MicroRNA-100 is involved in shrimp immune response to white spot syndrome virus (WSSV) and Vibrio alginolyticus infection

miR-2765 involved in ammonia nitrogen stress via negative regulation of autophagy in shrimp

MicroRNA (miRNA) is a highly conserved non-coding tiny endogenous RNA molecule that regulates various cellular functions by inhibiting mRNA translation or promoting the degradation of proteins. In this study, we identified a specific miRNA (designed as Pva-miR-2765) from Penaeus vannamei, which widely distributed in different tissues of shrimp, with the highest concentration found in the intestine. Through fluorescence in situ hybridization (FISH), we observed that Pva-miR-2765 is primarily located in the cytoplasm. Interestingly, we found that the expression of Pva-miR-2765 significantly decreased in hemocytes, hepatopancreas and gill under ammonia nitrogen stress. Furthermore, when Pva-miR-2765 was silenced, the autophagy level in shrimp significantly increased. Additionally, Pva-miR-2765 was found to promote pathological damage in the hepatopancreas of shrimp. Subsequently, correlation analysis revealed a negative relationship between the expression of Pva-miR-2765 and PvTBC1D7. To confirm this interaction, we conducted a dual luciferase reporter gene assay, which demonstrated that Pva-miR-2765 inhibit the expression of PvTBC1D7 by interacting with its 3'UTR. And the expression level of PvTBC1D7 in shrimp decreased significantly under ammonia nitrogen stress in Pva-miR-2765 overexpressed. Our findings suggest that Pva-miR-2765 can reduce autophagy in P. vannamei by inhibiting the regulation of PvTBC1D7, thereby participating in the oxidative stress of shrimp caused by ammonia nitrogen stress.

MicroRNA Regulation in Infectious Diseases and Its Potential as a Biosensor in Future Aquaculture Industry: A Review

An infectious disease is the most apprehensive problem in aquaculture as it can lead to high mortality in aquatic organisms and massive economic loss. Even though significant progress has been accomplished in therapeutic, prevention, and diagnostic using several potential technologies, more robust inventions and breakthroughs should be achieved to control the spread of infectious diseases. MicroRNA (miRNA) is an endogenous small non-coding RNA that post-transcriptionally regulates the protein-coding genes. It involves various biological regulatory mechanisms in organisms such as cell differentiation, proliferation, immune responses, development, apoptosis, and others. Furthermore, an miRNA also acts as a mediator to either regulate host responses or enhance the replication of diseases during infection. Therefore, the emergence of miRNAs could be potential candidates for the establishment of diagnostic tools for numerous infectious diseases. Interestingly, studies have revealed that miRNAs can be used as biomarkers and biosensors to detect diseases, and can also be used to design vaccines to attenuate pathogens. This review provides an overview of miRNA biogenesis and specifically focuses on its regulation during infection in aquatic organisms, especially on the host immune responses and how miRNAs enhance the replication of pathogens in the organism. In addition to that, we explored the potential applications, including diagnostic methods and treatments, that can be employed in the aquaculture industry.

Integrative analysis of the miRNA-mRNA regulation network in hemocytes of Penaeus vannamei following Vibrio alginolyticus infection

Penaeus vannamei is an important cultured shrimp that has high commercial value in the worldwide. However, the industry suffers heavy economic losses each year due to disease outbreaks caused by pathogenic bacteria. In the present study, after Vibrio alginolyticus infection, DNA damage in the hemocytes of the shrimp markedly increased, and autophagy and apoptosis increased significantly. Subsequently, hemocytes were sampled from the control and infected shrimp and sequenced for mRNA and microRNA (miRNA) 24 h after V. alginolyticus infection to better understand the response mechanism to bacterial infection in P. vannamei. We identified 1,874 and 263 differentially expressed mRNAs (DEGs) and miRNAs (DEMs) respectively, and predicted that 997 DEGs were targeted by DEMs. These DEGs were involved in the regulation of multiple signalling pathways, such as Toll and IMD signalling, TGF-beta signalling, MAPK signalling, and cell apoptosis, during Vibrio alginolyticus infection of the shrimp. We identified numerous mRNA-miRNA interactions, which provide insight into the defense mechanism that occur during the antimicrobial process of P. vannamei.

The Role of microRNA-133 in Hemocyte Proliferation and Innate Immunity of Scylla paramamosain

MicroRNAs (miRNAs) are important signaling regulators that are involved in regulating the innate immunity of crustacean. However, few studies focus on the role of crustacean miRNAs in the cellular immunity have been reported. In this study, we showed that the expression of miR-133 was significantly up-regulated in the mud crab Scylla paramamosain after infection by white spot syndrome virus (WSSV) or Vibrio parahaemolyticus. The anti-miRNA oligonucleotide AMO-miR-133 was used to knock down miR-133 expression in S. paramamosain. The number of WSSV copies increased significantly in WSSV-infected crabs after miR-133 knockdown. Knockdown of miR-133 also enhanced the mortality rates of WSSV-infected and V. parahaemolyticus-infected mud crabs, and it significantly enhanced the expression of the astakine, which was confirmed by real-time quantitative PCR and western blot analysis. The data also indicate that miR-133 may affect hemocyte proliferation in S. paramamosain by regulating astakine expression. miR-133 Knockdown enhanced the apoptosis or phagocytosis of crab hemocytes, and increased the mortality of mud crabs after WSSV or V. parahaemolyticus infection. These results indicate that miR-133 is involved in the host immune response to WSSV and V. parahaemolyticus infection in mud crabs. Taken together, our research provides new insights for the control of viral or vibrio diseases in S. paramamosain.

