Analysis of the immune function of Caspase-3 in Cristaria plicata.

Caspase-3 is generally considered to be the most important terminal shear enzyme in the process of apoptosis, as well as an important part of cytotoxic T lymphocytes (CTL) killing mechanism, which is confirmed to play an important role in vertebrate cell apoptosis and immune system, and is poorly reported in invertebrates. In this paper, we used bioinformatics to perform amino acid multiple sequence alignment and protein structural domain analysis, and constructed a phylogenetic tree to identify the full-length cDNA of the cloned caspase-3 of Cristaria plicata (Named CpCaspase-3). The expression of caspase-1, caspase-7, caspase-8, and caspase-9 was found to be down-regulated by double-stranded RNA interference of CpCaspase-3 in C. plicata. Some degree of disruption of the caspase signaling pathway occurs. The expression of CpCaspase-3 was affected after injection of Lipopolysaccharide (LPS), Peptidoglycan (PGN), polyinosinic-polycytidylic acid (poly(I:C)), and Aeromonas hydrophila. These results were suggested that CpCaspase-3 was involved in the immune response of C. plicata. The wound recovery process of C. plicata was simulated and CpCaspase-3 was found to promote wound recovery. An autophagy inhibition and autophagy activation model of mussels was constructed, where apoptosis and autophagy undergo crosstalk, and inhibition of autophagy induces the onset of apoptosis, and similarly autophagy activation inhibits the process of apoptosis instead. In addition, a recombinant CpCaspase-3-pEGFP-C1 plasmid was constructed for subcellular localization experiments and found that CpCaspase-3 was distributed in both the nucleus and the cytoplasm. This paper aims to unveil the immune mechanism of C. plicata and provide a theoretical basis for the healthy culture of shellfish.

Effects of suppressing Smads expression on wound healing in Hyriopsis cumingii.

As a specific pearl mussel in China, Hyriopsis cumingii has enormous economic value. However, the organism damage caused by pearl insertion is immeasurable. TGF-ß/Smad signal transduction pathways are involved in all phases of wound healing. We have previously reported on two cytoplasmic signal transduction factors, Smad3 and Smad5 in mussel H. cumingii (named HcSmads), suggesting their involvements in wound healing. Here, Smad4 was cloned and described. The full length cDNA of HcSmad4 was 2543 bp encoded 515 amino acids. Deduced HcSmad4 protein possessed conserved MH1 and MH2 domains, nuclear location signals (NLS), nuclear exput signals (NES) and Smad activation domain (SAD). Transcripts of Smad3, 4 and 5 were constitutively expressed in all detected tissues, at highest levels in muscles. Furthermore, HcSmad4 mRNA levels were significantly increased at incision site post wounding, and expression of downstream target genes of Smad4, such as HcMMP1, HcMMP19, HcTIMP1 and HcTIMP2 were upregulated to a certain extent. Whatever knocked down HcSmad3/4 or treated by specific inhibitors of Smad 3 (SIS3), expression levels of these genes displayed a significantly downregulated tendency compared with the wound group. In addition, histological evaluation suggested that Smad3 knockdown or SIS3 treatment was accelerated wound healing, and then Smad4 knockdown delayed the process of wound healing in mussels. These data implicate that Smad3/4 play an important role in tissue repair in mollusks.

Design, synthesis, anticancer activity and docking studies of novel 4-morpholino-7,8-dihydro-5H-thiopyrano[4,3-d]pyrimidine derivatives as mTOR inhibitors.

A series of 7,8-dihydro-5H-thiopyrano[4,3-d]pyrimidine derivatives (7a-q, 10a-q) were designed, synthesized and their chemical structures were confirmed by 1H NMR, 13C NMR, MS and HRMS spectrum.All the compounds were evaluated for the inhibitory activity against mTOR kinase at 10 µM level. Five selected compounds (7b, 7e, 7h, 10b and 10e) were further evaluated for the inhibitory activity against PI3Ka at 10 µM level, and the IC50 values against mTOR kinase and two cancer cell lines. Twelve of the target compounds exhibited moderate antitumor activities. The most promising compound 7e showed strong antitumor activities against mTOR kinase, H460 and PC-3 cell lines with IC50 values of 0.80 ± 0.15 µM, 7.43 ± 1.45 µM and 11.90 ± 0.94 µM, which were 1.28 to 1.71-fold more active than BMCL-200908069-1 (1.37 ± 0.07 µM, 9.52 ± 0.29 µM, 16.27 ± 0.54 µM), respectively. Structure-activity relationships (SARs) and docking studies indicated that the thiopyrano[4,3-d]pyrimidine scaffolds exerted little effect on antitumor activities of target compounds. Substitutions of aryl group at C-4 position had a significant impact on the antitumor activities, and 4-OH substitution produced the best potency.

