Extracellular Signal-regulated Kinase Mitogen-activated Protein Research Articles

CircUSP13 facilitates the fast-to-slow myofiber shift via the MAPK/ERK signaling pathway in goat skeletal muscles.

Understanding how skeletal muscle fiber proportions are regulated is essential for understanding muscle function and improving the quality of mutton. While circular RNA (circRNA) has a critical function in myofiber type transformation, the specific mechanisms are not yet fully understood. Prior evidence indicates that circular ubiquitin-specific peptidase 13 (circUSP13) can promote myoblast differentiation by acting as a ceRNA, but its potential role in myofiber switching is still unknown. Herein, we found that circUSP13 enhanced slow myosin heavy chain (MyHC-slow) and suppressed MyHC-fast expression in goat primary myoblasts (GPMs). Meanwhile, circUSP13 evidently enhanced the remodeling of the mitochondrial network while inhibiting the autophagy of GPMs. We obtained fast-dominated myofibers, via treatment with rotenone, and further demonstrated the positive role of circUSP13 in the fast-to-slow transition. Mechanistically, activation of the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway significantly impaired the slow-to-fast shift in fully differentiated myotubes, which was restored by circUSP13 or IGF1 overexpression. In conclusion, circUSP13 promoted the fast-to-slow myofiber type transition through MAPK/ERK signaling in goat skeletal muscle. These findings provide novel insights into the role of circUSP13 in myofiber type transition and contribute to a better understanding of the genetic mechanisms underlying meat quality.

Chlorovirus Glycoproteins and SOD1G93A Significantly Enhance, While Cellular Proteins IRF3 and ERK MAP-kinase Significantly Dampen, Production of ALS-associated Inflammatory Factors from Murine Macrophages (P6-11.017)

Chlorovirus Glycoproteins and SOD1G93A Significantly Enhance, While Cellular Proteins IRF3 and ERK MAP-kinase Significantly Dampen, Production of ALS-associated Inflammatory Factors from Murine Macrophages (P6-11.017)

AESIS-1, a Rheumatoid Arthritis Therapeutic Peptide, Accelerates Wound Healing by Promoting Fibroblast Migration in a CXCR2-Dependent Manner.

In patients with autoimmune disorders such as rheumatoid arthritis (RA), delayed wound healing is often observed. Timely and effective wound healing is a crucial determinant of a patient's quality of life, and novel materials for skin wound repair, such as bioactive peptides, are continuously being studied and developed. One such bioactive peptide, AESIS-1, has been studied for its well-established anti-rheumatoid arthritis properties. In this study, we attempted to use the anti-RA material AESIS-1 as a therapeutic wound-healing agent based on disease-modifying antirheumatic drugs (DMARDs), which can help restore prompt wound healing. The efficacy of AESIS-1 in wound healing was assessed using a full-thickness excision model in diabetic mice; this is a well-established model for studying chronic wound repair. Initial observations revealed that mice treated with AESIS-1 exhibited significantly advanced wound repair compared with the control group. In vitro studies revealed that AESIS-1 increased the migration activity of human dermal fibroblasts (HDFs) without affecting proliferative activity. Moreover, increased HDF cell migration is mediated by upregulating chemokine receptor expression, such as that of CXC chemokine receptor 2 (CXCR2). The upregulation of CXCR2 through AESIS-1 treatment enhanced the chemotactic reactivity to CXCR2 ligands, including CXC motif ligand 8 (CXCL8). AESIS-1 directly activates the ERK and p38 mitogen-activated protein kinase (MAPK) signaling cascades, which regulate the migration and expression of CXCR2 in fibroblasts. Our results suggest that the AESIS-1 peptide is a strong wound-healing substance that increases the movement of fibroblasts and the expression of CXCR2 by turning on the ERK and p38 MAPK signaling cascades.

Macleaya cordata Extract Inhibits LPS-Induced IPEC-J2 Inflammation Through TLR4-Mediated NF-κB and MAPK Signaling Pathways

