Phosphorylation Status Research Articles

Loss of the DNA repair protein, polynucleotide kinase/phosphatase, activates the type 1 interferon response independent of ionizing radiation.

DNA damage has been implicated in the stimulation of the type 1 interferon (T1IFN) response. Here, we show that downregulation of the DNA repair protein, polynucleotide kinase/phosphatase (PNKP), in a variety of cell lines causes robust phosphorylation of STAT1, upregulation of interferon-stimulated genes and persistent accumulation of cytosolic DNA, all of which are indicators for the activation of the T1IFN response. Furthermore, this did not require damage induction by ionizing radiation. Instead, our data revealed that production of reactive oxygen species (ROS) synergises with PNKP loss to potentiate the T1IFN response, and that loss of PNKP significantly compromises mitochondrial DNA (mtDNA) integrity. Depletion of mtDNA or treatment of PNKP-depleted cells with ROS scavengers abrogated the T1IFN response, implicating mtDNA as a significant source of the cytosolic DNA required to potentiate the T1IFN response. The STING signalling pathway is responsible for the observed increase in the pro-inflammatory gene signature in PNKP-depleted cells. While the response was dependent on ZBP1, cGAS only contributed to the response in some cell lines. Our data have implications for cancer therapy, since PNKP inhibitors would have the potential to stimulate the immune response, and also to the neurological disorders associated with PNKP mutation.

Fetal growth restriction and placental defects in obese mice are associated with impaired decidualisation: the role of increased leptin signalling modulators SOCS3 and PTPN2

Decidualisation of the endometrium is a key event in early pregnancy, which enables embryo implantation. Importantly, the molecular processes impairing decidualisation in obese mothers are yet to be characterised. We hypothesise that impaired decidualisation in obese mice is mediated by the upregulation of leptin modulators, the suppressor of cytokine signalling 3 (SOCS3) and the protein tyrosine phosphatase non-receptor type 2 (PTPN2), together with the disruption of progesterone (P4)-signal transducer and activator of transcription (STAT3) signalling. After feeding mice with chow diet (CD) or high-fat diet (HFD) for 16 weeks, we confirmed the downregulation of P4 and oestradiol (E2) steroid receptors in decidua from embryonic day (E) 6.5 and decreased proliferation of stromal cells from HFD. In vitro decidualised mouse endometrial stromal cells (MESCs) and E6.5 deciduas from the HFD showed decreased expression of decidualisation markers, followed by the upregulation of SOCS3 and PTPN2 and decreased phosphorylation of STAT3. In vivo and in vitro leptin treatment of mice and MESCs mimicked the results observed in the obese model. The downregulation of Socs3 and Ptpn2 after siRNA transfection of MESCs from HFD mice restored the expression level of decidualisation markers. Finally, DIO mice placentas from E18.5 showed decreased labyrinth development and vascularisation and fetal growth restricted embryos. The present study revealed major defects in decidualisation in obese mice, characterised by altered uterine response to E2 and P4 steroid signalling. Importantly, altered hormonal response was associated with increased expression of leptin signalling modulators SOCS3 and PTPN2. Elevated levels of SOCS3 and PTPN2 were shown to molecularly affect decidualisation in obese mice, potentially disrupting the STAT3-PR regulatory molecular hub.

S100A9 deletion in microglia/macrophages ameliorates brain injury through the STAT6/PPARγ pathway in ischemic stroke.