Inhibition of JNK transcription via the Nrf2/Keap1a pathway to resist microcystin-induced oxidative stress and apoptosis in freshwater mussels Cristaria plicata.

With global warming and increasing eutrophication of water bodies, a variety of algal toxins, including microcystin (MC), released into water by cyanobacterial blooms pose a serious threat to the survival of aquatic organisms. To investigate the mechanism of the Nrf2/Keap1a pathway on resisting MC-induced oxidative stress and apoptosis in Cristata plicata, we cloned the full-length cDNA of CpBcl-2. The cDNA full-length of CpBcl-2 was 760 bp, encoded a 177 amino acid peptide, and contained a highly conserved Bcl-2-like superfamily domain. MC stimulation increased the expression and activity levels of related antioxidant enzymes. After CpNrf2 knockdown, the transcription levels of NAD(P)H quinone redox Enzyme-1 (NQO1) and related antioxidant enzymes activity in the gills and kidney of C. plicata were significantly down-regulated upon MC stress, but that was significantly upregulated after knockdown of CpKeap1a. Additionally, Upon MC stress, the mRNA levels of CpBcl-2 were increased in the gills and kidney after knockdown of CpNrf2 at 24 h, and that of CpBcl-2 were decreased at 72 and 96 h in the CpKeap1a-siRNA+MC group. Moreover, MC stimulation significantly inhibited CpJNK expression in the gills and kidney, but which regulated the Nrf2/Keap1a pathway in C. plicata. However, the JNK inhibitor SP600125 promoted the expression of CpNrf2 and related enzymes with antioxidant response element (ARE-driven enzyme) in the gills and kidney. Then, we speculated that CpKeap1a was a negative regulator of CpNrf2, and C. plicata resisted MC-induced oxidative damage and apoptosis by inhibiting JNK transcription via the Nrf2/Keap1a pathway.

Integrating network pharmacology and experimental models to identify notoginsenoside R1 ameliorates atherosclerosis by inhibiting macrophage NLRP3 inflammasome activation.

Atherosclerosis is a cardiovascular disease, accounting for the most common mortality cause worldwide. Notoginsenoside R1 (NGR1) is a characteristic saponin of Radix notoginseng that exhibits anti-inflammatory and antioxidant effects while modulating lipid metabolism. Evidence suggests that NGR1 exerts cardioprotective, neuroprotective, and anti-atherosclerosis effects. However, underlying NGR1 mechanisms alleviating atherosclerosis (AS) have not been examined. This study used a network pharmacology approach to construct the drug-target-disease correlation and protein-protein interaction (PPI) network of NGR1 and AS. Moreover, functional annotation and pathway enrichment analyses deciphered the critical biological processes and signaling pathways potentially regulated by NGR1. The protective effect of NGR1 against AS and the underlying mechanism(s) was assessed in an atherogenic apolipoprotein E-deficient (ApoE-/-) mice in vivo and an oxidized low-density lipoprotein (ox-LDL)-induced macrophage model in vitro. The network pharmacology and molecular docking analyses revealed that NGR1 protects against AS by targeting the NLRP3/caspase-1/IL-1ß pathway. NGR1 reduced foam cell formation in ox-LDL-induced macrophages and decreased atherosclerotic lesion formation, serum lipid metabolism, and inflammatory cytokines in AS mice in vivo. Therefore, NGR1 downregulates the NLRP3 inflammasome complex gene expression of NLRP3, caspase-1, ASC, IL-1ß, and IL-18, in vivo and in vitro.

Identification of Nrf2/Keap1 pathway and its transcriptional regulation of antioxidant genes after exposure to microcystins in freshwater mussel Cristaria plicata.

