathways and rapid development of their natural inducers, HO-1 may serve as a preventive and therapeutic target for metabolic and neurological disorders.

Heme Oxygenase-1 suppresses duck Tembusu virus replication in vitro

Heme Oxygenase-1 (HO-1) is a ubiquitously expressed enzyme which plays important functions in antioxidant, anti-inflammatory and anti-apoptosis. Recent studies have demonstrated that HO-1 also has significant antiviral properties, inhibiting the replication of some kinds of viruses such as human immunodeficiency virus (HIV), hepatitis C virus (HCV), and dengue fever virus (DFV). In this study, we evaluated the role of HO-1 in Duck Tembusu virus (DTMUV) replication in vitro. The results showed that, the mRNA expression level of HO-1 was transient up-regulated and then significantly decreased in duck embryo fibroblast (DEF) infected with DTMUV. HO-1 induction by transfection of HO-1 over-expression plasmid or treatment with cobalt protoporphyrin (CoPP), a potent HO-1 inducer, could inhibit DTMUV replication effectively. In contrast, HO-1 siRNA knockdown in DEF increased DTMUV replication, implied that HO-1 was an important cellular factor against DTMUV replication. Furthermore, we found that ferric ion (Fe³⁺) but not biliverdin and carbon monoxide, products of heme degradation by HO-1, mediated the HO-1-induced anti-DTMUV effect. Overall, these finding revealed that a drug induced the HO-1 signal pathway was a promising strategy for treating DTMUV infection.

Interactions Among Expressed MicroRNAs and mRNAs in the Early Stages of Fowl Adenovirus Aerotype 4-Infected Leghorn Male Hepatocellular Cells

Hydropericardium-hepatitis syndrome (HHS) is caused by some strains of fowl adenovirus serotype 4 (FAdV-4). However, the mechanism of FAdV-4 entry is not well understood. Therefore, to investigate the changes in host cellular response at the early stage of FAdV-4 infection, a conjoint analysis of miRNA-seq and mRNA-seq was utilized with leghorn male hepatocellular (LMH) cells at 30, 60, and 120 min after FAdV-4 infection. In total, we identified 785 differentially expressed (DE) miRNAs and 725 DE mRNAs in FAdV-4-infected LMH cells. Most miRNAs and mRNAs, including gga-miR-148a-3p, gga-miR-148a-5p, gga-miR-15c-3p, CRK, SOCS3, and EGR1, have not previously been reported to be associated with FAdV-4 infection. The conjoint analysis of the obtained data identified 856 miRNA–mRNA pairs at three time points. The interaction network analysis showed that gga-miR-128-2-5p, gga-miR-7475-5p, novel_miR205, and TCF7L1 were located in the core of the network. Furthermore, the relationship between gga-miR-128-2-5p and its target OBSL1 was confirmed using a dual-luciferase reporter system and a real-time quantitative polymerase chain reaction assay. In vitro experiments revealed that both gga-miR-128-2-5p overexpression and OBSL1 loss of function inhibited FAdV-4 entry. These results suggested that gga-miR-128-2-5p plays an important role in FAdV-4 entry by targeting OBSL1. To the best of our knowledge, the present study is the first to analyze host miRNA and mRNA expression at the early stage of FAdV-4 infection; furthermore, the results of this study help to elucidate the molecular mechanisms of FAdV-4 entry.