Microglia and infiltrated macrophages (M/M) are integral components of the innate immune system that play a critical role in facilitating brain repair after ischemic stroke (IS) by clearing cell debris. Novel therapeutic strategies for IS therapy involve modulating M/M phenotype shifting. This study aims to elucidate the pivotal role of S100A9 in M/M and its downstream STAT6/PPARγ signaling pathway in neuroinflammation and phagocytosis after IS. In the clinical study, we initially detected the expression pattern of S100A9 in monocytes from patients with acute IS and investigated its association with the long-term prognosis. In the invivo study, we generated the S100A9 conditional knockout (CKO) mice and compared the stroke outcomes with the control group. We further tested the S100A9-specific inhibitor paqunimod (PQD), for its pharmaceutical effects on stroke outcomes. Transcriptomics and invitro studies were adopted to explore the mechanism of S100A9 in modulating the M/M phenotype, which involves the regulation of the STAT6/PPARγ signaling pathway. S100A9 was predominantly expressed in classical monocytes and was correlated with unfavorable outcomes in patients of IS. S100A9 CKO mitigated infarction volume and white matter injury, enhanced cerebral blood flow and functional recovery, and prompted anti-inflammation phenotype and efferocytosis after tMCAO. The STAT6/PPARγ pathway, an essential signaling cascade involved in immune response and inflammation, might be the downstream target mediated by S100A9 deletion, as evidenced by the STAT6 phosphorylation inhibitor AS1517499 abolishing the beneficial effect of S100A9 inhibition in tMCAO mice and cell lines. Moreover, S100A9 inhibition by PQD treatment protected against neuronal death invitro and brain injuries invivo. This study provides evidence for the first time that S100A9 in classical monocytes could potentially be a biomarker for predicting IS prognosis and reveals a novel therapeutic strategy for IS. By demonstrating that S100A9-mediated M/M polarization and phagocytosis can be reversed by S100A9 inhibition in a STAT6/PPARγ pathway-dependent manner, this study opens up new avenues for drug development in the field.

Cortactin: A major cellular target of viral, protozoal, and fungal pathogens.

Many viral, protozoal, and fungal pathogens represent major human and animal health problems due to their great potential of causing infectious diseases. Research on these pathogens has contributed substantially to our current understanding of both microbial virulence determinants and host key factors during infection. Countless studies have also shed light on the molecular mechanisms of host-pathogen interactions that are employed by these microbes. For example, actin cytoskeletal dynamics play critical roles in effective adhesion, host cell entry, and intracellular movements of intruding pathogens. Cortactin is an eminent host cell protein that stimulates actin polymerization and signal transduction, and recently emerged as fundamental player during host-pathogen crosstalk. Here we review the important role of cortactin as major target for various prominent viral, protozoal and fungal pathogens in humans, and its role in human disease development and cancer progression. Most if not all of these important classes of pathogens have been reported to hijack cortactin during infection through mediating up- or downregulation of cortactin mRNA and protein expression as well as signaling. In particular, pathogen-induced changes in tyrosine and serine phosphorylation status of cortactin at its major phospho-sites (Y-421, Y-470, Y-486, S-113, S-298, S-405, and S-418) are addressed. As has been reported for various Gram-negative and Gram-positive bacteria, many pathogenic viruses, protozoa, and fungi also control these regulatory phospho-sites, for example, by activating kinases such as Src, PAK, ERK1/2, and PKD, which are known to phosphorylate cortactin. In addition, the recruitment of cortactin and its interaction partners, like the Arp2/3 complex and F-actin, to the contact sites between pathogens and host cells is highlighted, as this plays an important role in the infection process and internalization of several pathogens. However, there are also other ways in which the pathogens can exploit the function of cortactin for their needs, as the cortactin-mediated regulation of cellular processes is complex and involves numerous different interaction partners. Here, the current state of knowledge is summarized.

Discovery of novel penetrating peptides able to target human leukemia and lymphoma for enhanced PROTAC delivery

Proteolysis targeting chimeras (PROTAC) are bifunctional chimeric molecules capable of directly degrading binding proteins through the ubiquitin-proteasome pathway. PROTACs have demonstrated significant potential in overcoming drug resistance and targeting previously untreatable targets. However, several limitations still need to be addressed, including their high molecular weight resulting in poor membrane permeability and bioavailability. In this study, we proposed that cancer-targeted penetrating peptides could enhance the cell permeability of PROTACs. We developed 26 novel targeted penetrating peptides for leukemia and lymphoma cells, among which C9C-f(3Bta) and Cyclo-C9C–R exhibited superior membrane permeability, targetability, and stability. By combining C9C-f(3Bta) and Cyclo-C9C–R with IMA-PROTAC, we effectively enhanced the anti-proliferative activity of IMA-PROTAC, facilitated degradation of Bcr-Abl protein in K562 cells, and reduced downstream STAT5 phosphorylation. Furthermore, the combined application promoted cell apoptosis while blocking G1 phase progression. HPLC-MRM-MS revealed that the combination of C9C-f(3Bta) or Cyclo-C9C–R with IMA-PROTAC significantly enhanced intracellular IMA-PROTAC content. In summary, our proof-of-concept study validated the hypothesis that combining PROTACs with targeted penetrating peptides can improve protein degradation efficiency as well as anti-proliferative capabilities.

