LncRNA SNHG8 regulates the migration and angiogenesis of pHUVECs induced by high glucose via the TRPM7/ERK1/2 signaling axis.

This study aimed to evaluate the regulatory effect and molecular mechanism of long noncoding RNA small nucleolus RNA host gene 8 (LncRNA SNHG8) in the migration and angiogenesis of primary human umbilical vein endothelial cells (pHUVECs) under high-glucose (HG) conditions. The HG-induced endothelial injury model was established in vitro.The cell model of silencing SNHG8, overexpressing SNHG8, and silencing TRPM7 was established by transfecting SNHG8-siRNA, SNHG8 plasmid and TRPM7-siRNA into cells with liposomes.The SNHG8 level was determined through reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The expression levels of transient receptor potential melastatin 7 (TRPM7), endothelial nitric oxide synthase (eNOS), p-eNOS, extracellular signal-regulated kinase 1/2(ERK1/2), and p-ERK1/2 were assessed through western blot. Nitric oxide (NO) levels were measured with DAF-FM. pHUVEC migration was examined through wound healing and Transwell assay, and pHUVEC angiogenesis was observed through a tube formation assay. Results showed that HG promoted the expression of lncRNA SNHG8 and TRPM7 and decreased the ratio of p-eNOS/eNOS and p-ERK1/2/ERK1/2 in pHUVECs . NO production, migration , and angiogenesis were inhibited in pHUVECs under HG conditions. Silencing lncRNA SNHG8 and TRPM7 could significantly reverse the HG-induced decrease in eNOS activation, NO production , migration, and angiogenesis . SNHG8 and U0126 (ERK pathway inhibitor) overexpression enhanced the HG effects, whereas using U0126 did not affect the TRPM7 expression. In conclusion, lncRNA SNHG8 participates in HG-induced endothelial cell injury and likely regulates NO production, migration, and angiogenesis of pHUVECs via the TRPM7/ERK1/2 signaling axis.

A conserved arginine within the αC-helix of Erk1/2 is a latch of autoactivation and of oncogenic capabilities.

Eukaryotic protein kinases (EPKs) adopt an active conformation following phosphorylation of a particular activation loop residue. Most EPKs spontaneously autophosphorylate this residue. While structure-function relationships of the active conformation are essentially understood, those of the "prone-to-autophosphorylate" conformation are unclear. Here, we propose that a site within the αC-helix of EPKs, occupied by Arg in the mitogen-activated protein kinase (MAPK) Erk1/2 (Arg84/65), impacts spontaneous autophosphorylation. MAPKs lack spontaneous autoactivation, but we found that converting Arg84/65 of Erk1/2 to various residues enables spontaneous autophosphorylation. Furthermore, Erk1 molecules mutated in Arg84 are oncogenic. Arg84/65 thus obstructs the adoption of the "prone-to-autophosphorylate" conformation. All MAPKs harbor an Arg that is equivalent to Arg84/65 of Erks, whereas Arg is rarely found at the equivalent position in other EPKs. We observed that Arg84/65 of Erk1/2 interacts with the DFG motif, suggesting that autophosphorylation may be inhibited by the Arg84/65-DFG interactions. Erk1/2s mutated in Arg84/65 autophosphorylate not only the TEY motif, known as critical for catalysis, but also on Thr207/188. Our MS/MS analysis revealed that a large proportion of the Erk2R65H population is phosphorylated on Thr188 or on Tyr185 + Thr188, and a small fraction is phosphorylated on the TEY motif. No molecules phosphorylated on Thr183 + Thr188 were detected. Thus, phosphorylation of Thr183 and Thr188 is mutually exclusive suggesting that not only TEY-phosphorylated molecules are active but perhaps also those phosphorylated on Tyr185 + Thr188. The effect of mutating Arg84/65 may mimic a physiological scenario in which allosteric effectors cause Erk1/2 activation by autophosphorylation.

Ethylene enhances MdMAPK3-mediated phosphorylation of MdNAC72 to promote apple fruit softening.

