Extracellular Signal-regulated Kinase Signaling Pathway Research Articles

Exosomes derived from stem cells from apical papilla promote angiogenesis via miR-126 under hypoxia.

To explore the effect of exosomal miR-126 derived from stem cells from the apical papilla (SCAPs) under hypoxia on human umbilical vein endothelial cell (HUVEC) angiogenesis. miR-126 mimics plasmids were used to upregulate miR-126 in SCAPs. Internalization of PKH26-labeled exosomes was examined by fluorescent microscopy. CCK-8 assay, Transwell assay, scratch assay, tube formation assay, and Matrigel plug assay were performed to detect the effects of exosomes on the angiogenic ability of HUVECs. The luciferase reporter assay and rescue assay were performed to examine the relationship between miR-126 and sprouty-related, EVH1 domain-containing protein 1 (SPRED1). The involvement of SPRED1 and the extracellular signal-regulated kinase (ERK) signaling pathway was evaluated by western blotting. miR-126 expression was upregulated in SCAPs and in SCAP-derived exosomes under hypoxia. miR-126 expression was increased in HUVECs when cocultured with SCAP-derived exosomes. Induced overexpression of miR-126 in hypoxic SCAPs and secreted exosomes resulted in enhanced angiogenesis both in vitro and in vivo. Western blot analysis revealed that miR-126-mediated SPRED1 downregulation induced activation of ERK signaling. Under hypoxic conditions, exosomes derived from SCAPs can promote HUVEC angiogenesis through expression of miR-126, which subsequently suppresses SPRED1 and activates the ERK signaling pathway.

Upregulated SPAG6 promotes acute myeloid leukemia progression through MYO1D that regulates the EGFR family expression

AbstractChromosomal aberrations and gene mutations have been considered to be the major reasons for high recurrence rates and poor survival among acute myeloid leukemia (AML) patients. However, the underlying molecular mechanism of AML gene mutation remains largely unclear. Here, we show that SPAG6 (sperm-associated antigen 6), one of the most markedly increased SPAG genes in AML, significantly contributed to the proliferation and migration of leukemic cells. SPAG6 was highly expressed in AML, and its upregulation was negatively correlated with the prognosis of the disease. In vitro, SPAG6 promoted the proliferation and migration of leukemia cells and promoted cell cycle progression from the G1 phase to the S phase. In vivo, low expression of SPAG6 reduced the proliferation and infiltration of leukemia cells and prolonged the survival of xenograft tumor mice. Furthermore, immunoprecipitation and mass spectrometry analysis showed that SPAG6 interacts with MYO1D (myosin 1D). Specifically, overexpression of SPAG6 promoted the translocation of MYO1D into the cell membrane, thus upgrading the expression level of the EGFR family and thereby promoting the progression of AML. Overall, our study found that SPAG6 combined with MYO1D and translocated MYO1D from the cytosol to the cytomembrane, which induced the PI3K (phosphoinositide 3-kinase)/AKT (protein kinase B) signaling and ERK (extracellular signal-regulated kinase) signaling pathway to regulate the growth and prognosis of AML. SPAG6 may become a new target gene for the treatment of AML.

Abrogation of ARF6 in promoting erastin-induced ferroptosis and mitigating capecitabine resistance in gastric cancer cells.

ADP ribosylation factor 6 (ARF6) is a member of the Rat sarcoma virus (RAS) superfamily that is involved in the regulation of vesicular trafficking, membrane lipid remodeling, and signaling pathways. Our earlier work discovered that ARF6, as a downstream effector of the Kirsten rat sarcoma viral oncogene (Kras)/extracellular signal-regulated kinases (ERK) signaling pathway, may increase proliferation and induce the Warburg effect in gastric cancer (GC) cells. Additionally, ARF6 appears to be a potential biomarker for predicting the prognosis of GC. Ferroptosis has recently been described as a type of nonapoptotic iron-dependent cell death that is strongly associated with the Kras mutation. Therefore, it is critical to continue investigating the link between ARF6 and ferroptosis. We first created ARF6 silenced cancer cell lines with lentivirus transfection. The knockdown efficiency was confirmed through quantitative polymerase chain reaction (qPCR) and western blotting. Subsequently, we used Cell Counting Kit-8 (CCK-8) and malondialdehyde (MDA) assay for lipid peroxidation measurement. Following this, qPCR and western blotting were conducted to clarify the mechanism involved. Finally, immunohistochemistry was used to stain human GC samples. Our findings established that, whereas ARF6 did not directly regulate lipid peroxidation, it did render GC cells susceptible to oxidative stress, particularly erastin-induced lipid peroxidation. Additionally, our research demonstrated that ARF6 may control capecitabine resistance via several routes. ARF6 may play a critical role in the development of GC.