Objectives: The Macleaya cordata has long been utilized as a traditional medicinal remedy for treating inflammation in certain countries, and it is also being considered as a potential alternative to antibiotic growth promoters in livestock breeding. However, the molecular mechanisms underlying its anti-inflammatory characteristics have not been thoroughly investigated. In this study, we assessed the anti-inflammatory effects of the Macleaya cordata extract (MCE) and elucidated the molecular mechanism in the porcine intestinal epithelial cell line J2 (IPEC-J2) stimulated by lipopolysaccharide (LPS). Methods: The IPEC-J2 cells were pretreated with various concentrations of MCE (50 ng/mL, 100 ng/mL, and 150 ng/mL) prior to stimulation with LPS to induce of inflammation. Subsequently, the secretion levels and mRNA expression of the inflammatory cytokines IL-6, TNF-α, IFN-γ, and IL-10 were assessed. The impact of MCE on the activation of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways was investigated. Results: The results demonstrated that MCE significantly suppressed the production and mRNA expression levels of pro-inflammatory cytokines in LPS-induced IPEC-J2 cells, while promoting the expression of anti-inflammatory cytokines. Moreover, it down-regulated the phosphorylation of NF-κB (p65) and attenuated the expression of phosphorylated JNK, ERK, and p38 MAPKs in a concentration-dependent manner. Furthermore, MCE downregulated the expression of TLR4 and MyD88, which serve as crucial upstream signaling molecules. The findings of this study suggest that the anti-inflammatory effect of MCE is attributed to its ability to regulate inflammatory cytokines and mediators by inhibiting the TLR4-mediated NF-κB and MAPK signaling pathways. Conclusions: Therefore, MCE holds promise as a potential therapeutic and preventive agent for managing inflammatory reactions and diseases in livestock and poultry breeding, warranting further investigation.

Abstract 620: Screening of small-molecule MAPK pathway inhibitors on a panel of 130 human cancer cell lines identifies determinants of response in RAS-mutant subgroups

Abstract Oncogenic mutations in members of the RAS family, HRAS, NRAS, and KRAS, are frequently identified in various cancers and often lead to increased signaling of the mitogen-activated protein kinase (MAPK) pathway. KRAS is the most frequently mutated RAS isoform, with a mutation incidence of >10% across all cancers, and up to 70% and 20% in pancreatic and non-small cell lung cancer (NSCLC), respectively. RAS has long been considered to be undruggable, and direct inhibition of RAS with small molecule inhibitors has only recently been achieved, with the approval of the KRAS G12C-mutant selective inhibitors sotorasib and adagrasib for treatment of NSCLC. Indirect targeting of RAS-mutated cancers by inhibitors of downstream components such as MEK and ERK has shown variable responses. Novel insights into MAPK signaling have renewed interest into targeting the MAPK pathway in RAS-mutant cancer, with pan-RAF dimer inhibitors and dual RAF/MEK inhibitors reaching clinical trials. To improve the chances of success, it is important to determine which patient populations are most likely to respond to these inhibitors. To gain more insight into the cellular targeting of MAPK pathway inhibitors, eighteen inhibitors of the MAPK components KRAS, RAF, MEK, and ERK were profiled on a panel of 130 cell lines in cell viability assays (the Oncolines® panel). The cell lines represented a diverse range of tumor tissues and had different genomic backgrounds. Many of the cell lines had mutations in KRAS, NRAS, or BRAF. Drug responses were determined by exposing the cell lines to nine-point duplicate dose ranges of the inhibitors. Using bioinformatics, cell line responses to the inhibitors were related to genomic and transcriptomic features, to identify determinants of drug response in both tissue-agnostic and tissue-specific contexts. The results of our analyses revealed variable responses of KRAS-mutant cell lines to the inhibitors, reflecting clinical responses. Tissue-focused analyses showed that the different responses could be traced back to the different KRAS amino acid substitutions. For instance, in pancreatic cancer cell lines, the KRAS Q61H mutation predicted increased sensitivity to MAPK pathway inhibitors compared to other KRAS amino acid substitutions. Additionally, in tissue groups with a more heterogenous mutation profile, co-mutations explained the decreased effectivity of MAPK pathway inhibitors in KRAS-mutant cell lines, such as PIK3CA mutations in colorectal cancer cell lines. Lastly, a gene expression-based signature of MAPK activity predicted response to MAPK pathway inhibitors, independent of mutation status. Our findings have uncovered determinants of response to MAPK pathway inhibitors in RAS-mutant cell lines. These determinants can serve as markers to select patients who are most likely to benefit from MAPK inhibitors. Citation Format: Jeffrey J. Kooijman, Awan Al Koerdi, Daphne J. Kluitmans, Esmee van den Bossche, Jelle Dylus, Jeroen A. de Roos, Janneke J. Melis, Guido J. Zaman. Screening of small-molecule MAPK pathway inhibitors on a panel of 130 human cancer cell lines identifies determinants of response in RAS-mutant subgroups [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 620.

