P38 Kinase Research Articles

Inhibiting autophagy further promotes Ginkgolide B's anti-osteoclastogenesis ability

Excessive osteoclast activity could cause skeletal diseases including osteoporosis. Additionally, autophagy plays an initial role in osteoclast differentiation and function. Ginkgolide B (GB), a key compound in Ginkgo biloba, improves bone mass and suppresses mature osteoclast formation in vitro. This study examines the role of GB role in regulating osteoclast formation via autophagy. Using murine bone marrow-derived macrophages in vitro, we explored GB's effects on autophagy and osteoclast formation. We also assessed bone loss prevention in an ovariectomized (OVX) mouse model using GB combined with an autophagy inhibitor. Tartrate-resistant acid phosphatase staining was used to observe osteoclast formation. Autophagy-related proteins and intracellular microtubule associated protein 1 light chain 3 beta puncta were observed using western blotting and immunofluorescence. The impact of GB on OVX mice was evaluated using micro-computed tomography and hematoxylin and eosin staining. GB directly promoted autophagy in osteoclast precursors (OCPs), but inhibited osteoclast differentiation by reducing receptor activator of nuclear factor kappa B ligand (RANKL)-induced autophagy. GB inhibits the phosphorylation of RANKL downstream signaling pathways, such as Jun N-terminal kinase (JNK), p38, and extracellular signal-regulated kinase (ERK). Anisomycin (ANI), a JNK activator, reversed GB's inhibitory effects on RANKL-induced autophagy and osteoclastogenesis. Inhibiting autophagy using 3-Methyladenine (3-MA) or small interfering RNA significantly suppressed osteoclast differentiation both in vitro and in vivo. Our findings suggested that GB inhibits osteoclast formation by decreasing JNK phosphorylation and autophagy under RANKL stimulation. Interestingly, GB also directly promotes autophagy in OCPs. Thus, GB markedly reduces osteoclast differentiation and prevents bone loss, with its anti-osteoclastogenesis effect being enhanced by 3-MA. Accordingly, inhibiting GB-induced direct autophagy could further increase its therapeutic effect on bone disease resulting from excessive osteoclast activity.

Selective PPARδ Agonist GW501516 Protects Against LPS-Induced Macrophage Inflammation and Acute Liver Failure in Mice via Suppressing Inflammatory Mediators.

Inflammation is critical in the development of acute liver failure (ALF). Peroxisome proliferator-activated receptor delta (PPARδ) regulates anti-inflammatory responses and is protective in several diseases such as obesity and cancer. However, the beneficial effects and underlying mechanisms of PPARδ agonist GW501516 in ALF remain unclear. This study investigated the molecular mechanisms underlying the anti-inflammatory effects of GW501516 in macrophages and assessed its protective potential against lipopolysaccharide (LPS)/galactosamine (GalN)-induced ALF. In vivo administration of GW501516 significantly reduced LPS/GalN-induced hepatotoxicity, as evidenced by lower mortality, decreased liver damage, and attenuated secretion of IL-1β, IL-6, and TNF-α. GW501516 treatment also decreased LPS-induced nitric oxide synthase 2 (NOS2) expression and nitric oxide (NO) production in RAW264.7 cells, an effect reversed by PPARδ siRNA. Additionally, GW501516 inhibited LPS-induced phosphorylation of p38 and c-Jun N-terminal kinase (JNK), suggesting that inactivation of these MAPKs contributes to its effects. The secretion of IL-6, TNF-α, and NF-κB DNA-binding activity were also suppressed by GW501516, while the nuclear translocation of the NF-κB p65 subunit was unaffected. In conclusion, our findings suggest that GW501516 exerts protective effects in ALF by inhibiting the production of inflammatory mediators. Therefore, GW501516 may act as a potential agent for developing anti-inflammatory therapies for ALF.