The phytohormone ethylene plays an important role in promoting the softening of climacteric fruits, such as apples (Malus domestica); however, important aspects of the underlying regulatory mechanisms are not well understood. In this study, we identified apple MITOGEN-ACTIVATED PROTEIN KINASE 3 (MdMAPK3) as an important positive regulator of ethylene-induced apple fruit softening during storage. Specifically, we show that MdMAPK3 interacts with and phosphorylates the transcription factor NAM-ATAF1/2-CUC2 72 (MdNAC72), which functions as a transcriptional repressor of the cell wall degradation-related gene POLYGALACTURONASE1 (MdPG1). The increase in MdMAPK3 kinase activity was induced by ethylene, which promoted the phosphorylation of MdNAC72 by MdMAPK3. Additionally, MdPUB24 functions as an E3 ubiquitin ligase to ubiquitinate MdNAC72, resulting in its degradation via the 26S proteasome pathway, which was enhanced by ethylene-induced phosphorylation of MdNAC72 by MdMAPK3. The degradation of MdNAC72 increased the expression of MdPG1, which in turn promoted apple fruit softening. Notably, using variants of MdNAC72 that were mutated at specific phosphorylation sites, we observed that the phosphorylation state of MdNAC72 affected apple fruit softening during storage. This study thus reveals that the ethylene-MdMAPK3-MdNAC72-MdPUB24 module is involved in ethylene-induced apple fruit softening, providing insights into climacteric fruit softening.

VEGFR3 suppression through miR-1236 inhibits proliferation and induces apoptosis in ovarian cancer via ERK1/2 and AKT signaling pathways.

Vascular endothelial growth factor receptor 3 (VEGFR3) is expressed in cancer cell lines and exerts a critical role in cancer progression. However, the signaling pathways of VEGFR3 in ovarian cancer cell proliferation remain unclear. This study aimed to demonstrate the signaling pathways of VEGFR3 through the upregulated expression of miR-1236 in ovarian cancer cells. We found that the messenger RNA and protein of VEGFR3 were expressed in the ovarian cancer cell lines, but downregulated after microRNA-1236 (miR-1236) transfection. The inhibition of VEGFR3, using miR-1236, significantly reduced cell proliferation, clonogenic survival, migration, and invasion ability in SKOV3 and OVCAR3 cells (p < 0.01). The flow cytometry results indicated that the rate of apoptotic cells in SKOV3 (38.65%) and OVCAR3 (41.95%) cells increased following VEGFR3 inhibition. Moreover, VEGFR3 stimulation (using a specific ligand, VEGF-CS) significantly increased extracellular signal-regulated kinase 1/2 (ERK1/2) and protein kinase B (AKT) phosphorylation (p < 0.01), whereas VEGFR3 suppression reduced p-ERK1/2 (67.94% in SKOV3 and 93.52% in OVCAR3) and p-AKT (59.56% in SKOV3 and 78.73% in OVCAR3) compared to the VEGF-CS treated group. This finding demonstrated that miR-1236 may act as an endogenous regulator of ERK1/2 and AKT signaling by blocking the upstream regulator of VEGFR3. Overall, we demonstrated the important role of the miR-1236/VEGFR3 axis in ovarian cancer cell proliferation by regulating the ERK1/2 and AKT signaling that might be an effective strategy against ovarian cancer.

BPL3 binds the long non-coding RNA nalncFL7 to suppress FORKED-LIKE7 and modulate HAI1-mediated MPK3/6 dephosphorylation in plant immunity.

