FoxO3 Modulates LPS-Activated Hepatic Inflammation in Turbot (Scophthalmus maximus L.)

Molecular characterization, expression pattern and the function of TRAF2 from blood parrot Amphilophus citrinellus ×Vieja melanura response to LPS stimulation

Tumor necrosis factor receptor-associated factor (TRAF) family is a critical signal transduction protein, and plays important roles in cell growth, apoptosis, and immune response, etc. In this study, molecular characteristics, expression patterns, and the role of TRAF2 in blood parrot Vieja synspila ♀ × Amphilophus citrinellus ♂, an important ornamental fish, were explored response to lipopolysaccharide (LPS) challenge. The full length of blood parrot TRAF2 was 2725 bp, with an open reading frame (ORF) of 1551 bp encoding 516 amino acids, and a molecular weight of 58.58 kDa. Blood parrot TRAF2 contained four conserved domains: RING, TRAF-type zinc finger, TRAF_BIRC3_bd, and MATH (Meprin and TRAF-C homology). Analysis of phylogenetic relationships showed that TRAF2 were conserved in different species, indicating that its role might be similar. Blood parrot TRAF2 mRNA could be detected in all of the tissues examined, and was distributed in both the cytoplasm and nucleus. The expression of blood parrot TRAF2 was up-regulated during LPS challenge. Overexpression of TRAF2 could significantly inhibit the activities of nuclear factor κB (NF-κB) and activated protein 1 (AP-1), and reduce the ratio of Bax/Bcl-2. This study indicated that the TRAF2 might play important roles in organisms during pathogen infection.

m6A methylation dynamically participates in the immune response against Vibrio anguillarum in half-smooth tongue sole (Cynoglossus semilaevis)

N6-methyladenosine (m6A) is the most prevalent RNA modification and a multifaceted regulator capable of affecting various aspects of mRNA metabolism, thereby playing important roles in numerous physiological processes. However, it is still unknown whether, when, and to what extent m6A modulation are implicated in the immune response of an economically important aquaculture fish, half-smooth tongue sole (Cynoglossus semilaevis). Herein, we systematically profiled and characterized the m6A epitranscriptome and transcriptome in C. semilaevis after the infection of Vibrio anguillarum. We demonstrated that m6A could be modulated as early as 4-h post infection (hpi), and the overall intensity of m6A methylation was enhanced following infection. Both conservative and novel motifs were uncovered from the m6A modification sites. Furthermore, differentially m6A methylated genes (DMGs) and differentially expressed genes (DEGs) were identified, and functional enrichment revealed multiple immune-related pathways, especially the FoxO signaling pathway which showed significance in every comparison. Joint analysis highlighted the remarkedly dynamic role of m6A on gene expression, i.e. early on, m6A mainly prioritized the down-regulation of specific genes, and later, it switched gears to promote expression of another set of genes. Moreover, key candidate genes, mainly involved in immunity and energy metabolism, were identified. Validations were performed by qPCR and MeRIP-qPCR. To our limited knowledge, this is the first study comprehensively characterizing the global m6A atlas in aquaculture fish species. The presented results provide new insights into the dynamics of m6A modifications in the transcriptome of the half-smooth tongue sole following bacterial infection, and further studies are warranted to elucidate the functional significance of these changes in depth.

Rosmarinic acid attenuated inflammation and apoptosis in folic acid-induced renal injury: Role of FoxO3/ NFκB pathway

Objectives

Rosmarinic acid (RA) is a herbal compound with various antioxidant and anti-inflammatory effects. This study aimed to explore the anti-inflammatory and anti-apoptotic properties of RA in folic acid-induced renal injury.

Materials and Methods

Thirty-six male C57/BL6 mice were randomly divided into six groups (N=6): Control (received normal saline), NaHCO3 (received NaHCO3 as folic acid solvent), FA (received folic acid (FA)(IP) to induce renal injury), RA (received 100 mg/kg RA), RA50-FA (received 50 mg/kg RA solution after folic acid injection), and RA100-FA (received 100 mg/kg RA after folic acid injection). For ten days, the treatment groups received RA by gavage. The effects of RA were assessed using H & E staining, biochemical tests, western blotting, and ELISA in the kidney tissues of the mice. Real-time RT-PCR was also performed to evaluate the expression changes of renal genes.