Evaluation of CacyBP/SIP expression and its relationship with ERK1/2 and p38 kinase in testicular seminoma

Testicular cancer accounts for approximately 5% of all urologic cancers. The most common histopathological diagnosis of testicular neoplastic lesions are germ cell tumors (90-95% of cases), among which the majority of cases are seminomas, the most common malignant tumors among men aged 15-44. For better clinical diagnosis and treatment, it is important to understand the molecular mechanisms of tumor formation. In this study, the expression of the CacyBP/SIP protein and ERK1/2 and p38 kinases was analyzed for the first time in seminomas and normal testicular tissues. The research was carried out using archival tissue material from 30 patients undergoing surgery due to testicular seminoma, whereas the comparative material consisted of the adjacent normal tissues. Immunohistochemistry and qRT-PCR were used to identify the expression of CacyBP/SIP, ERK1/2, and p38. A marked weakening of the immunohistochemical reaction was observed in the cancerous tissue compared to the control tissue. PCR testing of the marked proteins confirmed their lower expression in seminoma. Our findings suggest the involvement of the CacyBP/SIP protein in the ERK1/2 and p38 signalling pathways, which may be involved in the processes of testicular seminoma carcinogenesis. The results of our research provide the basis for further research in this area.

Leptin on the apical surface inhibits casein production and STAT5 phosphorylation in mammary epithelial cells

Leptin is a peptide hormone present in both the blood and milk. A close relationship between leptin and milk production in lactating mammary glands has been previously reported. However, how leptin influences milk production in lactating mammary glands remains unclear. Also, whether leptin in milk or blood influences mammary epithelial cells (MECs) during lactation needs further investigation. This study investigated the effects of leptin on mouse MECs using a culture model in which MECs produced milk components and formed less permeable tight junctions. Our results showed that β-casein production in MEC was inhibited by leptin in a concentration-dependent manner. Leptin also inactivated the signal transducer and activator of transcription 5 (STAT5), a transcription factor that facilitates milk production in MECs. Leptin treatment induced the activation of p38 and c-Jun N-terminal kinase (JNK) in MEC before STAT5 inactivation, and anisomycin, an activator of p38 and JNK, induced the inactivation of STAT5. Furthermore, leptin exposure on the apical surface of MECs inhibited β-casein production and inactivated STAT5. However, leptin exposure on the basolateral surface hardly caused these effects. These findings suggested that milk leptin, but not plasma leptin, inhibited milk production in MECs.

Exploring the impact of sEH inhibition on intestinal cell differentiation and Colon Cancer: Insights from TPPU treatment

Inhibition of soluble epoxide hydrolase (sEH) appears to be promising for the treatment of many diseases. Studies have focused on the beneficial effects of epoxyeicosatrienoic acids (EETs), which are sEH substrates. However, our recent studies have shown that the sEH activity is crucial for the proper intestinal cell differentiation. In this recent study, we investigated the impact of TPPU, an inhibitor of sEH, on the colon cancer cell lines Caco2 and HT-29. We analysed the changes in the expression of the cytoskeletal protein ezrin and the phosphorylated protein kinase p38 (p-p38). Our results showed a decrease in ezrin expression in differentiated cells and an increase in p-p38 expression after TPPU treatment. Immunocytochemical staining revealed a higher staining intensity of p-p38 in the nuclei of HT-29 cells following TPPU treatment. Immunohistochemical staining was performed on human samples of normal colon tissue, grade 2 tumours, and embryonal/foetal tissues. The staining intensity of ezrin in tumours was reduced in the surface area compared to the crypts. Additionally, we observed the translocation of p-p38 expression from the cytoplasm to the nucleus during differentiation. The tumour samples exhibited higher levels of p-p38 in the cytoplasm, similar to normal undifferentiated tissue. To observe the disruption of the cytoskeleton after TPPU treatment, confocal microscopy was used. It was found that β-actin associated with ezrin forms clusters under the plasma membranes. All of these results are significant because sEH inhibitors are being tested in clinical trials, but they could cause an unexpected adverse effects.

High-Density Lipoprotein Mimetic Peptide 4F Reduces Toxic Amyloid-Beta Exposure to the Blood-Brain Barrier Endothelium in Alzheimer's Disease Transgenic Mice.