RNA-binding proteins (RBPs) participate in a diverse set of biological processes in plants, but their functions and underlying mechanisms in plant-pathogen interactions are largely unknown. We previously showed that Arabidopsis thaliana BPA1-LIKE PROTEIN3 (BPL3) belongs to a conserved plant RBP family and negatively regulates reactive oxygen species (ROS) accumulation and cell death under biotic stress. In this study, we demonstrate that BPL3 suppresses FORKED-LIKE7 (FL7) transcript accumulation and raises levels of the cis-natural antisense long non-coding RNA (lncRNA) of FL7 (nalncFL7). FL7 positively regulated plant immunity to Phytophthora capsici while nalncFL7 negatively regulated resistance. We also showed that BPL3 directly binds to and stabilizes nalncFL7. Moreover, nalncFL7 suppressed accumulation of FL7 transcripts. Furthermore, FL7 interacted with HIGHLY ABA-INDUCED PP2C1 (HAI1), a type 2C protein phosphatase, and inhibited HAI1 phosphatase activity. By suppressing HAI1 activity, FL7 increased the phosphorylation levels of MITOGEN-ACTIVATED PROTEIN KINASE 3 (MPK3) and MPK6, thus enhancing immunity responses. BPL3 and FL7 are conserved in all plant species tested, but the BPL3-nalncFL7-FL7 cascade was specific to the Brassicaceae. Thus, we identified a conserved BPL3-nalncFL7-FL7 cascade that coordinates plant immunity.

Bim downregulation by activation of NF-κB p65, Akt, and ERK1/2 is associated with adriamycin and dexamethasone resistance in multiple myeloma cells.

Multiple myeloma (MM) frequently acquires multidrug resistance (MDR), which is due to poor prognosis. Our previous study indicated that high expression of Survivin and multidrug resistance protein 1 (MDR1) and decreased expression of Bim are associated with MDR in adriamycin- and dexamethasone-resistant cells. However, the fundamental mechanism of MDR in adriamycin- and dexamethasone-resistant MM cells is still unidentified. In this study, we examined the MDR mechanism in adriamycin- and dexamethasone-resistant cells. RPMI8226/ADM, ARH-77/ADM, RPMI8226/DEX, and ARH-77/DEX cells exhibited enhanced nuclear factor κB (NF-κB) p65, Akt, and extracellular signal-regulated kinase 1/2 (ERK1/2) activation. Combination treatment with NF-κB p65, phosphoinositide 3-kinase (PI3K), and mitogen-activated protein kinase 1/2 (MEK1/2) inhibitors resensitized to adriamycin and dexamethasone via increased Bim expression. Although treatment with MDR1 or Survivin siRNA did not overcome adriamycin and dexamethasone resistance in RPMI8226/ADM and RPMI8226/DEX cells, administration of Bim siRNA induced adriamycin and dexamethasone resistance in RPMI8226 cells. Moreover, low expression of Bim was related to poor prognosis in MM patients. These results indicate that activation of NF-κB p65, Akt, and ERK1/2 is associated with adriamycin and dexamethasone resistance via decreasing Bim expression, and these signal inhibitor combinations overcome drug resistance in MM. These findings suggest that combination treatment with these inhibitors and adriamycin or dexamethasone may be a promising therapy for adriamycin- and dexamethasone-resistant MM.

MTHFD2 suppresses glioblastoma progression via the inhibition of ERK1/2 phosphorylation.

Glioblastoma (GBM) is a WHO grade 4 tumor and is the most malignant form of glioma. Methylenetetrahydrofolate dehydrogenase 2 (MTHFD2), a mitochondrial enzyme involved in folate metabolism, has been reported to be highly expressed in several human tumors. However, little is known about the role of MTHFD2 in GBM. In this study, we aimed to explore the biological functions of MTHFD2 in GBM and identify the associated mechanisms. We performed experiments such as immunohistochemistry, Western blot, and transwell assays and found that MTHFD2 expression was lower in high-grade glioma than in low-grade glioma. Furthermore, a high expression of MTHFD2 was associated with a favorable prognosis, and MTHFD2 levels showed good prognostic accuracy for glioma patients. The overexpression of MTHFD2 could inhibit the migration, invasion, and proliferation of GBM cells, whereas its knockdown induced the opposite effect. Mechanistically, our findings revealed that MTHFD2 suppressed GBM progression independent of its enzymatic activity, likely by inducing cytoskeletal remodeling through the regulation of extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation, thereby influencing GBM malignance. Collectively, these findings uncover a potential tumor-suppressor role of MTHFD2 in GBM cells. MTHFD2 may act as a promising diagnostic and therapeutic target for GBM treatment.

Proteomic characterization of spinal cord synaptoneurosomes from Tg-SOD1/G93A mice supports a role for MNK1 and local translation in the early stages of amyotrophic lateral sclerosis.

