GSIV serine/threonine kinase can induce apoptotic cell death via p53 and pro-apoptotic gene Bax upregulation in fish cells

CyHV-2 infection triggers mitochondrial-mediated apoptosis in GiCF cells by upregulating the pro-apoptotic gene ccBAX

Apoptosis is a physiological cell death phenomenon, representing one of the fundamental physiological mechanisms for maintaining homeostasis in living organisms. Previous studies have observed typical apoptotic features in Carassius auratus gibelio caudal fin cell (GiCF) infected with Cyprinid herpesvirus 2 (CyHV-2), and found a significant up-regulation of ccBAX expression in these infected cells. However, the specific apoptotic mechanism involved remains unclear. In this study, we utilized the GiCF cell line to investigate the apoptotic mechanism during CyHV-2 infection. Immunofluorescence staining revealed translocation of ccBAX into mitochondria upon CyHV-2 infection. Flow cytometry analysis demonstrated that overexpression of ccBAX expedited virus-induced apoptosis, characterized by heightened mitochondrial depolarization, increased transcriptional levels of Cytochrome c (Cyto c) in both the cytoplasm and mitochondria, and augmented Caspase 3/7 enzyme activity. Bax inhibitor peptide V5 (BIP-V5), an inhibitor interfering with the function of Bax proteins, inhibited Bax-mediated apoptotic events through the mitochondrial pathway and attenuated apoptosis induced by CyHV-2. In this study, it was identified for the first time that CyHV-2 induces apoptosis via the mitochondrial pathway in GiCF cells, bridging an important gap in our understanding regarding cell death mechanisms induced by herpesvirus infections in fish species. These findings provide a theoretical basis for comprehending viral apoptotic regulation mechanisms and the prevention and control of cellular pathologies caused by CyHV-2 infection.

Immunosuppression and apoptosis activation mediated by p53-Bcl2/Bax signaling pathway -The potential mechanism of goldfish (Carassius auratus Linnaeus) gill disease caused by Myxobolus ampullicapsulatus

Myxobolus, a major harmful type of myxospora, is one of the main parasitic pathogens of freshwater fish. Once myxoboliosis occurs, treatment can be extremely difficult. Therefore, clear understandings of the etiology of myxoboliosis and its pathological mechanism are keys for prevention and control. Here, histology, transmission electron microscopy, transcriptome study, tunel assay, and immunohistochemistry were carried out, revealing the morphology, pathological effects as well as host response mechanism of goldfish gill to Myxobolus ampullicapsulatus. Histological studies showed that the mature spores of Myxobolus ampullicapsulatus were composed of three parts, the spore shell, sporoplasm and bottle shaped polar capsule containing double S-shaped polar filaments. Transcriptome analysis revealed that Myxobolus ampullicapsulatus -infected (Myx) goldfish gills were characterized by apoptosis activation mediated by "p53 signaling pathway" with significantly up-regulated apoptosis-related differential genes dominated by p53-Bcl2/Bax signaling pathway. In addition, tunel assay revealed severe gill apoptosis in the Myx group. Transcriptome analysis also revealed that Myx group showed changes in immune response and significantly down-regulated immune-related differential genes. Beyond that, immunohistochemistry showed that there was no significant increase in the number of gill lymphocyte after parasite infection. These results suggest that the pathological mechanism of Myxobolus ampullicapsulatus infection on gills of goldfish may be related to apoptosis and immunosuppression. Subsequent qRT-PCR showed that apoptosis-related genes (Caspase3,Bad, Bax) and anti-inflammatory gene IL-10 were significantly increased, while immune-related pro-inflammatory genes (IL-1β, IL-8) were markedly down-regulated, further verifying the transcriptome results. Based on the above results, we concluded that p53-Bcl2/Bax related networks that dominant the expression of apoptosis genes were activated while immunity was suppressed in the gills of Myxobolus ampullicapsulatus infected goldfish. Our study is not only of benefit to enrich the taxonomy of Myxobolus but also clarifies its pathogenic mechanism, thus providing targets for prevention and control of myxoboliosis.

