The involvement of MiR-1-clathrin pathway in the regulation of phagocytosis

Expression Analysis of Moritella viscosa-Challenged Atlantic Salmon Identifies Disease-Responding Genes, MicroRNAs and Their Predicted Target Genes and Pathways

Moritella viscosa is a bacterial pathogen causing winter-ulcer disease in Atlantic salmon. The lesions on affected fish lead to increased mortality, decreased fish welfare, and inferior meat quality in farmed salmon. MicroRNAs (miRNAs) are small non-coding RNAs involved in post-transcriptional regulation by guiding the miRNA-induced silencing complex to specific mRNA transcripts (target genes). The goal of this study was to identify miRNAs responding to Moritella viscosa in salmon by investigating miRNA expression in the head-kidney and the muscle/skin from lesion sites caused by the pathogen. Protein coding gene expression was investigated by microarray analysis in the same materials. Seventeen differentially expressed guide-miRNAs (gDE-miRNAs) were identified in the head-kidney, and thirty-nine in lesion sites, while the microarray analysis reproduced the differential expression signature of several thousand genes known as infection-responsive. In silico target prediction and enrichment analysis suggested that the gDE-miRNAs were predicted to target genes involved in immune responses, hemostasis, angiogenesis, stress responses, metabolism, cell growth, and apoptosis. The majority of the conserved gDE-miRNAs (e.g., miR-125, miR-132, miR-146, miR-152, miR-155, miR-223 and miR-2188) are known as infection-responsive in other vertebrates. Collectively, the findings indicate that gDE-miRNAs are important post-transcriptional gene regulators of the host response to bacterial infection.

MicroRNAs as Regulators of Phagocytosis

MicroRNAs (miRNAs) are short non-coding RNAs that regulate gene expression and thus act as important regulators of cellular phenotype and function. As their expression may be dysregulated in numerous diseases, they are of interest as biomarkers. What is more, attempts of modulation of some microRNAs for therapeutic reasons have been undertaken. In this review, we discuss the current knowledge regarding the influence of microRNAs on phagocytosis, which may be exerted on different levels, such as through macrophages polarization, phagosome maturation, reactive oxygen species production and cytokines synthesis. This phenomenon plays an important role in numerous pathological conditions.

Global mRNA and miRNA Analysis Reveal Key Processes in the Initial Response to Infection with WSSV in the Pacific Whiteleg Shrimp

White Spot Disease (WSD) presents a major barrier to penaeid shrimp production. Mechanisms underlying White Spot Syndrome Virus (WSSV) susceptibility in penaeids are poorly understood due to limited information related to early infection. We investigated mRNA and miRNA transcription in Penaeus vannamei over 36 h following infection. Over this time course, 6192 transcripts and 27 miRNAs were differentially expressed—with limited differential expression from 3–12 h post injection (hpi) and a more significant transcriptional response associated with the onset of disease symptoms (24 hpi). During early infection, regulated processes included cytoskeletal remodelling and alterations in phagocytic activity that may assist WSSV entry and translocation, novel miRNA-induced metabolic shifts, and the downregulation of ATP-dependent proton transporter subunits that may impair cellular recycling. During later infection, uncoupling of the electron transport chain may drive cellular dysfunction and lead to high mortalities in infected penaeids. We propose that post-transcriptional silencing of the immune priming gene Dscam (downregulated following infections) by a novel shrimp miRNA (Pva-pmiR-78; upregulated) as a potential mechanism preventing future recognition of WSSV that may be suppressed in surviving shrimp. Our findings improve our understanding of WSD pathogenesis in P. vannamei and provide potential avenues for future development of prophylactics and treatments.

A potent and selective PARP14 inhibitor decreases protumor macrophage gene expression and elicits inflammatory responses in tumor explants

PARP14 has been implicated by genetic knockout studies to promote protumor macrophage polarization and suppress the antitumor inflammatory response due to its role in modulating interleukin-4 (IL-4) and interferon-γ signaling pathways. Here, we describe structure-based design efforts leading to the discovery of a potent and highly selective PARP14 chemical probe. RBN012759 inhibits PARP14 with a biochemical half-maximal inhibitory concentration of 0.003 μM, exhibits >300-fold selectivity over all PARP family members, and its profile enables further study of PARP14 biology and disease association both in vitro and in vivo. Inhibition of PARP14 with RBN012759 reverses IL-4-driven protumor gene expression in macrophages and induces an inflammatory mRNA signature similar to that induced by immune checkpoint inhibitor therapy in primary human tumor explants. These data support an immune suppressive role of PARP14 in tumors and suggest potential utility of PARP14 inhibitors in the treatment of cancer.