The isolation of synaptoneurosomes (SNs) represents a useful means to study synaptic events. However, the size and density of synapses varies in different regions of the central nervous system (CNS), and this also depends on the experimental species studied, making it difficult to define a generic protocol for SNs preparation. To characterize synaptic failure in the spinal cord (SC) in the Tg-SOD1/G93A mouse model of amyotrophic lateral sclerosis (ALS), we applied a method we originally designed to isolate cortical and hippocampal SNs to SC tissue. Interestingly, we found that the SC SNs were isolated in a different gradient fraction to the cortical/hippocampal SNs. We compared the relative levels of synaptoneurosomal proteins in wild type (WT) animals, with control (Tg-SOD1) or Tg-SOD1/G93A mice at onset and those that were symptomatic using iTRAQ proteomics. The results obtained suggest that an important regulator of local synaptic translation, MNK1 (MAP kinase interacting serine/threonine kinase 1), might well influence the early stages of ALS.

The role of ERK-1 and ERK-2 gene polymorphisms in PCOS pathogenesis.

BACKGROUND: Ovulation is regulated by extracellular signal-regulated kinase-1 (ERK-1) and ERK-2 signaling mechanisms, and ERK-1/2 kinases modulates the function of most of the LH-regulated genes. Defective ERK kinase signaling that is secondary to a genetic problem contributes to both ovulatory dysfunction and metabolic problems in polycystic ovary syndrome (PCOS). We planned to investigate ERK-1 and ERK-2 gene polymorphisms in PCOS for the first time in the Turkish population. METHODS: One hundred two PCOS patients and 102 healthy controls were recruited for this patient control study. HOMA-IR, Ferriman-Gallwey score (FGS), waist-to-hip ratio (WHR), and body mass index (BMI) were assessed. Lipid profile levels, CRP, and total testosterone were determined. ERK-2 rs2276008 (G > C) and ERK-1 rs11865228 (G > A) SNPs were analyzed with a real-time PCR system. RESULTS: ERK-1 and ERK-2 genotypes were found to differ between the PCOS and control groups. In patients with PCOS, ERK-1 GA and ERK-2 GC genotypes were different in terms of BMI, FGS, HOMA-IR, CRP, total testosterone, and total cholesterol levels. CONCLUSIONS: ERK-1 and ERK-2 genes are involved in PCOS pathogenesis. BMI, FGS, HOMA-IR, and CRP levels are related to the heterozygote polymorphic types of ERK-1 and ERK-2 genes.

Participation of lipopolysaccharide in hyperplasic adipose expansion: Involvement of NADPH oxidase/ROS/p42/p44 MAPK-dependent Cyclooxygenase-2.

Obesity is a world-wide problem, especially the child obesity, with the complication of various metabolic diseases. Child obesity can be developed as early as the age between 2 and 6. The expansion of fat mass in child age includes both hyperplasia and hypertrophy of adipose tissue, suggesting the importance of proliferation and adipogenesis of preadipocytes. The changed composition of gut microbiota is associated with obesity, revealing the roles of lipopolysaccharide (LPS) on manipulating adipose tissue development. Studies suggest that LPS enters the circulation and acts as a pro-inflammatory regulator to facilitate pathologies. Nevertheless, the underlying mechanisms behind LPS-modulated obesity are yet clearly elucidated. This study showed that LPS enhanced the expression of cyclooxygenase-2 (COX-2), an inflammatory regulator of obesity, in preadipocytes. Pretreating preadipocytes with the scavenger of reactive oxygen species (ROS) or the inhibitors of NADPH oxidase or p42/p44 MAPK markedly decreased LPS-stimulated gene expression of COX-2 together with the phosphorylation of p47phox and p42/p44 MAPK, separately. LPS activated p42/p44 MAPK via NADPH oxidase-dependent ROS accumulation in preadipocytes. Reduction of intracellular ROS or attenuation of p42/p44 MAPK activation both reduced LPS-mediated COX-2 expression and preadipocyte proliferation. Moreover, LPS-induced preadipocyte proliferation and adipogenesis were abolished by the inhibition of COX-2 or PEG2 receptors. Taken together, our results suggested that LPS enhanced the proliferation and adipogenesis of preadipocytes via NADPH oxidase/ROS/p42/p44 MAPK-dependent COX-2 expression.