MicroRNA-124 Promotes Singapore Grouper Iridovirus Replication and Negatively Regulates Innate Immune Response

Viral infections seriously affect the health of organisms including humans. Now, more and more researchers believe that microRNAs (miRNAs), one of the members of the non-coding RNA family, play significant roles in cell biological function, disease occurrence, and immunotherapy. However, the roles of miRNAs in virus infection (entry and replication) and cellular immune response remain poorly understood, especially in low vertebrate fish. In this study, based on the established virus-cell infection model, Singapore grouper iridovirus (SGIV)-infected cells were used to explore the roles of miR-124 of Epinephelus coioides, an economically mariculture fish in southern China and Southeast Asia, in viral infection and host immune responses. The expression level of E. coioides miR-124 was significantly upregulated after SGIV infection; miR-124 cannot significantly affect the entry of SGIV, but the upregulated miR-124 could significantly promote the SGIV-induced cytopathic effects (CPEs), the viral titer, and the expressions of viral genes. The target genes of miR-124 were JNK3/p38α mitogen-activated protein kinase (MAPK). Overexpression of miR-124 could dramatically inhibit the activation of NF-κB/activating protein-1 (AP-1), the transcription of proinflammatory factors, caspase-9/3, and the cell apoptosis. And opposite results happen when the expression of miR-124 was inhibited. The results suggest that E. coioides miR-124 could promote viral replication and negatively regulate host immune response by targeting JNK3/p38α MAPK, which furthers our understanding of virus and host immune interactions.

Notch pathway inhibitor DAPT accelerates in vitro proliferation and adipogenesis in infantile hemangioma stem cells

The Notch signaling pathway is crucial in both adipogenesis and tumor development. It serves a vital role in the development and stability of blood vessels and may be involved in the proliferative phase of infantile hemangiomas, which express various related receptors. Therefore, it was hypothesized that the Notch signaling pathway inhibitor N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT), a γ-secretase inhibitor, might help accelerate the regression of infantile hemangiomas. The present in vitro study evaluated whether inhibition of the Notch signaling pathway using DAPT could alter adipogenesis in hemangioma stem cells (HemSCs) derived from infantile hemangioma (IH) specimens. A total of 20 infants (age, ≤6 months) with hemangiomas who had not yet received any treatment were selected, and their discarded hemangioma tissues were obtained. HemSCs were isolated from the fresh, sterile IH specimens and treated with DAPT. Reverse transcription-quantitative PCR and western blotting were used to demonstrate the inhibition of the Notch signaling pathway by DAPT. A proliferation assay (Cell Counting Kit-8), oil red O staining, flow cytometry and a transwell assay were used to detect proliferation, adipogenesis, apoptosis and migration of HemSCs. Treatment with DAPT upregulated the expression levels of CCAAT/enhancer-binding protein (C/EBP) α, C/EBPβ, peroxisome proliferator-activated receptor-γ, adiponectin and insulin-like growth factor 1, and promoted the proliferation, apoptosis, migration and lipid accumulation in HemSCs in vitro. Targeting the Notch signaling pathway using DAPT may potentially accelerate the regression of infantile hemangiomas.

Andrographolide as a potent and promising antiviral agent

Andrographolide is a labdane diterpenoid extracted and purified from the aerial parts of plants belonging to genus Andrographis (Acanthaceae). The research has shown the plant based compound is low cytotoxic, having antimicrobial, anti-cancer, antiviral and anti-parasitic effects. Andrographolide both prevent spread as well as transmission of virus to neighboring cells by interfering with different cell signaling pathways. In addition to its medicinal value, plant has been found having nutritional value. Therefore being cost effective, easy availability and having nutritional value as a natural supplement, can be used to improve the quality of life in countries having low standard of living. Due to the limited number of effective vaccines, the plant-based antiviral drugs have provided considerable hope for fighting against the viral infections. The plant-derived compound when produced in large quantities is cost effective with low cytotoxic effects. However, much deep insight research at the molecular level is needed to develop the molecules against the viral infection. This paper aims to highlight the antiviral role of Andrographolide that can made significant contributions toward the improvement of human health and will also summarize the current status and future strategies concerning the therapeutic applications of Andrographolide to combat different viral disease in humans.