Effects of gE/gI deletions on the miRNA expression of PRV-infected PK-15 cells

Pseudorabies virus (PRV) belongs to the Alphaherpesvirinae subfamily of Herpesviridae. PRV-induced pseudorabies is a highly contagious disease that has caused huge economic losses to the global swine industry. The PRV gE/gI gene deletion vaccine strain (Fa ΔgE/gI strain) constructed from the PRV Fa wild-type strain was shown to have a protective effect against infection. However, the interaction between PRV gE/gI genes and host miRNA needs further exploration, and little is known about the regulatory mechanisms of non-coding RNAs during PRV infection. miRNAs play a key regulatory role in viral infection and immune responses, so we analyzed the differential expression of miRNAs induced by the PRV Fa ΔgE/gI strain and Fa wild-type strain in the PK15 cell line. High-throughput sequencing reads were aligned to known Sus scrofa pre-miRNAs in the miRBase database. Target genes of differentially expressed miRNAs were predicted using the miRGen 3.0 database, then filtered miRNA target genes were subjected to Gene Ontology (GO) analysis and Search Tool for the Retrieval of Interacting Genes/ Proteins (STRING) analysis. Stem-loop quantitative real-time PCR was performed to confirm the accuracy of high-throughput sequencing data. In total, 387, 472, and 490 annotated and novel mature miRNAs were identified from PRV Fa ΔgE/gI strain-infected, Fa wild-type strain-infected, and non-infected PK-15 cells, respectively. Five PRV-encoded miRNAs were also identified. GO analysis showed that target genes of differentially expressed miRNAs in PRV Fa ΔgE/gI strain-infected and Fa wild-type strain-infected PK-15 cells were mainly involved in biological regulation and metabolic processes. STRING analysis showed that immune-related target genes of differentially expressed miRNAs in the Toll-like receptor signaling pathway, B cell receptor signaling pathway, T cell receptor signaling pathway, nuclear factor-κB signaling pathway, and transforming growth factor-β signaling pathway were interrelated. This is the first report of the small RNA transcriptome in PRV mutant wild-type strain-infected and Fa ΔgE/gI strain-infected porcine cell lines. Our findings will contribute to the prevention and treatment of PRV mutant strains.

Molecular and Cellular Mechanisms for PRRSV Pathogenesis and Host Response to Infection

•

PRRSV has evolved to arm with various strategies to modify host antiviral response.

•

Viral modulation of homeostatic cellular processes provides favorable conditions for PRRSV survival during infection.

•

PRRSV modulation of cellular processes includes pathways for interferons, apoptosis, microRNAs, cytokines, autophagy, and viral genome recombination.

Porcine reproductive and respiratory syndrome virus (PRRSV) has caused tremendous amounts of economic losses to the swine industry for more than three decades, but its control is still unsatisfactory. A significant amount of information is available for host cell-virus interactions during infection, and it is evident that PRRSV has evolved to equip various strategies to disrupt the host antiviral system and provide favorable conditions for survival. The current study reviews viral strategies for modulations of cellular processes including innate immunity, apoptosis, microRNAs, inflammatory cytokines, and other cellular pathways.

MicroRNA-155 inhibits dengue virus replication by inducing heme oxygenase-1-mediated antiviral interferon responses

MicroRNAs (miRNAs) have been reported to directly alter the virus life cycle and virus-host interactions, and so are considered promising molecules for controlling virus infection. In the present study, we observed that miR-155 time-dependently downregulated upon dengue virus (DENV) infection. In contrast, exogenous overexpression of miR-155 appeared to limit viral replication in vitro, suggesting that the low levels of miR-155 would be beneficial for DENV replication. In vivo, overexpression of miR-155 protected ICR suckling mice from the life-threatening effects of DENV infection and reduced virus propagation. Further investigation revealed that the anti-DENV activity of miR-155 was due to target Bach1, resulting in the induction of the heme oxygenase-1 (HO-1)-mediated inhibition of DENV NS2B/NS3 protease activity, ultimately leading to induction of antiviral interferon responses, including interferon-induced protein kinase R (PKR), 2'-5'-oligoadenylate synthetase 1 (OAS1), OAS2, and OAS3 expression, against DENV replication. Collectively, our results provide a promising new strategy to manage DENV infection by modulation of miR-155 expression.