Hemocyte-Mediated Phagocytosis in Crustaceans

Phagocytosis is an ancient, highly conserved process in all multicellular organisms, through which the host can protect itself against invading microorganisms and environmental particles, as well as remove self-apoptotic cells/cell debris to maintain tissue homeostasis. In crustacean, phagocytosis by hemocyte has also been well-recognized as a crucial defense mechanism for the host against infectious agents such as bacteria and viruses. In this review, we summarized the current knowledge of hemocyte-mediated phagocytosis, in particular focusing on the related receptors for recognition and internalization of pathogens as well as the downstream signal pathways and intracellular regulators involved in the process of hemocyte phagocytosis. We attempted to gain a deeper understanding of the phagocytic mechanism of different hemocytes and their contribution to the host defense immunity in crustaceans.

Shrimp Antiviral mja-miR-35 Targets CHI3L1 in Human M2 Macrophages and Suppresses Breast Cancer Metastasis

Virus infection can change host's metabolism, while tumorigenesis results from metabolic disorder. MicroRNAs (miRNAs), crucial regulatory factors overlaying transcriptional control mechanisms, can guide metabolic homeostasis. In terms of metabolic disorder, antiviral miRNAs may have anti-tumor activity. However, this issue has not been extensively investigated. In the present study, the results revealed that shrimp mja-miR-35, which showed antiviral activity in shrimp against white spot syndrome virus (WSSV) infection, could suppress the metastasis of breast cancer by targeting human CHI3L1 gene of M2 macrophages in a cross-phylum manner. Furthermore, the feed expressing shrimp mja-miR-35 had antiviral capacity in shrimp and anti-tumor activity in humans, leading to the simultaneous control of virus infection and tumor progression. Therefore, our findings indicated that the antiviral miRNAs derived from shrimp stress responses against virus infection might be an important source of human anti-tumor drugs and miRNAs could bridge the control of aquaculture diseases and the prevention of human tumors.

Canine respiratory coronavirus employs caveolin-1-mediated pathway for internalization to HRT-18G cells

Canine respiratory coronavirus (CRCoV), identified in 2003, is a member of the Coronaviridae family. The virus is a betacoronavirus and a close relative of human coronavirus OC43 and bovine coronavirus. Here, we examined entry of CRCoV into human rectal tumor cells (HRT-18G cell line) by analyzing co-localization of single virus particles with cellular markers in the presence or absence of chemical inhibitors of pathways potentially involved in virus entry. We also targeted these pathways using siRNA. The results show that the virus hijacks caveolin-dependent endocytosis to enter cells via endocytic internalization.

MicroRNA-1 acts as a tumor suppressor microRNA by inhibiting angiogenesis-related growth factors in human gastric cancer

BACKGROUND

We recently reported that miR-1 was one of the most significantly downregulated microRNAs in gastric cancer (GC) patients from The Cancer Genome Atlas microRNA sequencing data. Here we aim to elucidate the role of miR-1 in gastric carcinogenesis.

METHODS

We measured miR-1 expression in human GC cell lines and 90 paired primary GC samples, and analyzed the association of its status with clinicopathological features. The effect of miR-1 on GC cells was evaluated by proliferation and migration assay. To identify the target genes of miR-1, bioinformatic analysis and protein array analysis were performed. Moreover, the regulation mechanism of miR-1 with regard to these predicted targets was investigated by quantitative PCR (qPCR), Western blot, ELISA, and endothelial cell tube formation. The putative binding site of miR-1 on target genes was assessed by a reporter assay.

RESULTS

Expression of miR-1 was obviously decreased in GC cell lines and primary tissues. Patients with low miR-1 expression had significantly shorter overall survival compared with those with high miR-1 expression (P = 0.0027). Overexpression of miR-1 in GC cells inhibited proliferation, migration, and tube formation of endothelial cells by suppressing expression of vascular endothelial growth factor A (VEGF-A) and endothelin 1 (EDN1). Conversely, inhibition of miR-1 with use of antago-miR-1 caused an increase in expression of VEGF-A and EDN1 in nonmalignant GC cells or low-malignancy GC cells.