Double‐edged sword role of shrimp miRNA explains an evolutionary language between shrimp‐pathogen interactions that unties the knot of shrimp infection

Shrimp production, using a small‐scale enclosed pond system, is a rapidly growing aquaculture sector, which is valued around USD 18.30 billion in 2020. Intensified shrimp culture leads to the outbreak of transmissible diseases to eventually cause a huge loss in the production process and thus the economy. Studies on microRNA (miRNA) reveal that miRNA has an influential role in the host‐pathogen interaction during an infection. Recently, shrimp miRNA has been shown to help pathogen‐like viruses for their replication and infection. Several shrimp miRNAs were reported to be involved in enhancing host immunity against viral infection, especially white spot syndrome virus (WSSV) infection and Vibrio infection caused by bacterial species, whereas some shrimp miRNAs were reported to be hijacked by WSSV and to enhance the viral replication and establish the infection in shrimp. This gives an insight into the double‐edged sword role played by shrimp miRNA during host‐pathogen interaction. In future, this role could be employed against the virus to strengthen the shrimp culture. In this review, we discuss the role of shrimp miRNA and their mechanism(s) associated with the establishment of host‐pathogen interaction during infection, which will reveal the complexity associated with shrimp infection.

Differential expression of microRNAs in mud crab Scylla paramamosain in response to white spot syndrome virus (WSSV) infection

Till date numerous microRNAs (miRNAs) have been discovered from various organisms, including fish, shellfish and crustaceans. The miRNAs are known to regulate immune functions in crustaceans, but little is known about the role of miRNAs against viral infection in crab. We performed small RNA sequencing to characterize the differentially expressed miRNAs in WSSV infected Scylla paramamosain, in comparison to that in uninfected crab, at 2 h and 12 h post infection. In total, 24 host miRNAs were up-regulated and 25 host miRNAs were down-regulated in response to WSSV infection at 2 h post infection. And 27 host miRNAs were up-regulated and 30 host miRNAs were down-regulated in response to WSSV infection at 12 h post infection. Further, the gene ontology analysis revealed that many signaling pathways were mediated by these miRNAs. The integral component of membrane is the most important biological process and endocytosis pathway is the most important pathway, which indicates that endocytosis is very important for WSSV infection. This study is one important attempt at characterizing crab miRNAs that response to WSSV infection, and will help unravel the miRNA pathways involved in antiviral immunity of crab.

Identification and Comparison of microRNAs in the Gonad of the Yellowfin Seabream (Acanthopagrus Latus)

Yellowfin seabream (Acanthopagrus latus) is a commercially important fish in Asian coastal waters. Although natural sex reversal has been described in yellowfin seabream, the mechanisms underlying sexual differentiation and gonadal development in this species remain unclear. MicroRNAs (miRNAs) have been shown to play crucial roles in gametogenesis and gonadal development. Here, two libraries of small RNAs, constructed from the testes and ovaries of yellowfin seabream, were sequenced. Across both gonads, we identified 324 conserved miRNAs and 92 novel miRNAs: 67 ovary-biased miRNAs, including the miR-200 families, the miR-29 families, miR-21, and miR-725; and 88 testis-biased miRNAs, including the let-7 families, the miR-10 families, miR-7, miR-9, and miR-202-3p. GO (Gene Ontology) annotations and KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment analyses of putative target genes indicated that many target genes were significantly enriched in the steroid biosynthesis pathway and in the reproductive process. Our integrated miRNA-mRNA analysis demonstrated a putative negatively correlated expression pattern in yellowfin seabream gonads. This study profiled the expression patterns of sex-biased miRNAs in yellowfin seabream gonads, and provided important molecular resources that will help to clarify the miRNA-mediated post-transcriptional regulation of sexual differentiation and gonadal development in this species.

A novel microRNA and its pfk target control growth length in the freshwater shrimp Neocaridina heteropoda

MicroRNAs (miRNAs) are small non-coding RNAs that negatively regulate gene expression and play roles in a wide range of physiological processes, including ontogenesis. Herein, we discovered a novel miRNA, novel miR-26, which inhibits translation of the phosphofructokinase (PFK) gene by targeting the 3' untranslated region (UTR) of pfk directly, thereby inhibiting molting and body length growth of the freshwater shrimp Neocaridina heteropoda Lowering expression of pfk by RNA interference (RNAi) led to a longer ecdysis cycle and smaller individuals. This phenotype was mirrored in shrimps injected with novel miR-26 agomirs, but the opposite phenotype occurred in shrimps injected with novel miR-26 antagomirs (i.e. the ecdysis cycle was shortened and body length was increased). After injection of 20-hydroxyecdysone (ecdysone 20E), expression of the novel miR-26 was decreased, while expression of pfk was up-regulated, and the fructose-1,6-diphosphate metabolite of PFK accumulated correspondingly. Furthermore, expression of eIF2 (eukaryotic initiation factor 2) increased under stimulation with fructose-1,6-diphosphate, suggesting that protein synthesis was stimulated during this period. Taken together, our results suggest that the novel miR-26 regulates expression of pfk and thereby mediates the molting and growth of N. heteropoda.