TGFβ2 Regulates Human Trabecular Meshwork Cell Contractility via ERK and ROCK Pathways with Distinct Signaling Crosstalk Dependent on the Culture Substrate

Purpose Transforming growth factor-beta 2 (TGFβ2) is a major contributor to the pathologic changes occurring in human trabecular meshwork (HTM) cells in primary open-angle glaucoma (POAG). TGFβ2 activates extracellular-signal-regulated kinase (ERK) and Rho-associated kinase (ROCK) signaling pathways, both affecting HTM cell behavior. However, exactly how these signaling pathways converge to regulate HTM cell contractility is unclear. Here, we investigated the molecular mechanism underlying TGFβ2-induced pathologic HTM cell contractility, and the crosstalk between ERK and ROCK signaling pathways with different culture substrates. Methods Hydrogels were engineered by mixing collagen type I, elastin-like polypeptide, and hyaluronic acid, each containing photoactive functional groups, followed by UV crosslinking. Primary HTM cells were seeded atop pre-formed hydrogels for comparisons with glass, or encapsulated within the hydrogels. Changes in actin cytoskeleton, extracellular matrix (ECM) production, phospho-myosin light chain (p-MLC) levels, and hydrogel contraction were assessed. Results HTM cell morphology and filamentous (F)-actin organization were affected by the underlying culture substrates. TGFβ2 increased HTM cell contractility via ERK and ROCK signaling pathways by differentially regulating F-actin, α-smooth muscle actin (αSMA), fibronectin (FN), and p-MLC in HTM cells. ERK inhibition, even as short as 4 h, further increased TGFβ2-induced p-MLC in HTM cells on hydrogels, but not on glass. This translated into hypercontractility of HTM cell-laden hydrogels. ROCK inhibition had precisely the opposite effects and potently relaxed the TGFβ2-induced hydrogels. Conclusions Our data suggest that ERK signaling negatively regulates ROCK-mediated HTM cell contractility. These findings emphasize the critical importance of using tissue-mimetic ECM substrates for investigating HTM cell physiology and glaucomatous pathophysiology in vitro.

Progress on the role of mixed lineage kinase 3 in cardiovascular diseases

<p indent="0mm">Despite great changes in the spectrum of human diseases, cardiovascular diseases (CVDs) have been the leading cause of human death worldwide for more than <sc>20 years.</sc> According to a report from the World Health Organization, an estimated 17.9 million people die of CVDs every year, accounting for 32% of total deaths worldwide. Developing countries are those with the greatest loss of healthy life years. China is the largest developing country in the world, and deaths from CVDs in China have ranked first among total causes of death for urban and rural residents for many years. According to the latest <italic>Annual Report on Cardiovascular Health and Diseases in China (2021)</italic>, the number of patients with CVDs in China has reached 330 million, which has brought a heavy disease burden to the national economy and medical system. Therefore, further exploration of the potential pathogenesis and possible therapeutic targets of CVDs is of great significance for disease prevention and human health promotion. Mixed lineage kinase 3 (MLK3, also known as MAP3K11) is a member of the mitogen-activated protein kinase (MAPK) family. It is an important molecule in the cell life cycle and regulates many critical pathophysiological processes such as cell proliferation, differentiation, apoptosis, and energy metabolism through c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (p38 MAPK), extracellular signal-regulated kinase (ERK) and adenosine monophosphate-activated protein kinase (AMPK) signaling pathways. In addition, it is involved in the initiation and development processes of numerous types of tumors in the digestive system, nervous system, reproductive system, and some other physiological systems. It is noteworthy that recent studies suggest that MLK3 is also closely associated with CVDs, and plays a significant role in the pathophysiological processes of CVDs such as heart failure, myocardial hypoxic injury, and sepsis-induced cardiomyopathy. It has been found that MLK3 is likely to be involved in the initiation and development of these diseases through activation of the inflammatory response, damage from reactive oxygen species, induction of cell apoptosis, and through its influence on metabolic and energy homeostasis. However, the role of MLK3 in different CVDs differs; in recent studies, some of its effects are controversial and need to be further verified. Overall, MLK3 is likely to be a potential therapeutic target for CVDs. Here, we provide a general overview and summarize related signaling pathways of MLK3 in the physiological state, while elucidating the mechanisms of MLK3 in common CVDs based on the latest research results. This provides a baseline for broadening research and exploring preventive and therapeutic ideas in CVDs.