Results

Our data showed that treatment by RA led to the over-expression of FoxO3 (P<0.05) and decrease in NFκB levels (P<0.01 and P<0.05) and expression of TNFα (P<0.05) and IL6 (P<0.001 and P<0.01). Other evaluations showed a decrease in p53 (P<0.01 and P<0.001), Bax/Bcl-2 ratio expression (P<0.01 and P<0.05), and Caspase-3 level (P<0.01 and P<0.05) compared to the folic acid group. Histological and biochemical results also confirmed the attenuation of tissue damage.

Conclusion

This study revealed that RA's positive effects on folic acid-induced renal injury might result from the involvement of the FoxO3/NFκB pathway, thereby suppressing inflammation and apoptosis.

Inhibition of TREM-1 ameliorates angiotensin II-induced atrial fibrillation by attenuating macrophage infiltration and inflammation through the PI3K/AKT/FoxO3a signaling pathway

Inflammation and infiltration of immune cells are intricately linked to the pathogenesis of atrial fibrillation (AF). Triggering receptor expressed on myeloid cells-1 (TREM-1), an enhancer of inflammation, is implicated in various cardiovascular disorders. However, the precise role and potential mechanisms of TREM-1 in the development of AF remain ambiguous. Atrial samples from patients with AF were used to assess the expression levels of TREM-1. An angiotensin II (Ang II)-induced AF mouse model was established to assess the functionality of TREM-1. Cardiac function and AF inducibility were assessed through echocardiography, programmed transvenous cardiac pacing, and atrial electrophysiological mapping. Peripheral blood and atrial inflammatory cells were assessed using flow cytometry. Using histology, bulk RNA sequencing, biochemical analyses, and cell cultures, the mechanistic role of TREM-1 in AF was elucidated. TREM-1 expression was upregulated and co-localized with macrophages in the atria of patients with AF. Pharmacological inhibition of TREM-1 decreased Ang II-induced atrial enlargement and electrical remodeling. TREM-1 inhibition also ameliorated Ang II-induced NLRP3 inflammasome activation, inflammatory factor release, atrial fibrosis, and macrophage infiltration. Transcriptomic analysis revealed that TREM-1 modulates Ang II-induced inflammation through the PI3K/AKT/FoxO3a signaling pathway. In vitro studies further supported these findings, demonstrating that TREM-1 activation exacerbates Ang II-induced inflammation, while overexpression of FoxO3a counteracts this effect. This study discovered the critical role of TREM-1 in the pathogenesis of AF and its underlying molecular mechanisms. Inhibition of TREM-1 provides a new therapeutic strategy for the treatment of AF.

Advancing insights into microgravity induced muscle changes using Caenorhabditis elegans as a model organism

Spaceflight presents significant challenges to the physiological state of living organisms. This can be due to the microgravity environment experienced during long-term space missions, resulting in alterations in muscle structure and function, such as atrophy. However, a comprehensive understanding of the adaptive mechanisms of biological systems is required to devise potential solutions and therapeutic approaches for adapting to spaceflight conditions. This review examines the current understanding of the challenges posed by spaceflight on physiological changes, alterations in metabolism, dysregulation of pathways and the suitability and advantages of using the model organism Caenorhabditis elegans nematodes to study the effects of spaceflight. Research has shown that changes in the gene and protein composition of nematodes significantly occur across various larval stages and rearing environments, including both microgravity and Earth gravity settings, often mirroring changes observed in astronauts. Additionally, the review explores significant insights into the fundamental metabolic changes associated with muscle atrophy and growth, which could lead to the development of diagnostic biomarkers and innovative techniques to prevent and counteract muscle atrophy. These insights not only advance our understanding of microgravity-induced muscle atrophy but also lay the groundwork for the development of targeted interventions to mitigate its effects in the future.

Loss of Macrophage mTORC2 Drives Atherosclerosis via FoxO1 and IL-1β Signaling

BACKGROUND

The mTOR (mechanistic target of rapamycin) pathway is a complex signaling cascade that regulates cellular growth, proliferation, metabolism, and survival. Although activation of mTOR signaling has been linked to atherosclerosis, its direct role in lesion progression and in plaque macrophages remains poorly understood. We previously demonstrated that mTORC1 (mTOR complex 1) activation promotes atherogenesis through inhibition of autophagy and increased apoptosis in macrophages.