CONCLUSIONS

MiR-1 acts as a tumor suppressor by inhibiting angiogenesis-related growth factors in human gastric cancer. Downregulated miR-1 not only promotes cellular proliferation and migration of GC cells, but may activates proangiogenesis signaling and stimulates the proliferation and migration of endothelial cells, indicating the possibility of new strategies for GC therapy.

Shrimp miR-34 from Shrimp Stress Response to Virus Infection Suppresses Tumorigenesis of Breast Cancer

During host stress response against virus infection, some animal microRNAs (miRNAs) can be upregulated to restore the virus-caused metabolic disorder of host cells via suppressing the expressions of miRNAs' target genes. These antiviral miRNAs may have antitumor capacity, because tumorigenesis results from metabolic disorder of cells. However, this subject has not been explored. In this study, the results showed that shrimp miR-34, which was upregulated during white spot syndrome virus (WSSV) infection, had antiviral activity in shrimp. The expression of shrimp miR-34 in breast cancer cells and in mice suppressed the growth and metastasis of breast cancer by targeting human CCND1, CDK6, CCNE2, E2F3, FOSL1, and MET genes in a cross-phylum manner. The results of this study indicated that miRNAs with antiviral activities can be promising sources for antitumor drug discovery.

Transcriptome-wide analysis of microRNAs in Branchiostoma belcheri upon Vibrio parahemolyticus infection

MicroRNAs (miRNAs) are endogenous small non-coding RNAs that participate in diverse biological processes via regulating expressions of target genes at post-transcriptional level. Amphioxus, as modern survivor of an ancient chordate lineage, is a model organism for comparative genomics study. However, miRNAs involved in regulating immune responses in Branchiostoma belcheri are largely unclear. Here, we systematically investigated the microRNAs (miRNAs) involved in regulating immune responses in the cephalochordate amphioxus (Branchiostoma belcheri) through next-generation deep sequencing of amphioxus samples infected with Vibrio parahemolyticus. We identified 198 novel amphioxus miRNAs, consisting of 12 conserved miRNAs, 33 candidate star miRNAs and 153 potential amphioxus-specific-miRNAs. Using microarray profiling, 14 miRNAs were differentially expressed post infection, suggesting they are immune-related miRNAs. Eight miRNAs (bbe-miR-92a-3p, bbe-miR-92c-3p, bbe-miR-210-5p, bbe-miR-22-3p, bbe-miR-1∼bbe-miR-133 and bbe-miR-217∼bbe-miR-216 clusters) were significantly increased at 12 h post-infection, while bbe-miR-2072-5p was downregulated at 6 h and 12 h. Three miRNAs, bbe-miR-1-3p, bbe-miR-22-3p and bbe-miR-92a-3p, were confirmed to be involved in immune responses to infection by qRT-PCR. Our findings further clarify important regulatory roles of miRNAs in the innate immune response to bacterial infection in amphioxus.

MicroRNA-27a restrains the immune response to mycobacterium tuberculosis infection by targeting IRAK4, a promoter of the NF-κB pathway

This study aimed to explore the influence of microRNA-27a on immune response to mycobacterium tuberculosis (Mtb) and the molecular mechanism. MiRNA-27a was screened one of the downregulated miRNAs in Mtb infected macrophages. The concentrations of IFN-γ, IL-β, IL-6, and TNF-α in THP-1 macrophages after infection with Mtb and simultaneous transfection with miR-27a mimics or inhibitor were determined by ELISA. Colony-forming unit (CFU) assay was used to determine the survival situation of THP-1 infected with Mtb after transfection with miR-27a mimics or inhibitor. We used luciferase reporter assay and western blotting to study the relationship between miR-27a and IRAK4. MiR-27a was found differential expressed in Mtb infected macrophages, and the expressions of miR-27a in Mtb-infected THP-1 were remarkably downregulated with the increase of time and dose. Compared with the control, the levels of IFN-γ, IL-β, IL-6, and TNF-α were enhanced after macrophages infected with Mtb, while further transfection of miR-27a mimics abolished the increase. IRAK4 was found the target gene of miR-27a and transfection of miR-27a mimics decreased the relative level of IRAK4. The concentration of IFN-γ, IL-β, IL-6, and TNF-α in Mtb infected macrophages were reduced significantly after transfection of miR-27a mimics, while simultaneous transfection of pcDNA-IRAK4 abolished the decrease, which is the upstream molecular of NF-κB. In conclusion, miR-27a plays a key role in immune response to Mtb infection and intervening on miR-27a may be an effective way to treat TB.