Aβ accumulation in the blood-brain barrier (BBB) endothelium, which lines the cerebrovascular lumen, is a significant contributor to cerebrovascular dysfunction in Alzheimer's disease (AD). Reduced high-density lipoprotein (HDL) levels are associated with increased AD risk, and the HDL mimetic peptide 4F has been developed as a promising therapeutic agent to improve cerebrovascular health in AD. In this study, we evaluated the impact of 4F on 125I-Aβ42 blood-to-brain distribution using dynamic SPECT/CT imaging in both wild-type and APP/PS1 transgenic mice. Graphical analysis of the imaging data demonstrated that 4F significantly reduced the blood-to-brain influx rate in wild-type mice and the distribution of 125I-Aβ42 in the BBB endothelium in APP/PS1 mice. To elucidate the molecular mechanisms underlying the effect of 4F, we evaluated its impact on the p38 pathway and its role in mediating Aβ42 trafficking in human BBB endothelial cell monolayers. Treatment with 4F significantly decreased Aβ42 induced p38 activation in BBB endothelial cells. Furthermore, inhibition of p38 kinase significantly reduced endothelial accumulation of fluorescence-labeled Aβ42 and luminal-to-abluminal permeability across the cell monolayer. While our previous publication has hinted at the potential of 4F to reduce Aβ accumulation in the brain parenchyma, the current findings demonstrated the protective effect of 4F in reducing Aβ42 accumulation in the BBB endothelium of AD transgenic mice. These findings revealed the impact of a clinically tested agent, the HDL mimetic peptide 4F, on Aβ exposure to the BBB endothelium and offer novel mechanistic insights into potential therapeutic strategies to treat cerebrovascular dysfunction in AD.

Shengqiyichang decoction regulates antitumor immunity in colorectal cancer by downregulating lymphocyte antigen 6 family member G6D via the protein kinase B/p38 mitogen-activated protein kinase signaling pathway

The traditional Chinese medicine (TCM) formulation Shengqiyichang Decoction (SQYCD) has been reported to stimulate host immunity, and it has been administered for the treatment of colorectal cancer (CRC). Here, we applied network and bioinformatics analyses to elucidate the mechanisms by which SQYCD ameliorates CRC and validated its modes of action via in vivo and in vitro experiments. We identified 46 active compounds in SQYCD and selected 237 proteins as potential therapeutic targets in CRC, most notably p38 mitogen-activated protein kinase (p38⍺). Bioinformatics analyses demonstrated differential expression in CRC tissues and prognostic value of the genes encoding TNFα, MAPK14, CASP-3, MAPK1, AKT1, PRKACA, VEGF, IL-6, EGFR and ESR1. We then plotted receiver operating curves (ROC) and time-ROC for the differentially expressed genes (DEGs) ESR1 and AKT1 to predict the progress of CRC. We speculated that the AKT/p38α-MAPK signaling pathway is associated with the clinical prognosis of CRC. In a mouse model, we found that SQYCD inhibits CRC tumor growth by increasing CD4+ and CD8+ T cell abundance and decreasing the ratio of T-regulatory cells (Tregs) in the tumor microenvironment. In cultured mouse CRC cells, SQYCD selectively upregulated levels of the CRC-associated protein lymphocyte antigen 6 family member G6D, while the AKT activator SC-79 reversed this effect. The discoveries made herein suggest that SQYCD exerts a therapeutic effect in CRC by inhibiting Treg recruitment via inhibition of the AKT/p38α/LY6G6D signaling axis.

Nonylphenol displays immunotoxicity by triggering hemocyte extracellular traps in Manila clam via ROS burst, ERK pathway and glycolysis

Nonylphenol (NP), an endocrine disruptor, has been demonstrated to be a harmful environmental contaminant and toxic to organisms. In this study, to address concerns regarding the immunotoxicity of NP, we treated clam Ruditapes philippinarum hemocytes with NP in vitro and explored the underlying mechanisms of NP-induced extracellular traps (ETs). NP could induce the formation of hemocytes ETs in a dose-dependent manner. Transcriptomics analysis revealed changes of signaling pathway involved in immunity and energy metabolism in hemocytes after NP stimulation. In this process, both reactive oxygen species (ROS) and myeloperoxidase (MPO) were up-regulated. Moreover, mitogen-activated protein kinase (MAPK) signaling pathway was proved to be activated in the formation of NP-induced ETs, manifested as enhanced phosphorylation of extracellular signal-regulated kinase (ERK) but not p38 or c-Jun N-terminal kinase (JNK). In the presence of U0126, an ERK phosphorylation inhibitor, the NP-induced expression of NADPH oxidase enzyme (NOX) was significantly decreased, which further alleviated the ROS production and ultimately limited the release of ETs. NP exposure increased glucose uptake, along with enhanced activities of glycolysis-related enzymes such as hexokinase (HK) and pyruvate kinase (PK). After inhibiting glycolysis by the inhibitor 2-DG, the formation of NP-induced ETs was significantly suppressed. ERK could regulate mTOR signaling and the PI3K/AKT pathway, potentially directing ETs formation by orchestrating the glycolysis through the activation of key transcription factors c-Myc and HIF-1α. Collectively, the results preliminary confirm that the ERK-NOX-ROS axis and glycolysis are involved in NP-induced ETs formation, contributing to the cellular immunotoxicity in clam.

