An intracellular bacterial pathogen triggers RIG-I/MDA5-dependent necroptosis.

RIG-I and MDA5 are members of RIG-I-like receptors (RLRs) that detect viral RNA within the cytoplasm and subsequently initiate antiviral immune responses. Necroptosis is a form of programmed cell death (PCD) executed by mixed lineage kinase domain-like (MLKL), which, upon phosphorylation by receptor-interacting protein kinase 3 (RIPK3), causes necrotic cell death. To date, no link between RLRs and necroptosis has been observed during bacterial infection.

Pufferfish gasdermin Ea is a significant player in the defense against bacterial pathogens.

Unlabelled: Gasdermins (GSDMs) are proteins cleaved by caspase (CASP) to trigger pyroptosis. In teleosts, pyroptosis is mediated by gasdermin E (GSDME). The Pufferfish, , possesses two GSDME orthologs: named TrGSDMEa and TrGSDMEb.

IL-18 signaling is regulated by caspase 6/8 and IL-18BP in turbot (Scophthalmus maximus).

Interleukin (IL)-18 is synthesized as a precursor that requires intracellular processing to become functionally active. In human, IL-18 is processed by caspase 1 (CASP1). In teleost, the maturation and signal transduction mechanisms of IL-18 are unknown.

The molecular mechanism and evolutionary divergence of caspase 3/7-regulated gasdermin E activation.

Caspase (CASP) is a family of proteases involved in cleavage and activation of gasdermin, the executor of pyroptosis. In humans, CASP3 and CASP7 recognize the same consensus motif DxxD, which is present in gasdermin E (GSDME). However, human GSDME is cleaved by CASP3 but not by CASP7.

Bacillus cereus cereolysin O induces pyroptosis in an undecapeptide-dependent manner.

Bacillus cereus is a clinically significant foodborne pathogen that causes severe gastrointestinal and non-gastrointestinal disease. Cereolysin O (CLO) is a putative virulence factor of B. cereus, and its function remains to be investigated.

MLKL-mediated necroptosis is activated by RIPK1/3 and involved in anti-microbial immunity.

Necroptosis is a type of proinflammatory programmed necrosis essential for innate immunity. The receptor interacting protein kinases 1/3 (RIPK1/3) and the substrate mixed lineage kinase domain-like protein (MLKL) are core components of the necroptotic axis. The activation and immunological function of necroptosis in fish remain elusive.

Metabolic proteins with crucial roles in antioxidative adaptation and intracellular proliferation.

is a significant fish pathogen that can live in challenging environments of reactive oxygen species (ROS), such as inside the phagocytes. Metabolic reconfiguration has been increasingly associated with bacterial oxidative tolerance and virulence. However, the metabolic proteins of involved in such processes remain elusive.

Tongue sole creatine kinases function as DAMP and activate antimicrobial immunity TLR2.

Creatine kinase (CK) is an enzyme that regulates adenosine triphosphate (ATP) metabolism to maintain energy homeostasis. Although CK has been reported to be involved in pathogen infection, the immune function of CK remains elusive. In this study, we identified two muscle-type CK from the teleost tongue sole (designated CsCKM-1 and CsCKM-2).

New insights into the evolutionary dynamic and lineage divergence of gasdermin E in metazoa.

Gasdermin (GSDM) is a family of pore-forming proteins that induce pyroptosis. To date, the origin and evolution of GSDM in Metazoa remain elusive. Here, we found that GSDM emerged early in Placozoa but is absent in a large number of invertebrates.

Chromosome-level genome assembly of largemouth bass (Micropterus salmoides) using PacBio and Hi-C technologies.

The largemouth bass (Micropterus salmoides) has become a cosmopolitan species due to its widespread introduction as game or domesticated fish. Here a high-quality chromosome-level reference genome of M. salmoides was produced by combining Illumina paired-end sequencing, PacBio single molecule sequencing technique (SMRT) and High-through chromosome conformation capture (Hi-C) technologies.

RGD-Labeled Hemocytes With High Migration Activity Display a Potential Immunomodulatory Role in the Pacific Oyster .

Immunocyte migration to infection sites is important for host cellular defense, but the main types of migrating hemocytes and their mechanisms against pathogen invasions are unclear in invertebrates. In the present study, a population of hemocytes in the Pacific oyster labeled with a fluorescein isothiocyanate (FITC)-conjugated Arg-Gly-Asp (RGD)-containing peptide was sorted. RGD hemocytes were characterized by a smaller cell size and cytoplasmic-nucleo ratio, fewer cytoplasmic granules, and higher levels of myeloperoxidase, reactive oxygen species, and intracellular free calcium concentration.

A Teleost CXCL10 Is Both an Immunoregulator and an Antimicrobial.

Chemokines are a group of cytokines that play important roles in cell migration, inflammation, and immune defense. In this study, we identified a CXC chemokine, CXCL10, from Japanese flounder (named PoCXCL10) and investigated its immune function. Structurally, PoCXCL10 possesses an N-terminal coil, three β-strands, and a C-terminal α-helix with cationic and amphipathic properties.