JianPiTongLuo (JPTL) Recipe regulates anti-apoptosis and cell proliferation in colorectal cancer through the PI3K/AKT signaling pathway

BackgroundJianPiTongLuo Recipe (JPTL Recipe) is a traditional Chinese medicine formula commonly used in the clinical treatment of colorectal cancer. Clinical studies have found that it can significantly improve the prognosis of patients with colorectal cancer. However, its mechanisms of action are not well understood, which has limited its further clinical application. MethodsWe investigated the potential mechanisms of action of the JianPiTongLuo (JPTL) Recipe on colorectal cancer (CRC) using a multi-step approach. Initially, network pharmacology and bioinformatics analyses were conducted using databases such as TCMSP, HERB, BATMAN-TCM, and STRING to identify active components of JPTL Recipe and predict their therapeutic targets. Interaction networks and functional enrichment analyses were constructed to hypothesize relevant biological processes and pathways. In vitro studies involved treating human CRC cell lines HCT116, LoVo and SW480 with varying concentrations of JPTL Recipe extract, measuring cell viability with the CCK-8 assay, assessing apoptosis via flow cytometry, and analyzing signaling pathways through Western blotting. To corroborate these findings, in vivo experiments were performed on BALB/c nude mice implanted with HCT116 cells, divided into control, JPTL Recipe-treated, 5-fluorouracil (5-FU)-treated, and JPTL Recipe combined with 5-FU groups, with tumor growth and histological changes monitored. Mechanistic studies focused on the PI3K/AKT signaling pathway, examining the phosphorylation status of key pathway proteins using immunofluorescence and Western blot analyses to elucidate JPTL Recipe 's interaction with pathway activity. ResultsWe demonstrated that JPTL Recipe effectively inhibits colorectal cancer cell proliferation, anti-apoptotic ability, and exerts synergistic therapeutic effects with fluorouracil. Further analysis revealed that JPTL Recipe affects the activity of colorectal cancer cells by inhibiting the phosphorylation of the PI3K/AKT signaling pathway. ConclusionIn summary, we have discovered and confirmed that the traditional Chinese medicine compound JPTL Recipe can serve as a novel adjuvant therapy for colorectal cancer, offering a new treatment approach for the integration of traditional Chinese and Western medicine in the treatment of colorectal cancer.

Suppression of gp130 attenuated insulin-mediated signaling and glucose uptake in skeletal muscle cells

The aim of the present study was to investigate the effects of Oncostatin M receptor (OSMR) subunit gp130 knockdown on insulin-stimulated glucose metabolism-related signaling pathways and glucose uptake in skeletal muscle cells. siRNA-mediated gp130 knockdown was conducted in C2C12 muscle cells, and insulin was added and incubated for 1 h. The cells were cultivated to analyze the mRNA levels of gp130, phosphorylation of STAT3, and glucose metabolism-regulated signaling pathways, and OSM levels in the culture medium were analyzed. The phosphorylation of STAT 3 was significantly decreased in gp130−/− cell. The insulin stimulation was significantly increased in both gp130−/− and gp130+/+ and the phosphorylation of IRS-1 Ser 1101 was significantly decreased in gp130−/−. PI3-kinase activity and Akt Thr 308 phosphorylation were significantly decreased in gp130−/−. The insulin-stimulated increase in glucose uptake rate was significantly attenuated in gp130−/−. In the culture medium, OSM levels were significantly lower in gp130+/+compared to gp130−/− cell. In conclusion, the knockdown of gp130 caused a decrease in STAT 3 phosphorylation and resulted in the attenuation of insulin-mediated glucose metabolism signaling in skeletal muscle cells. Thus, an excessive increase in extracellular OSM may induce blunted insulin action in skeletal muscle cells.

Interleukin-22 Promotes Cell Proliferation to Combat Virus Infection in Human Intestinal Epithelial Cells.