Cellular microRNA miR-c89 inhibits replication of porcine reproductive and respiratory syndrome virus by targeting the host factor porcine retinoid X receptor β

MicroRNAs (miRNAs) play critical roles in the complex networks of virus-host interactions. Our previous research showed that porcine reproductive and respiratory syndrome virus (PRRSV) infection markedly upregulates miR-c89 expression, suggesting that miR-c89 may play an important role in PRRSV infection. The present study sought to determine the function of miR-c89 and its molecular mechanism during PRRSV infection. Using quantitative reverse transcription PCR (RT-qPCR) verification, we demonstrated that both highly pathogenic PRRSV and low-pathogenic PRRSV infection induced miR-c89 expression. The overexpression of miR-c89 significantly suppressed the replication of a variety of PRRSV strains, regardless of the timing of infection. Further, miR-c89 can directly target the 3'UTR of porcine retinoid X receptor β (RXRB) mRNA in a sequence-specific manner. Knockdown affected RXRB expression, as siRNA can suppress the replication of a variety of PRRSV strains. This work not only provides new insights into PRRSV-cell interactions, but also highlights the potential for the use of miR-c89 in the development of new antiviral strategies to combat PRRSV infection.

MiR-375 Has Contrasting Effects on Newcastle Disease Virus Growth Depending on the Target Gene

MicroRNAs regulate post-transcriptional gene expression via either translational repression or mRNA degradation. They have important roles in both viral infection and host anti-infection processes. We discovered that the miR-375 is significantly upregulated in Newcastle disease virus (NDV)-infected chicken embryonic visceral tissues using a small RNA sequencing approach. Further research revealed that the overexpression of miR-375 markedly decreases the replication of the velogenic NDV F48E9 and the lentogenic NDV La Sota by targeting the M gene of NDV in DF-1 cells. Interestingly, miR-375 has another target, ELAVL4, which regulates chicken fibrocyte cell cycle progression and decreases NDV proliferation. In addition, miR-375 can influence bystander cells by its secretion in culture medium. Our results indicated that miR-375 is an inhibitor of NDV, but can also enhance NDV growth by reducing the expression of its target ELAVL4. These results emphasize the complex roles of microRNAs in the regulation of viral infections.

Heme oxygenase-1 as a potential therapeutic target in rheumatic diseases

BACKGROUND

Heme oxygenase-1 (HO-1), a cellular stress protein, serves a vital metabolic function as the rate-limiting enzyme in the degradation of heme to generate carbon monoxide (CO), iron, and biliverdin (BR). HO-1 may function as one of the most momentous factors of cell adaptation to oxidase stress, as well as a regulator of inflammatory signaling programs through the generation of its biologically active end products. Intensive investigation is now focusing on the potential function of HO-1 in inflammatory disorders, among which rheumatic diseases are one of the principal issues.

METHODS

"Heme oxygenase-1", "rheumatic diseases"; "lupus", "rheumatic arthritis", "osteoarthritis" and "oxidative stress" were used as key words for searching in Pubmed and Google scholar database.

RESULTS

Collected information from the related articles revealed the important role of pathogenesis and therapeutic potential of HO-1 in rheumatic diseases. Conclusions and discussions HO-1 has potential as a target for the treatment of rheumatic diseases due to its characteristic anti-inflammatory and anti-oxidative role. However, it is essential to monitor the HO-1 expression during particular stage of the disorders, and levels of HO-1 in different tissues and organs should be further confirmed in order to correlate it with clinical symptoms and other hallmarks of rheumatic diseases.

MicroRNA miR-24-3p Reduces Apoptosis and Regulates Keap1-Nrf2 Pathway in Mouse Cardiomyocytes Responding to Ischemia/Reperfusion Injury

