MMP-14 regulates innate immune responses to Eriocheir sinensis via tissue degradation

ERK/CREB and p38 MAPK/MMP14 Signaling Pathway Influences Spermatogenesis through Regulating the Expression of Junctional Proteins in Eriocheir sinensis Testis

The hemolymph-testis barrier (HTB) is a reproduction barrier in Crustacea, guaranteeing the safe and smooth process of spermatogenesis, which is similar to the blood-testis barrier (BTB) in mammals. The MAPK signaling pathway plays an essential role in spermatogenesis and maintenance of the BTB. However, only a few studies have focused on the influence of MAPK on crustacean reproduction. In the present study, we knocked down and inhibited MAPK in Eriocheir sinensis. Increased defects in spermatogenesis were observed, concurrently with a damaged HTB. Further research revealed that es-MMP14 functions downstream of ERK and p38 MAPK and degrades junctional proteins (Pinin and ZO-1); es-CREB functions in the ERK cascade as a transcription factor of ZO-1. In addition, when es-MMP14 and es-CREB were deleted, the defects in HTB and spermatogenesis aligned with abnormalities in the MAPK. However, JNK impacts the integrity of the HTB by changing the distribution of intercellular junctions. In summary, the MAPK signaling pathway maintains HTB integrity and spermatogenesis through es-MMP14 and es-CREB, which provides insights into the evolution of gene function during barrier evolution.

Effects of berberine hydrochloride on immune response in the crab Charybdis japonica

Berberine hydrochloride is the main effective component of Coptis spp. used in Chinese herbal medicine and its underlying molecular mechanisms, responsible for inducing effects in crustacean species, are not fully understood. In this study, the molecular response of the crab Charybdis japonica to berberine hydrochloride exposure was studied using transcriptome sequencing. The survival rate, gene expression and activities of several immune enzymes were measured after berberine hydrochloride treatments, with or without injection of the pathogenic bacterium Aeromonas hydrophila. A total of 962 differentially expressed genes (464 up-regulated and 498 down-regulated) were observed during exposure to 100 mg/L of berberine hydrochloride and in the control group after 48 h. Enrichment analysis revealed that these genes are involved in metabolism, cellular processes, signal transduction and immune functions, indicating that exposure to berberine hydrochloride activated the immune complement system. This bioactive compound simultaneously activated fibrinogen beta (FGB), fibrinogen alpha (FGA), alpha-2-macroglobulin (A2M), kininogen (KNG), fibrinogen gamma chain (FGB), alpha-2-HS-glycoprotein (AHSG), caspase-8 (CASP8), cathepsin L (CTSL), adenylate cyclase 3 (Adcy3) and MMP1. Its action could significantly increase the survival rate of the crabs injected with A. hydrophila and promote the activity of LZM, Caspas8, FGA, ACP and AKP in the hepatopancreas. When A. hydrophila was added, the neutralization of 300 mg/L berberine hydrochloride maximized the activities of Caspas8, LZM, ACP and AKP. Our results provide a new understanding of the potential effects of berberine hydrochloride on the immune system mechanisms in crustaceans.

Comparative Transcriptome Analysis on the Regulatory Mechanism of Thoracic Ganglia in Eriocheir sinensis at Post-Molt and Inter-Molt Stages

Eriocheir sinensis is an aquatic species found distributed worldwide. It is found in the Yangtze River of China, where the commercial fishing of this valuable catadromous aquatic species has been banned. As an important member of the phylum Arthropoda, E. sinensis grows by molting over its whole lifespan. The central nervous system of Eriocheir sinensis plays an important regulatory role in molting growth. Nevertheless, there are no reports on the regulatory mechanisms of the nervous system in E. sinensis during the molting cycle. In this study, a comparative transcriptome analysis of E. sinensis thoracic ganglia at post-molt and inter-molt stages was carried out for the first time to reveal the key regulatory pathways and functional genes operating at the post-molt stage. The results indicate that pathways and regulatory genes related to carapace development, tissue regeneration, glycolysis and lipolysis and immune and anti-stress responses were significantly differentially expressed at the post-molt stage. The results of this study lay a theoretical foundation for research on the regulatory network of the E. sinensis nervous system during the post-molt developmental period. Detailed knowledge of the regulatory network involved in E. sinensis molting can be used as a basis for breeding improved E. sinensis species, recovery of the wild E. sinensis population and prosperous development of the E. sinensis artificial breeding industry.

Integrative omics analysis highlights the immunomodulatory effects of the parasitic dinoflagellate hhematodinium on crustacean hemocytes

Parasitic dinoflagellates in genus Hematodinium have caused substantial economic losses to multiple commercially valuable marine crustaceans around the world. Recent efforts to better understand the life cycle and biology of the parasite have improved our understanding of the disease ecology. However, studies on the host-parasite interaction, especially how Hematodinium parasites evade the host immune response are lacking. To address this shortfall, we used the comprehensive omics approaches (miRNA transcriptomics, iTRAQ-based proteomics) to get insights into the host-parasite interaction between hemocytes from Portunus trituberculatus and Hematodinium perezi in the present study. The parasitic dinoflagellate H. perezi remodeled the miRNome and proteome of hemocytes from challenged hosts, modulated the host immune response at both post-transcriptional and translational levels and caused post-transcriptional regulation to the host immune response. Multiple important cellular and humoral immune-related pathways (ex. Apoptosis, Endocytosis, ECM-receptor interaction, proPO activation pathway, Toll-like signaling pathway, Jak-STAT signaling pathway) were significantly affected by Hematodinium parasites. Through modulation of the host miRNome, the host immune responses of nodulation, proPO activation and antimicrobial peptides were significantly suppressed. Cellular homeostasis was imbalanced via post-transcriptional dysregulation of the phagosome and peroxisome pathways. Cellular structure and communication was seriously impacted by post-transcriptional downregulation of ECM-receptor interaction and focal adhesion pathways. In conclusion, H. perezi parasites could trigger striking changes in the miRNome and proteome of crustacean hemocytes, and this parasite exhibited multifaceted immunomodulatory effects and potential immune-suppressive mechanisms in crustacean hosts.