Interferon lambdas (IFN-λs) are crucial to control virus infections at mucosal surfaces. Interleukin-22 (IL-22) was reported to help IFN-λ control rotavirus infection in the intestinal epithelium of mice either by aiding in the induction of interferon-stimulated genes (ISGs) or by increasing cell proliferation thereby clearing virally infected cells. We investigated whether IL-22 and IFN-λs exhibit similar synergistic effects in human intestinal epithelial cells (IECs) models. Our results showed that co-treatment of IL-22 and IFN-λ induced more phosphorylation of STAT1 than either cytokine used alone. However, this increased STAT1 activation did not translate to increased ISGs production or antiviral protection. Transcriptomics analysis revealed that despite sharing a common subunit (IL-10Rb) within their heterodimeric receptors and activating similar STATs, the signaling generated by IL-22 and IFN-λs is independent, with IFN-λ signaling inducing ISGs and IL-22 signaling inducing cell proliferation genes. Using human intestinal organoids, we confirmed that IL-22 increased the size of the organoids through increased cell proliferation and expression of the stem cell marker (OLFM4). These findings suggest that in human intestinal cells, IFN-λs and IL-22 act independently to clear virus infections. IFN-λs induce ISGs to control virus replication and spread, whereas IL-22 increases cell proliferation to eliminate infected cells and repair the damage epithelium. Although these two cytokines do not act synergistically, each plays a key function in the protection of human IECs.

HDAC8 Enhances the Function of HIF-2α by Deacetylating ETS1 to Decrease the Sensitivity of TKIs in ccRCC.

Drug resistance after long-term use of Tyrosine kinase inhibitors (TKIs) has become an obstacle for prolonging the survival time of patients with clear cell renal cell carcinoma (ccRCC). Here, genome-wide CRISPR-based screening to reveal that HDAC8 is involved in decreasing the sensitivity of ccRCC cells to sunitinib is applied. Mechanically, HDAC8 deacetylated ETS1 at the K245 site to promote the interaction between ETS1 and HIF-2α and enhance the transcriptional activity of the ETS1/HIF-2α complex. However, the antitumor effect of inhibiting HDAC8 on sensitized TKI is not very satisfactory. Subsequently, inhibition of HDAC8 increased the expression of NEK1, and up-regulated NEK1 phosphorylated ETS1 at the T241 site to promote the interaction between ETS1 and HIF-2α by impeded acetylation at ETS1-K245 site is showed. Moreover, TKI treatment increased the expression of HDAC8 by inhibiting STAT3 phosphorylation in ccRCC cells is also found. These 2 findings highlight a potential mechanism of acquired resistance to TKIs and HDAC8 inhibitors in ccRCC. Finally, HDAC8-in-PROTACs to optimize the effects of HDAC8 inhibitors through degrading HDAC8 and overcoming the resistance of ccRCC to TKIs are synthesized. Collectively, the results revealed HDAC8 as a potential therapeutic candidate for resistance to ccRCC-targeted therapies.

Hedgehog signaling pathway regulates Th17 cell differentiation in asthma via IL-6/STAT3 signaling

Asthma is the most prevalent chronic inflammatory disease of the airways in children. The most prevalent phenotype of asthma is eosinophilic asthma, which is driven by a Th2 immune response and can be effectively managed by inhaled corticosteroid therapy. However, there are phenotypes of asthma with Th17 immune response that are insensitive to corticosteroid therapy and manifest a more severe phenotype. The treatment of this corticosteroid-insensitive asthma is currently immature and requires further attention. The objective of this study is to elucidate the regulation of the Hedgehog signaling pathway in Th17 cell differentiation in asthma. The study demonstrated that both Smo and Gli3, key components of the Hedgehog signaling pathway, were upregulated in Th17 polarization in vitro and in a Th17-dominant asthma model in vivo. Inhibiting Smo with a small molecule inhibitor or genetically knocking down Gli3 was found to suppress Th17 polarization. Smo was found to increase in Th1, Th2, Th17 and Treg polarization, while Gli3 specifically increased in Th17 polarization. ChIP-qPCR analyses indicated that Gli3 can directly interact with IL-6 in T cells, inducing STAT3 phosphorylation and promoting Th17 cell differentiation. Furthermore, the study demonstrated a correlation between elevated Gli3 expression and IL-17A and IL-6 expression in children with asthma. In conclusion, the study demonstrated that the Hedgehog signaling pathway plays an important role in the pathogenesis of asthma, as it regulates the differentiation of Th17 cells through the IL-6/STAT3 signaling. This may provide a potential therapeutic target for corticosteroid-insensitive asthma driven by Th17 cells.