Long-term influence of cyanobacterial bloom on the immune system of Litopenaeus vannamei

Cyanobacteria are ubiquitously distributed in water on the Earth. It has long been known that the cyanobacterial bloom in aquaculture ponds can cause acute and massive deaths of shrimp. However, the long-term and chronic effects of the cyanobacterial bloom on shrimp are still poorly understood. In this study, the immune state of white pacific shrimp, Litopenaeus vannamei, surviving a naturally occurring cyanobacterial bloom was investigated and tracked for 70 d. Compared with the control, the growth of shrimp suffering high concentrations of cyanobacteria was obviously postponed. In these shrimp, the activities of the NF-κB, JAK/STAT and P38 MAPK immune signaling pathways and the expression of many antimicrobial peptide genes were down-regulated, whereas the expression of C-type lectins was significantly up-regulated. Although the mRNA level of lysozyme was reduced, the expression of the invertebrate-type lysozyme gene was increased. Furthermore, the concentration of hemocytes in hemolymph was greatly decreased, but the phagocytic activity of hemocytes was increased. These suggested that the cyanobacterial bloom has significant and complex influences on the immune system of shrimp, and in turn, alteration of the immune state could be a factor by which few shrimp can survive the cyanobacterial bloom. Thus, the current study could help further understand the interactions between the aquaculture water environment and the immune system of shrimp.

Lipopolysaccharide-Induced Differential Expression of miRNAs in Male and Female Rhipicephalus haemaphysaloides Ticks

Lipopolysaccharide (LPS) stimulates the innate immune response in arthropods. In tick vectors, LPS activates expression of immune genes, including those for antibacterial peptides. miRNAs are 21-24 nt non-coding small RNAs that regulate target mRNAs at the post-transcriptional level. However, our understanding of tick innate immunity is limited to a few cellular immune reactions and some characterized immune molecules. Moreover, there is little information on the regulation of the immune system in ticks by miRNA. Therefore, this study aimed to analyze the differential expression of miRNAs in male and female ticks after LPS injection. LPS was injected into male and female Rhipicephalus haemaphysaloides ticks to stimulate immune response, with phosphate buffered saline (PBS)-injected ticks as negative controls. miRNAs from each group were sequenced and analyzed. In the PBS- and LPS-injected female ticks, 11.46 and 12.82 million reads of 18-30 nt were obtained respectively. There were 13.92 and 15.29 million reads of 18-30 nt obtained in the PBS- and LPS-injected male ticks, respectively. Expression of miRNAs in male ticks was greater than that in female ticks. There were 955 and 984 conserved miRNA families in the PBS- and LPS-injected female ticks, respectively, and correspondingly 1684 and 1552 conserved miRNA families in male ticks. Nine novel miRNAs were detected as common miRNAs in two or more tested samples. There were 37 known miRNAs up-regulated >10-fold and 33 down-regulated >10-fold in LPS-injected female ticks; and correspondingly 52 and 59 miRNAs in male ticks. Differential expression of miRNAs in PBS- and LPS-injected samples supports their involvement in the regulation of innate immunity. These data provide an important resource for more detailed functional analysis of miRNAs in this species.

Roles of small RNAs in the immune defense mechanisms of crustaceans

Small RNAs, 21-24 nucleotides in length, are non-coding RNAs found in most multicellular organisms, as well as in some viruses. There are three main types of small RNAs including microRNA (miRNA), small-interfering RNA (siRNA), and piwi-interacting RNA (piRNA). Small RNAs play key roles in the genetic regulation of eukaryotes; at least 50% of all eukaryote genes are the targets of small RNAs. In recent years, studies have shown that some unique small RNAs are involved in the immune response of crustaceans, leading to lower or higher immune responses to infections and diseases. SiRNAs could be used as therapy for virus infection. In this review, we provide an overview of the diverse roles of small RNAs in the immune defense mechanisms of crustaceans.