New genetically‐encodable tools to probe the nuanced regulation of the Extracellular signal‐regulated kinase (ERK) pathway

The Extracellular signal‐regulated kinase (ERK) signaling axis is activated by a host of divergent signaling molecules which each induce their own specific responses. These cellular responses include fundamental processes such as proliferation, differentiation, migration, and, under certain conditions, even apoptosis. Thus, the ubiquitous utilization of ERK signaling in variable and contrasting cellular processes makes it difficult to inhibit the pathway without causing adverse side effects. Furthermore, dysregulation of the Ras/Raf/MEK/ERK signaling pathway is directly implicated in a variety of disorders ranging from cancer to diabetes. Here, we report new tools to elucidate the nuanced mechanisms of differential regulation of the ERK pathway. First, we report a new genetically‐encodable tool to inhibit ERK at specific subcellular locations, allowing us to explore the specific function and mechanisms of regulation of ERK with extremely precise subcellular resolution. Additionally, we report a new genetically‐encodable fluorescent biosensor based on previous generations of the ERK‐kinase activity reporter (EKAR). Our new biosensor, which we have termed reDox‐EKAR1, allows us to probe into the spatiotemporal activity of ERK towards a different class of substrates than substrates probed by previous generations of EKAR. Utilizing these new tools, we report how specific pools of ERK regulate particular cellular functions previously underappreciated in the field, and we present our preliminary results detailing how these specific subcellular pools of ERK are differentially regulated.

Study on the Protective Effect of Schizandrin B against Acetaminophen-Induced Cytotoxicity in Human Hepatocyte.

Drug-induced liver injury (DILI) occurs frequently worldwide. Acetaminophen (APAP) is a common drug causing DILI. Current treatment methods are difficult to achieve satisfactory results. Therefore, there is an urgent need to provide safe and effective treatment for patients. Schizandrin B (Sch B), the main component of Schisandra, has a protective effect on liver. However, the potential mechanism of Sch B in the treatment of APAP induced liver injury has not been elucidated to date. In our research, we studied the effect of Sch B on protecting damaged liver cells and explored the potential mechanism underlying its ability to reduce APAP liver injury. We found that Sch B could reduce hepatocyte apoptosis, oxidative stress injury and inflammatory response. These effects were positively correlated with the dose of Sch B. Sch B regulated glucose 6-phosphate dehydrogenase expression by upregulating the expression of p21-activated kinase 4 and polo-like kinase 1. Sch B could inhibit the mitogen-activated protein kinase (MAPK)-c-Jun N-terminal kinase (JNK)-extracellular signal-regulated kinase (ERK) signaling pathway and regulate the expression of apoptosis-related proteins to reduce the incidence of cell apoptosis. In addition, Sch B reduced the expression levels of reactive oxygen species and inflammatory cytokines in hepatocyte. Consequently, we described for the first time that Sch B could not only activate the pentose phosphate pathway but also inhibit the MAPK-JNK-ERK signaling pathway, thereby achieving antioxidative and anti-inflammatory effects and inhibiting hepatocyte apoptosis. These findings indicated the potential use of Sch B in curing liver damage induced by APAP.

Retraction.

Retraction: "TMEM206 promotes the malignancy of colorectal cancer cells by interacting with AKT and extracellular signal-regulated kinase signaling pathways", by Jinbo Zhao, Dehua Zhu, Xiupeng Zhang, Yong Zhang, Jianping Zhou, and Ming Dong, J Cell Physiol. 2019; 10888-10898: The above article, published online on 11 November 2018 in Wiley Online Library (https://onlinelibrary.wiley.com/doi/full/10.1002/jcp.27751), has been retracted by agreement between the authors, the journal's Editor in Chief, Prof. Dr. Gregg Fields, and Wiley Periodicals LLC. The retraction has been agreed following an investigation based on allegations raised by a third party. Several flaws and inconsistencies between results presented and experimental methods described were found, the editors consider the conclusions of this article to be invalid.