Starch phosphorylation—A needle in a haystack

Phosphoesterification is the only naturally occurring covalent starch modification identified to date, and it has a major impact on overall starch metabolism. The incorporation of phosphate groups mediated by dikinases [α-glucan, water dikinase (GWD), EC 2.7.9.4; phosphoglucan, water dikinase (PWD), EC 2.7.9.5] massively alters the starch granule properties; however, previous studies did not determine whether the starch-related dikinases bind the phosphate to the glucosyl units within the amylopectin molecules in a specific pattern or randomly. In order to answer this challenging question, a number of approaches were initially pursued until a protocol could be established that enabled a massive step forward in the in vitro analysis of phosphorylated glucan chains obtained from starch. For this purpose, phosphorylation by GWD was investigated, including the final state of phosphorylation i.e., the state of substrate saturation when GWD lacks further free hydroxyl groups at OH-C6 for the catalysis of monophosphate esters. Since the separated phosphorylated glucan chains were required for the analysis, isoamylase digestion was performed to cleave the α-1,6-glycosidic bonds and to allow for the removal of the huge number of existing neutral chains by means of anion exchange chromatography. Via Matrix-Assisted Laser Desorption/Ionization–Time of Flight (MALDI-TOF) MS and MALDI-MS/MS, the phosphorylated α-glucan chains were analysed, and the position of the phosphate group within the chain in relation to the reducing end was determined. Here, we demonstrate a protocol that enables the analysis of phosphorylated oligosaccharides, even in small quantities.

Possible effects of treatments durations with Ruxolitinib on inhibiting jak phosphorylation of STAT1 in A549 lung cancer cells

This study explores the effects of different treatment durations of Ruxolitinib on inhibiting JAK phosphorylation of STAT1 in A549 lung cancer cells. The JAK/STAT signaling pathway is critical in lung cancer development and progression. By utilizing western blotting, a STAT luciferase reporter assay, and an MTT viability assay, the study evaluates the impact of Ruxolitinib treatment on STAT1 phosphorylation, STAT activation, and cell viability. Understanding how treatment duration influences JAK/STAT pathway inhibition provides valuable insights for developing targeted therapies in lung cancer. This research contributes to addressing the challenges of lung cancer treatment by exploring the potential of Ruxolitinib as a therapeutic agent.

Threonine Deficiency Increases Triglyceride Deposition in Primary Duck Hepatocytes by Reducing STAT3 Phosphorylation.

Liver lipid metabolism disruption significantly contributes to excessive fat buildup in waterfowl. Research suggests that the supplementation of Threonine (Thr) in the diet can improve liver lipid metabolism disorder, while Thr deficiency can lead to such metabolic disorders in the liver. The mechanisms through which Thr regulates lipid metabolism remain unclear. STAT3 (signal transducer and activator of transcription 3), a crucial transcription factor in the JAK-STAT (Janus kinase-signal transducer and activator of transcription) pathway, participates in various biological processes, including lipid and energy metabolism. This research investigates the potential involvement of STAT3 in the increased lipid storage seen in primary duck hepatocytes as a result of a lack of Thr. Using small interfering RNA and Stattic, a specific STAT3 phosphorylation inhibitor, we explored the impact of STAT3 expression patterns on Thr-regulated lipid synthesis metabolism in hepatocytes. Through transcriptome sequencing, we uncovered pathways related to lipid synthesis and metabolism jointly regulated by Thr and STAT3. The results showed that Thr deficiency increases lipid deposition in primary duck hepatocytes (p < 0.01). The decrease in protein and phosphorylation levels of STAT3 directly caused this deposition (p < 0.01). Transcriptomic analysis revealed that Thr deficiency and STAT3 knockdown jointly altered the mRNA expression levels of pathways related to long-chain fatty acid synthesis and energy metabolism (p < 0.05). Thr deficiency, through mediating STAT3 inactivation, upregulated ELOVL7, PPARG, MMP1, MMP13, and TIMP4 mRNA levels, and downregulated PTGS2 mRNA levels (p < 0.01). In summary, these results suggest that Thr deficiency promotes lipid synthesis, reduces lipid breakdown, and leads to lipid metabolism disorders and triglyceride deposition by downregulating STAT3 activity in primary duck hepatocytes.