Abstract 3081: Targeting lipid kinases to enhance autophagy inhibition for the treatment of pancreatic cancer

Abstract Pancreatic ductal adenocarcinoma (PDAC) is characterized as the most KRAS-addicted cancer type, with KRAS mutations found in >95% of cases. Mutant KRAS relies on dysregulated metabolism to support growth. One dysregulated pathway upregulated in PDAC is autophagy, a lysosome-mediated process that degrades proteins and organelles to supply macromolecules for growth. Our lab and others have shown that inhibition of KRAS or the mitogen activated protein kinase (MAPK) components, MEK or ERK, further increases PDAC dependency on autophagy as a resistance mechanism. Cotreatment with ERK MAPK inhibitors and the autophagy inhibitor chloroquine (CQ) decreased autophagic flux, inhibited proliferation, and induced apoptosis in PDAC cells. CQ is the only FDA-approved autophagy inhibitor, and it demonstrates low potency in vivo, motivating our studies to identify strategies to improve autophagy inhibition in PDAC. We utilized a CRISPR-Cas9 loss-of-function screen to identify sensitizers to CQ in PDAC and identified 25 autophagy-related targets. We hypothesize that targeting the autophagy pathway at multiple nodes will increase the efficacy of CQ treatment in PDAC. To validate hits identified in the CRISPR-Cas9 screen, I designed an siRNA array that contained three distinct oligos for each target. I quantified changes in proliferation in a panel of four PDAC cell lines after siRNA-mediated suppression of the target genes following 3- or 6-day time points. I hypothesized that targets identified to be non-essential on their own would allow for potential synthetic lethality with CQ. To test this, I performed a 3-day knockdown followed by 3-day exposure to a dose response of CQ. I found that suppression of lipid kinases PIP4K2A, PIP4K2C, or PIK3C3 shift the dose response to CQ in a panel of PDAC lines. This indicates that loss of those targets sensitizes PDAC cells to CQ treatment. Furthermore, we found that pharmacological inhibition of VPS34, the lipid kinase encoded by PIK3C3 by the ATP-competitive inhibitor SAR-405 synergizes with CQ. My future studies will be focused on validating other targets identified in the loss-of-function CRISPR-Cas9 screen. I will measure changes in autophagic flux and apoptosis due to the loss of validated targets. The long-term goal of this project is to enhance the translatability of autophagy inhibition for patient care through identifying combinational approaches to improve CQ response in PDAC. Citation Format: Elyse G. Schechter, Jonathan M. DeLiberty, Clint A. Stalnecker, Kirsten L. Bryant. Targeting lipid kinases to enhance autophagy inhibition for the treatment of pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3081.

Abstract 6979: Uncovering the BRAF interactome to identify novel therapeutic targets for BRAF driven melanoma and lung cancer

Abstract BRAF protein kinases act downstream of RAS-GTP and upstream of MEK>ERK MAP Kinase signaling. Notably, mutational activation of BRAF is a driver of approximately 8% of all cancers, with a particular prevalence in lung cancer, thyroid cancer, and melanoma. Importantly, melanoma is responsible for the largest number of skin cancer deaths per year. Patients whose melanoma is driven by mutationally-activated BRAF account for ~50% of cutaneous melanoma cases. The most common mutational alteration is BRAFT1799A, which encodes the BRAFV600E oncoprotein kinase. Combined inhibition of BRAFV600E plus MEK1/2 has been approved for the treatment of BRAFV600E-driven melanoma and lung cancer. Although patients with mutationally-activated BRAF often have a significant response to BRAFV600E-targeted therapeutics, many patients develop lethal drug-resistant disease. The BRAFV600E oncoprotein kinase is proposed to be a monomer, yet many questions remain regarding the biochemistry of these signaling interactions. Thus, we aim to better understand the molecular mechanisms driving BRAFV600E-mediated melanoma and lung cancer cell growth. Preliminary data using gel filtration chromatography and immunoblotting analysis indicates that BRAFV600E is detected in a large multiprotein complex. Interestingly, the addition of a BRAFV600E inhibitor, vemurafenib, shifted the elution of complexes with BRAFV600E into lower molecular weight fractions. Based on these preliminary results, we characterized the components of these complexes to advance our understanding of how mutationally activated BRAF exists in melanoma cells; and thus, provide future insight into how we can better therapeutically target BRAFV600E. Moreover, in order to further elucidate BRAF interactions, we employed a novel form of proximity labeling, TurboID, to unbiasedly identify novel BRAF interactors and better understand how drug treatments change the BRAF interactome. The top ten statistically significant interactors are being investigated to understand how BRAF complexes are formed within the cell, how the complexes are influenced by drug treatments, and how important the individual components are in the formation of complexes with BRAF. Here, we investigate an interaction between BRAFV600E and the tumor suppressor, TP53. Moreover, elucidating the molecular architecture of BRAFV600E signaling complexes could highlight new therapeutic options for patients who display either primary or acquired resistance to inhibitors of BRAFV600E signaling. Citation Format: Kayla T. OToole. Uncovering the BRAF interactome to identify novel therapeutic targets for BRAF driven melanoma and lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6979.

Methanol extract of Ligusticum chuanxiong Hort. Rhizome ameliorates bilateral common carotid artery stenosis-induced cognitive deficit in mice by altering microglia and astrocyte activation.