Exogenous Reactive Oxygen Species Augments SMAD4 Expression And TGF-β Paradox in Human Breast Cancer

Background: The Transforming growth factor-β (TGF-β) functions to induce apoptosis, cell cycle arrest, and differentiation is central to sustaining tissue homeostasis and maintaining genomic stability. TGF-β normally, an effective tumor-suppressor that restricts the uncontrolled division of cells augments the development and progression of human malignancies when cytostatic activities of TGF-β are resisted by genetic and epigenetic events caused by tumorigenesis. This dichotomic nature of TGF-β during oncogenesis termed as “TGF-β Paradox,” persists to be the most crucial and puzzling query regarding its physio-pathological function and the role of cellular antioxidant status is highly interrelated which warrants more studies on the role of endogenous reactive oxygen species (ROS) in deciding epithelial-mesenchymal transition (EMT) process. The objective of the study was to check whether enhanced ROS augments the TGF-β pathway facilitating EMT. Methods: In vitro toxicity assay was performed to assess the appropriate concentration of hydrogen peroxide (H2O2) imparting oxidative stress. Comet assay and 8-OHdG (8-hydroxy-2’-deoxyguanosine) enzyme-linked immunosorbent assay (ELISA) were performed to check the extent of DNA damage and adduct production respectively. Mitogen-activated protein kinase (MAPK) p38 ELISA and mRNA gene expression analysis of TGF-β and SMAD were done to verify the effect of H2O2 on these signaling. Results: The objective of the study was to check whether enhanced ROS augments the TGF-β pathway facilitating EMT. Along with morphological alterations, a dose-dependent decrease in cell viability was seen at 300µM of H2O2 compared to 75µM. DCFDA labeling discovered the dose-dependent gradation of intracellular ROS generation and this was correlated to increased cellular DNA damage and DNA adduct production which was increased linearly with increasing H2O2 as evident with comet test and 8-OHdG ELISA. Significantly reduced MAPK p38 activity revealed by indirect ELISA analysis suggests lessened suppression of cell growth. Conclusions: The study establishes that higher intracellular ROS will facilitate the TGF-β paradox leading to epithelial mesenchymal transition which can adversely affect therapeutic strategies targeting EMT

The Gastroprotective Effect of Sicyos angulatus Against Hydrochloric Acid/Ethanol-Induced Acute Gastritis and Gastric Ulcer in Mice.

Gastritis and gastric ulcers are common gastric diseases that are caused by infection, drugs, alcohol consumption, or stress. These conditions lead to increased inflammatory cytokines and recruitment of leukocytes, which damage the stomach mucosa and exacerbate disease severity. Sicyos angulatus (SA), an annual vine in the Cucurbitaceae family, is known to have an anti-inflammatory effect, but its efficacy for preventing gastritis and gastric ulcers has not yet been evaluated. In the present study, we investigated the gastroprotective effect of SA using a hydrochloric acid/ethanol-induced gastric mucosal injury mouse model and lipopolysaccharide (LPS)-stimulated KATO III cells. Macroscopic analysis revealed a reduction in gastric ulcer area. Similarly, histopathological analysis showed a dose-dependent decrease in gastric mucosal injury, with significant improvement at 750 mg/kg of SA treatment. Gene expressions of inflammatory cytokines, chemokines, and adhesion molecule were reduced in the SA-administered group. Immunohistochemical staining indicated that SA significantly decreased neutrophil infiltration in the lamina propria and epithelium of the stomach. Kaempferol, a major bioactive flavonoid of SA, also improved gastric injury by reducing macroscopic and microscopic lesions, inflammatory mediator gene expression, and neutrophil infiltration. Furthermore, both SA and kaempferol downregulated LPS-mediated increases in inflammatory cytokines and chemokines following inhibition of p38 and c-Jun N-terminal kinase (JNK) phosphorylation in KATO III cells. These results suggest that SA can ameliorate gastric mucosal injury by inhibiting the recruitment of inflammatory cells, particularly neutrophils, and by suppressing p38 and JNK phosphorylation.