Expression and regulation of ccBAX by miR-124 in the caudal fin cell of C. auratus gibelio upon cyprinid herpesvirus 2 infection

Bcl2 family proteins play a critical role in cell death or survival. BAX, the death-promoting protein of bcl2 family, mediated mitochondrial pathway inducing cells' apoptosis in mammal. MiRNAs have been implicated as negative regulators down-regulating genes' expression after post-transcriptional level. At present, little is known about the regulatory mechanism of miRNA on the Bcl2 family proteins during CyHV-2 infection in silver crucian carp (Carassius auratus gibelio). In this study, the ccBAX (silver crucian carp BAX) gene was cloned and expressed, and polyclonal antibodies were raised in mouse against the purified ccBAX-GST fusion protein. The structure analysis indicated that ccBAX protein included four conserve domains (BH1, BH2, BH3 and transmembrane domains) and the expression of ccBAX protein occurred throughout the cells. Furthermore, two miRNAs (miR-124 and miRNA-29b) were identified to negatively regulate ccBAX gene expression in GiCF cell. miR-124 was found to suppress the expression of WT-ccBAX (wild type), but not the MT-ccBAX (mutant). Overall, the results demonstrated that the expression of the ccBAX gene was significantly down-regulated by miR-124 in silver crucian carp (Carassius auratus gibelio) during CyHV-2 infection.

Haimufang decoction, a Chinese medicine formula for lung cancer, arrests cell cycle, stimulates apoptosis in NCI-H1975 cells, and induces M1 polarization in RAW 264.7 macrophage cells

BACKGROUND

Lung cancer has the highest morbidity and mortality in the world and novel treatment strategies are still needed. Haimufang decoction (HMF) is a patented clinical prescription of traditional Chinese medicine for lung cancer treatment. HMF is composed of four herbs and has been applied clinically in advanced cancer patients. However, its therapeutic mechanisms are still unclear. This study aims to elucidate the possible mechanisms of HMF for the treatment of lung cancer.

METHODS

3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay was applied for evaluating the proliferative effect of HMF in lung cancer cells and monocyte macrophage RAW264.7 cells. Flow cytometer was used to detect the effects of HMF on cell cycle and apoptosis, and western blotting was employed to explore the potential apoptotic mechanisms of HMF on lung cancer cells. For immunomodulatory effect, co-culture system was used to detect the activation of macrophage RAW264.7 cells when treated with HMF, and neutral red assay was used to measure the effect of HMF on the phagocytosis of the activated macrophages. Enzyme linked immunosorbent assay, flow cytometer, and immunofluorescence staining method were employed for the investigation on the underlying mechanisms of the immunomodulatory effect on RAW264.7 induced by HMF.

RESULTS

HMF inhibited the proliferation, induced S phase cell cycle arrest, and stimulated apoptosis in lung cancer NCI-H1975 cells, while had negligible cytotoxicity on macrophage RAW264.7 cells. Moreover, HMF could activate macrophage RAW264.7 cells and promote the inhibition activity of RAW264.7 cells against lung cancer cells. And also, HMF activated macrophages and increased their phagocytic activity in a concentration-dependent manner. HMF increased the expression of macrophage activation marker CD40, the level of nitric oxide, the generation of intracellular reactive oxygen species, as well as M1 macrophages cytokines including tumor necrosis factor-α, interleukin-1β, interleukin 12 p70, and interleukin 6. Further investigation showed that HMF induced M1 but not M2 phenotype polarization in RAW264.7 cells.

CONCLUSIONS

HMF can mainly exert anticancer activity via (1) cytotoxicity to human lung cancer cells by proliferation inhibition, cell cycle arrest, and apoptosis induction; and also via (2) immunomodulation via macrophage cells activation and M1 phenotype polarization induction.

Chinese Giant Salamander (Andrias davidianus) Iridovirus Infection Leads to Apoptotic Cell Death through Mitochondrial Damage, Caspases Activation, and Expression of Apoptotic-Related Genes