In recent years, microRNAs (miRNAs) have received increasing attention for their role in ischemia/reperfusion injury (I/RI), and many miRNAs have been demonstrated to play a very important role in cardiac I/RI. The miRNA miR-24-3p is a tumor suppressor that regulates multiple tumors; however, it remains unclear whether the expression level of miR-24-3p is altered in cardiac cells under I/RI. In this study, we used mouse primary cardiomyocytes and the H9C2 cardiomyocyte cell line to perform in vitro stimulated ischemia/reperfusion (SI/R) and then detected miR-24-3p expression level using quantitative real-time PCR (qRT-PCR). We discovered that the expression of miR-24-3p was significantly increased in cardiomyocytes following SI/R, and that the miR-24-3p level was inversely correlated to the ischemia marker HIF-1a. Furthermore, we transfected cardiomyocytes with miR-24-3p mimic or inhibitor to explore the role of miR-24-3p in cardiomyocyte ischemia/reperfusion injury in vitro. We performed flow cytometry to detect the apoptotic rate of H9C2 cardiomyocytes and found that the transfection of miR-24-3p mimic resulted in the decrease of the apoptosis rate of cardiomyocytes after SI/R, whereas the transfection of miR-24-3p inhibitor increased the number of apoptotic cardiomyocytes. These data suggest that the overexpression of miR-24-3p could reduce in vitro myocardial cell apoptosis induced by I/R injury. Finally, we applied the dual luciferase reporter gene system to verify whether miR-24-3p targets the Keap1 gene, and found that the luciferase signal intensity from a vector carrying the Keap1 wild-type reporter gene was significantly reduced after transfection with miR-24-3p mimic. The Keap1 protein level was also reduced following the transfection of miR-24-3p. The results from this study suggest a novel function of miR-24-3p in protecting cardiomyocytes from ischemia/reperfusion injury by the activation of the Nrf2-Keap1 pathway.

Novel and differentially abundant microRNAs in sperm cells, seminal plasma, and serum of boars due to porcine reproduction and respiratory syndrome virus infection

The objectives of this study were to identify and determine relative abundance of miRNAs in boar sperm, seminal plasma (SP), and serum pre- and post-viral infection. Functional enrichment analyses on predicted targets of miRNAs of interest were performed. Boars (n = 6) were inoculated with porcine reproductive and respiratory syndrome virus (PRRSv) strain 1-8-4 (Day 0). Semen and serum were collected on Day -2 and 6. Sperm and SP were separated and aliquots were flash frozen and stored at -80 °C. Serum was frozen and stored at -80 °C. Total RNA was isolated from sperm and SP samples and subjected to RNA sequencing. Microarray analysis was performed using the Day -2 and 6 RNA samples from serum, sperm and SP. Potential miRNA targets were predicted using miRanda 3.3a and targets were then analyzed for enrichment of Gene Ontology) and InterPro terms and were considered to be enriched if P <  0.01 using the Bonferroni correction. Microarray analyses resulted in 83, 13, and 10 miRNAs with differences in abundances in sperm, serum, and SP, respectively, when comparing Day -2 and 6. Results from enrichment analyses indicated that the predicted targets of 35, nine, and five miRNAs with differences in abundances for sperm, SP, and serum, respectively, that have functions and/or conserved protein domains that are enriched when compared to the pig genome. Enriched terms for P2X purinoceptors were identified for sperm, SP and serum. Enriched terms for cell adhesion were identified for sperm and serum transcripts. Enriched terms for cell signaling were identified for sperm and SP transcripts.

MicroRNA-30c targets the interferon-alpha/beta receptor beta chain to promote type 2 PRRSV infection

Porcine reproductive and respiratory syndrome (PRRS) is one of the most important diseases in pigs. MicroRNAs (miRNAs) have emerged as an important regulator of virus-host cell interactions and miR-30c has been found to facilitate PRRSV replication. Here, we found that the interferon-alpha/beta receptor beta chain (IFNAR2) was down-regulated, while miR-30c was up-regulated during HV (a highly pathogenic type 2 PRRSV strain) and CH-1a (a classic type 2 PRRSV strain) infection. Subsequently, using bioinformatics analysis, we predicted that the IFNAR2 was targeted by miR-30c. A luciferase assay verified that the 3' UTR of IFNAR2 was targeted by miR-30c, as a mutation on either the target sequence or the miR-30c seed sequence reversed the luciferase activity. In addition, miR-30c and IFNAR2 mRNA were physically co-localized in RNA-induced silencing complex (RISC). Importantly, we showed that miR-30c also impaired the induction of IFN-stimulated genes (ISGs) by targeting IFNAR2. Our findings further reveal the mechanism of miR-30c promoting PRRSV replication.