The sterol regulatory element binding protein homolog of Penaeus vannamei modulates fatty acid metabolism and immune response

The sterol regulatory element binding proteins (SREBPs) transcription factors family, which regulate the expression of genes involved in cellular lipid metabolism and homeostasis, have recently been implicated in various physiological and pathophysiological processes such as immune regulation and inflammation in vertebrates. Consistent with other invertebrates, we identified a single SREBP ortholog in Penaeus vannamei (designated PvSREBP) with transcripts ubiquitously expressed in tissues and induced by lipopolysaccharide (LPS), Vibrio parahaemolyticus and Streptococcus iniae. In vivo RNA interference (RNAi) of PvSREBP attenuated the expression of several fatty acid metabolism-related genes (i.e., cyclooxygenase (PvCOX), lipoxygenase (PvLOX), fatty acid binding protein (PvFABP) and fatty acid synthase (PvFASN)), which consequently decreased the levels of total polyunsaturated fatty acids (ΣPUFAs). In addition, PvSREBP silencing decreased transcript levels of several immune-related genes such as hemocyanin (PvHMC) and trypsin (PvTrypsin), as well as genes encoding for heat-shock proteins (i.e., PvHSP60, PvHSP70 and PvHSP90). Moreover, in silico analysis revealed the presence of SREBP binding motifs on the promoters of most of the dysregulated genes, while shrimp depleted of PvSREBP were more susceptible to V. parahaemolyticus infection. Collectively, we demonstrated the involvement of shrimp SREBP in fatty acids metabolism and immune response, and propose that PvSREBP and PvHMC modulate each other through a feedback mechanism to establish homeostasis. The current study is the first to show the dual role of SREBP in fatty acid metabolism and immune response in invertebrates and crustaceans.

MicroRNA-654-3p enhances cisplatin sensitivity by targeting QPRT and inhibiting the PI3K/AKT signaling pathway in ovarian cancer cells

Dysregulation of microRNAs serves a crucial role in the chemosensitivity to cisplatin (DDP) in ovarian cancer (OVC). The abnormal expression of microRNA (miR)-654-3p has been reported in several types of human cancer. However, the association between miR-654-3p and cisplatin resistance in human OVC remains unclear. The present study aimed to investigate the role and mechanism of miR-654-3p in DDP resistance in OVC. The results demonstrated that miR-654-3p was significantly downregulated in ovarian cancer tissues and cells, as well as DDP-resistant IGROV-1/DDP cells, compared with adjacent non-tumoral tissue and IOSE386 cells. Overexpression of miR-654-3p significantly suppressed the proliferation and migration of ovarian cancer cells and increased the sensitivity of IGROV-1/DDP cells to DDP. Luciferase reporter assay demonstrated that quinolinate phosphoribosyl transferase (QPRT) was a target of miR-654-3p; overexpression of miR-654-3p inhibited QPRT expression by binding to the 3'-untranslated region of QPRT. In addition, inhibition of miR-654-3p reversed the suppressive effects of QPRT-targeting short interfering RNA on the proliferation and chemoresistance of ovarian cancer cells. Therefore, the results of the present study revealed a previously unrecognized regulatory mechanism that miR-654-3p enhances DDP sensitivity of OVC cells by downregulating QPRT expression; in addition, the present study highlighted the therapeutic implications of miR-654-3p upregulation in OVC.

microRNA-589-5p modulates the expression of hemocyanin as part of the anti-WSSV immune response in Litopenaeus vannamei

The respiratory glycoprotein, hemocyanin (HMC) has multiple immune-related functions, including antiviral activity. In this study, in silico methods were used to predict seven miRNAs targeting Litopenaeus vannamei HMC (LvHMC), out of which miR-589-5p was selected for further investigation because of its role in immune response. Transcript levels of miR-589-5p were ubiquitously distributed in all shrimp tissues examined, and significantly induced in hemocytes and hepatopancreas upon challenge with white-spot syndrome virus (WSSV) as well as by marine bacterial pathogens, which suggest that miR-589-5p is involved in shrimp immune response to pathogens. Morever, using Drosophila S2 cells stably overexpressing EGFP-LvHMC, flow cytometry and dual luciferase reporter assays, miR-589-5p was shown to significantly inhibit the in vitro expression of LvHMC. In addition, in vivo knockdown of miR-589-5p using antagomir-589-5p resulted in significant down-regulation in LvHMC expression, while overexpression of miR-589-5p using agomir-589-5p decreased the level of LvHMC expression in shrimp hemocytes and hepatopancreas. Further, the increased expression of miR-589-5p resulted in high shrimp mortality following WSSV challenge, coupled with an increase in the number of WSSV copies in hemocytes and hepatopancreas. These results suggest that miR-589-5p is involved in shrimp immune response to WSSV by negatively regulating the expression of LvHMC.

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.

Heat shock protein 70 from Litopenaeus vannamei (LvHSP70) is involved in the innate immune response against white spot syndrome virus (WSSV) infection

White spot syndrome (WSS) caused by white spot syndrome virus (WSSV) is a severe infectious disease in shrimp aquaculture. To find effective therapeutics to control WSSV, it is indispensable to understand the innate immune responses of shrimp to WSSV infection. Previous report demonstrated that the Litopenaeus vannamei heat shock protein 70 (LvHSP70) could induce shrimp innate immunity against bacterial infection. Herein, we further investigate the role of LvHSP70 in anti-WSSV infection. The temporal expression of LvHSP70 was significantly upregulated 2.5- and 1.5-fold at 6 and 24 h post systemic WSSV infection suggesting that the LvHSP70 was a WSSV responsive gene. The recombinant protein of LvHSP70 (rLvHSP70) was produced in an Escherichia coli system and its effect in protection against WSSV infection was investigated. Intramuscularly injection of juvenile shrimp with 1 nmol of rLvHSP70 could significantly prolong 50% mortality of WSSV-infected shrimp from 3 days to 5 days as compared to the control group injected with bovine serum albumin (BSA). Consistently, the injection of rLvHSP70 resulted in 24-fold, 20-fold and 100-fold decrease in the viral copy number after 6, 12 and 24 h post injection, respectively, compared to the control shrimp injected with BSA. Interestingly, it was found that the rLvHSP70 enhanced the expression of the key gene in the prophenoloxidase (proPO) activating system, LvproPO, but reduced the expression of Lvcaspase2 and LvIAP in WSSV-infected shrimp. These results suggested that the LvHSP70 is an important molecule involved in antiviral defense in shrimp presumably via modulating the proPO system and apoptosis.

miRNAs induced by white spot syndrome virus involve in immunity pathways in shrimp Litopenaeus vannamei

White shrimp Litopenaeus vannamei are widely cultured in the world and white spot syndrome virus (WSSV) led to huge economic losses in the shrimp industry every year. In the present study, miRNAs involved in the response of shrimp L. vannamei to WSSV infection were obtained through the Illumina HiSeq 2500 high-throughput next-generation sequencing technique. A total number of 7 known miRNAs and 54 putative novel miRNAs were obtained. Among them, 14 DEMs were identified in the shrimp infected with WSSV. The putative target genes of these DEMs were related to host immune response or signaling pathways, indicating the importance of miRNAs in shrimp against WSSV infection. The results will provide information for further research on shrimp response to virus infection and contribute to the development of new strategies for effective protection against WSSV infections.