Role of peroxinectin in the antibacterial immune response of the Chinese mitten crab, Eriocheir sinensis

To elucidate the antibacterial role of peroxinectin (referred to as PXN) and its molecular mechanism in Chinese mitten crab Eriocheir sinensis, we analyzed the bacterial binding and removal of the peroxinectin recombinant protein in vitro and the interaction of peroxinectin with integrin and CuZn-SOD through GST-pulldown and bimolecular fluorescence complementation methods. Concurrently, the effect of peroxinectin interference on the expression of other immune-related genes was studied using RNA interference. The results showed that the recombinant peroxinectin protein could bind to Bacillus subtilis, Staphylococcus aureus, Aeromonas hydrophila, and Vibrio parahaemolyticus with different affinities in vitro and could eliminate Vibrio parahaemolyticus in vivo. The findings also indicated that peroxinectin could establish interactions with integrin and CuZn-SOD in vitro. Furthermore, 48 h after the injection of the peroxinectin gene siRNA in vivo, the expression of peroxinectin mRNA decreased significantly (P < 0.05), integrin mRNA expression decreased by 16.8%, and CuZn-SOD mRNA expression decreased by 62.84% (P < 0.01). The expression levels of Dorsal, GPx, GST, PPAF, and Relish (P < 0.01), as well as that of lectin (P < 0.001) were significantly decreased. When peroxinectin siRNA was injected in vivo for 48 h and Aeromonas hydrophila was injected into mitten crabs, the expression of immune-related genes significantly increased. All data indicate that the recombinant peroxinectin protein in Chinese mitten crabs can recognize and bind different bacteria and promote the elimination of Vibrio parahaemolyticus from the body. Furthermore, peroxinectin may establish interactions with integrin and CuZn-SOD to activate the expression of related immune genes to elicit responses to bacterial infections and achieve immune protection.

Apostichopus japonicus matrix metalloproteinase-16 might act as a pattern recognition receptor

Matrix metalloproteinases (MMPs) are an important family of proteinases involved in various physiological processes and associated with the immune response. However, the role of MMPs in the immune response remains unclear. To explore the possible role of MMPs in innate immunity, this study selected the MMP-16 gene encoding peptidoglycan (PGN) binding domain identified in the sea cucumber Apostichopus japonicus (named AjMMP-16, GenBank accession No. AQT26486) for microbial polysaccharide-induced transcriptional expression analysis by quantitative real-time PCR, correlation analysis with nine representative genes from A. japonicus immune pathways in microbial polysaccharide-induced transcriptional expression by using Pearson's correlation test, and prokaryotic recombinant expression. Next, its recombinant protein was employed for microbial polysaccharide-binding analysis with ELISA and bacterial binding analysis with the indirect immunofluorescence method. The results showed that AjMMP-16 was significantly induced by diaminopimelic acid (DAP)-type PGN, lipopolysaccharide, mannan, and β-1,3-glucan and was closely correlated with myeloid differentiation factor 88 (MyD88) in microbial polysaccharide-induced transcriptional expression. In addition, recombinant AjMMP-16 bound to lysine-type PGN, DAP-type PGN, lipopolysaccharide, mannan, β-1,3-glucan, Vibrio splendidus, Pseudoalteromonas nigrifaciens, Shewanella baltica, Bacillus cereus, Escherichia coli, and Staphylococcus aureus. These results suggest that AjMMP-16 might act as a pattern recognition receptor in innate immunity and play an important role in initiating the MyD88-dependent Toll-like receptor signaling pathway.

Polystyrene nanoplastics exacerbated the ecotoxicological and potential carcinogenic effects of tetracycline in juvenile grass carp (Ctenopharyngodon idella)

This study aims to evaluate the ecotoxicity effects of single tetracycline (TC) exposure and mixture exposure in presence of polystyrene nanoplastics (PS-NPs, 80 nm) on juvenile Ctenopharyngodon idella. We carried out single and combined exposure of TC (5000 μg/L) and PS-NPs (20, 200, 2000 μg/L) for 7 days. Compared to TC single exposure, co-exposure to PS-NPs and TC significantly changed the levels of antioxidant entities, including T-AOC, SOD, and CAT in the liver and intestine of C. idella, indicating that PS-NPs might enhance the oxidative damage caused by TC. Further, the co-exposure significantly upregulated the mRNA expression levels of MMP2, MMP9, and IL-8 in a concentration-dependent manner in the liver and intestine tissues of C. idella, compared to the control and TC single exposure groups. Moreover, the phylogenetic tree showed that MMP2 and MMP9 in C. idella are relatively conservative, and the mRNA expressions of MMP2 are significantly positively correlated with TGFβ1, IL8, and MMP9 in Liver hepatocellular carcinoma (LIHC) and Colon adenocarcinoma (COAD). The above genes in LIHC and COAD were significantly correlated with various immune cells. Further, histopathological analysis revealed tissue lesions in the intestine and gill of fish in all the exposed groups, compared to the control group. In short, the present study illustrated that the toxicological effects of organic pollutants such as TC could be influenced by the presence of NPs in the C. idella.