Acyl-CoA Synthetase Medium-Chain Family Member 5–Mediated Fatty Acid Metabolism Dysregulation Promotes the Progression of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver cancer, with high incidence and mortality worldwide. Despite diagnostic and therapeutic advancements, HCC remains poorly responsive to treatment with a poor prognosis. Understanding the molecular mechanisms driving HCC is crucial for developing effective therapies. Emerging evidence indicates that dysregulated fatty acid metabolism contributes to HCC. Acyl-CoA medium-chain synthetase 5 (ACSM5), involved in fatty acid metabolism, is downregulated in HCC, however, its role is not well understood. In the study, we analyzed ACSM5 expression in HCC patient samples and cell lines. Using newly established ACSM5-overexpressing HCC cell lines, Huh7-ACSM5 and Hepa1-6-ACSM5, we investigated the effects and regulatory mechanisms of ACSM5. Our results showed that ACSM5 was significantly downregulated in HCC tumor tissues compared to non-tumor tissues. ACSM5 expression was regulated by DNA methylation, with a DNMT1 inhibitor effectively increasing ACSM5 expression and reducing promoter region methylation. Overexpression of ACSM5 in Huh7 cells reduced fatty acid accumulation, decreased cell proliferation, migration, and invasion in vitro, and inhibited tumor growth in mouse xenografts. Furthermore, ACSM5 overexpression also decreased STAT3 phosphorylation, subsequently affecting downstream cytokine TGFB and FGF12 mRNA levels. Our findings suggest that ACSM5 downregulation contributes to HCC progression, providing insights into its oncogenic role and highlighting its potential as a biomarker and therapeutic target for HCC.

IL-10 Enhances the Inhibitory Effect of Adipose-Derived Stromal Cells on Insulin Resistance/Liver Gluconeogenesis by Treg Cell Induction.

The modulation of cellular phenotypes within adipose tissue provides a potential means for therapeutic intervention for diabetes. Endogenous interleukin-10 (IL-10) protects against diet-induced insulin resistance. We examined the effects and mechanisms of action of IL-10-treated adipose-derived stromal cells on diabetes-induced insulin resistance and liver gluconeogenesis. We harvested stromal vascular fractions (SVFs) from the adipose tissue of diabetic (Leprdb/db) mice and treated them with IL-10 in vitro. SVFs treated with 10 or 100 ng of IL-10 were injected into the inguinal adipose tissue of Leprdb/db mice. IL-10 treatment suppressed the mRNA expression of IL-6, IL-33, CCL2, TNF-α, and IL-1β. Additionally, it suppressed the protein expression of IL-6, pmTOR, pJNK, and pNF-κB but enhanced Foxp3 mRNA expression in SVFs from diabetic mice. Meanwhile, IL-10 treatment repressed CCL2 and PDGFRα expression in adipose tissue macrophages (ATMs) and IL-6 expression in non-ATMs but increased the Foxp3 and IL-10 mRNA expression of ATMs from diabetic mice. Injection of IL-10-treated SVFs decreased the IL-6, IL-33, CCL2, IL-1β, and CCL2 but enhanced the Foxp3 and IL-10 mRNA expression of adipose tissue from Leprdb/db mice. Furthermore, injection of IL-10-treated SVFs increased CD4+ regulatory T cells (Tregs) in SVFs and adipose IL-10 levels and suppressed plasma adiponectin levels and DPP4 activity in diabetic mice. Injection of IL-10-treated SVFs decreased hepatic G6PC and PCK1 mRNA expression and increased Akt activation, STAT3 phosphorylation in the liver, and glucose tolerance in diabetic mice. Our data suggest that IL-10 treatment decreases inflammation in adipose SVFs of diabetic mice. Injection of IL-10-treated SVFs into the adipose tissue decreased diabetes-induced gluconeogenesis gene expression, DPP4 activity, and insulin resistance by enhancing Treg cells in diabetic mice. These data suggest that IL-10-treated adipose stromal vascular cells could be a promising therapeutic strategy for diabetes mellitus.

FXa-mediated PAR-2 promotes the efficacy of immunotherapy for hepatocellular carcinoma through immune escape and anoikis resistance by inducing PD-L1 transcription

BackgroundThe high metastasis rate is one of the main reasons for the poor prognosis of patients with hepatocellular carcinoma (HCC). Coagulation factor Xa (FXa) and its receptor proteinase-activated receptor-2 (PAR-2)...