The memory modulatory effect of agmatine in passive avoidance task coincides with alterations of hippocampal CaMKII-α and ERK signaling in mice

Agmatine is a polyamine suggested to act as a supposed neurotransmitter in the brain. Evidence has indicated that acute agmatine administration might modulate memory. The present study aimed to investigate the effect of repeated agmatine treatment on passive avoidance memory, hippocampal calcium–calmodulin-dependent protein kinase II-alpha (CaMKII-α), and Extracellular Signal-Regulated Kinase (ERK) signaling pathways in naive mice. Adult male NMRI mice were treated with agmatine (10, 20, 30, 40, and 80 mg/kg/ip) or saline for 11 days. Acquisition and retention tests of passive avoidance memory were performed on days 10 and 11, respectively. Following the memory retention test, the hippocampi were assessed for the levels of CaMKII-α and ERK using the western blotting technique. The results revealed the dose-dependent effect of agmatine on the passive avoidance memory. Accordingly, the memory was impaired in lower doses, but was improved in higher ones. Agmatine in none of the doses affected the nociception of the mice in tail-flick test. Furthermore, agmatine increased the phosphorylation of CaMKII-α and ERK in the hippocampus at memory enhancing doses, while ERK phosphorylation decreased following the impairing doses of agmatine. Thus, the dose-dependent effect of agmatine on memory might be related to its modulatory effect on CaMKII-α and ERK signal transduction, eventually regulating the memory process.

Protective Effect of Amber Extract on Human Dopaminergic Cells against 6-Hydroxydopamine-Induced Neurotoxicity.

Parkinson’s disease (PD) is the second most common progressive neurodegenerative disease, after Alzheimer’s disease. In our previous study, we found that amber—a fossilized plant resin—can protect cells from apoptosis by decreasing the generation of reactive oxygen species (ROS). In this study, we focused on the effect of amber on 6-hydroxydopamine-induced cell apoptosis in the human neuroblastoma cell line SHSY5Y (one model for PD). Initially, we determined the protective effect of amber on the PD model. We found that amber extract has a protective effect against 6-hydroxydopamine-induced cell apoptosis. The decrease in ROS, cleaved caspase-3, pERK, and extracellular signal-regulated kinase (ERK) protein levels confirmed that amber extract decreases apoptosis via the ROS-mediated ERK signaling pathway. Furthermore, we determined the effects of amber extract on autophagy. The results showed that amber extract increased the levels of LC3II and Beclin-1, suggesting that amber extract can protect neuronal cells against 6-hydroxydopamine-induced cell apoptosis by promoting autophagy.

A new cell death program regulated by toll-like receptor 9 through p38 mitogen-activated protein kinase signaling pathway in a neonatal rat model with sepsis associated encephalopathy.

Background:Sepsis, a serious condition with high mortality, usually causes sepsis associated encephalopathy (SAE) that involves neuronal cell death. However, the cell death programs involved and their underlying mechanisms are not clear. This study aimed to explore the regulatory mechanisms of different cell death programs in SAE.Methods:A neonatal rat model of SAE was established by cecal ligation and perforation. Survival rate and vital signs (mean arterial pressure and heart rate) were monitored, nerve reflexes were evaluated, and cortical pathological changes were observed by hematoxylin and eosin staining. The expression of pyroptosis, apoptosis, and necroptosis (PANoptosis)-related proteins, mitogen- activated protein kinase (MAPK), and its upstream regulator toll-like receptor 9 (TLR9) were detected. The expression of TLR9 in neurons was observed by immunofluorescence staining. The ultrastructure of neurons was observed by transmission electron microscope.Results:First, PANoptosis was found in cortical nerve cells of the SAE rats. Meanwhile, the subunits of MAPKs, p38 MAPK, Jun N- terminal kinase, and extracellular signal-regulated kinase (ERK) were activated. After pharmacologically inhibiting each of the subunits, only p38 MAPK was found to be associated with PANoptosis. Furthermore, blocking the p38 MAPK signaling pathway activated necroptosis but inhibited apoptosis and pyroptosis. When necroptosis was pharmacologically inhibited, apoptosis and pyroptosis were reactivated. Finally, we found that the expression of TLR9, a regulator of MAPKs, was significantly increased in this model. After down-regulation of TLR9, p38 MAPK, and ERK signaling pathways were inhibited, which led to the inhibition of PANoptosis. Further analysis found that down-regulation of TLR9 improved the survival rate and reduced the pathological changes in SAE rats.Conclusions:Our study showed that the programs comprising PANoptosis are activated simultaneously in SAE rats. TLR9 activated PANoptosis through the p38 MAPK signaling pathway. TLR9 may work as a potential target for SAE treatment.