Cardiac Hypertrophy is Positively Regulated by MicroRNA‑24 in Rats

Background:

MicroRNA-24 (miR-24) plays an important role in heart failure by reducing the efficiency of myocardial excitation-contraction coupling. Prolonged cardiac hypertrophy may lead to heart failure, but little is known about the role of miR-24 in cardiac hypertrophy. This study aimed to preliminarily investigate the function of miR-24 and its mechanisms in cardiac hypertrophy.

Methods:

Twelve Sprague-Dawley rats with a body weight of 50 ± 5 g were recruited and randomly divided into two groups: a transverse aortic constriction (TAC) group and a sham surgery group. Hypertrophy index was measured and calculated by echocardiography and hematoxylin and eosin staining. TargetScans algorithm-based prediction was used to search for the targets of miR-24, which was subsequently confirmed by a real-time polymerase chain reaction and luciferase assay. Immunofluorescence labeling was used to measure the cell surface area, and ³H-leucine incorporation was used to detect the synthesis of total protein in neonatal rat cardiac myocytes (NRCMs) with the overexpression of miR-24. In addition, flow cytometry was performed to observe the alteration in the cell cycle. Statistical analysis was carried out with GraphPad Prism v5.0 and SPSS 19.0. A two-sided P < 0.05 was considered as the threshold for significance.

Results:

The expression of miR-24 was abnormally increased in TAC rat cardiac tissue (t = −2.938, P < 0.05). TargetScans algorithm-based prediction demonstrated that CDKN1B (p27, Kip1), a cell cycle regulator, was a putative target of miR-24, and was confirmed by luciferase assay. The expression of p27 was decreased in TAC rat cardiac tissue (t = 2.896, P < 0.05). The overexpression of miR-24 in NRCMs led to the decreased expression of p27 (t = 4.400, P < 0.01), and decreased G0/G1 arrest in cell cycle and cardiomyocyte hypertrophy.

Conclusion:

MiR-24 promotes cardiac hypertrophy partly by affecting the cell cycle through down-regulation of p27 expression.

Utilizing host endogenous microRNAs to negatively regulate the replication of porcine reproductive and respiratory syndrome virus in MARC-145 cells

MicroRNAs (miRNAs) contribute to gene regulation at the post-transcriptional level and are capable of mRNA silencing by binding to target sites exhibiting high degrees of complementarity. Therefore, cloning host miRNA-recognition sequences into the genome of RNA viruses represents a rational strategy for manipulating viral replication. Here, we performed deep sequencing to obtain small-RNA (sRNA)-expression profiles from in vitro-cultured MARC-145 cells post infection with porcine reproductive and respiratory syndrome virus (PRRSV) and chose six candidate miRNAs of different abundance (miR-21, miR-140-3p, miR-185, miR-26a, miR-505, and miR-199a) for further study. Based on the full-length cDNA clone p7USC, we constructed a number of PRRSV mutants that provided complementary base-pairing target sites for the miRNAs in 3′ untranslated regions. Our results showed that all low- and moderate- abundant miRNA-target mutants showed similar growth properties, whereas the highest-abundant miRNA-target mutant blocked both viral transcription and replication. Discontinuous mutations in high-abundant miRNA-target sites subsequently recovered viral viability and propagation. These results demonstrated the copy number of endogenous miRNAs and the extent of sRNA complementarity were key factors to silence potential mRNA expression/translation, thereby determining PRRSV viability. Interestingly, the mutant containing miR-140-target sites (v140-t) showed strong suppression of viral replication from P1 to P3 in vitro, as shown by virus titer, plaque morphology, and qRT-PCR assays. To assess genetic stability, sequencing of v140-t (P1, P3, P5 and P10) revealed spontaneous mutations preferentially located among several nucleotides near the 3′ end of the insertion region and corresponding to the “seed region” of miR-140-3p, explaining the induced viral repression and the direction of virus evolution. This approach provided a general silencing strategy for limiting PRRSV replication by endogenous miRNAs in MARC-145 cells.