Bacillus cereus cytotoxin K triggers gasdermin D-dependent pyroptosis.

Bacillus cereus is well known as a causative agent of foodborne gastrointestinal diseases and systemic non-gastrointestinal diseases. We have recently identified a pathogenic B. cereus (named H2) from a deep-sea cold-seep.

TNFR2 is a regulatory target of pol-miR-194a and promotes the antibacterial immunity of Japanese flounder Paralichthys olivaceus.

MicroRNAs (miRNAs) are regulatory RNAs that modulate target gene expression after transcription. Pol-miR-194a had been reported to be a miRNA of Japanese flounder (Paralichthys olivaceus) involved in Edwardsiella tarda infection. Here, we identified tumor necrosis factor receptor 2 (TNFR2) as a target gene of pol-miR-194a.

GSDMEa-mediated pyroptosis is bi-directionally regulated by caspase and required for effective bacterial clearance in teleost.

Gasdermin (GSDM) is a family of pore-forming proteins that, after cleavage by caspase (CASP), induce a type of programmed necrotic cell death called pyroptosis. Gasdermin E (GSDME) is the only pyroptosis-inducing member of the GSDM family existing in teleost. To date, the regulation and function of teleost GSDME in response to bacterial infection remain elusive.

The Involvement of Thiamine Uptake in the Virulence of .

is a pathogenic bacterium, which can infect a number of fish species and cause a disease termed edwardsiellosis, threatening global fish farming with high prevalence and mortality. Thiamine (Vitamin B1), functioning in the form of thiamine pyrophosphate (TPP), is essential for almost all organisms. Bacteria acquire TPP by biosynthesis or by transportation of exogenous thiamine.

A calcification-related calmodulin-like protein in the oyster Crassostrea gigas mediates the enhanced calcium deposition induced by CO exposure.

Calcium transportation and homeostasis are essential for marine bivalves to maintain basic metabolism and build their shells. Calmodulin-like proteins (CaLPs) are important calcium sensors and buffers and can respond to ocean acidification (OA) in marine calcifiers. However, no further study of their physiological function in calcium metabolism under elevated CO has been performed.

Megalocytivirus Induces Complicated Fish Immune Response at Multiple RNA Levels Involving mRNA, miRNA, and circRNA.

Megalocytivirus is an important viral pathogen to many farmed fishes, including Japanese flounder (). In this study, we examined megalocytivirus-induced RNA responses in the spleen of flounder by high-throughput sequencing and integrative analysis of various RNA-seq data. A total of 1327 microRNAs (miRNAs), including 368 novel miRNAs, were identified, among which, 171 (named DEmiRs) exhibited significantly differential expressions during viral infection in a time-dependent manner.

Fabrication of fish gelatin / sodium alginate double network gels for encapsulation of probiotics.

Background: To improve the environmental resistance of probiotics, and particularly their survival in the gastrointestinal environment, a fish gelatin (FG) / sodium alginate (SA) double network gelation (FSDN) was developed to encapsulate them. Thermal treatment and calcium ion inducement were adopted to fabricate fish gelatin and sodium alginate gels. It was feasible to scale up this process.

A Fish Galectin-8 Possesses Direct Bactericidal Activity.

Galectins are a family of animal lectins with high affinity for β-galactosides. Galectins are able to bind to bacteria, and a few mammalian galectins are known to kill the bound bacteria. In fish, no galectins with direct bactericidal effect have been reported.

Coral gasdermin triggers pyroptosis.

Gasdermins are executioners of the inflammatory cell death pathway pyroptosis that has so far been studied exclusively in vertebrates. In this study, we identified gasdermin E (GSDME) homologs in several invertebrate species including corals. We report that coral GSDME was cleaved by caspase 3 at two sites, yielding two active isoforms of GSDME N-terminal domain that were capable of inducing pyroptosis.

Phosphatase and Tensin Homolog (PTEN) of Japanese Flounder-Its Regulation by miRNA and Role in Autophagy, Apoptosis and Pathogen Infection.

MicroRNAs (miRNAs) are small non-coding RNAs with important roles in diverse biological processes including immunity. Japanese flounder () is an aquaculture fish species susceptible to the infection of bacterial and viral pathogens including . In a previous study, pol-miR-novel_547, a novel miRNA of flounder with unknown function, was found to be induced by .

Tongue sole (Cynoglossus semilaevis) interleukin 10 receptors are involved in the immune response against bacterial infection.

Interleukin (IL)-10, an immune-regulatory cytokine, exerts various biological functions through interaction with IL-10 receptors. In teleost, very limited functional studies on IL-10 receptors have been documented. In this study, we reported the expression patterns of IL-10 receptor 1 (CsIL-10R1) and receptor 2 (CsIL-10R2) of tongue sole (Cynoglossus semilaevis) and examined their biological properties.