METHODS

Using macrophage-specific Rictor- and mTOR-deficient mice, we now dissect the distinct functions of mTORC2 pathways in atherogenesis.

RESULTS

In contrast to the atheroprotective effect seen with blockade of macrophage mTORC1, macrophage-specific mTORC2-deficient mice exhibit an atherogenic phenotype, with larger, more complex lesions and increased cell death. In cultured macrophages, we show that mTORC2 signaling inhibits the FoxO1 (forkhead box protein O1) transcription factor, leading to suppression of proinflammatory pathways, especially the inflammasome/IL (interleukin)-1β response, a key mediator of vascular inflammation and atherosclerosis. In addition, administration of FoxO1 inhibitors efficiently rescued the proinflammatory response caused by mTORC2 deficiency both in vitro and in vivo. Interestingly, collective deletion of macrophage mTOR, which ablates mTORC1- and mTORC2-dependent pathways, leads to minimal change in plaque size or complexity, reflecting the balanced yet opposing roles of these signaling arms.

CONCLUSIONS

Our data provide the first mechanistic details of macrophage mTOR signaling in atherosclerosis and suggest that therapeutic measures aimed at modulating mTOR need to account for its dichotomous functions.

The rules and regulatory mechanisms of FOXO3 on inflammation, metabolism, cell death and aging in hosts

The FOX family of transcription factors was originally identified in 1989, comprising the FOXA to FOXS subfamilies. FOXO3, a well-known member of the FOXO subfamily, is widely expressed in various human organs and tissues, with higher expression levels in the ovary, skeletal muscle, heart, and spleen. The biological effects of FOXO3 are mostly determined by its phosphorylation, which occurs in the nucleus or cytoplasm. Phosphorylation of FOXO3 in the nucleus can promote its translocation into the cytoplasm and inhibit its transcriptional activity. In contrast, phosphorylation of FOXO3 in the cytoplasm leads to its translocation into the nucleus and exerts regulatory effects on biological processes, such as inflammation, aerobic glycolysis, autophagy, apoptosis, oxidative stress, cell cycle arrest and DNA damage repair. Additionally, FOXO3 isoform 2 acts as an important suppressor of osteoclast differentiation. FOXO3 can also interfere with the development of various diseases, including inhibiting the proliferation and invasion of tumor cells, blocking the production of inflammatory factors in autoimmune diseases, and inhibiting β-amyloid deposition in Alzheimer's disease. Furthermore, FOXO3 slows down the aging process and exerts anti-aging effects by delaying telomere attrition, promoting cell self-renewal, and maintaining genomic stability. This review suggests that changes in the levels and post-translational modifications of FOXO3 protein can maintain organismal homeostasis and improve age-related diseases, thus counteracting aging. Moreover, this may indicate that alterations in FOXO3 protein levels are also crucial for longevity, offering new perspectives for therapeutic strategies targeting FOXO3.

LPS-Induced Liver Injury of Magang Geese through Toll-like Receptor and MAPK Signaling Pathway