Microcystins (MC) are one of the most abundant and widely distributed cyanotoxins in aquatic systems. MC inhibits the functions of protein phosphatase 1 and 2A (PP1/2A), which can seriously affect ecosystem integrity. The NF-E2-related nuclear factor 2 (Nrf2)/Kelch-like epichlorohydrin-related protein-1 (Keap1) signaling pathway protects against oxidative damage by activating phase II detoxification/antioxidant enzymes. Our previous study revealed that MC upregulates the expression and enhances the activities of the antioxidant enzymes by stimulating the CpNrf2 signaling pathway. In the current study, to further clarify the regulatory role of Keap1 in response to MC-induced oxidative stress in shellfish, we cloned the full-length cDNA of Keap1a and Keap1b from Cristaria plicata (designated CpKeap1a and CpKeap1b), which are 2952 and 3710 bp peptides, respectively. The amino acid sequence of CpKeap1a and CpKeap1b contained Tram-track and Bric-a-brac (BTB), Intervening region (IVR), and Double glycine repeat (DGR) domain. Additionally, CpKeap1a contained two cysteine residues analogous to Cys-273 and -288 in zebrafish, but CpKeap1b did not. Moreover, CpKeap1a and -1b formed a homodimer and heterodimer, respectively, and also formed a heterodimer with CpNrf2. In the hepatopancreas, the expression levels of CpKeap1a and -1b were the highest, but MC treatment down-regulated the expression of these proteins. Moreover, the transcription of antioxidant enzymes with antioxidant response element (ARE-driven enzymes), including CpMnSOD, CpCu/ZnSOD, CpTRX, CpPrx, CpSe-GPx, and Cpsigma-GST was upregulated by CpNrf2 in the hepatopancreas. Compared with the MC-induced group, CpKeap1a-siRNA1117 injection significantly increased the transcription of mRNAs for ARE-driven enzymes and Nrf2. CpKeap1a-siRNA1117 also enhanced the activities of antioxidation enzymes. These findings demonstrated that Keap1a negatively regulated the expression of Nrf2 protein and MC-induced oxidative stress response in C. plicata. Therefore, we speculated that CpKeap1a promoted CpNrf2 by recognizing and binding MC. These events then protected molluscs from MC-induced oxidative damage.

GST-Mu of Cristaria plicata is regulated by Nrf2/Keap1 pathway in detoxification microcystin and has antioxidant function.

Glutathione S-transferase is a crucial phase II metabolic enzyme involved in detoxification and metabolism in aquatic organisms. This study aimed to investigate the regulation of Nrf2/Keap1 pathway on microcystin-induced CpGST-Mu expression and CpGST-Mu resistance to hydrogen peroxide. A mu class GST from Cristaria plicata (CpGST-Mu) was identified. The full-length cDNA was 1026 bp, with an open reading frame of 558 bp. Subcellular localization revealed that CpGST-Mu was localized in cytoplasm. The optimum pH and temperature for the catalytic activity of CpGST-Mu protein was pH 6 and 40 °C, respectively. The results of Real-time quantitative PCR showed that CpGST-Mu mRNA was constitutively expressed in tissues, with the highest expression level in hepatopancreas and the lowest expression level in gill. The mRNA level of CpGST-Mu was significantly increased under the stress of microcystins and hydrogen peroxide. CpGST-Mu had an antagonistic effect on hydrogen peroxide. In the knockdown experiments, the mRNA levels of CpGST-Mu exhibited corresponding changes while Nrf2 and Keap1 genes were individually knocked down. These findings indicated that GST-Mu exhibited antioxidant properties and its expression was regulated by Nrf2/Keap1 signaling pathway. The study provided new information on the function of GST-Mu and could contribute to future studies on how to excrete microcystins in molluscs.

P62/SQSTM1 upregulates NQO1 transcription via Nrf2/Keap1a signaling pathway to resist microcystins-induced oxidative stress in freshwater mussel Cristaria plicata.

Microcystins (MCs) are the most frequent and widely distributed type of cyanotoxin in aquatic systems, and they cause an imbalance of the body's oxidative system. In a previous experiment, we demonstrated that the mollusk Cristaria plicata can protect against MC-induced oxidative damage through the nuclear factor erythroid 2-related factor 2(Nrf2)/Kelch-like epichlorohydrin-related protein-1 (Keap1) pathway. Here, we evaluated whether selective autophagy affects the Nrf2/Keap1a anti-oxidative stress pathway in C. plicata. Full-length cDNA sequences of p62/SQSTM1 from C. plicata (Cpp62) were divided into 2484 bp fragments. From N-terminal to C-terminal, the amino acid sequence of Cpp62 contained PB1 (Phox and Bem1p domain), ZNF (zinc finger domain) chain, LIR (LC3 interacting region) and UBA (ubiquitin-associated domain) domains, but not the KIR (Keap1 interacting region) domain. We confirmed that Cpp62 did not bind to CpKeap1a in vitro, and the relative level of Cpp62 was the highest in the hepatopancreas. Moreover, MCs significantly upregulated the mRNA and protein levels of Cpp62 in the hepatopancreas after CpKeap1a knockdown, whereas Nrf2 upregulated the transcription levels of Cpp62, suggesting that MCs increased Cpp62 expression via the Nrf2/Keap1a signaling pathway. Moreover, Cpp62 and CpNrf2 proteins have a strong affinity for the NQO1 promoter, but MCs inhibited the ability of CpNrf2 and Cpp62 to upregulate luciferase activity. The results show that Nrf2 and the p62 protein induced p62 expression by binding to ARE (antioxidant response element) sequences in the p62 promoter of C. plicata, thereby promoting p62 to resist MC-induced oxidative stress. Therefore, we speculate that MCs induce p62-dependent autophagy in C. plicata, resulting in the inhibition of Nrf2 transcription and Cpp62 promoter activity. These findings help to reveal the mechanism by which the p62-Nrf2/Keap1 pathway mitigates MC-induced oxidative damage in mussels.