Chinese giant salamander iridovirus (GSIV) is the causative pathogen of Chinese giant salamander (Andrias davidianus) iridovirosis, leading to severe infectious disease and huge economic losses. However, the infection mechanism by GSIV is far from clear. In this study, a Chinese giant salamander muscle (GSM) cell line is used to investigate the mechanism of cell death during GSIV infection. Microscopy observation and DNA ladder analysis revealed that DNA fragmentation happens during GSIV infection. Flow cytometry analysis showed that apoptotic cells in GSIV-infected cells were significantly higher than that in control cells. Caspase 8, 9, and 3 were activated in GSIV-infected cells compared with the uninfected cells. Consistently, mitochondria membrane potential (MMP) was significantly reduced, and cytochrome c was released into cytosol during GSIV infection. p53 expression increased at an early stage of GSIV infection and then slightly decreased late in infection. Furthermore, mRNA expression levels of pro-apoptotic genes participating in the extrinsic and intrinsic pathway were significantly up-regulated during GSIV infection, while those of anti-apoptotic genes were restrained in early infection and then rose in late infection. These results collectively indicate that GSIV induces GSM apoptotic cell death involving mitochondrial damage, caspases activation, p53 expression, and pro-apoptotic molecules up-regulation.

Iron (II) Polypyridyl Complexes as Antiglioblastoma Agents to Overcome the Blood-Brain Barrier and Inhibit Cell Proliferation by Regulating p53 and 4E-BP1 Pathways

Background and Purpose: It is urgently required to develop promising candidates to permeate across blood-brain barrier (BBB) efficiently with simultaneous disrupting vasculogenic mimicry capability of gliomas. Previously, a series of iron (II) complexes were synthesized through a modified method. Hence, the aim of this study was to evaluate anticancer activity of Fe(PIP)₃SO₄ against glioma cancer cells. Methods: Cytotoxic effects were determined via MTT assay, and IC₅₀ values were utilized to evaluate the cytotoxicity. Cellular uptake of Fe(PIP)₃SO₄ between U87 and HEB cells was conducted by subtracting content of the complex remaining in the cell culture supernatants. Propidium Iodide (PI)-flow cytometric analysis was used to analyze cell cycle proportion of U87 cells treated with Fe(PIP)₃SO₄. The reactive oxygen species levels induced by Fe(PIP)₃SO₄ were measured by 2'-deoxycoformycin (DCF) probe; ABTS assay was utilized to examine the radical scavenge capacity of Fe(PIP)₃SO₄. To study the bind efficiency to thioredoxin reductase (TrxR), Fe(PIP)₃SO₄ was introduced into solution containing TrxR. To verify if Fe(PIP)₃SO₄ could penetrate BBB, HBMEC/U87 coculture as BBB model was established, and penetrating capability of Fe(PIP)₃SO₄ was tested. In vitro U87 tumor spheroids were formed to test the permeating ability of Fe(PIP)₃SO₄. Acute toxicity and biodistribution of Fe(PIP)₃SO₄ were tested on mice for 72 h. Protein profiles associated with U87 cells treated with Fe(PIP)₃SO₄ were determined by Western blotting analysis. Results: Results showed that Fe(PIP)₃SO₄ could suppress cell proliferation by inducing G2/M phase cycle retardation and apoptotic pathways, which was related with expression of p53 and initiation factor 4E binding protein 1. In addition, Fe complex could suppress cell proliferation by downregulating reactive oxygen species levels via scavenging free radicals and interaction with TrxR. Furthermore, Fe(PIP)₃SO₄ could permeate across BBB and simultaneously inhibited the vasculogenic mimicry-channel of U87 cells, suggesting favorable antiglioblastoma efficacy. Acute toxicity manifested lower degree of the complex compared with cisplatin and temozolomide. Conclusion: Fe(PIP)₃SO₄ exhibited favorable anticancer activity against glioma cells associated with p53 and 4E binding protein 1, accompanied with negligible toxic effects on normal tissues. Herein, Fe(PIP)₃SO₄ could be developed as a promising metal-based chemotherapeutic agent to overcome BBB and antagonize glioblastomas.