In traditional Asian medicine, Ligusticum chuanxiong Hort also known as Conioselinum anthriscoides "Chuanxiong", is mainly used for improving blood circulation or for analgesic and anti-inflammatory purposes, but they also have a long history of use for pain disorders in the head and face, such as headache. Despite the possibility that the plant is effective for diseases such as cerebral infarction and vascular dementia (VaD), the mechanism of action is not well understood. To determine if the dried rhizomes of L. chuanxiong (Chuanxiong Rhizoma, CR) methanol extract (CRex) has activity in a VaD mice model. Through network analysis, we confirm that CR is effective in cerebrovascular diseases. In mice, we induce cognitive impairment, similar to VaD in humans, by chronically reducing the cerebral blood flow by performing bilateral common carotid artery stenosis (BCAS) and administering CRex for 6weeks. We measure behavioral changes due to cognitive function impairment and use immunofluorescence staining to confirm if CRex can inhibit the activation of astrocytes and microglia involved in the inflammatory response in the brain. We quantify proteins involved in the mechanism, such as mitogen-activated protein kinases (MAPK), in the hippocampus and surrounding white matter, and analyze gene expression and protein interaction networks through RNA sequencing to interpret the results of the study. CRex administration rescued cognitive impairment relating to a novel object and inhibited the activation of astrocytes and microglia. Western blotting analysis revealed that CRex regulated the changes in protein expression involved in MAPK signaling such as extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (p38). The administration of CRex suppressed approximately 44% of the pathological changes in gene expression caused by BCAS. CRex extract effectively inhibited cognitive impairment caused by BCAS, and the mechanism through which this occurred is inhibited activation of astrocytes and microglia.

ACA-28, an ERK MAPK Signaling Modulator, Exerts Anticancer Activity through ROS Induction in Melanoma and Pancreatic Cancer Cells.

The extracellular signal-regulated kinase (ERK) MAPK pathway is dysregulated in various human cancers and is considered an attractive therapeutic target for cancer. Therefore, several inhibitors of this pathway are being developed, and some are already used in the clinic. We have previously identified an anticancer compound, ACA-28, with a unique property to preferentially induce ERK-dependent apoptosis in melanoma cells. To comprehensively understand the biological cellular impact induced by ACA-28, we performed a global gene expression analysis of human melanoma SK-MEL-28 cells exposed to ACA-28 using a DNA microarray. The transcriptome analysis identified nuclear factor erythroid 2-related factor 2 (Nrf2), a master transcription factor that combats oxidative stress, as the most upregulated genetic pathway after ACA-28 treatment. Consistently, ACA-28 showed properties to increase the levels of reactive oxygen species (ROS) as well as Nrf2 protein, which is normally repressed by proteasomal degradation and activated in response to oxidative stresses. Furthermore, the ROS scavenger N-acetyl cysteine significantly attenuated the anticancer activity of ACA-28. Thus, ACA-28 activates Nrf2 signaling and exerts anticancer activity partly via its ROS-stimulating property. Interestingly, human A549 cancer cells with constitutively high levels of Nrf2 protein showed resistance to ACA-28, as compared with SK-MEL-28. Transient overexpression of Nrf2 also increased the resistance of cells to ACA-28, while knockdown of Nrf2 exerted the opposite effect. Thus, upregulation of Nrf2 signaling protects cancer cells from ACA-28-mediated cell death. Notably, the Nrf2 inhibitor ML385 substantially enhanced the cell death-inducing property of ACA-28 in pancreatic cancer cells, T3M4 and PANC-1. Our data suggest that Nrf2 plays a key role in determining cancer cell susceptibility to ACA-28 and provides a novel strategy for cancer therapy to combine the Nrf2 inhibitor and ACA-28.

The size-dependence and reversibility of polystyrene nanoplastics-induced lipid accumulation in mice: Possible roles of lysosomes