A3 adenosine receptor agonist IB-MECA reverses chronic cerebral ischemia-induced inhibitory avoidance memory deficit

BackgroundChronic cerebral ischemia (CCI) is a major cause of subcortical ischemic vascular dementia. Here, we examined the neuroprotective action of the A3 adenosine receptor agonist N6-(3-iodobenzyl)-adenosine-5′-N-methylcarboxamide (IB-MECA) on white matter lesions following CCI. MethodsA CCI mouse model was established using unilateral common carotid artery occlusion. IB-MECA and 3-propyl-6-ethyl-5-[(ethylthio)carbonyl]-2 phenyl-4-propyl-3-pyridine carboxylate (MRS1523), an antagonist of the A3 adenosine receptor, were administered by intraperitoneal injection. The inhibitory avoidance test was used to examine changes in memory performance. Microtubule-associated protein 2 (MAP-2) and neurofilament were assessed by immunohistochemistry, while expressions of phosphorylated extracellular signal-regulated kinase (ERK), ERK, interferon-beta (IFN-β), and glial fibrillary acidic protein (GFAP) were assessed by western blot assay. ResultsThe memory retention score was reduced in vehicle-treated mice compared with IB-MECA-treated (p < 0.05) mice. Compared to sham-operated mice, p-ERK, GFAP and IFN-β were increased, while MAP-2 and neurofilament were reduced in vehicle-treated mice (p < 0.01 for each). IB-MECA reduced ERK phosphorylation (p < 0.01) and GFAP expression (p < 0.05), but upregulated MAP-2 and IFN-β (p < 0.01 for both), compared with vehicle. MRS1523 suppressed the effects of IB-MECA on the memory deficit, ERK phosphorylation, and on MAP-2, neurofilament, GFAP and IFN-β levels. ConclusionOur results suggest that A3 adenosine receptor stimulation ameliorates CCI-induced memory deficits, modulates the ERK signaling pathway, preserves MAP-2 and neurofilament expression, regulates GFAP expression, and upregulates the anti-inflammatory cytokine IFN-β. Thus, the A3 adenosine receptor may be a therapeutic target for treatment of cognitive disorders and cerebral inflammatory diseases.

Effects of miR-490-5p targeting CDK1 on proliferation and apoptosis of colon cancer cells via ERK signaling pathway.

The aim of this study was to investigate the effects of micro ribonucleic acid (miR)-490-5p on the proliferation and apoptosis of colon cancer cells, and to explore its potential mechanism. The mRNA expression of miR-490-5p in 30 pairs of colon cancer tissues and adjacent normal tissues was detected via reverse transcription-polymerase chain reaction (RT-PCR). Human colon cancer SW480 cell lines were cultured in vitro and divided into Control group and miR-490-5p overexpression group (miR-490-5p mimic group). The nonsense sequence and miR-490-5p mimic were transfected using liposome transfection technique into colon cancer cells in control group and miR-490-5p mimic group, respectively. Cell proliferation and apoptosis in each group were then observed. At the same time, the effect of miR-490-5p on the growth of colon cancer in vivo was explored using subcutaneous tumorigenesis assay. The protein expressions of extracellular signal-regulated kinase (ERK)1/2 signaling pathway and cyclin-dependent kinase 1 (CDK1) were determined via Western blotting. Furthermore, immunohistochemical staining was performed to verify the protein expression of CDK1 in vivo. The expression of miR-490-5p in colon cancer tissues was significantly lower than that in adjacent normal tissues (p<0.05). After transfection with miR-490-5p mimic in vitro, EdU staining and colony formation assay showed that the proliferation ability of SW480 cells was significantly weakened (p<0.05). Meanwhile, the number of colonies in miR-490-5p mimic group was markedly less than that in Control group (p<0.05). The results of Western blotting revealed that overexpression of miR-490-5p remarkably up-regulated the Bax/Bcl-2 and C-Caspase3/T-Caspase3 ratios in cancer cells (p<0.05). Subsequent results indicated that the subcutaneous tumorigenesis of colon cancer cells was markedly inhibited by overexpression of miR-490-5p (p<0.05). According to the results of Western blotting, the activation of ERK signaling pathway and the protein expression of CDK1 were significantly suppressed by overexpression of miR-490-5p (p<0.05). In vivo experiments further revealed that the protein expression of CDK1 in colon cancer tissues increased significantly (p<0.05). MiR-490-5p was found lowly expressed in colon cancer patients. In addition, overexpression of miR-490-5p inhibited the proliferation and promoted the apoptosis of colon cancer cells via down-regulating CDK1 both in vitro and in vivo.

Protective Effects of a Novel Lactobacillus brevis Strain with Probiotic Characteristics against Staphylococcus aureus Lipoteichoic Acid-Induced Intestinal Inflammatory Response.

