ABSTRACT
Peptidoglycan recognition proteins (PGRPs) are the most important pattern recognition receptors (PRRs) in insects. PGRPs can recognize pathogenic microorganism peptidoglycans (PGs) and play an important role in innate immunity. Twelve PGRPs have been identified in silkworms. However, the specific roles played by these PGPRs in the silkworm innate immune system have not been elucidated to date. In this study, we systematically investigated the biological functions of BmPGRP-S1 in silkworms. We observed that BmPGRP-S1 was highly expressed in silkworm immune-related organs and was upregulated in response to bacterial challenges. Furthermore, we determined that BmPGRP-S1 can bind to bacteria or PGs and activate antimicrobial peptide (AMP) expression. Inhibition of the expression of BmPGRP-S1 by siRNA reduced AMP gene expression in silkworms. Further experiments demonstrated that BmPGRP-S1 is involved in IMD pathway activation to induce AMP expression. Taken together, these results demonstrate that BmPGRP-S1 serves as a receptor to activate AMP gene expression through the IMD pathway to address bacterial challenges.
Subject(s)
Antimicrobial Peptides/genetics , Bombyx/immunology , Carrier Proteins/metabolism , Insect Proteins/metabolism , Animals , Bombyx/genetics , Bombyx/metabolism , Immunity, Innate , Insect Proteins/genetics , Larva , Signal Transduction/immunologyABSTRACT
Peptidoglycan recognition proteins (PGRPs) are pattern recognition receptors that can recognize bacterial peptidoglycans and trigger the innate immune response of insects. Here, we identified and characterized a novel short-type Bombyx mori peptidoglycan recognition proteins short-4 (BmPGRP-S4) in a lepidopteran insect, Bombyx mori. BmPGRP-S4 exhibited a cDNA sequence length of 600 bp, encoding 199 aa with a protein molecular weight of 22 kDa. Multiple sequence alignment revealed that BmPGRP-S4 contains a conserved PGRP domain. Quantitative real-time polymerase chain reaction analysis showed that BmPGRP-S4 is highly expressed in the early developmental stages of silkworm larvae and presents tissue-specific expression in hemocytes. Interestingly, BmPGRP-S4 expression is significantly induced by bacterial infection in the midgut, fat body, and hemocytes. Furthermore, a dual luciferase reporter gene assay revealed that BmPGRP-S4 can activate the expression of the antimicrobial peptide genes lebocin, moricin, cecropin D, cecropin B, and attacin. Taken together, these results suggest that BmPGRP-S4 plays an important role in the innate immune response of silkworms.
Subject(s)
Bombyx/genetics , Carrier Proteins/genetics , Immunity, Innate/genetics , Amino Acid Sequence/genetics , Animals , Antimicrobial Cationic Peptides/genetics , Carrier Proteins/chemistry , Cloning, Molecular , DNA, Complementary/genetics , DNA, Complementary/immunology , Gene Expression Regulation/genetics , Gene Expression Regulation/immunology , Insect Proteins/genetics , Larva/chemistry , Larva/genetics , Sequence AlignmentABSTRACT
Liver X receptors (LXRs) are involved in various diseases associated with lipid disorders, and in regulating cancer cell proliferation. However, the underlying molecular mechanisms, especially those in gastric cancer (GC) remain to be clarified. In this study, immunohistochemistry analysis revealed that LXRß was mainly expressed in GC tissue, with less expression in adjacent normal tissues. The LXRß agonist T0901317 efficiently suppressed the proliferation and colony formation of various GC cell lines. We further showed that LXRß translocated from the cytoplasm to the nucleus when activated by T0901317. LXRß nuclear localization suppressed the activation of Wnt signalling and decreased the expression of target genes such as MYC, BMP4, and MMP7 through binding to their promoters. Moreover, we demonstrated that the LXR agonist efficiently suppressed GC tumour growth in a nude mouse xenograft model. Taken together, these results revealed that LXRß agonist inhibited GC cells proliferation by suppressing Wnt signalling via LXRß relocalization. The results strongly suggest that LXRß could be a promising target in GC therapy.