LncR-133a Suppresses Myoblast Differentiation by Sponging miR-133a-3p to Activate the FGFR1/ERK1/2 Signaling Pathway in Goats.

Long noncoding RNAs (lncRNAs) are involved in a variety of biological processes and illnesses. While a considerable number of lncRNAs have been discovered in skeletal muscle to far, their role and underlying processes during myogenesis remain mostly unclear. In this study, we described a new functional lncRNA named lncR-133a. Gene overexpression and interference studies in goat skeletal muscle satellite cells (MuSCs) were used to establish its function. The molecular mechanism by which lncR-133a governs muscle differentiation was elucidated primarily using quantitative real-time PCR (qRT-PCR), Western blotting, dual-luciferase activity assays, RNA immunoprecipitation, biotin-labeled probe, and RNA fluorescence in situ hybridization analyses. LncR-133a was found to be substantially expressed in longissimus thoracis et lumborum muscle, and its expression levels changed during MuSC differentiation in goats. We validated that lncR-133a suppresses MuSC differentiation in vitro. Dual-luciferase reporter screening, Argonaute 2 (AGO2) RNA immunoprecipitation assays, biotin-labeled lncR-133a capture, and fluorescence in situ hybridization showed that lncR-133a interacted with miR-133a-3p. Additionally, miR-133a-3p facilitated MuSC differentiation, but lncR-133a reversed this effect. The luciferase reporter assay and functional analyses established that miR-133a-3p directly targets fibroblast growth factor receptor 1 (FGFR1). Moreover, lncR-133a directly reduced miR-133a-3p's capacity to suppress FGFR1 expression, and positively regulated the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2). In summary, our results suggested that lncR-133a suppresses goat muscle differentiation by targeting miR-133a-3p and activating FGFR1/ERK1/2 signaling pathway.

Liver tumor-initiating cells initiate the formation of a stiff cancer stem cell microenvironment niche by secreting LOX.

Accumulating evidence has shown that the traits of tumor-initiating cells (TICs) are controlled by the microenvironment niches (MENs), but the composition and remodeling mechanisms of the MENs of TICs are poorly defined. Here, we report that the voltage-gated calcium channel α2δ1 subunit-positive TICs of hepatocellular carcinoma (HCC) specifically secret lysyl oxidase (LOX), which leads to the cross-linking of collagen, forming a stiff extracellular matrix (ECM) that is sufficient to drive the formation of TICs with a stiff mechanical trait and is subsequently required for the maintenance the properties of HCC TICs. Furthermore, the cross-linked collagen results in the upregulation of integrin α7 (ITGA7), increased phosphorylation of FAK and extracellular signal-regulated kinase 1/2 (ERK1/2). Inhibition of ITGA7 abolishes all the effects of cross-linked collagen mediated by LOX. Hence, the α2δ1+ HCC TICs initiate ECM remodeling by secreting LOX to create a stiff MEN of TIC with cross-linked collagen, which drives the acquisition and subsequent maintenance of the properties of HCC TICs through ITGA7-FAK-ERK1/2 signaling pathway.

AREG is involved in scleral remodeling in form-deprivation myopia via the ERK1/2-MMP-2 pathway.