Role of DCP1-DCP2 complex regulated by viral and host microRNAs in DNA virus infection

The DCP1-DCP2 complex can regulate the antiviral immunity of animals by the decapping of retrovirus RNAs and the suppression of RNAi during RNA virus infection. However, the influence of DCP1-DCP2 complex on DNA virus infection and the regulation of DCP1-DCP2 complex by microRNAs (miRNAs) remain unclear. In this study, the role of miRNA-regulated DCP1-DCP2 complex in DNA virus infection was characterized. Our results showed that the DCP1-DCP2 complex played a positive role in the infection of white spot syndrome virus (WSSV), a DNA virus of shrimp. In the DCP1-DCP2 complex, the N-terminal regulatory domain of DCP2 was interacted with the EVH1 domain of DCP1. Furthermore, shrimp miRNA miR-87 inhibited WSSV infection by targeting the host DCP2 gene and viral miRNA WSSV-miR-N46 took a negative effect on WSSV replication by targeting the host DCP1 gene. Therefore, our study provided novel insights into the underlying mechanism of DCP1-DCP2 complex and its regulation by miRNAs in virus-host interactions. IMPORTANCE: During RNA virus infection, the DCP1-DCP2 complex can play important roles in the animal antiviral immunity by decapping retrovirus RNAs and suppressing RNAi. In the present study, the findings indicated that the silencing of DCP1 and DCP2 inhibited the infection of WSSV, a DNA virus of shrimp, suggesting that the DCP1-DCP2 complex facilitated DNA virus infection. Due to the suppressive role of the DCP1-DCP2 complex in shrimp RNAi against WSSV infection, the DCP1-DCP2 complex could promote WSSV infection in shrimp. The results showed that WSSV-miR-N46 and shrimp miR-87 could respectively suppress the expressions of DCP1 and DCP2 to affect virus infection. Therefore, our study contributed novel aspects of the DCP1-DCP2 complex and its regulation by miRNAs in virus-host interactions.

Gonadal microRNA Expression Profiles and Their Potential Role in Sex Differentiation and Gonadal Maturation of Mud Crab Scylla paramamosain

Although the sexual dimorphism in terms of gonadal development and gametogenesis of mud crab has been described, the internal regulating mechanism and sex differentiation process remain unclear. A comparative gonadal miRNA transcriptomic study was conducted to identify miRNAs that are differentially expressed between testes and ovaries, and potentially uncover miRNAs that might be involved in sex differentiation and gonadal maturation mechanisms of mud crabs (Scylla paramamosain). A total of 10 known miRNAs and 130 novel miRNAs were identified, among which 54 were differentially expressed. Target gene prediction revealed a significant enrichment in 30 KEGG pathways, including some reproduction-related pathways, e.g. phosphatidylinositol signalling system and inositol phosphate metabolism pathways. Further analysis on six differentially expressed known miRNAs, six differentially expressed novel miRNAs and their reproduction-related putative target genes shows that both miRNAs and putative target genes showed stage-specific expression during gonadal maturation, suggesting their potential regulatory roles in sex differentiation and reproductive development. This study reveals the sex-biased miRNA profile and establishes a solid foundation for understanding the sex differentiation and gonadal maturation mechanisms of S. paramamosain.

Ligustrazin increases lung cell autophagy and ameliorates paraquat-induced pulmonary fibrosis by inhibiting PI3K/Akt/mTOR and hedgehog signalling via increasing miR-193a expression

Background

Reactive oxygen species (ROS) levels largely determine pulmonary fibrosis. Antioxidants have been found to ameliorate lung fibrosis after long-term paraquat (PQ) exposure. The effects of antioxidants, however, on the signalling pathways involved in PQ-induced lung fibrosis have not yet been investigated sufficiently. Here, we examined the impacts of ligustrazin on lung fibrosis, in particular ROS-related autophagy and pro-fibrotic signalling pathways, using a murine model of PQ-induced lung fibrosis.

Methods

We explored the effects of microRNA-193 (miR-193a) on Hedgehog (Hh) and PI3K/Akt/mTOR signalling and oxidative stress in lung tissues. Levels of miR-193a, protein kinase B (Akt), phosphoinositide 3-Kinase (PI3K), ceclin1, mammalian target of rapamycin (mTOR), sonic hedgehog (SHH), myosin-like Bcl2 interacting protein (LC3), smoothened (Smo), and glioma-associated oncogene-1 (Gli-1) mRNAs were determined with quantitative real-time PCR. Protein levels of PI3K, p-mTOR, p-Akt, SHH, beclin1, gGli-1, LC3, smo, transforming growth factor-β1 (TGF-β1), mothers against DPP homologue-2 (Smad2), connective tissue growth factor (CTGF), collagen I, collagen III, α-smooth muscle actin (α-SMA) nuclear factor erythroid 2p45-related factor-2 (Nrf2), and p-Smad2 were detected by western blotting. In addition, α-SMA, malondialdehyde, ROS, superoxide dismutase (SOD), oxidised and reduced glutathione, hydroxyproline, and overall collagen levels were identified in lung tissues using immunohistochemistry.