JNK regulates the Nrf2/NQO1-ARE pathway against Microcystins-Induced oxidative stress in freshwater mussel Cristaria plicata.

In response to stress, cells can utilize several processes, such as the activation of the Nrf2/Keap1 pathway as a critical regulator of oxidative stress to protect against oxidative damage. C-Jun N-terminal kinase (JNK), a member of the mitogen-activated protein kinase (MAPK) family, is involved in regulating the NF-E2-related nuclear factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathway. NAD(P)H quinone redox enzyme-1 (NQO1), a downstream target gene of the Nrf2 pathway, plays a vital role in removing peroxide and providing resistance to oxidative injury. We found that microcystins (MCs) stimulated CpNrf2 to express and increase anti-oxidative enzyme activities in a previous experiment. In our current study, the full-length cDNAs of JNK and NQO1 from Cristaria plicata (designated CpJNK and CpNQO1) were cloned. The relative levels of CpJNK and CpNQO1 were high in hepatopancreas. Upon MCs induction, the relative level of CpNQO1 was increased, whereas that of CpJNK was decreased significantly. In contrast, CpNrf2 knockdown upregulated the expression of CpJNK mRNA and phosphorylation of CpJNK protein (Cpp-JNK), but inhibited CpNQO1 expression. Additionally, we found that JNK inhibitor SP600125 stimulated expression of CpNQO1 and CpNrf2 upon exposure to MCs, and we further confirmed that CpNrf2 protein combined with the ARE element in CpNQO1 gene promoter in vitro, and increased CpNQO1-ARE-luciferase activity in a CpNrf2-dependent manner. These findings indicated C. plicata effectively alleviated MC-induced oxidative injury through JNK participated in regulating the Nrf2/NQO1-ARE pathway.

Enhancement of fluorescence and anti-tumor effect of ZnO QDs by La doping.

ZnO quantum dots (QDs) have received much attention as biomarkers and drug delivery systems in cancer treatment, due to their low cost, ease of preparation, and pH-responsive degradation. However, its applications are limited by the low quantum yield and light absorption. In this work, a lanthanum-doped zinc oxide (La-ZnO) QDs-based drug delivery platform was constructed. The results show that 4% La doping is the most beneficial for improving the fluorescent properties of the ZnO QDs. After loading the drug, the cell activity was 15% at ZnO@DOX and 12% at La-ZnO@DOX. According to in vitro and in vivo experiment results, the La-ZnO QDs show enhancement of the antitumor effect. Dual enhancement of fluorescence and anti-tumor effects make La-ZnO QDs promising as a drug delivery system in cancer treatment.

MAPK/MAK/MRK overlapping kinase mediated apoptosis through caspase signaling pathway from Cristaria plicata.

MAPK/MAK/MRK Overlapping Kinase (MOK) belongs to MAP kinase superfamily, which plays an important role in regulating cell growth, division, and differentiation. Caspase-3, as the final executor of apoptosis, has an important position in the caspase-mediated apoptotic signaling pathway. The full-length cDNA of MOK and caspase-3 were cloned from Cristaria plicata (designated CpMOK and CpCaspase-3). The CpMOK gene was sequence with a full-length of 1413 bp, encoding a total of 470 amino acids, and containing an S_TKc structural domain. CpCaspase-3 has a sequence of 2425 bp, encoding 322 amino acids, containing a CASc domain. Real-time fluorescence quantitative PCR analysis showed that CpMOK and CpCaspase-3 distributed in various tissues of C. plicata, and the highest expression of CpMOK and CpCaspase-3 mRNA was in hepatopancreas. The expression of CpMOK was significantly changed in hepatopancreas, gills, and kidneys by the construction of wound model as well as stimulation of LPS, PGN, Poly I: C and Aeromonas hydrophila. Subcellular localization experiments confirmed that CpMOK was localized in the nucleus. Furthermore, the double-stranded RNA (dsRNA) of CpMOK was constructed for interference experiment, and the results showed that the mRNA expression of apoptotic gene signals caspase-1, caspase-3, caspase-7, caspase-8, and caspase-9 were increased. The expression of caspase-1, -3, -7, -9, cytochrome C (Cyt-c) and tumor necrosis factor-α (TNF-α) was detected by ELISA. Fluorescent staining of apoptotic cells using the Tunnel method revealed an increase in the number of apoptotic cells after interference. These results suggested that CpMOK knockdown could induce caspase-mediated apoptosis in C. plicata, and the phosphorylation of the kinase was disrupted during the process.