Previous studies have found that amphiregulin (AREG) may participate in eye elongation during the development of myopia, but the mechanism remains unclear. Here, we tested tear concentrations of AREG in adults and detected the role of AREG in scleral remodeling in form-deprivation myopia (FDM) in guinea pigs. We found the tear concentrations of AREG in myopes were significantly higher than those in emmetropes using enzyme-linked immunosorbent assay (ELISA). Tear concentrations of AREG were negatively correlated with spherical equivalent refraction and positively correlated with axial length (AL) and AL/corneal radii. We then used RNAi, DNA transfection and PD98059 treatments to determine the effects of AREG on extracellular signal-regulated kinase 1/2 (ERK1/2) and matrix metalloprotease-2 (MMP-2) in primary scleral fibroblasts (SFs). The hypothesis was further verified via loss- and gain-of-function experiments by intravitreal application of anti-AREG antibody (anti-AR) or AREG in form-deprivation eyes in guinea pigs. Immunofluorescence assay was used for cell type identification. Western-blot and q-PCR were used for the detection of relative expressions. Transmission electron microscopy was performed for posterior scleral observation. In vitro, we found AREG overexpression increased phospho-ERK1/2 and MMP-2 expression, while depletion of AREG inhibited their expressions. PD98059 (an effective ERK1/2 inhibitor) inhibited AREG-induced MMP-2 upregulation. In vivo, we found anti-AR treatments suppressed FDM by inhibiting scleral remodeling, while AREG treatments promoted FDM. Our results suggest that AREG in tear fluids can serve as a potential biomarker in myopes. AREG is involved in scleral remodeling through the ERK1/2-MMP-2 pathway. AREG is a potential target for myopia control.

Mycobacterium tuberculosis glycolipoprotein LprG inhibits inflammation through NF-κB signaling of ERK1/2 and JNK in LPS-induced murine macrophage cells.

Mycobacterium tuberoculosis (Mtb) is a contagious pathogen that causes human tuberculosis (TB). TB is a major global health threat that causes 9.6 million illnesses and 1.5 million deaths per year. Recent studies have suggested Mtb-secreted proteins as new candidates for therapeutic drugs and vaccines. LprG is a Mtb-secreted surface glycolipoprotein encoded by lprG (Rv1411c), which forms an operon with Rv1410c, where Rv1410c encodes P55, an efflux pump membrane protein. Various in vitro and in vivo studies have reported on the target-binding activity, cell envelope biosynthesis, and mycobacterial virulence of LprG. However, the anti-inflammatory effect of LprG in macrophages has not yet been investigated. In this study, we demonstrated that LprG can suppress lipopolysaccharide (LPS)-induced inflammation in a macrophage model. LprG inhibited LPS-stimulated nitric oxide (NO) production. LprG also suppressed expression of inducible cyclooxygenase-2 (COX-2) and nitric oxide synthase (iNOS) at the transcriptional and protein levels. In addition, LprG decreased mRNA expression of the pro-inflammatory cytokines interleukin-1ß (IL-1ß), IL-6, and tumor necrosis factor-α (TNF-α). Furthermore, LprG attenuated nuclear factor kappa-B (NF-κB) translocation and IκB phosphorylation. Moreover, LprG specifically inhibited phosphorylated kinases such as c-Jun N-terminal kinase (p-JNK) and extracellular signal-regulated kinase 1/2 (p-ERK1/2), but not p-p38. Taken together, these results suggest that LprG inhibits LPS-stimulated inflammation via downregulation of NO, COX-2, iNOS, and pro-inflammatory cytokines through the NF-κB, AP-1, and MAPK signaling pathways. The present study will aid in the development of anti-inflammatory medications using Mtb. The organism, which has long been regarded as a human pathogenic or human health-threating agent, can be utilized as a future medical resource.

Mesenchyme homeobox 2 has a cancer-inhibiting function in breast carcinoma via affection of the PI3K/AKT/mTOR and ERK1/2 pathways.

A cancer-inhibiting role of mesenchyme homeobox 2 (MEOX2) has been observed in several malignancies. However, the association between MEOX2 and breast carcinoma has not been addressed. This research focused on investigating the possible relevance of MEOX2 in breast carcinoma. Initial expression analysis by TCGA data uncovered low levels of MEOX2 in breast carcinoma. We then confirmed that MEOX2 was poorly expressed in clinical tumor specimens of breast carcinoma by real-time quantitative PCR and immunoblotting assays. Moreover, low levels of MEOX2 in breast carcinoma patients were found to be correlated with reduced overall survival. A series of cellular function assays showed that the forced expression of MEOX2 had anticancer effects, including the inhibition of cell proliferation, the induction of G0-G1 phase arrest, the restraint of metastatic potential, and the enhancement of chemosensitivity. Further analysis revealed that MEOX2 negatively modulated the phosphatidyl-inositol-3 kinase (PI3K)/AKT/mammalian target of the rapamycin (mTOR) and extracellular signal-regulated kinase (ERK1/2) pathways. Reactivation of AKT by a chemical activator reversed MEOX2-mediated anticancer effects. An in vivo xenograft assay validated the anticancer function of MEOX2 in breast carcinoma. Taken together, these data show that MEOX2 exerts a cancer-inhibiting role in breast carcinoma by affecting the PI3K/AKT/mTOR and ERK1/2 pathways. This work suggests MEOX2 as a new contributor for breast carcinoma progression, which may be a candidate target for anticancer therapy development.