Results

Long-term PQ exposure blocked miR-193a expression, reduced PI3K/Akt/mTOR signalling, increased oxidative stress, inhibited autophagy, increased Hh signalling, and facilitated the formation of pulmonary fibrosis. Ligustrazin blocked PI3K/Akt/mTOR and Hh signalling as well as reduced oxidative stress via increasing miR-193a expression and autophagy, all of which reduced pulmonary fibrosis. These effects of ligustrazin were accompanied by reduced TGF-β1, CTGF, and Collagen I and III expression.

Conclusions

Ligustrazin blocked PQ-induced PI3K/Akt/mTOR and Hh signalling by increasing miR-193a expression, thereby attenuating PQ-induced lung fibrosis.

WSSV-host interaction: Host response and immune evasion

As invertebrates, shrimps rely on multiple innate defense reactions, including humoral immunity and cellular immunity to recognize and eliminate various invaders, such as viruses. White spot syndrome virus (WSSV) causes the most prevalent and devastating viral disease in penaeid shrimps, which are the most widely cultured species in the coastal waters worldwide. In the last couple of decades, studies about WSSV implicate a dual role of the immune system in protecting shrimps against the infection; these studies also explore on the pathogenesis of WSSV infection. Herein, we review our current knowledge of the innate immune responses of shrimps to WSSV, as well as the molecular mechanisms used by this virus to evade host immune responses or actively subvert them for its own benefit. Deciphering the interactions between WSSV and the shrimp host is paramount to understanding the mechanisms that regulate the balance between immune-mediated protection and pathogenesis during viral infection and to the development of a safe and effective WSSV defensive strategy.

Differential expression of microRNAs in Portunus trituberculatus in response to Hematodinium parasites

Latest studies have indicated that microRNAs (miRNAs) play important roles in defending against bacterial and viral infections in marine crustacean, whereas little is known regarding the immunological roles of crustacean miRNAs in response to parasitic infection. To further reveal the host-parasite interactions between the parasitic dinoflagellate Hematodinium and its crustacean hosts, we applied the high-throughput sequencing technology to identify and characterize miRNAs in the Chinese swimming crab Portunus trituberculatus challenged with the Hematodinium parasite at a timescale of 16 days (d). A total of 168 miRNAs were identified and 51 miRNAs were differentially expressed in the hepatopancreas tissues of affected hosts. Eleven of the differentially expressed miRNAs were selected and verified by the quantitative real-time RT-PCR (qRT-PCR), manifesting the consistency between the high throughout sequencing and qRT-PCR assays. Further analysis of the putative target genes indicated that various immune-related pathways (e.g. endocytosis, Fc gamma R-mediated phagocytosis, lysosome, ECM-receptor interaction, complement and coagulation cascades, antigen processing and presentation, focal adhesion, etc.) and signal transduction pathways (e.g. JAK-STAT signaling pathway, MAPK signaling pathway, p53 signaling pathway, etc.) were mediated by the differentially expressed miRNAs. The results presented fundamental knowledge on the immunological roles of crustacean miRNAs and contributed to the better understanding of hosts' miRNAs-mediated immunity against the parasitic infection.

White Spot Syndrome Virus-Induced Shrimp miR-315 Attenuates Prophenoloxidase Activation via PPAE3 Gene Suppression

MicroRNAs (miRNAs), the small non-coding RNAs, play a pivotal role in post-transcriptional gene regulation in various cellular processes. However, the miRNA function in shrimp antiviral response is not clearly understood. This research aims to uncover the function of pmo-miR-315, a white spot syndrome virus (WSSV)-responsive miRNAs identified from Penaeus monodon hemocytes during WSSV infection. The expression of the predicted pmo-miR-315 target mRNA, a novel PmPPAE gene called PmPPAE3, was negatively correlated with that of the pmo-miR-315. Furthermore, the luciferase assay indicated that the pmo-miR-315 directly interacted with the target site in PmPPAE3 suggesting the regulatory role of pmo-miR-315 on PmPPAE3 gene expression. Introducing the pmo-miR-315 into the WSSV-infected shrimp caused the reduction of the PmPPAE3 transcript level and, hence, the PO activity activated by the PmPPAE3 whereas the WSSV copy number in the shrimp hemocytes was increased. Taken together, our findings state a crucial role of pmo-miR-315 in attenuating proPO activation via PPAE3 gene suppression and facilitating the WSSV propagation in shrimp WSSV infection.

Comparative transcriptomic analysis of crab hemocytes in response to white spot syndrome virus or Vibrio alginolyticus infection

To assess the immune response of hemocytes to white spot syndrome virus (WSSV) or Vibrio alginolyticus infection in the mud crab Scylla paramamosain, a transcriptome analysis was performed. We report the analysis of 45131 transcripts from S. paramamosain hemocytes by de novo assembly. A comparison with GenBank protein and nucleotide sequences identified 33699 genes as previously known. The length distribution of the genes was 8147 genes ≥200 bp, 4714 genes ≥300 bp, and 3517 genes ≥2000 bp. A total of 21579 simple sequence repeats (SSRs) were found in the transcriptomic dataset, including 9% monomers, 53.34% dimers and 32.55% trimers. A total of 13172 and 5087 differentially expressed transcripts were found in the V. alginolyticus-infected group and WSSV-infected group, respectively. Of these, 5920 transcripts were up-regulated and 7252 were down-regulated in the V. alginolyticus-infected crabs and 2302 transcripts were up-regulated and 2785 were down-regulated in the WSSV-infected crabs. Additionally, 3096 transcripts were differentially expressed simultaneously in the V. alginolyticus-infected crabs and the WSSV-infected crabs. Several known immune-related genes such as heat shock protein, Janus kinase, STAT, relish, caspase, Ca²⁺-transporting ATPase and lysosomal alpha-mannosidase were found among the differentially expressed transcripts. Transcription and its regulation were significant biological processes, and ATP binding and zinc ion binding were significant molecular functions. This is the first report of comparative transcriptomic analysis of crab hemocytes in response to WSSV or V. alginolyticus infection. These findings will contribute to our understanding of the immune response to WSSV and V. alginolyticus infection in crustaceans.