Involvement of mitogen- and stress-activated protein kinase 1 in BMP-6–induced chondrocyte differentiation

Bone morphogenetic proteins (BMPs) are involved in several cellular responsive actions, such as development, cell differentiation, and apoptosis, via their specific transmembrane receptors. In particular, BMPs promote the differentiation and maturation of bone and cartilage from mesenchymal stem cells. Based on comprehensive analyses performed with a large number of antibodies, mitogen- and stress-activated protein kinase (MSK)1 was found to be immediately phosphorylated in the mouse chondrocyte precursor cell line, ATDC5, upon BMP-6 stimulation. The overexpression and knockdown of MSK1 in ATDC5 cells also enhanced and suppressed BMP-6-induced chondrocyte differentiation, respectively. Similar to ATDC5 cells, an exvivo organ culture system using mouse embryonic metatarsal bones also demonstrated that BMP-6-mediated MSK1 activation might play a role in chondrocyte differentiation. Using several inhibitors, the p38 kinase pathway was confirmed to be implicated in BMP-6-induced phosphorylation of MSK1. Furthermore, MSK1 mutants lacking kinase activities and those lacking serine/threonine residues targeted by p38 kinase severely impaired their ability to potentiate BMP-6-induced chondrogenic differentiation of ATDC5 cells. Interestingly, a loss-of-function study for Smad4 perturbed BMP-6-induced phosphorylation of p38 kinase to inhibit BMP-6-mediated chondrocyte differentiation via MSK1 activation. Overall, both Smad-dependent and independent pathways require BMP-6-induced chondrocyte differentiation via MSK1 activation in ATDC5 cells.

Pentraxin 3 mediates inflammation and adipogenesis in Graves' orbitopathy pathogenesis.

Pentraxin 3 (PTX3) is a prototypic humoral soluble pattern-recognition molecule known to function in immunity-related inflammation. Given the lack of information on the precise functions of PTX3 in the pathogenesis of Graves' orbitopathy (GO), this study investigated the role of PTX3 in the inflammation and adipogenesis mechanisms of GO. We first compared the PTX3 expression between orbital tissues from patients with GO and normal controls using real-time PCR, which estimated significantly higher PTX3 transcript levels in the GO tissues than in the normal tissues. In addition, PTX3 production was markedly increased upon interleukin (IL)-1β and adipogenic stimulation. We then evaluated the effects of silencing PTX3 in primary orbital fibroblast cultures by analyzing the expression levels of pro-inflammatory cytokines, adipogenesis-related proteins, and downstream transcription factors in cells transfected with or without small interfering RNA against PTX3, using western blot. Silencing PTX3 attenuated the IL-1β-induced secretion of pro-inflammatory cytokines, including IL-6, IL-8, monocyte chemotactic protein-1, intercellular adhesion molecule-1, and cyclooxygenase-2, and suppressed the IL-1β-mediated activation of p38 kinase, nuclear factor-κB, and extracellular signal-regulated kinase. Moreover, PTX3 knockdown suppressed adipogenic differentiation, as assessed using Oil Red O staining, as well as the expression of adipogenesis-associated transcription factors including peroxisome proliferator-activated receptor-γ, CCAAT/enhancer-binding proteins α and β, adipocyte protein 2, adiponectin, and leptin. Thus, this study suggests that PTX3 plays a significant role in the pathogenesis of GO and may serve as a novel therapeutic target for the condition.

FPS-ZM1 attenuates the deposition of lipid in the liver of diabetic mice by sterol regulatory element binding protein-1c