Structural basis for TNIP1 binding to FIP200 during mitophagy

TNIP1 has been increasingly recognized as a security check to finely adjust the rate of mitophagy by disrupting the recycling of the Unc-51-like kinase (ULK) complex during autophagosome formation. Through tank-binding kinase 1 (TBK1)-mediated phosphorylation of the TNIP1 FIR motif, the binding affinity of TNIP1 for FIP200, a component of the ULK complex, is enhanced, allowing TNIP1 to outcompete autophagy receptors. Consequently, FIP200 is released from the autophagosome, facilitating further autophagosome expansion. However, the molecular basis by which FIP200 utilizes its claw domain to distinguish the phosphorylation status of residues in the TNIP1 FIP200 interacting region (FIR) motif for recognition is not well understood. Here, we elucidated multiple crystal structures of the complex formed by the FIP200 claw domain and various phosphorylated TNIP1 FIR peptides. Structural and isothermal titration calorimetry (ITC) analyses identified the crucial residues in the FIP200 claw domain responsible for the specific recognition of phosphorylated TNIP1 FIR peptides. Additionally, utilizing structural comparison and molecular dynamics (MD) simulation data, we demonstrated that the C-terminal tail of TNIP1 peptide affected its binding to the FIP200 claw domain. Moreover, the phosphorylation of TNIP1 Ser123 enabled the peptide to effectively compete with the peptide p-CCPG1 (the FIR motif of the autophagy receptor CCPG1) for binding with the FIP200 claw domain. Overall, our work provides a comprehensive understanding of the specific recognition of phosphorylated TNIP1 by the FIP200 claw domain, marking an initial step toward fully understanding the molecular mechanism underlying the TNIP1-dependent inhibition of mitophagy.

A single, maximal dose of celecoxib, ibuprofen, or flurbiprofen does not reduce the muscle signalling response to plyometric exercise in young healthy adults.

Non-steroidal anti-inflammatory drugs (NSAIDs) possess analgesic and anti-inflammatory properties by inhibiting cyclooxygenase (COX) enzymes. Conflicting evidence exists on whether NSAIDs influence signaling related to muscle adaptations and exercise with some research finding a reduction in muscle protein synthesis signaling via the AKT-mTOR pathway, changes in satellite cell signaling, reductions in muscle protein degradation, and reductions in cell proliferation. In this study, we determined if a single maximal dose of flurbiprofen (FLU), celecoxib (CEL), ibuprofen (IBU), or a placebo (PLA) affects the short-term muscle signaling responses to plyometric exercise. This was a block randomized, double-masked, crossover design, where 12 participants performed four plyometric exercise bouts consisting of 10 sets of 10 plyometric jumps at 40% 1RM. Two hours before exercise, participants consumed a single dose of celecoxib (CEL 200mg), IBU (800mg), FLU (100mg) or PLA with food. Muscle biopsy samples were collected before and 3-h after exercise from the vastus lateralis. Data were analyzed using a repeated measures (RM) ANOVA, ANOVA, or a Friedman test. Significance was considered at p < 0.05. We found no treatment effects on the mRNA expression of PTSG1, PTSG2, MYC, TBP, RPLOP, MYOD1, Pax7, MYOG, Atrogin-1, or MURF1 (all, p > 0.05). We also found no treatment effects on AKT-mTOR signaling or MAPK signaling measured through the phosphorylation status of mTORS2441, mTORS2448, RPS6 235/236, RPS 240/244, 4EBP1, ERK1/2, p38 T180/182 normalized to their respective total abundance (all, p > 0.05). However, we did find a significant difference between MNK1 T197/202 in PLA compared to FLU (p < .05). A single, maximal dose of IBU, CEL, or FLU taken prior to exercise did not affect the signaling of muscle protein synthesis, protein degradation, or ribosome biogenesis three hours after a plyometric training bout.

Elucidation of anti-pneumonia pharmacodynamic material basis and potential mechanisms of Xiebai San by combining spectrum–efficacy relationship and surface plasmon resonance