Subject(s)
Anticholesteremic Agents/pharmacology , Antineoplastic Agents/pharmacology , Gene Expression Regulation, Neoplastic , Hydrocarbons, Fluorinated/pharmacology , Liver X Receptors/genetics , Stomach Neoplasms/drug therapy , Sulfonamides/pharmacology , Aged , Animals , Bone Morphogenetic Protein 4/antagonists & inhibitors , Bone Morphogenetic Protein 4/genetics , Bone Morphogenetic Protein 4/metabolism , Cell Line, Tumor , Cell Movement/drug effects , Cell Nucleus/drug effects , Cell Nucleus/metabolism , Cell Proliferation/drug effects , Cytoplasm/drug effects , Cytoplasm/metabolism , Female , Humans , Liver X Receptors/agonists , Liver X Receptors/metabolism , Male , Matrix Metalloproteinase 7/genetics , Matrix Metalloproteinase 7/metabolism , Mice , Mice, Nude , Middle Aged , Promoter Regions, Genetic , Protein Binding , Protein Transport , Proto-Oncogene Proteins c-myc/antagonists & inhibitors , Proto-Oncogene Proteins c-myc/genetics , Proto-Oncogene Proteins c-myc/metabolism , Stomach Neoplasms/genetics , Stomach Neoplasms/metabolism , Stomach Neoplasms/pathology , Tumor Burden/drug effects , Wnt Signaling Pathway , Xenograft Model Antitumor AssaysABSTRACT
Insects lack an acquired immune system and rely solely on the innate immune system to combat microbial infection. The innate immunity of insects mainly depends on the interaction between the host's pattern recognition receptor (PRR) and pathogen-associated molecular pattern (PAMP). The peptidoglycan recognition proteins (PGRPs) family is the most important pattern recognition receptor (PRR) for insects. It can recognize the main component of the cell wall of the pathogenic microorganism, peptidoglycan (PGN), and plays an important role in the innate immunity of insects. In this paper, the structure, classification, and function of PGRPs is summarized, and the role of PGRPs in the innate immunity of insects is also discussed.
Subject(s)
Immunity, Innate , Insect Proteins/immunology , Insecta/immunology , Peptidoglycan/immunology , Receptors, Pattern Recognition/immunology , AnimalsABSTRACT
The traditional view holds that apoptosis is non-immunogenic and does not induce an inflammatory response. However, recent studies have suggested that certain chemotherapeutic drugs that induce tumor cell apoptosis can induce immunogenic cell death (ICD) in cancer cells. This process is characterized by not only up-regulation of a series of signaling molecules in cancer cells, including expose of calreticulin (CRT), secretion of adenosine triphosphate (ATP) and release of high mobility group box 1 (HMGB1). In this review, we summarize recent progress in identifying and classifying ICD inducers; concepts and molecular mechanisms of ICD; and the impact and potential applications of ICD in clinical studies. We also discuss the contributions of ICD inducers in combination with other anticancer drugs in clinical applications.
Subject(s)
Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Neoplasms/drug therapy , Signal Transduction/drug effects , Adenosine Triphosphate/immunology , Adenosine Triphosphate/metabolism , Animals , Antineoplastic Agents/immunology , Apoptosis/immunology , Calreticulin/immunology , Calreticulin/metabolism , Endoplasmic Reticulum Stress/drug effects , Endoplasmic Reticulum Stress/immunology , HMGB1 Protein/immunology , HMGB1 Protein/metabolism , Humans , Neoplasms/immunology , Neoplasms/metabolism , Oxaliplatin/immunology , Oxaliplatin/pharmacology , Reactive Oxygen Species/immunology , Reactive Oxygen Species/metabolism , Signal Transduction/immunologyABSTRACT
Liver X receptor (LXR) agonists inhibit various types of tumor growth and have been applied to preclinical research. In colon cancer cells, LXR agonists induce pyroptotic cell death through the predominant cytoplasmic localisation of LXRß. In the present study, we determined whether tumor cell death induced by LXR agonists in colon cancer cells could elicit immunogenic cell death (ICD). LXR agonist-treated-colon cancer cells exhibited translocation of calreticulin (CRT) and release of HMGB1 and ATP into the medium. Expression levels of CRT and HMGB1 were also increased in T0901317-treated Balb/c mice. Furthermore, compared with control mice, mice vaccinated with T0901317-treated CT26 cells showed reduced tumor volumes and protection against a challenge with live tumor cells. Inhibition of CRT or HMGB1 expression in CT26 cells abolished this protection in Balb/c mice. In conclusion, the LXR agonist T0901317 induces ICD in colon cancer cells. CRT exposure and HMGB1 release play a critical role in the immunogenicity of this treatment.
Subject(s)
Antineoplastic Agents/pharmacology , Cell Death/drug effects , Colonic Neoplasms/drug therapy , Liver X Receptors/agonists , Animals , Calreticulin/metabolism , Cell Line, Tumor , Colonic Neoplasms/metabolism , Female , HCT116 Cells , HMGB1 Protein/metabolism , Humans , Hydrocarbons, Fluorinated/pharmacology , Liver Neoplasms/drug therapy , Liver Neoplasms/metabolism , Mice , Mice, Inbred BALB C , Mice, Nude , Sulfonamides/pharmacologyABSTRACT
Due to their numerous advantages, baculovirus expression vector systems (BEVS) have been widely used to express recombinant proteins for different purposes. Different strategies have been adopted to increase recombinant protein production. In this study, we transiently or stably expressed mouse c-Myc in High Five cells using a commercial pIB/V5 vector. Under the control of the OpIE2 promoter, this vector could enhance recombinant protein production. We found that transient expression of c-Myc in High Five cells improved recombinant protein production. Furthermore, we established two stable cell lines, High Five-c-Myc #1 and High Five-c-Myc #2, that stably expressed mouse c-Myc. We further found that the expression level of the recombinant protein was increased in these stable cell lines compared to control cell lines. These data indicate that overexpressing c-Myc in cells is a promising way to improve recombinant protein production in BEVS.