BackgroundNonalcoholic fatty liver disease (NAFLD) shares common pathogenic mechanisms of type 2 diabetes mellitus (T2DM) with upregulated advanced glycation end products (AGEs). Here, we aim to investigate the effect of FPS-ZM1, an inhibitor for receptor for AGEs (RAGE), on lipid deposition in the liver of mice.MethodsKK-Ay mice were used as models of T2DM with NAFLD, while C57BL/6j mice were controls. Additionally, KK-Ay mice were treated with DMSO (with a concentration of 1%), with or without FPS-ZM1 (3 mg/kg/day, i.p). Lipid deposition in hepatocytes was observed using oil red O stain. Levels of AGEs and RAGE were measured. Sterol regulatory element-binding protein-1c (SREBP-1c), as well as nuclear factor κB p65 (p65 nfκb) and mitogen-activated protein kinase p38 (p38 MAPK), were also detected.ResultsLipid deposition is increased in the hepatocytes of KK-Ay mice compared to C57BL/6j mice. In addition, not only were the levels of AGEs elevated in plasma, but also the levels of RAGE in liver tissue. Although total SREBP-1c levels did not change in the liver of diabetic mice, mature SREBP-1c increased in KK-Ay mice with diabetes mellitus. Moreover, diabetic mice showed increased levels of phosphorylated-p65 nfκb (p-p65 nfκb) and phosphorylated-p38 MAPK (p-p38 MAPK). On the contrary, FPS-ZM1 decreased lipid deposition in liver cells, as well as mature SREBP-1c, p-p65 nfκb and p-p38 MAPK levels in liver tissue.ConclusionGenerally, FPS-ZM1 may attenuate lipid deposition in hepatocytes of diabetic mice via SREBP-1c down-regulation. This may depend on the downregulation of p65 nfκb and p38 MAPK phosphorylation.

Anti-tumor effects of the eIF4A inhibitor didesmethylrocaglamide and its derivatives in human and canine osteosarcomas

Inhibition of translation initiation using eIF4A inhibitors like (−)-didesmethylrocaglamide [(−)-DDR] and (−)-rocaglamide [(−)-Roc] is a potential cancer treatment strategy as they simultaneously diminish multiple oncogenic drivers. We showed that human and dog osteosarcoma cells expressed higher levels of eIF4A1/2 compared with mesenchymal stem cells. Genetic depletion of eIF4A1 and/or 2 slowed osteosarcoma cell growth. To advance preclinical development of eIF4A inhibitors, we demonstrated the importance of (−)-chirality in DDR for growth-inhibitory activity. Bromination of DDR at carbon-5 abolished growth-inhibitory activity, while acetylating DDR at carbon-1 was tolerated. Like (−)-DDR, (±)-DDR, and (−)-Roc, (±)-DDR-acetate increased γH2A.X levels and induced G2/M arrest and apoptosis. Consistent with translation inhibition, these rocaglates decreased the levels of several mitogenic kinases, the STAT3 transcription factor, and the stress-activated protein kinase p38. However, phosphorylated p38 was greatly enhanced in treated cells, suggesting activation of stress response pathways. RNA sequencing identified RHOB as a top upregulated gene in both (−)-DDR- and (−)-Roc-treated osteosarcoma cells, but the Rho inhibitor Rhosin did not enhance the growth-inhibitory activity of (−)-DDR or (−)-Roc. Nonetheless, these rocaglates potently suppressed tumor growth in a canine osteosarcoma patient-derived xenograft model. These results suggest that these eIF4A inhibitors can be leveraged to treat both human and dog osteosarcomas.

Decreased expression of DRA (SLC26A3) by a p38-driven IL-1α response contributes to diarrheal disease following in vivo challenge with Brachyspira spp.

In this study, we uncovered the novel mechanism of IL-1α-mediated downregulated in adenoma (DRA) (SLC26A3) downregulation in the context of Brachyspira spp.-induced malabsorptive diarrhea. Experimentally infected pigs with Brachyspira spp. had significantly reduced DRA expression in the colon accompanied by IL-1α upregulation. This response was recapitulated in vitro by exposing Caco-2 cells to either Brachyspira lysate or IL-1α. Both p38 and MAPK-activated protein kinase 2 (MAPKAPK-2 also referred as MK-2) showed an increased phosphorylation after exposure to either. SB203580 application, a p38 inhibitor blocked the MK-2 phosphorylation and attenuated the DRA and IL-1α response to both lysate and IL-1α. Exposure to IL-1 receptor antagonist (IL-1RA) produced a similar response. In addition, exposure of cells to either of these blockers without IL-1α or lysate results in increased DRA and decreased IL-1α expression, revealing that DRA needs IL-1α signaling for basal physiological expression. Dual inhibition with both blockers completely inhibited the effect from IL-1α while significantly attenuating the response from Brachyspira lysate, suggesting a minor contribution from another pathway. Together this demonstrates that Brachyspira activates p38 MAPK signaling driving IL-1α expression, which activates IL-1R1 causing DRA downregulation while also driving upregulation of IL-1α through p38 in a positive feedback mechanism. In conclusion, we elucidated a major pathway involved in DRA downregulation and its role in Brachyspira-induced diarrhea. In addition, these observations will aid in our understanding of other inflammatory and infectious diarrhea conditions.NEW & NOTEWORTHY The diarrheal disease caused by the two infectious spirochete spp. B. hyodysenteriae and B. hampsonii reduced the expression of DRA (SLC26A3), a major Cl-/HCO-3 exchanger involved in Cl- absorption. This is attributed to the upregulation of IL-1α driven by p38 MAPK. This work also describes a potential new mechanism in inflammatory diseases while showing the importance of IL-1α in maintaining DRA levels.