Nanoplastics (NPs) continue to accumulate in global aquatic and terrestrial systems, posing a potential threat to human health through the food chain and/or other pathways. Both in vivo and in vitro studies have confirmed that the liver is one of the main organs targeted for the accumulation of NPs in living organisms. However, whether exposure to NPs induces size-dependent disorders of liver lipid metabolism remains controversial, and the reversibility of NPs-induced hepatotoxicity is largely unknown. In this study, the effects of long-term exposure to environmentally relevant doses of polystyrene nanoplastics (PS-NPs) on lipid accumulation were investigated in terms of autophagy and lysosomal mechanisms. The findings indicated that hepatic lipid accumulation was more pronounced in mice exposed to 100 nm PS-NPs compared to 500 nm PS-NPs. This effect was effectively alleviated after 50 days of self-recovery for 100 nm and 500 nm PS-NPs exposure. Mechanistically, although PS-NPs exposure activated autophagosome formation through ERK (mitogen-activated protein kinase 1)/mTOR (mechanistic target of rapamycin kinase) signaling pathway, the inhibition of Rab7 (RAB7, member RAS oncogene family), CTSB (cathepsin B), and CTSD (cathepsin D) expression impaired lysosomal function, thereby blocking autophagic flux and contributing to hepatic lipid accumulation. After termination of PS-NPs exposure, lysosomal exocytosis was responsible for the clearance of PS-NPs accumulated in lysosomes. Furthermore, impaired lysosomal function and autophagic flux inhibition were effectively alleviated. This might be the main reason for the alleviation of PS-NPs-induced lipid accumulation after recovery. Collectively, we demonstrate for the first time that lysosomes play a dual role in the persistence and reversibility of hepatotoxicity induced by environmental relevant doses of NPs, which provide novel evidence for the prevention and intervention of liver injury associated with nanoplastics exposure.

LOGGIC/FIREFLY-2: a phase 3, randomized trial of tovorafenib vs. chemotherapy in pediatric and young adult patients with newly diagnosed low-grade glioma harboring an activating RAF alteration

BackgroundPediatric low-grade glioma (pLGG) is essentially a single pathway disease, with most tumors driven by genomic alterations affecting the mitogen-activated protein kinase/ERK (MAPK) pathway, predominantly KIAA1549::BRAF fusions and BRAF V600E mutations. This makes pLGG an ideal candidate for MAPK pathway-targeted treatments. The type I BRAF inhibitor, dabrafenib, in combination with the MEK inhibitor, trametinib, has been approved by the United States Food and Drug Administration for the systemic treatment of BRAF V600E-mutated pLGG. However, this combination is not approved for the treatment of patients with tumors harboring BRAF fusions as type I RAF inhibitors are ineffective in this setting and may paradoxically enhance tumor growth. The type II RAF inhibitor, tovorafenib (formerly DAY101, TAK-580, MLN2480), has shown promising activity and good tolerability in patients with BRAF-altered pLGG in the phase 2 FIREFLY-1 study, with an objective response rate (ORR) per Response Assessment in Neuro-Oncology high-grade glioma (RANO-HGG) criteria of 67%. Tumor response was independent of histologic subtype, BRAF alteration type (fusion vs. mutation), number of prior lines of therapy, and prior MAPK-pathway inhibitor use.MethodsLOGGIC/FIREFLY-2 is a two-arm, randomized, open-label, multicenter, global, phase 3 trial to evaluate the efficacy, safety, and tolerability of tovorafenib monotherapy vs. current standard of care (SoC) chemotherapy in patients < 25 years of age with pLGG harboring an activating RAF alteration who require first-line systemic therapy. Patients are randomized 1:1 to either tovorafenib, administered once weekly at 420 mg/m2 (not to exceed 600 mg), or investigator’s choice of prespecified SoC chemotherapy regimens. The primary objective is to compare ORR between the two treatment arms, as assessed by independent review per RANO-LGG criteria. Secondary objectives include comparisons of progression-free survival, duration of response, safety, neurologic function, and clinical benefit rate.DiscussionThe promising tovorafenib activity data, CNS-penetration properties, strong scientific rationale combined with the manageable tolerability and safety profile seen in patients with pLGG led to the SIOPe-BTG-LGG working group to nominate tovorafenib for comparison with SoC chemotherapy in this first-line phase 3 trial. The efficacy, safety, and functional response data generated from the trial may define a new SoC treatment for newly diagnosed pLGG.Trial registrationClinicalTrials.gov: NCT05566795. Registered on October 4, 2022.

Immunoglobulin heavy constant gamma 1 silencing decreases tonicity-responsive enhancer-binding protein expression to alleviate diabetic nephropathy.

The molecular mechanisms of diabetic nephropathy (DN) are poorly identified. However, the advantage of an increasing amount on microarray data of diabetic nephropathy intrigued us to explore the mechanisms based on bioinformatics prediction for diabetic nephropathy. Bioinformatics analysis was conducted to screen the hub genes associated with diabetic nephropathy. The average human renal tubular epithelial cells were exposed to high glucose (HG) to generate an in vitro cell model. In addition, a mouse model of diabetic nephropathy was established using a high-fat diet and streptozotocin injection. Finally, the shRNA targeting immunoglobulin heavy constant gamma 1 (IGHG1) was introduced in vitro and in vivo to illustrate its effect on downstream factors and on the development diabetic nephropathy. Bioinformatics analysis revealed that IGHG1, TRIM11 (tripartite motif protein 11), and TonEBP are highly expressed in diabetic nephropathy. In vitro cell experiments demonstrated that IGHG1 positively regulates the expression of TRIM11 and TonEBP (tonicity-responsive enhancer binding protein) in HK2 cells treated with high glucose. Furthermore, TRIM11 upregulates the expression of TonEBP through activation of the MEK/ERK (mitogen-activated protein kinase/extracellular signal-regulated kinase) signaling pathway in HK2 cells treated with high glucose. In vivo, animal experiments further confirmed that silencing IGHG1 could prevent the occurrence and development of diabetic nephropathy. The silencing of IGHG1 alleviated diabetic nephropathy by inhibiting the TRIM11/MEK/ERK axis and by downregulating TonEBP.