Circular RNA CircEZH2 Suppresses Transmissible Gastroenteritis Coronavirus-induced Opening of Mitochondrial Permeability Transition Pore via Targeting MiR-22 in IPEC-J2

Transmissible gastroenteritis (TGE) is a contagious and infectious disease that is characterized by severe vomiting and diarrhea of swine , especially piglet, and caused by transmissible gastroenteritis coronavirus (TGEV) . TGEV infection provokes mitochondrial damage of porcine intestinal epthelial cell (IPEC), which is responsible for inflammation and cell death. In our previous study, we have demonstrated that circular RNA circEZH2 was down-regulated during TGEV infection and promoted the activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) via targeting miR-22 in porcine intestinal epithelial cell line (IPEC-J2). Activation of NF-κB is an important factor for mitochondrial damage. Mitochondrial permeability transition pore (mPTP) opening is a key reason for mitochondrial damage. So, we speculate that circEZH2 may regulate TGEV-induced mPTP opening via NF-kB pathway. In the present study, we found that mPTP opening of IPEC-J2 was occured during TGEV infection and suppressed by circEZH2 via attaching miR-22. Hexokinase 2 (HK2) and interleukin 6 (IL-6) were identified as the targets of miR-22. Silencing HK2 enhanced TGEV-induced mPTP opening, while no effect on NF-κB pathway. Silencing IL-6 promoted TGEV-induced mPTP opening and inhibited NF-κB pathway. Inhibitor of NF-κB increased TGEV-induced mPTP opening. The data revealed that TGEV-induced mPTP opening was regulated via two pathways: circEZH2/miR-22/HK2 axis and circEZH2/miR-22/IL-6/NF-κB axis.

The immune evasion strategies of fish viruses

Viral infection of a host rapidly triggers intracellular signaling events that induce interferon production and a cellular antiviral state. Viral diseases are important concerns in fish aquaculture. The major mechanisms of the fish antiviral immune response are suggested to be similar to those of mammals, although the specific details of the process require further studies. Throughout the process of pathogen-host coevolution, fish viruses have developed a battery of distinct strategies to overcome the biochemical and immunological defenses of the host. Such strategies include signaling interference, effector modulation, and manipulation of host apoptosis. This review provide an overview of the different mechanisms that fish viruses use to evade host immune responses. The basic mechanisms of immune evasion of fish virus are discussed, and some examples are provided to illustrate particular points.

Lespedeza bicolor ameliorates endothelial dysfunction induced by methylglyoxal glucotoxicity

BACKGROUND

Lespedeza species have been used as a traditional medicine to treat nephritis, azotemia, inflammation, energy depletion, diabetes, and diuresis.

PURPOSE

The purpose of this study is to screen the most potent Lespedeza species against methylglyoxal (MGO)-induced glucotoxicity, and to elucidate the mechanisms of action. Also, we will attempt to identify small chemical metabolites that might be responsible for such anti-glucotoxicity effects.

METHODS

Firstly, the protective effect of 26 different Lespedeza species against MGO-induced toxicity in human umbilical vein endothelial cells was investigated. The chemical metabolites of the most potent species (Lespedeza bicolor 1 (LB1) were identified by high pressure liquid chromatography quadrupole time-of-flight tandem mass spectrometry (HPLC-Q-TOF-MS/MS), then quantified by HPLC. The effects of LB1 on MGO-induced apoptosis were measured by annexin V-FITC staining and western blot. Inhibitory effects of LB1 on MGO-induced ROS generation, and effect of LB1 on advanced glycation end products (AGEs) inhibitor or a glycated cross-link breaker are also measured.

RESULTS

Among different Lespedeza species, LB1 extract was shown to reduce intracellular reactive oxidative species, exhibit anti-apoptotic effects, strongly inhibit all the mitogen-activated protein kinase signals, inhibit MGO-induced AGEs formation, and break down preformed AGEs. We tentatively identified 17 chemical constituents of LB1 by HPLC-Q-TOF-MS/MS. Among those, some components, such as genistein and quercetin, significantly reduced the AGEs formation and increased the AGEs-breaking activity, resulting in the reduction of glucotoxicity.

CONCLUSION

LB1 extract has shown to be effective in preventing or treating MGO-induced endothelial dysfunction.