Probiotics can effectively modulate host immune responses and prevent gastrointestinal diseases. The objective of this study was to investigate the probiotic characteristics of Lactobacillus brevis KU15152 isolated from kimchi and its protective potential against intestinal inflammation induced by Staphylococcus aureus lipoteichoic acid (aLTA). L. brevis KU15152 exhibited a high survival rate in artificial gastric and bile environments. Additionally, the adhesion capability of the strain to HT-29 cells was higher than that of L. rhamnosus GG. L. brevis KU15152 did not produce harmful enzymes, such as β-glucuronidase, indicating that it could be used as a potential probiotic. The anti-inflammatory potential of L. brevis KU15152 was determined in HT-29 cells. Treatment with L. brevis KU15152 suppressed the production of interleukin-8 without inducing significant cytotoxicity. The downregulatory effects of L. brevis KU15152 were involved in the suppression of nuclear factor-kappa B activation mediated by the extracellular signal-regulated kinase and Akt signaling pathways. Collectively, these data suggest that L. brevis KU15152 can be used in developing therapeutic and prophylactic products to manage and treat aLTA-induced intestinal damage.

Identification and validation of new ERK substrates by phosphoproteomic technologies including Phos-tag SDS-PAGE

The extracellular signal-regulated kinase (ERK), a member of the mitogen-activated protein (MAP) kinase family, governs various cellular processes by phosphorylating a large set of substrates. Although many studies have expanded the number of ERK substrates, it is likely that additional substrates remain to be discovered. Here we have employed a quantitative phosphoproteomic approach to explore novel ERK substrates in NIH3T3 fibroblasts stably expressing a fusion protein between B-Raf and estrogen receptor. Among ERK-dependent phosphorylation targets, we focused on NGFI-A-binding protein 2 (Nab2), forkhead box protein K1 (Foxk1), and Disks large-associated protein 5 (Dlgap5/HURP). Phos-tag SDS-PAGE followed by Western blotting confirmed ERK-dependent phosphorylation of these three proteins in cells. Phos-tag SDS-PAGE of in vitro kinase assay samples revealed high degrees of phosphorylation of these proteins by active ERK. Furthermore, in-gel digestion of the phosphorylated protein bands from Phos-tag SDS-PAGE followed by LC-MS/MS indicated that active ERK directly phosphorylates the same sites in vitro as those observed in cells. This study demonstrates the usefulness of Phos-tag SDS-PAGE for validation of candidate substrates of protein kinases. SignificanceLabel-free quantitative phosphoproteomics identified 1439 phosphopeptides derived from 840 proteins that were significantly increased by ERK activation in mouse fibroblasts. Through gene ontology and pathway analysis, we selected three proteins involved in transcriptional regulation and/or tumorigenesis. The identified phosphorylation sites of these proteins conform to the ERK consensus motif and were directly phosphorylated by active ERK in vitro. Phos-tag SDS-PAGE was useful for detecting ERK-mediated phosphorylation of these substrates both in cells and in vitro. Further characterization of these new ERK substrates will be needed to better understand the ERK signaling pathway, and our phosphoproteomic data provide useful information for studying downstream substrates of ERK.

Ginsenoside 20(R)-Rg3 enhances natural killer cell activity by increasing activating receptor expression through the MAPK/ERK signaling pathway

Ginseng is one of the most widely used herbal remedies for various diseases worldwide. Ginsenoside Rg3 (G-Rg3), the main component of ginseng, possesses several pharmacological properties, including anti-inflammatory, anti-tumor, antioxidant, anti-obesity, and immunomodulatory activities. However, the effect of G-Rg3 on natural killer (NK) cells in humans is not fully understood. Here, we investigated the effect of G-Rg3 on NK cell function and differentiation and elucidated the underlying mechanism. G-Rg3 increased NK cell cytotoxicity and simultaneously increased the expression of NK-activating receptors, NKp44, NKp46, and NKp30. Additionally, G-Rg3 increased the mRNA expression of NK cytolytic molecules, granzyme B and perforin. The expression of CD107a, a marker of NK cell degranulation, also increased in G-Rg3–treated NK cells. We therefore proceeded to identify which MAPK signaling pathway was involved in G-Rg3–mediated cytolytic activity. Treatment with G-Rg3 increased the phosphorylation levels of extracellular signal–regulated kinase (ERK), whereas ERK inhibition eliminated G-Rg3–induced NK cell cytotoxicity, suggesting the involvement of the ERK pathway. G-Rg3 did not affect the rate of differentiation of human cord-blood–derived NK cells; however, it increased the functional maturation of differentiated NK cells and promoted their cytotoxicity. The G-Rg3 isomer, 20(R)-Rg3, effectively activated NK cells via the extracellular signal-regulated kinase (ERK) signaling pathway, whereas 20(S)-Rg3 had no effect on NK cell activity. Altogether, the results demonstrated that 20(R)-Rg3 promoted NK cell activity via activation of the MAPK/ERK pathway, suggesting that 20(R)-Rg3 may be used as an activator of NK cell cytotoxicity for the treatment of diverse types of cancers.