Systemic Hemodynamics, Cardiac Mechanics, and Signaling Pathways Induced by Extracorporeal Membrane Oxygenation in a Cardiogenic Shock Model.

Peripheral venoarterial extracorporeal membrane oxygenation (VA-ECMO) is increasingly being used in patients suffering from refractory cardiogenic shock (CS). Although considered life-saving, peripheral VA-ECMO may also be responsible for intracardiac hemodynamic changes, including left ventricular overload and dysfunction. Venoarterial extracorporeal membrane oxygenation may also increase myocardial wall stress and stroke work, possibly affecting the cellular cardioprotective and apoptosis signaling pathways, and thus the infarct size. To test this hypothesis, we investigated the effects of increasing the peripheral VA-ECMO blood flow (25-100% of the baseline cardiac output) on systemic and cardiac hemodynamics in a closed-chest CS model. Upon completion of the experiment, the hearts were removed for assessment of infarct size, histology, apoptosis measurements, and phosphorylation statuses of p38 and protein Kinase B (Akt), and extracellular signal-regulated kinase mitogen-activated protein kinases (ERK-MAPK). Peripheral VA-ECMO restored systemic perfusion but induced a significant and blood flow-dependent increase in left ventricular preload and afterload. Venoarterial extracorporeal membrane oxygenation did not affect infarct size but significantly decreased p38-MAPK phosphorylation and cardiac myocyte apoptosis in the border zone.

Peiminine Exerts Its Anti-Acne Effects by Regulating the NF-κB Pathway.

Peiminine is the main natural alkaloid compound extracted from the Chinese herb Fritillaria. Although peiminine is known for its antioxidant and anti-inflammatory effects in conditions such as mastitis and arthritis, its impact on inflammation induced by Cutibacterisum acnes (C. acnes) has not been explored. The aim of this study was to investigate the effect of peiminine on C. acnes-induced inflammatory responses in the skin and to identify the underlying mechanism involved. We discovered that peiminine inhibits the C. acnes-induced expression of inflammatory mediators such as pro-interleukin-1β (pro-IL-1β), cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in mouse bone marrow-derived macrophages (BMDMs). Peiminine suppressed the activation of nuclear factor-kappa B (NF-κB) without affecting the activation of mitogen-activated protein kinase (MAPK) pathways such as JNK, ERK, and p38 MAPK. In addition, we found that peiminine suppressed inflammatory cytokine expression and ameliorated histological symptoms in C. acnes-induced mouse skin. Our study is the first to provide evidence that peiminine has an inhibitory effect on acne, and it points toward the potential of incorporating peiminine into cosmetic and pharmaceutical formulations for acne treatment.

The guanine nucleotide exchange factor RapGEF2 is required for ERK-dependent immediate-early gene (Egr1) activation during fear memory formation.

The MAP kinase ERK is important for neuronal plasticity underlying associative learning, yet specific molecular pathways for neuronal ERK activation are undetermined. RapGEF2 is a neuron-specific cAMP sensor that mediates ERK activation. We investigated whether it is required for cAMP-dependent ERK activation leading to other downstream neuronal signaling events occurring during associative learning, and if RapGEF2-dependent signaling impairments affect learned behavior. Camk2α-cre+/-::RapGEF2fl/fl mice with depletion of RapGEF2 in hippocampus and amygdala exhibit impairments in context- and cue-dependent fear conditioning linked to corresponding impairment in Egr1 induction in these two brain regions. Camk2α-cre+/-::RapGEF2fl/fl mice show decreased RapGEF2 expression in CA1 and dentate gyrus associated with abolition of pERK and Egr1, but not of c-Fos induction, following fear conditioning, impaired freezing to context after fear conditioning, and impaired cAMP-dependent long-term potentiation at perforant pathway and Schaffer collateral synapses in hippocampal slices ex vivo. RapGEF2 expression is largely eliminated in basolateral amygdala, also involved in fear memory, in Camk2α-cre+/-::RapGEF2fl/fl mice. Neither Egr1 nor c-fos induction in BLA after fear conditioning, nor cue-dependent fear learning, are affected by ablation of RapGEF2 in BLA. However, Egr1 induction (but not that of c-fos) in BLA is reduced after restraint stress-augmented fear conditioning, as is freezing to cue after restraint stress-augmented fear conditioning, in Camk2α-cre+/-::RapGEF2fl/fl mice. Cyclic AMP-dependent GEFs have been genetically associated as risk factors for schizophrenia, a disorder associated with cognitive deficits. Here we show a functional link between one of them, RapGEF2, and cognitive processes involved in associative learning in amygdala and hippocampus.