Molecular characterization of shrimp harbinger transposase derived 1 (HARBI1)-like and its role in white spot syndrome virus and Vibrio alginolyticus infection

The role of the nuclease, HARBI1-like protein (mjHARBI1-like) in the innate immunity of Marsupenaeus japonicus was explored in this study. The 1361 bp cDNA sequence of mjHARBI1-like was cloned from M. japonicus using RACE. RT-qPCR analysis results showed that the gills and hepatopancreas of M. japonicus were the main tissues where mjHARBI1-like is expressed. In addition, it was also found that white spot syndrome virus (WSSV) or Vibrio alginolyticus challenge could stimulate mjHARBI1-like expression. After mjHARBI1-likewas inhibited, expression of immune genes such as toll, p53, myosin, and proPO were significantly downregulated (P < 0.01). However, in shrimp hemocytes, hemocyanin and tumor necrosis factor-α (TNF-α) were up-regulated significantly (P < 0.01). This study demonstrated that mjHARBI1-like plays a key role in the progression of WSSV and V. alginolyticus infection. Specifically, the cumulative mortality of WSSV-infected and V. alginolyticus-infected shrimp was significantly advanced by double-strand RNA interference (dsRNAi) of mjHARBI1-like. Apoptosis studies indicated that mjHARBI1-dsRNA treatment caused a reduction in hemocyte apoptosis in bacterial and viral groups. In addition, phagocytosis experiments illustrated that mjHARBI1-dsRNA treatment led to a lower phagocytosis rate in hemocytes of V. alginolyticus-challenged shrimp. It was also found that knockdown of mjHARBI1-like inhibited shrimp phenoloxidase (PO) activity, superoxide dismutase (SOD) activity, and total hemocyte count (THC) after WSSV or V. alginolyticus infection. These data indicate a regulative role of mjHARBI1-likein the immunity of shrimp in response to pathogen infection. Resultantly, it was concluded that mjHARBI1-like might have a positive effect on the anti-WSSV immune response of shrimp by regulating apoptosis, THC, PO activity, and SOD activity. Additionally, mjHARBI1-like might promote anti-V. alginolyticus infection by participating in regulating phagocytosis, apoptosis, SOD activity, PO activity, and THC.

Epigallocatechin-3-gallate protects Kuruma shrimp Marsupeneaus japonicus from white spot syndrome virus and Vibrio alginolyticus

Epigallocatechin-3-gallate (EGCG) is the most abundant catechin in green tea and exhibits potential antibacterial and anticancer activities. In this study, EGCG was used in pathogen-challenge experiments in shrimp to discover its effect on the innate immune system of an invertebrate. Kuruma shrimp Marsupeneaus japonicus was used as an experimental model and challenged with white spot syndrome virus (WSSV) and the Gram-negative bacterium Vibrio alginolyticus. Pathogen-challenge experiments showed that EGCG pretreatment significantly delayed and reduced mortality upon WSSV and V. alginolyticus infection, with VP-28 copies of WSSV also reduced. Quantitative reverse transcription polymerase chain reaction revealed the positive influence of EGCG on several innate immune-related genes, including IMD, proPO, QM, myosin, Rho, Rab7, p53, TNF-alpha, MAPK, and NOS, and we observed positive influences on three immune parameters, including total hemocyte count and phenoloxidase and superoxide dismutase activities, by EGCG treatment. Additionally, results showed that EGCG treatment significantly reduced apoptosis upon V. alginolyticus challenge. These results indicated the positive role of EGCG in the shrimp innate immune system as an enhancer of immune parameters and an inhibitor of apoptosis, thereby delaying and reducing mortality upon pathogen challenge. Our findings provide insight into potential therapeutic or preventive functions associated with EGCG to enhance shrimp immunity and protect shrimp from pathogen infection.

Molecular characterization of diphthamide biosynthesis protein 7 in Marsupenaeus japonicus and its role in white spot syndrome virus infection

Diphthamide biosynthesis protein 7 (Dph7) is a vital protein for diphthamide biosynthesis in archaea and eukaryotes. The 1143 bp cDNA sequence of Dph7 was cloned from the gills of Marsupenaeus japonicus using RT-PCR and RACE. Data showed that Dph7 was highly expressed in the gills and digestive gland of M. japonicus. Furthermore, the expression of dph7 was induced by infection with white spot syndrome virus (WSSV). When Dph7 was knocked down, immune genes such as toll, prophenoloxidase (proPO), p53, tumor necrosis factor-α (TNF-α) and signal transducer and activator of transcription (STAT) were significantly down-regulated (P < 0.01) in hemocytes. First, we demonstrated that Dph7 is very important in the progression of WSSV infection and that the time of death for WSSV-infected shrimp was significantly advanced following RNAi targeting of Dph7. We also investigated the effect of Dph7 on apoptosis rate in M. japonicas and found that Dph7-dsRNA treatment caused lower levels of apoptosis in hemocytes, both in the disease-free group and the WSSV group. Knock-down of Dph7 affected the activity of both phenoloxidase (PO) and superoxide dismutase (SOD), and total hemocyte count (THC) after infection with WSSV, indicating that Dph7 plays a regulatory role in the immunological reaction of shrimp in response to WSSV infection. Thus, we conclude that Dph7 may promote the anti-WSSV immune response of shrimp by regulating apoptosis, SOD and PO activity, and can influence the progression of WSSV infection.