Poly-GR repeats associated with ALS/FTD gene C9ORF72 impair translation elongation and induce a ribotoxic stress response in neurons.

Hexanucleotide repeat expansion in the C9ORF72 gene is the most frequent inherited cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The expansion results in multiple dipeptide repeat proteins, among which arginine-rich poly-GR proteins are highly toxic to neurons and decrease the rate of protein synthesis. We investigated whether the effect on protein synthesis contributes to neuronal dysfunction and degeneration. We found that the expression of poly-GR proteins inhibited global translation by perturbing translation elongation. In iPSC-differentiated neurons, the translation of transcripts with relatively slow elongation rates was further slowed, and stalled, by poly-GR. Elongation stalling increased ribosome collisions and induced a ribotoxic stress response (RSR) mediated by ZAKα that increased the phosphorylation of the kinase p38 and promoted cell death. Knockdown of ZAKα or pharmacological inhibition of p38 ameliorated poly-GR-induced toxicity and improved the survival of iPSC-derived neurons from patients with C9ORF72-ALS/FTD. Our findings suggest that targeting the RSR may be neuroprotective in patients with ALS/FTD caused by repeat expansion in C9ORF72.

Empagliflozin demonstrates cytotoxicity and synergy with tamoxifen in ER-positive breast cancer cells: anti-proliferative and anti-survival effects.

Accumulating evidence suggests that sodium-glucose cotransporter 2 (SGLT2) inhibitors may be effective at eliminating tumor cells. While empagliflozin exhibits nearly the highest selectivity for SGLT2 over SGLT1, its specific impact alone and in combination with tamoxifen remains largely unexplored in estrogen receptor α-positive (ERα +) breast cancer. This study investigated the anticancer effects of empagliflozin and its potential synergy with tamoxifen in MCF-7 breast cancer cells. The individual and combined cytotoxic effects of empagliflozin and tamoxifen were assessed using the xCELLigence system. The activities of AMP-activated protein kinase α (AMPKα), p38 mitogen-activated protein kinase (p38 MAPKα), p70-S6 kinase 1 (p70S6K1), and protein kinase B (Akt) were assessed using Western blotting. The gene expression levels of peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α) and Forkhead box O3a (FOXO3a) were assessed via qPCR. Our results revealed time- and concentration-dependent cytotoxic effects of empagliflozin and tamoxifen whether administered separately or in combination. While tamoxifen exhibits potency with an IC50 value of 17 μM, approximately ten times greater than that of empagliflozin (IC50 = 177 μM), synergistic effects are observed when the concentrations of the two agents approach their respective IC50 values. Additionally, empagliflozin significantly increases AMPKα activity while concurrently inhibiting Akt, p70S6K1, and p38 MAPKα, and these effects are significantly enhanced when empagliflozin is combined with tamoxifen. Moreover, empagliflozin modulates the gene expression, downregulating PGC-1α while upregulating FOXO3a. Empagliflozin exerts anti-proliferative and anti-survival effects by inhibiting mTOR, Akt, and PGC-1α, and it exhibits synergy with tamoxifen in MCF-7 breast cancer cells.

Exploring the Potential of Cyclic Peptidyl Antitumor Agents Derived from Natural Macrocyclic Peptide Phakellistatin 13.