Synergistic effect of Aloe vera flower and Aloe gel on cutaneous wound healing targeting MFAP4 and its associated signaling pathway: In-vitro study

Ethnopharmacological relevanceAloe vera (L.) Burm. f. (Liliaceae family) is a well-known traditional medicinal plant, that has been used to treat a variety of illnesses, for decades ranging from cancer to skin disorders including wounds. It has been included in the traditional and herbal healthcare systems of many cultures around the world, as well as the pharmacopeia of different countries. Several in vitro and in vivo studies have also confirmed its potential antioxidant, anti-inflammatory, and wound-healing activities, etc. in the consistency of its historical and traditional uses. However, most studies to date are based on the A. vera gel and latex including its wound-healing effects. Very few studies have been focused on its flower, and rarely with its effects on cutaneous wound healing and its molecular mechanism.Aim of the Study: To the best of our knowledge, this is the first study to report on the synergistic effect of the A. vera flower (AVF) and Aloe gel (PAG) on cutaneous wound-healing, as well as revealing its molecular mechanism targeting microfibril-associated glycoprotein 4 (MFAP4) and its associated signaling pathway. MethodsTo investigate the synergistic effect of A. vera flower and Aloe gel in cutaneous wound healing, cell viability, and cell migration, as well proliferation assay was performed. This was followed by quantitative real-time polymerase chain reaction and Western blot analyses in wounded conditions to check the effects of this mixture on protein and mRNA levels in normal human dermal fibroblast (NHDF) cells. Moreover, small interfering RNA (siRNA) -mediated knockdown of MFAP4 in NHDF cells was performed followed by migration assay and cell cycle analysis, to confirm its role in cutaneous wound healing. Additionally, HaCaT cells were included in this study to evaluate its migratory and anti-inflammatory effects. ResultsBased on our obtained results, the PAG and AVF mixture synergistically induced the proliferation, migration, and especially ECM formation of NHDF cells by enhancing the expression of MFAP4. Other extracellular components associated with MFAP4 signaling pathway, such as fibrillin, collagen, elastin, TGF β, and α-SMA, also increased at both the protein and mRNA levels. Subsequently, this mixture initiated the phosphorylation of the extracellular signal-regulated kinase (ERK) and AKT signaling pathways, and the S-phase of the cell cycle was also slightly modified. Also, the mixture induced the migration of HaCaT cells along with the suppression of inflammatory cytokines. Moreover, the siRNA-mediated knockdown highlighted the crucial role of MFAP4 in cutaneous wound healing in NHDF cells. ConclusionThis study showed that the mixture of PAG and AVF has significant wound healing effects targeting MFAP4 and its associated signaling pathway. Additionally, MFAP4 was recognized as a new potential biomarker of wound healing, which can be confirmed by further in vivo studies.

Antrodia camphorata-Derived Antrodin C Inhibits Liver Fibrosis by Blocking TGF-Beta and PDGF Signaling Pathways.

Hepatic stellate cells (HSCs) play an essential role in the development of liver fibrosis. Antrodia camphorata (A. camphorata) is a medicinal fungus with hepatoprotective effect. This study investigated whether Antrodin C, an A. camphorata-fermented metabolite, could exert a protective role on liver fibrosis both in vitro and in vivo. The anti-fibrotic effect of Antrodin C was investigated in CFSC-8B cell (hepatic stellate cell) stimulated by transforming growth factor-β1 (TGF-β1) or platelet-derived growth factor-BB (PDGF-BB) in vitro and in CCl4 induced liver fibrosis in mice. Antrodin C (50 μM) inhibited TGF-β1 or PDGF-BB stimulated CFSC-8B cell activation, migration and extracellular matrix (ECM) accumulation (all p < 0.05). Antrodin C (3, 6 mg/kg/d) oral administration reduced the degree of liver fibrosis induced by CCl4 in mice. Antrodin C down-regulated the expression of α-smooth muscle actin (α-SMA) and collagen I in fibrotic livers. Furthermore, Antrodin C ameliorated alanine aminotransferase (ALT) and aspartate aminotransferase (AST) elevation in serum (all p < 0.05). Mechanistically, Antrodin C executes its anti-fibrotic activity through negatively modulate TGF-β1 downstream SMAD Family Member 2 (Smad2), AKT Serine/Threonine Kinase 1 (AKT), extracellular signal-regulated kinase (ERK), and P38 MAP Kinase (P38), as well as PDGF-BB downstream AKT and ERK signaling pathways. Antrodin C ameliorates the activation, migration, ECM production in HSCs and CCl4-induced liver fibrosis in mice, suggesting that Antrodin C could serve as a protective molecule against liver fibrosis.