Lipopolysaccharide (LPS) is one of the main virulence factors of Gram-negative bacteria. In the process of waterfowl breeding, an inflammatory reaction due to LPS infection is easily produced, which leads to a decline in waterfowl performance. The liver plays a vital role in the immune response and the removal of toxic components. Therefore, it is necessary to study the mechanism of liver injury induced by LPS in goose. In this study, a total of 100 1-day-old goslings were randomly divided into a control group and LPS group after 3 days of pre-feeding. On days 21, 23, and 25 of the formal experiment, the control group was intraperitoneally injected with 0.5 mL normal saline, and the LPS group was intraperitoneally injected with LPS 2 mg/(kg body weight) once a day. On day 25 of the experiment, liver samples were collected 3 h after the injection of saline and LPS. The results of histopathology and biochemical indexes showed that the livers of the LPS group had liver morphological structure destruction and inflammatory cell infiltration, and the levels of ALT and AST were increased. Next, RNA sequencing analysis was used to determine the abundances and characteristics of the transcripts, as well as the associated somatic mutations and alternative splicing. We screened 727 differentially expressed genes (DEGs) with p < 0.05 and |log2(Fold Change)| ≥ 1, as the thresholds; GO and KEGG enrichment analysis showed that LPS-induced liver injury may be involved in the Toll-like receptor signaling pathway, MAPK signaling pathway, NOD-like receptor signaling pathway, FoxO, and PPAR signaling pathway. Finally, we intersected the genes enriched in the key pathway of LPS-induced liver injury with the top 50 key genes in protein−protein interaction networks to obtain 28 more critical genes. Among them, 17 genes were enriched in Toll-like signaling pathway and MAPK signaling pathway. Therefore, these results suggest that LPS-induced liver injury in geese may be the result of the joint action of Toll-like receptor, MAPK, NOD-like receptor, FoxO, and PPAR signaling pathway. Among them, the TLR7-mediated MAPK signaling pathway plays a major role.

A novel full-length transcriptome resource from multiple immune-related tissues in turbot (Scophthalmus maximus) using Pacbio SMART sequencing

Turbot (Scophthalmus maximus) is an important cold-water economic fish. However, the production and development of turbot industry has been constantly hindered by the frequent occurrence of some diseases. Lacking full-length transcriptome for turbot limits immune gene discoveries and gene structures analysis. Therefore, we generated a full-length transcriptome using mixed immune-related tissues of turbot with PacBio Sequel platform. In this study, a total of 31.7 Gb high quality data were generated with the average subreads length of 2618 bp. According to the presence of 5' and 3' primers as well as poly (A) tails, FL (Full-length) and NFL (Non-full-length) isoforms were obtained. Meanwhile, we identified 32,003 non-redundant transcripts, 76.02% of which was novel isoforms of known genes. In addition, 12,176 alternative splicing (AS) events, 6614 polyadenylation (APA) events, 1905 transcription factors, and 2703 lncRNAs were identified. This work is a comprehensive report on the full-length transcriptome of immune-related tissues of turbot, and it also provides valuable molecular resources for future research on the adaptation mechanisms and functional genomics of turbot.

Integrated Analysis of Transcriptome and Metabolome Reveals Distinct Responses of Pelteobagrus fulvidraco against Aeromonas veronii Infection at Invaded and Recovering Stage

Yellow catfish (Pelteobagrus fulvidraco) is an important aquaculture fish susceptible to Aeromonas veronii infection, which causes acute death resulting in huge economic losses. Understanding the molecular processes of host immune defense is indispensable to disease control. Here, we conducted the integrated and comparative analyses of the transcriptome and metabolome of yellow catfish in response to A. veronii infection at the invaded stage and recovering stage. The crosstalk between A. veronii-induced genes and metabolites uncovered the key biomarkers and pathways that strongest contribute to different response strategies used by yellow catfish at corresponding defense stages. We found that at the A. veronii invading stage, the immune defense was strengthened by synthesizing lipids with energy consumption to repair the skin defense line and accumulate lipid droplets promoting intracellular defense line; triggering an inflammatory response by elevating cytokine IL-6, IL-10 and IL-1β following PAMP-elicited mitochondrial signaling, which was enhanced by ROS produced by impaired mitochondria; and activating apoptosis by up-regulating caspase 3, 7 and 8 and Prostaglandin F1α, meanwhile down-regulating FoxO3 and BCL6. Apoptosis was further potentiated via oxidative stress caused by mitochondrial dysfunction and exceeding inflammatory response. Additionally, cell cycle arrest was observed. At the fish recovering stage, survival strategies including sugar catabolism with D-mannose decreasing; energy generation through the TCA cycle and Oxidative phosphorylation pathways; antioxidant protection by enhancing Glutathione (oxidized), Anserine, and α-ketoglutarate; cell proliferation by inducing Cyclin G2 and CDKN1B; and autophagy initiated by FoxO3, ATG8 and ATP6V1A were highlighted. This study provides a comprehensive picture of yellow catfish coping with A. veronii infection, which adds new insights for deciphering molecular mechanisms underlying fish immunity and developing stage-specific disease control techniques in aquaculture.