The Inhibition of Mitogen-Activated Protein Kinases (MAPKs) and NF-κB Underlies the Neuroprotective Capacity of a Cinnamon/Curcumin/Turmeric Spice Blend in Aβ-Exposed THP-1 Cells.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by an increased level of β-amyloid (Aβ) protein deposition in the brain, yet the exact etiology remains elusive. Nowadays, treatments only target symptoms, thus the search for novel strategies is constantly stimulated, and looking to natural substances from the plant kingdom. The aim of this study was to investigate the neuroprotective effects of a spice blend composed of cinnamon bark and two different turmeric root extracts (CCSB) in Aβ-exposed THP-1 cells as a model of neuroinflammation. In abiotic assays, CCSB demonstrated an antioxidant capacity up to three times stronger than Trolox in the ORAC assay, and it reduced reactive oxygen species (ROS) induced by the amyloid fragment in THP-1 cells by up to 39.7%. Moreover, CCSB lowered the Aβ stimulated secretion of the pro-inflammatory cytokines IL-1β and IL-6 by up to 24.9% and 43.4%, respectively, along with their gene expression by up to 25.2% and 43.1%, respectively. The mechanism involved the mitogen-activated protein kinases ERK, JNK and p38, whose phosphorylation was reduced by up to 51.5%, 73.7%, and 58.2%, respectively. In addition, phosphorylation of p65, one of the five components forming NF-κB, was reduced by up to 86.1%. Our results suggest that CCSB can counteract the neuroinflammatory stimulus induced by Aβ-exposure in THP-1 cells, and therefore can be considered a potential candidate for AD management.

Inhibition of Toll-like Receptor 4 (TLR4) Promotes Erythroid and Myeloid Differentiation in Myelodysplastic Syndrome (MDS) and Acute Myeloid Leukemia (AML)

Introduction: The hallmark of Myelodysplastic Syndrome (MDS) is a block in differentiation of hematopoietic precursors resulting in single or multilineage cytopenias. Evaluation of regulatory pathways that are inappropriately overactive and lead to a blockade in erythroid and myeloid differentiation is an important process in determining future therapeutic targets for the treatment of MDS. The Toll-like receptor (TLR) pathways play an important role in the innate immune response and are also highly expressed on hematopoietic stem cells. Aberrant overactivation of these pathways can stimulate inflammation and cytokine production in the marrow microenvironment. Also, while the overactivation of interleukin-1 receptor-associated kinase 4 (IRAK4), tumor necrosis factor receptor associated factor 6 (TRAF6) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathways has been seen in Myelodysplastic Syndrome and Acute Myeloid Leukemia (AML), the upstream signals that drive their activation are not fully identified. Results: We investigated the expression of all TLRs in a large database of MDS CD34+ marrow samples and age-matched controls. Our findings revealed that TLR6 and TLR4 were the most significantly overexpressed receptors in MDS samples (FDR&amp;lt;0.001). Furthermore, we observed that the TLR4 cofactor lymphocyte antigen 96 (LY96), also known as myeloid differentiation factor 2 (MD-2), was also overexpressed in MDS samples when compared to controls. Furthermore, the S100A8 and S100A9 proteins are ligands for TLR4 and were found to be positively associated with severity of anemia in the cohort of MDS samples. These data provided the rationale for determining the functional role of the TLR4 pathway in MDS/AML models. To obtain a potent and specific antibody against TLR4, we inoculated rabbits with recombinant human TLR4 and obtained high affinity antibodies that neutralized TLR4 function at low nano-molar range of doses. The TLR4 polyclonal antibody was able to inhibit lipopolysaccharide (LPS)-induced NF-κb activation in leukemic THP-1 cells. The TLR4 antibody also led to a decrease in proliferative phosphorylated extracellular signal-regulated kinase (ERK) mitogen-activated protein (MAP) kinase in leukemic cells. We then treated samples from MDS/AML patients (n=14) with the TLR4 antibody (1 nM dosing) and assessed for erythroid and myeloid growth and differentiation. Fluorescence activated cell sorting (FACS) analysis for erythroid differentiation showed increased expression of either CD71, CD235a or both after treatment with the TLR4 antibody. FACS analysis for myeloid differentiation showed increased expression of either CD11b, CD14 or both after treatment with the TLR4 antibody. This effect was more pronounced in the intermediate/high risk group than in the low-risk group of patients. Conclusion: Inhibition of the TLR4 pathway with a potent TLR4 antibody promotes erythroid and myeloid maturation and relieves the differentiation block on these lineages in MDS patient samples in the in vitro setting. Our preclinical data supports further evaluation of TLR4 inhibition as a therapeutic target in patients with MDS, as anemia and neutropenia are hallmarks of the disease.