Differential expression of microRNAs in hemocytes from white shrimp Litopenaeus vannamei under copper stress

MicroRNAs (miRNAs) are small noncoding RNAs that regulate diverse cellular processes, including organismal stress response, through posttranscriptional repression of gene transcripts. They are known to have antiviral functions in aquatic crustacean species, but little is known about the role of miRNAs against environmental stress caused by Cu, a common chemical contaminant in aquatic environment. We performed small RNA sequencing to characterize the differentially expressed microRNAs in Cu exposed shrimp. A total of 4524 known miRNAs and 73 novel miRNAs were significantly (P < .05) differentially expressed after Cu exposure. The peak size of miRNAs was 22 nt. Among them, 218 miRNAs were conserved across 115 species. The validation of 12 miRNAs by stem-loop quantitative RT-PCR were found to be coherent with the expression profile of deep sequencing data as evaluated with Pearson's correlation coefficient (r = 0.707). Target genes of these differentially expressed miRNAs related to immune defense, apoptosis, and xenobiotics metabolism also showed significant changes in expression under Cu stress. The present study provides the first characterization of L. vannamei miRNAs and some target genes expression in response to Cu stress, and the findings support the hypothesis that certain miRNAs along with their target genes might be essential in the intricate adaptive response regulation networks. Our current study will provide valuable information to take an insight into molecular mechanism of L. vannamei against environmental stress.

Different roles of a novel shrimp microRNA in white spot syndrome virus (WSSV) and Vibrio alginolyticus infection

In this study, Marsupeneaus japonicus microRNA-S5 (miR-S5) was found to be up-regulated 24 h post white spot syndrome virus (WSSV) or V. alginolyticus infection. The loss of function using an anti-microRNA oligonucleotide (AMO-miR-S5) showed that expression levels of multiple innate immune-related genes were affected. The expression of p53 and tumor necrosis factor-α (TNF-α) were significantly down-regulated, expression of myosin was significantly up-regulated. The miR-S5 knockdown delayed WSSV-induced death for 48 h, but the final mortality was not affected, while V. alginolyticus-induced mortality was increased by 30%. The effect of miR-S5 knockdown on phagocytosis and apoptosis rates showed that miR-S5 knock down significantly decreased phagocytosis rate of WSSV from 27.8% to 7.0%, and phagocytosis rate of V. alginolyticus from 27.2% to 21.4%, separately. WSSV-induced apoptosis decreased from 60.83% to 51.25%, but no effect on V. alginolyticus-induced apoptosis (43.72%-45.04%). We concluded that miR-S5 could be used by WSSV via regulating hemocyte phagocytosis and apoptosis processes, but helps to defend against bacterial infection by regulating the proPO system, superoxide dismutase activity and phagocytosis.

Molecular cloning of Kuruma shrimp Marsupenaeus japonicus endonuclease-reverse transcriptase and its positive role in white spot syndrome virus and Vibrio alginolyticus infection

This study investigated the function of endonuclease-reverse transcriptase (mjERT) in Marsupenaeus japonicus. The 1129 bp cDNA sequence of mjERT was cloned from M. japonicus using rapid amplification of cDNA ends (RACE) PCR, and RT-qPCR analysis indicated that mjERT was highly expressed in the gills and hepatopancreas of M. japonicus. We also found that white spot syndrome virus (WSSV) or Vibrio alginolyticus challenge could enhance the expression of mjERT. When mjERT was inhibited, immune genes such as toll, p53, hemocyanin and tumor necrosis factor-α (TNF-α) were significantly down-regulated (P < .01) in the hemocytes of shrimp, while myosin was significantly up-regulated (P < .01). We demonstrated that mjERT is very important for the progression of WSSV infection and that the cumulative mortality of WSSV-infected and V. alginolyticus-infected shrimps was significantly increased following mjERT RNA interfere (RNAi). Apoptosis data provided information to suggest that mjERT-dsRNA challenge caused less apoptosis in hemocytes in both the disease-free and viral group. We also revealed that mjERT-dsRNA treatment resulted in a lower phagocytosis rate in the hemocytes of V. alginolyticus-challenged shrimp. Finally, we found that the absence of mjERT had an significantly negative impact upon shrimp phenoloxidase (PO) activity, superoxide dismutase (SOD) activity and total hemocyte count (THC) following WSSV or V. alginolyticus infection, indicating a regulative role for mjERT in the innate immunity of shrimp in response to pathogenic infection. In summary, we concluded that mjERT might promote the anti-WSSV immune response of shrimp by regulating apoptosis, PO activity, THC and SOD activity, and also exert a positive role in the immune response against V. alginolyticus by regulating phagocytosis, SOD activity, PO activity and THC.

The shrimp hormone receptor acts as an anti-apoptosis and anti-inflammatory factor in innate immunity

Previously, we found that the expression of several genes, including HR, varied in Drosophila melanogaster after white spot syndrome virus (WSSV) infection. In this present study, we further investigated the role of HR in Kuruma shrimp, Marsupenaeus japonicus and determined its anti-apoptosis and anti-inflammation role in the innate immune system. We successfully identified a partial sequence (866 bp in length) of the M. japonicus hormone receptor ligand binding domain (mjHR_LBD/mjHR). The 5' end of mjHR was successfully obtained; the open reading frame (ORF) ran from 33 to 701 bp, and encoded a protein containing 222 amino acids. mjHR belonged to the ligand binding domain of hormone receptors, was most likely part of a nuclear hormone receptor, and shared a close evolutionary relationship with other arthropods, such as insects. mjHR was expressed predominantly in immunity tissues such as gills, hemolymph and the hepatopancreas. WSSV infection could cause the down-regulation of mjHR, while infection with Vibrio alginolyticus could cause significant up-regulation of mjHR. The expression of mjHR was knocked down by dsRNA expressed by an engineered LITMUS 38i-HR plasmid. Virus and bacteria challenge experiment showed that the mortality of WSSV-infected shrimps was elevated in the absence of HR while the mortality of shrimps infected with V. alginolyticus was slightly reduced. Phenoloxidase (PO) activity, phagocytosis and apoptosis were promoted, while superoxide dismutase (SOD) activity was impaired, indicating that mjHR functions in an anti-apoptosis and anti-inflammation manner to prevent shrimp death caused by an over-load of immunity responses. Differences between mjHR expression and mortality change after WSSV or V. alginolyticus infection indicated that there was a different strategy for viruses or bacteria when confronted with the innate immune system.