Betanodavirus B2 protein triggers apoptosis and necroptosis in lung cancer cells that suppresses autophagy

The betanodavirus B2 protein targets the mitochondria and acts as a "death factor", but its effect on lung cancer cells is unknown. We examined the effect of the B2 protein on triggering apoptosis or necroptosis via P53-dependent and P53-independent pathways and increased in suppression of autophagy. The B2 protein targets the mitochondria of A549 (P53+/+) and H1299 (P53-/-) lung cancer cells due to a specific signal sequence (41RTFVISAHAA50). This triggers generation of reactive oxygen species within the mitochondria, and a minor stress response in A549 cells, but a strong stress response in H1299 cells. We examined the molecular mechanism of this cell death pathway, and found that B2 protein induces the P53/Bax-mediated apoptotic pathway in A549 cells, and that a P53 specific inhibitor (pifithrin-α) switches this response to RIP3-mediated necroptosis. On the other hand, B2 induces RIP3-mediated necroptosis pathway in H1299 cells, and a necroptosis inhibitor (necrostatin-1) switches this response to the apoptotic pathway. Both types of cell death signals inhibited autophagy via a tightly increased balance of beclin-1 and Bcl-2. Thus, B2 protein triggers P53-dependent apoptosis in A549 cells and ROS/RIP3-mediated necroptosis in H1299 cells, and crosstalk of these pathways limits initiation of autophagy. These findings provide new insights into the possible control and treatment of lung cancer.

Fighting Cancer with Mathematics and Viruses

After decades of research, oncolytic virotherapy has recently advanced to clinical application, and currently a multitude of novel agents and combination treatments are being evaluated for cancer therapy. Oncolytic agents preferentially replicate in tumor cells, inducing tumor cell lysis and complex antitumor effects, such as innate and adaptive immune responses and the destruction of tumor vasculature. With the availability of different vector platforms and the potential of both genetic engineering and combination regimens to enhance particular aspects of safety and efficacy, the identification of optimal treatments for patient subpopulations or even individual patients becomes a top priority. Mathematical modeling can provide support in this arena by making use of experimental and clinical data to generate hypotheses about the mechanisms underlying complex biology and, ultimately, predict optimal treatment protocols. Increasingly complex models can be applied to account for therapeutically relevant parameters such as components of the immune system. In this review, we describe current developments in oncolytic virotherapy and mathematical modeling to discuss the benefit of integrating different modeling approaches into biological and clinical experimentation. Conclusively, we propose a mutual combination of these research fields to increase the value of the preclinical development and the therapeutic efficacy of the resulting treatments.

Anti-apoptotic genes Bcl-2 and Bcl-xL overexpression can block iridovirus serine/threonine kinase-induced Bax/mitochondria-mediated cell death in GF-1 cells

Although serine/threonine (ST) kinase is known to induce host cell death in GF-1 cells, it remains unclear how ST kinase induces mitochondrial function loss. In the present study, we addressed the issue of mitochondrial function loss by determining whether the Bcl-2 family members Bcl-2 and Bcl-xL can prevent ST kinase-induced cell death activity via interacting with the pro-apoptotic gene Bax. Grouper fin cells (GF-1) carrying EGFP-Bal-xL and EGFP-Bcl-2 fused genes were selected, established in cell culture, and used to examine the involvement of Bcl-2 and Bcl-xL overexpression in protection of GF-1 cells from the effects of the giant sea perch iridovirus (GSIV) ST kinase gene. Using the TUNEL assay, we found that EGFP-Bcl-2 and EGFP-Bcl-xL reduced GSIV ST kinase-induced apoptosis to 20% all at 24 h and 48 h post-transfection (pt). Also, Bcl-2 and Bcl-xL substantially reduced the percentage of cells with GSIV ST kinase-induced loss of mitochondrial membrane potential (Δψps) at 24 and 48 hpt, respectively, and this reduction correlated with a 30% and 50% enhancement of host cell viability at 24 and 48 hpt as compared with vector control. Moreover, analysis of the effect of Bcl-2 and Bcl-xL interaction with Bax targeted to mitochondria during ST kinase expression at 48 hpt found that Bcl-2 and Bcl-xL also interacted with Bax to block cytochrome c release. Finally, Bcl-2 and Bcl-xL overexpression caused blockage of ST kinase function at 48 hpt, which was correlated with preventing caspase-9 and -3 cleavage and activation, thereby blocking downstream death signaling events. Taken together, our results suggest that the ST kinase-induced Bax/mitochondria-mediated cell death pathway can be blocked by the interaction of Bcl-2 and Bcl-xL with Bax to inhibit cytochrome c release during MMP loss. This rescue activity also correlated with inhibition of caspase-9 and -3 activation, thereby enhancing cell viability.