ERK1/2 Activity Is Critical for the Outcome of Ischemic Stroke.

Ischemic disorders are the leading cause of death worldwide. The extracellular signal-regulated kinases 1 and 2 (ERK1/2) are thought to affect the outcome of ischemic stroke. However, it is under debate whether activation or inhibition of ERK1/2 is beneficial. In this study, we report that the ubiquitous overexpression of wild-type ERK2 in mice (ERK2wt) is detrimental after transient occlusion of the middle cerebral artery (tMCAO), as it led to a massive increase in infarct volume and neurological deficits by increasing blood-brain barrier (BBB) leakiness, inflammation, and the number of apoptotic neurons. To compare ERK1/2 activation and inhibition side-by-side, we also used mice with ubiquitous overexpression of the Raf-kinase inhibitor protein (RKIPwt) and its phosphorylation-deficient mutant RKIPS153A, known inhibitors of the ERK1/2 signaling cascade. RKIPwt and RKIPS153A attenuated ischemia-induced damages, in particular via anti-inflammatory signaling. Taken together, our data suggest that stimulation of the Raf/MEK/ERK1/2-cascade is severely detrimental and its inhibition is rather protective. Thus, a tight control of the ERK1/2 signaling is essential for the outcome in response to ischemic stroke.

Plectin Downregulation Inhibits Migration and Suppresses Epithelial Mesenchymal Transformation of Hepatocellular Carcinoma Cells via ERK1/2 Signaling.

Plectin, as a cytoskeleton-related protein, is involved in various physiological and pathological processes of many cell types. Studies have found that plectin affects cancer cell invasion and metastasis, but the exact mechanism is not fully understood. In this study, we aim to investigate the role of plectin in the migration of hepatocellular carcinoma (HCC) cells and explore its relevant molecular mechanism. Herein, we found that the expression of plectin in HCC tissue and cells was significantly increased compared with normal liver tissue and cells. After downregulation of plectin, the migration ability of HCC cells was significantly lower than that of the control group. Moreover, the expression of E-cadherin was upregulated and the expression of N-cadherin and vimentin was downregulated, suggesting that plectin downregulation suppresses epithelial mesenchymal transformation (EMT) of HCC cells. Mechanically, we found that plectin downregulation repressed the extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation. Activation of ERK1/2 recovered the plectin downregulation-inhibited migration and EMT of HCC cells. Taken together, our results demonstrate that downregulation of plectin inhibits HCC cell migration and EMT through ERK1/2 signaling, which provides a novel prognostic biomarker and potential therapeutic target for HCC.

Swine acute diarrhea syndrome coronavirus replication is reduced by inhibition of the extracellular signal-regulated kinase (ERK) signaling pathway.

Swine acute diarrhea syndrome coronavirus (SADS-CoV) is a newly discovered enteric coronavirus. We have previously shown that the caspase-dependent FASL-mediated and mitochondrion-mediated apoptotic pathways play a central role in SADS-CoV-induced apoptosis, which facilitates viral replication. However, the roles of intracellular signaling pathways in SADS-CoV-mediated cell apoptosis and the relative advantages that such pathways confer on the host or virus remain largely unknown. In this study, we show that SADS-CoV induces the activation of ERK during infection, irrespective of viral biosynthesis. The knockdown or chemical inhibition of ERK1/2 significantly suppressed viral protein expression and viral progeny production. The inhibition of ERK activation also circumvented SADS-CoV-induced apoptosis. Taken together, these data suggest that ERK activation is important for SADS-CoV replication, and contributes to the virus-mediated changes in host cells. Our findings demonstrate the takeover of a particular host signaling mechanism by SADS-CoV and identify a potential approach to inhibiting viral spread.