Common microRNA⁻mRNA Interactions in Different Newcastle Disease Virus-Infected Chicken Embryonic Visceral Tissues

To investigate the roles and explore the altered expression of microRNAs (miRNAs) and mRNAs in chicken embryos in response to Newcastle disease virus (NDV) infection, deep sequencing was performed. Then, a conjoint analysis of small RNA-seq and mRNA-seq was performed to screen interactional miRNA⁻mRNA pairs during NDV infection. In total, 15 and 17 up- and downregulated miRNAs were identified that potentially targeted 4279 and 6080 mRNAs in NDV-infected chicken embryonic tissues, respectively; in addition, 595 upregulated and 480 downregulated mRNAs were identified. The conjoint analysis of the obtained data identified 1069 miRNA⁻mRNA pairs. Among these pairs, 130 pairs were related to immune or inflammatory responses. The relationship between gga-miR-203a and its target transglutaminase 2 (TGM2) was confirmed using a dual-luciferase reporter system and a real time quantitative polymerase chain reaction (RT-qPCR) assay. Overall, the discovery of miRNAs, mRNAs, and their potential pairing relationships, which may be involved in the regulation of NDV infection, will facilitate our understanding of the complex regulatory relationship between the host and the virus.

Direct incorporation and extension of a fluorescent nucleotide through rolling circle DNA amplification for the detection of microRNA 24-3P

We designed and synthesized several fluorescent nucleotides from thiophene, anthracene and pyrene, which have different sizes, and screened their incorporation and extension capability during the rolling circle amplification of DNA. The thiophene-based fluorescent nucleotide (dUthioTP) could highly incorporate and extended into the rolling circle DNA product, while other fluorescent nucleotides (dUanthTP, and dUpyrTP) could not. This dUthioTP fluorescent nucleotide could be used for the detection of miRNA 24-3P, which is related PRRSV. This direct labeling system during rolling circle DNA amplification exhibited an increased fluorescence signal showing gel formation for the detection of miRNA 24-3P. This direct labeling system is a very simple and cost-efficient method for the detection miRNA 24-3P and also exhibited highly sensitive and selective detection properties.

MicroRNA-24 Modulates Staphylococcus aureus-Induced Macrophage Polarization by Suppressing CHI3L1

Macrophages play a crucial role in host innate anti-Staphylococcus aureus defense, which is tightly regulated by multiple factors, including microRNAs. A recent study showed that miR-24 plays an important role in macrophage polarization. Here, we investigated the biological function of miR-24 in S. aureus-stimulated macrophages. The results revealed that miR-24 expression was significantly decreased in both human and mouse macrophage cell lines with S. aureus stimulation in a time-dependent manner. Moreover, miR-24 overexpression significantly decreased the production of M1 phenotype markers, such as IL-6, iNOS, TNF-α, CD86, and CD80, whereas it increased the production of M2 markers, such as Arg1, CCL17, CCL22, CD163, and CD206, in S. aureus-stimulated macrophages. Conversely, knockdown of miR-24 promoted M1 macrophage polarization but diminished M2 macrophage polarization in S. aureus-stimulated macrophages. Furthermore, CHI3L1 was predicted as a target gene of miR-24 using bioinformatics software and identified by luciferase reporter assay. Additionally, miR-24 overexpression inhibited CHI3L1 expression and downregulated the downstream MAPK pathway in S. aureus-stimulated macrophages. Finally, CHI3L1 overexpression rescued macrophage polarization and MAPK pathway inhibition induced by miR-24 mimic transfection in S. aureus-stimulated macrophages. In conclusion, the data suggest that miR-24 serves as a molecular regulator in S. aureus-induced macrophage polarization through targeting of CHI3L1 and regulation of the MAPK pathway, which may provide a promising therapeutic target for S. aureus-related infections and inflammatory diseases.