Brain-derived neurotrophic factor (BDNF) downregulates mRNA levels of suppressor of cancer cell invasion (SCAI) variants in cortical neurons.

Suppressor of cancer cell invasion (SCAI) acts as a transcriptional repressor of serum response factor (SRF)-mediated gene expression by binding to megakaryoblastic leukemia (MKL)/myocardin-related transcription factor (MRTF), which is an SRF transcriptional coactivator. Growing evidence suggests that SCAI is a negative regulator of neuronal morphology, whereas MKL2/MRTFB is a positive regulator. The mRNA expression of SCAI is downregulated during brain development, suggesting that a reduction in SCAI contributes to the reduced suppression of SRF-mediated gene induction, thus increasing dendritic complexity and developing neuronal circuits. In the present study, we hypothesized that brain-derived neurotrophic factor (BDNF), which is important for neuronal plasticity and development, might alter SCAI mRNA levels. We therefore investigated the effects of BDNF on SCAI mRNA levels in primary cultured cortical neurons. Furthermore, because alternative splicing generates several SCAI variants in the brain, we measured SCAI variant mRNA after BDNF stimulation. Both SCAI variant 1 and total SCAI mRNA expression levels were downregulated by BDNF. Moreover, the extracellular signal-regulated protein kinase/mitogen-activated protein kinase (ERK/MAPK) pathway was involved in the BDNF-mediated decrease in SCAI mRNA expression. Our findings provide insights into the molecular mechanism underlying a neurotrophic factor switch for the repressive transcriptional complex that includes SCAI.

Metformin Suppresses Stemness of Non-Small-Cell Lung Cancer Induced by Paclitaxel through FOXO3a

Cancer stem cells (CSCs) play a pivotal role in drug resistance and metastasis. Among the key players, Forkhead box O3a (FOXO3a) acts as a tumor suppressor. This study aimed to unravel the role of FOXO3a in mediating the inhibitory effect of metformin on cancer stemness derived from paclitaxel (PTX)-resistant non-small-cell lung cancer (NSCLC) cells. We showed that CSC-like features were acquired by the chronic induction of resistance to PTX, concurrently with inactivation of FOXO3a. In line with this, knockdown of FOXO3a in PTX-sensitive cells led to changes toward stemness, while overexpression of FOXO3a in PTX-resistant cells mitigated stemness in vitro and remarkably curbed the tumorigenesis of NSCLC/PTX cells in vivo. Furthermore, metformin suppressed the self-renewal ability of PTX-resistant cells, reduced the expression of stemness-related markers (c-MYC, Oct4, Nanog and Notch), and upregulated FOXO3a, events concomitant with the activation of AMP-activated protein kinase (AMPK). All these changes were recapitulated by silencing FOXO3a in PTX-sensitive cells. Intriguingly, the introduction of the AMPK dominant negative mutant offset the inhibitory effect of metformin on the stemness of PTX-resistant cells. In addition, FOXO3a levels were elevated by the treatment of PTX-resistant cells with MK2206 (an Akt inhibitor) and U0126 (a MEK inhibitor). Collectively, our findings indicate that metformin exerts its effect on FOXO3a through the activation of AMPK and the inhibition of protein kinase B (Akt) and MAPK/extracellular signal-regulated kinase (MEK), culminating in the suppression of stemness in paclitaxel-resistant NSCLC cells.

Linear motif specificity in signaling through p38α and ERK2 mitogen-activated protein kinases.

Mitogen-activated protein kinase (MAPK) cascades are essential for eukaryotic cells to integrate and respond to diverse stimuli. Maintaining specificity in signaling through MAPK networks is key to coupling distinct inputs to appropriate cellular responses. Docking sites-short linear motifs found in MAPK substrates, regulators, and scaffolds-can promote signaling specificity through selective interactions, but how they do so remains unresolved. Here, we screened a proteomic library for sequences interacting with the MAPKs extracellular signal-regulated kinase 2 (ERK2) and p38α, identifying selective and promiscuous docking motifs. Sequences specific for p38α had high net charge and lysine content, and selective binding depended on a pair of acidic residues unique to the p38α docking interface. Finally, we validated a set of full-length proteins harboring docking sites selected in our screens to be authentic MAPK interactors and substrates. This study identifies features that help define MAPK signaling networks and explains how specific docking motifs promote signaling integrity.