Mitochondria-targeted triphenylphosphonium-based compounds inhibit FcεRI-dependent degranulation of mast cells by preventing mitochondrial dysfunction through Erk1/2.

AIMS: FcεRI-dependent activation and degranulation of mast cells (MC) play an important role in allergic diseases. We have previously demonstrated that triphenylphosphonium (TPP)-based antioxidant SkQ1 inhibits mast cell degranulation, but the exact mechanism of this inhibition is still unknown. This study focused on investigating the influence of TPP-based compounds SkQ1 and C12TPP on FcεRI-dependent mitochondrial dysfunction and signaling during MC degranulation. MAIN METHODS: MC were sensitized by anti-dinitrophenyl IgE and stimulated by BSA-conjugated dinitrophenyl. The degranulation of MC was estimated by ß-hexosaminidase release. The effect of TPP-based compounds on FcεRI-dependent signaling was determined by Western blot analysis for adapter molecule LAT, kinases Syk, PI3K, Erk1/2, and p38. Fluorescent microscopy was used to evaluate mitochondrial parameters such as morphology, membrane potential, reactive oxygen species and ATP level. KEY FINDINGS: Pretreatment with TPP-based compounds significantly decreased FcεRI-dependent degranulation of MC. TPP-based compounds also prevented mitochondrial dysfunction (drop in mitochondrial ATP level and mitochondrial fission), and decreased Erk1/2 kinase phosphorylation. Selective Erk1/2 inhibition by U0126 also reduced ß-hexosaminidase release and prevented mitochondrial fragmentation during FcεRI-dependent degranulation of MC. SIGNIFICANCE: These findings expand the fundamental understanding of the role of mitochondria in the activation of MC. It also contributes to the rationale for the development of mitochondrial-targeted drugs for the treatment of allergic diseases.

Dexmedetomidine Attenuates Hypoxia/Reoxygenation Injury of H9C2 Myocardial Cells by Upregulating miR-146a Expression via the MAPK Signal Pathway.

INTRODUCTION AND OBJECTIVE: Dexmedetomidine (Dex) and a number of miRNAs contribute to ischemia/reperfusion injury. We aimed to explore the role of Dex and miR-146a on myocardial cells injured by hypoxia/reoxygenation (H/R). METHOD: H9C2 cells were injured by H/R. Cell viability was tested using the cell counting kit-8. Lactate dehydrogenase (LDH) activity, superoxide dismutase (SOD) activity, and malondialdehyde (MDA) levels were determined using commercial kits. Flow cytometry was performed to determine apoptosis rate and reactive oxygen species (ROS) level. Protein and mRNA levels were assessed using Western blot and qPCR. RESULTS: miR-146a expression and cell viability of H9C2 cells were downregulated under the circumstance of H/R injury. The tendency could be reversed by Dex, which could also upregulate SOD activity and decrease apoptosis, LDH activity, MDA, 78-kDa glucose-regulated protein (GRP78), and C/EBP homologous protein (CHOP) levels of H9C2 cells. GRP78, CHOP levels, and cell viability were negatively modulated by miR-146a. Dex elevated cell viability, catalase, MnSOD, and NAD(P)H dehydrogenase (NQO1) levels but suppressed apoptosis rate, GRP78, and CHOP levels by increasing miR-146a expression and downregulating ROS, phosphorylation of p38, and extracellular signal-regulated kinases 1/2 levels. By using SB203580 (SB), the p38 mitogen-activated protein kinase (MAPK) inhibitor, Dex or the inhibition of miR-146 upregulated cell viability but downregulated GRP78 and CHOP levels. CONCLUSION: Dex might regulate miR-146a expression, which could further modulate the endoplasmic reticulum stress and oxidative stress and eventually affect the cell viability and apoptosis of myocardial cells injured by H/R via the MAPK signal pathway.