Ethnopharmacological relevanceXiebai San (XBS), a classic Chinese prescription, has been used for the clinical treatment of pneumonia-related diseases for thousands of years. However, the anti-pneumonia pharmacodynamic material basis of XBS and its underlying mechanisms remain unclear. Aim of the studyThis study aimed to comprehensively investigate and verify the anti-pneumonia pharmacodynamic material basis and mechanisms of XBS. Materials and methodsThis study explored the anti-pneumonia activity and key pneumonia targets of XBS in lipopolysaccharide (LPS)-induced zebrafish and RAW264.7 cells in vivo and in vitro through transcriptomics, western blotting, and reverse transcription–quantitative polymerase chain reaction (RT–qPCR). The chemical fingerprint of XBS was established using high-performance liquid chromatography, and the similarities and areas of characteristic peaks of 15 batches of XBS were analyzed. Based on the spectrum–efficacy relationship, the potential anti-inflammatory components were screened according to their peak areas and efficacy using principal component analysis (PCA), bivariate correlation, and partial least squares regression analysis. Active components that bind to core targets were further screened based on surface plasmon resonance (SPR). The binding mode of proteins and components was simulated via molecular docking, which enabled the identification of the primary active components of XBS, thereby elucidating its anti-pneumonia properties. Finally, the anti-inflammatory activities of these components were verified in vitro. ResultsXBS decreased neutrophil aggregation in zebrafish and nitric oxide (NO) secretion in RAW264.7 cells as well as suppressed the release of downstream inflammatory cytokines such as iNOS, TNF-α, IL-1β, IL-18, and CXCL10 related to TNF and JAK–STAT signaling pathways. The phosphorylation of IκBα, Akt, and Stat3 was alleviated after XBS in cells. The fingerprint similarities of 15 batches of XBS ranged from 0.381 to 0.994, with a large difference. A total of 15 characteristic peaks were identified, and the relative standard deviation of their peak areas ranged from 24.1% to 70.7%. The results of in vitro anti-inflammatory activities of 15 batches of XBS showed that all samples inhibited the expression levels of NO and nine inflammatory markers. The anti-inflammatory index of 15 batches of XBS was determined to be 0.69–0.96 based on transformation of the anti-inflammatory rate and composite index method via PCA. The spectrum–efficacy relationship model of 15 characteristic peak areas and the anti-inflammatory index showed that 7 main potential active components were related to the anti-inflammatory activity of XBS. Moreover, four components (mulberroside A, isoquercitrin, liquiritigenin, and glycyrrhizic acid) screened based on SPR had different affinities toward TNFR1, Akt1, and Stat3 proteins, and the binding modes were elucidated via molecular docking. Finally, in LPS-induced RAW264.7 cells, all four active components (at a concentration of 60 μM) significantly inhibited the expression levels of NO and inflammatory markers. ConclusionsBased on the comprehensive strategy of spectrum–efficacy relationship and SPR, mulberroside A, isoquercitrin, liquiritigenin, and glycyrrhizic acid were identified as the primary pharmacodynamic active components involved in the anti-pneumonia activity of XBS and were found to intervene in TNF and JAK–STAT signaling pathways.

Empagliflozin protects against heart failure with preserved ejection fraction partly by inhibiting the senescence-associated STAT1–STING axis

Heart failure with preserved ejection fraction (HFpEF) is a mortal clinical syndrome without effective therapies. Empagliflozin (EMPA) improves cardiovascular outcomes in HFpEF patients, but the underlying mechanism remains elusive. Here, mice were fed a high-fat diet (HFD) supplemented with L-NAME for 12 weeks and subsequently intraperitoneally injected with EMPA for another 4 weeks. A 4D-DIA proteomic assay was performed to detect protein changes in the failing hearts. We identified 310 differentially expressed proteins (DEPs) (ctrl vs. HFpEF group) and 173 DEPs (HFpEF vs. EMPA group). The regulation of immune system processes was enriched in all groups and the interferon response genes (STAT1, Ifit1, Ifi35 and Ifi47) were upregulated in HFpEF mice but downregulated after EMPA administration. In addition, EMPA treatment suppressed the increase in the levels of aging markers (p16 and p21) in HFpEF hearts. Further bioinformatics analysis verified STAT1 as the hub transcription factor during pathological changes in HFpEF mice. We next treated H9C2 cells with IFN-γ, a primary agonist of STAT1 phosphorylation, to investigate whether EMPA plays a beneficial role by blocking STAT1 activation. Our results showed that IFN-γ treatment caused cardiomyocyte senescence and STAT1 activation, which were inhibited by EMPA administration. Notably, STAT1 inhibition significantly reduced cellular senescence possibly by regulating STING expression. Our findings revealed that EMPA mitigates cardiac inflammation and aging in HFpEF mice by inhibiting STAT1 activation. The STAT1–STING axis may act as a pivotal mechanism in the pathogenesis of HFpEF, especially under inflammatory and aging conditions.Graphical abstractThe schematic figure depicts a mechanism model of the STAT1–STING axis in HFpEF (this figure was drawn using FigDraw software).