The exploration of novel anticancer compounds based on natural cyclopeptides has emerged as a pivotal paradigm in the contemporary advancement of macrocyclic pharmaceuticals. Phakellistatin 13 is a cycloheptapeptide derived from the brown snubby sponge and exhibits remarkable antitumor activity. In this study, we have designed and synthesized a series of chiral cyclopeptides incorporating the rigid isoindolinone moiety at various sites within the natural cycloheptapeptide Phakellistatin 13, with the aim of investigating conformationally constrained cyclopeptides as potential antitumor agents. Cyclopeptide 3, comprising alternating l-/d-amino acid residues, exhibited promising antihepatocellular carcinoma effects. Detailed biological experiments have revealed that Phakellistatin 13 analogs effectively inhibit the proliferation of tumor cells and induce apoptosis and autophagy, while also causing cell cycle arrest through the modulation of the p53 and mitogen-activated protein kinase (MAPK) signaling pathway. This study not only provides valuable insights into chemical structural modifications but also contributes to a deeper understanding of the biological mechanisms underlying the development of natural cyclopeptide-based drugs.

Neuroprotective Effects of Metformin on Cerebral Ischemia-Reperfusion Injury: Modulation of JNK and p38 MAP Kinase Signaling Pathways.

Cerebral ischemia-reperfusion injury (CIRI) is a significant pathological process in stroke, characterized by neuronal cell death and neurological dysfunction. Metformin, commonly used for diabetes management, has been noted for its neuroprotective properties, though its effects on CIRI and the mechanisms involved remain unclear. This study explored the neuroprotective impact of metformin on CIRI, focusing on its potential to modulate the c-Jun N-terminal kinase (JNK) and p38 MAP kinase (p38) signaling pathways. Using in vitro models of oxygen-glucose deprivation/reperfusion (OGD/R) in neuronal cells and in vivo mouse models of middle cerebral artery occlusion (MCAO), the effects of metformin were assessed. Cell viability was measured with Cell Counting Kit-8 (CCK-8), protein expression via Western Blot (WB), and apoptosis through flow cytometry. The extent of brain injury in mice was evaluated using 2,3,5-triphenyltetrazolium chloride (TTC) staining, while JNK and p38 activation statuses were detected through WB and phospho-JNK (p-JNK) immunofluorescence staining. Results showed that metformin significantly improved the viability of HT22 cells post-OGD/R, reduced apoptosis, and decreased OGD/R-induced phosphorylation of JNK and p38 in vitro. In vivo, metformin treatment notably reduced brain infarct volume in MCAO mice, inhibited p-p38 and p-JNK expression, and enhanced neurological function. These findings suggest that metformin exerts neuroprotective effects against CIRI by modulating the JNK/p38 signaling pathway, highlighting its potential therapeutic value in treating cerebral ischemia-reperfusion injury and paving the way for clinical applications.

Guava polysaccharides attenuate high fat and STZ-induced hyperglycemia by regulating gut microbiota and arachidonic acid metabolism

This study investigated the hypoglycemic mechanism of guava polysaccharides (GP) through the gut microbiota (GM) and related metabolites. Our findings demonstrated that GP significantly mitigated high-fat diet- and streptozotocin-induced hyperglycemia, insulin resistance, hyperlipidemia, elevated alanine aminotransferase, high hepatic inflammation levels, and prevented pancreatic atrophy and hepatomegaly. Interestingly, the benefits of GP were attributed to alterations in the GM. GP decreased the ratio of Firmicutes to Bacteroidetes, significantly inhibiting deleterious bacteria, including Uncultured_f_Desulfovibrionaceae, Bilophila, and Desulfovibrio, while promoting the proliferation of probiotic Bifidobacterium and Bacteroides. In addition, GP promoted the generation of short-chain fatty acids. Notably, the arachidonic acid (AA) metabolism pathway was enriched in liver metabolites. GP significantly elevated hepatic AA and 15-hydroxyeicosatetraenoic acid, while reducing prostaglandin E2 and 5- and 12-hydroxyeicosatetraenoic acid. This modulation is accompanied by the downregulation of hepatic cyclooxygenase-1, 12-lipoxygenase, P38, and c-Jun N-terminal kinase mRNA expression, and the upregulation of cytochrome P4502J5 and insulin receptor substrate 1/2 mRNA expression. However, GP antibiotic treatment did not induce significant alterations in FBG and AA levels or gene expression. Overall, our findings suggest that the hypoglycemic effect of GP may be intricately linked to alterations in AA metabolism, which depends on the GM.