Hemocytes of the mud crab Scylla paramamosain: Cytometric, morphological characterization and involvement in immune responses

Hemocytes play essential roles in the innate immune system of crustaceans. Characterization of hemocytes from estuary mud crab Scylla paramamosain was performed by flow cytometry and morphological studies such as cytochemical staining and electron microscopy. The hemocyte subsets were further separated using a modified Percoll density gradient centrifugation method. Based on the morphological characteristics of the cells, three distinct categories of hemocytes were identified: granulocytes with abundant large granularity representing 5.27 ± 0.42%, semigranulocytes with small or less granularity representing 76.03 ± 3.34%, and hyalinocytes (18.70 ± 3.92%) which were almost no granularity. The total hemocyte cell count and the percentage of hemocyte subsets varied after pathogen infection, including Vibrio alginolyticus and the viral double-stranded RNA analog Poly (I:C). The phagocytic process is of fundamental importance for crustaceans' cellular immune response as well as development and survival. The results of the in vitro phagocytosis assays analyzed by flow cytometry demonstrated that granulocytes and semigranulocytes had significantly higher phagocytic ability than hyalinocytes. A primary culture system, L-15 medium supplemented with 5-10% fetal bovine serum, was developed to further investigate the immune function of hemocytes. Furthermore, adenovirus can be utilized to effectively transfer GFP gene into hemocytes. Overall, three hemocyte sub-populations of S. paramamosain were successfully discriminated, moreover, their response to pathogen infections, phagocytic activity and adenovirus mediated transfection were also investigated for the first time. This study may contribute to a better understanding of the innate immune system of estuary crabs.

Identification and characterization of lymph organ microRNAs in red swamp crayfish, Procambarus clarkii infected with white spot syndrome virus

MicroRNAs (miRNAs) were important post-transcriptional regulators and played vital roles in innate immunity system of invertebrates, especially in the aspect of antivirus. In this study, using high-throughput small RNAs Illumina sequencing system, differentially expressed miRNAs (DEMs) from lymph organs in red swamp crayfish, Procambarus clarkii, infected with white spot syndrome virus, were identified. As a result, 32 known miRNAs and 7 novel miRNAs were identified in crayfish lymph organ small RNAs library of NG and WG. Among them, 7 differentially expressed miRNAs (DEMs) were predicted to be involved in the lymph organ antiviral innate immunity of P. clarkii. Besides, the results showed that putative target genes of these DEMs were related with tight junction, RNA transport, regulation of actin cytoskeleton, focal adhesion, vascular smooth muscle contraction, mRNA surveillance pathway, NOD-like receptor signaling pathway, leukocyte transendothelial migration, and protein processing in endoplasmic reticulum. These results might provide the guiding theoretical foundation for future studies about crustaceans' antiviral innate immunity.

Shrimp miR-10a Is Co-opted by White Spot Syndrome Virus to Increase Viral Gene Expression and Viral Replication

Members of the microRNA miR-10 family are highly conserved and play many important roles in diverse biological mechanisms, including immune-related responses and cancer-related processes in certain types of cancer. In this study, we found the most highly upregulated shrimp microRNA from Penaeus vannamei during white spot syndrome virus (WSSV) infection was miR-10a. After confirming the expression level of miR-10a by northern blot and quantitative RT-PCR, an in vivo experiment showed that the viral copy number was decreased in miR-10a-inhibited shrimp. We found that miR-10a targeted the 5′ untranslated region (UTR) of at least three viral genes (vp26, vp28, and wssv102), and plasmids that were controlled by the 5′ UTR of these genes produced enhanced luciferase signals in transfected SF9 cells. These results suggest a previously unreported role for shrimp miR-10a and even a new type of host–virus interaction, whereby a co-opts the key cellular regulator miR-10a to globally enhance the translation of viral proteins.

MicroRNA miR-214 inhibits snakehead vesiculovirus replication by targeting the coding regions of viral N and P

Snakeheadvesiculovirus (SHVV), a new member of the family Rhabdoviridae, has caused enormous economic losses in snakehead fish culture during the past years in China; however, little is known about the molecular mechanisms of its pathogenicity. MicroRNAs (miRNAs) are small non-coding RNAs that play important roles in virus infection. In this study, we identified that SHVV infection downregulated miR-214 in striped snakehead (SSN-1) cells in a time- and dose-dependent manner. Notably, transfecting SSN-1 cells with miR-214 mimic significantly inhibitedSHVV replication, whereas miR-214 inhibitor promoted it, suggesting that miR-214 acted as a negative regulator of SHVV replication. Our study further demonstrated that N and P of SHVV were the target genes of miR-214. Over-expression of P, but not N, inhibited IFN-α production in SHVV-infected cells, which could be restored by over-expression of miR-214. Taken together, these results suggest that miR-214 is downregulated during SHVV infection, and the downregulated miR-214 in turn increased N and P expression and decreased IFN-α production, thus facilitating SHVV replication. This study provides a better understanding of the molecular mechanisms on the pathogenesis of SHVV and a potential antiviral strategy against SHVV infection.