Chlorobisphenol A activated kisspeptin/GPR54-GnRH neuroendocrine signals through ERα and GPER pathway in neuronal GT1-7 cells

Chlorobisphenol A (ClxBPA) is a kind of novel estrogenic compounds. The present study aims to investigate the effects of three ClxBPA compounds on the kisspeptin/G protein-coupled receptor 54 (GPR54, also named KissR1)-gonadotropin-releasing hormone (GnRH) (KGG) system in neuronal GT1–7 cells with mechanistic insights by estrogen receptor signaling pathways. The study demonstrated that low-concentration ClxBPA induced the cell proliferation, promoted GnRH secretion, upregulated the expression of KGG neuroendocrine signal-related proteins (KissR1, GnRH1 and kisspeptin) and genes including Kiss1, GnRH1, KissR1, luteinizing hormone receptor (Lhr) and follicle-stimulating hormone receptor (Fshr) in GT1–7 cells. Additionally, ClxBPA activated nuclear estrogen receptor alpha (ERα) and member estrogen receptor G protein-coupled estrogen receptor (GPER)-regulated phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt) and extracellular signal-regulated kinase (Erk1/2) signaling pathways. Pretreatment of GT1–7 cells with GPER inhibitor G15 and ERα inhibitor ICI reduced the expression of KissR1, GnRH1 and kisspeptin proteins, attenuated mRNA levels of Kiss1, GnRH1, KissR1, Fshr and Lhr genes, and decreased ClxBPA-induced GT1–7 cell proliferation. The results suggested that ClxBPA activated the KGG neuroendocrine signals and induced the proliferation of GT1–7 cells via ERα and GPER signaling pathways. This study provides a new perspective to explore the neuroendocrine toxicity mechanism of ClxBPA. CapsuleClxBPA activated KGG neuroendocrine signaling pathway via ERα and GPER and induced the proliferation of GT1–7 cells.

Inorganic arsenic promotes apoptosis of human immortal keratinocytes through the TGF-β1/ERK signaling pathway.

Chronic exposure to high-dose inorganic arsenic through groundwater, air, or food remains a major environmental public health issue worldwide. Apoptosis, a method of cell death, has recently become a hot topic of research in biology and medicine. Previous studies have demonstrated that extracellular signal-regulated kinase (ERK) is related to arsenic-induced apoptosis. However, the reports are contradictory, and the knowledge of the above-mentioned mechanisms and their mutual regulation remains limited. In this study, the associations between the TGF-β1/ERK signaling pathway and arsenic-induced cell apoptosis were confirmed using the HaCaT cell model. The relative expressions of the indicators of the TGF-β1/ERK signaling pathway, apoptosis-related genes (cytochrome C, caspase-3, caspase-9, cleaved caspase-3, cleaved caspase-9, and Bax), the mitochondrial membrane potential, and the total apoptosis rate were significantly increased (P <.05), while the expression of the antiapoptosis gene Bcl-2 was significantly decreased (P <.05) in cells of the group exposed to arsenic. Moreover, the results demonstrated that the ERK inhibitor (PD98059) and TGF-β1 inhibitor (LY364947) could inhibit the activation of the ERK signaling pathway, thereby reducing the mitochondrial membrane potential, the total apoptosis rate, and the expression of pro-apoptosis-related genes in the cells, while the expression of the antiapoptosis gene Bcl-2 was significantly increased (P <.05). By contrast, the recombinant human TGF-β1 could promote apoptosis of the HaCaT cells by increasing the activation of the ERK signaling pathway (P <.05). These results indicate that inorganic arsenic promotes the apoptosis of human immortal keratinocytes through the TGF-β1/ERK signaling pathway.