Effect of microcystin on the expression of Nrf2 and its downstream antioxidant genes from Cristaria plicata.

Microcystin (MC) is a cyclic heptapeptide toxin. Nuclear factor erythocyte 2-related factor 2 (Nrf2) can enhance cellular survival by mediating phase 2 detoxification and antioxidant genes. In this study, CpNrf2 cDNA sequences were cloned from freshwater bivalve Cristaria plicata. The full-length CpNrf2 cDNA sequence was 4259 bp, and its homology was the highest with Mizuhopecten yessoensis, reaching 46%. CpNrf2 transcription levels were examined in all tested tissues, and the highest level was in hepatopancreas from C. plicata. The recombinant protein pET32-CpNrf2 was purified with the content of 1.375 mg/mL. The expression levels of CpNrf2 mRNA were raised in hepatopancreas after MC stimulation. After CpNrf2 knockdown, CpNrf2 mRNA levels were significantly down-regulated after 24 h. Compared with control group, the expression levels of ARE-driven enzymes (CpMnSOD, CpCuZnSOD, CpTRX, CpPrx, CpSe-GPx and Cpsigma-GST) were significantly increased, and those enzyme activities were also significantly up-regulated in MC-stimulated group. However, in CpNrf2-iRNA group, they were significantly down-regulated. The results revealed that Nrf2/ARE pathway is very crucial to protect molluscs from MC.

Cloning and characteristic of MMP1 gene from Hyriopsis cumingii and collagen hydrolytic activity of its recombinant protein.

Matrix metalloproteinases (MMPs) play an essential role in a variety of biological processes including wound healing, inflammation, cell invasion, angiogenesis and immune defense. In this study, a putative MMP1 cDNA was cloned and characterized from Hyriopsis cumingii (designated as HcMMP1). The cDNA was 1822 bp in length and encoded a putative protein of 510 amino acids, with a predicted molecular mass of 58.28 kDa and an isoelectric point (pI) of 9.27. HcMMP1 contained all prototype MMPs family signatures, such as signal peptide, prodomain, catalytic center, hinge region, and hemopexin like domain. Quantitative real time-PCR (qRT-PCR) revealed that in mussels HcMMP1 mRNA was expressed in all tissues tested, and the transcriptional expression levels were significantly up-regulated in hepatopancreas and hemocytes after Aeromonas hydrophila, peptidoglycan stimulations and in mantle after wounding. Moreover, the recombination HcMMP1 protein, successfully expressed in Escherichia coli, was purified by affinity chromatography with the concentration of final yield at 0.3 mg/mL. The recombinase had an essentially hydrolytic activity toward rat type I collagen, mouse II and IV collagen after renaturation.

Microcystin induction small Maf protein involve in transcriptional regulation of GST from freshwater mussel Cristaria plicata.

The small Mafs, MafF, MafG and MafK play critical roles in morphogenesis and homeostasis through associating with Cap "n" Collar family of transcription factors. In this study, we tried to identify a small Maf protein in the freshwater mussel Cristaria plicata. The MafK cDNA of C. plicata, designated as CpMafK, was cloned from the hemocytes using degenerate primers by the rapid amplification of cDNA ends PCR. The full length cDNA of CpMafK is 2170 bp, which includes an open reading frame of 570 bp, encoding 189 amino acids. CpMafK possesses four conserved domains and shows a low level (54-63%) of sequence similarity to small Mafs from other species. The results of Real-time quantitative PCR revealed that CpMafK mRNA was constitutively expressed in tissues, and the highest expression level was in hepatopancreas. After microcystin challenge, the expression levels of CpMafK mRNA were up-regulated in hemocytes and hepatopancreas. The cDNA of CpMafK was cloned into the plasmid pET-32, and the recombinant protein was expressed in Escherichia coli BL21(DE3). CpMafK could combine to the promoters of CpGST1 and CpGST2 with high-affinity in vitro. Therefore, CpMafK could regulate the expression of detoxification.