Phosphorylated MAPK11 promotes the progression of clear cell renal cell carcinoma by maintaining RUNX2 protein abundance.

Previous studies have demonstrated that mitogen-activated protein kinase 11 (MAPK11) functions as an important point of integration in signalling transduction pathways and controlling endocellular processes, including viability of cells, differentiation, proliferation and apoptosis, through the sequence phosphorylation of the substrate protein Ser/Thr kinase protein cascade. Though MAPK 11 plays an important role in various tumours, especially in the invasive and metastatic processes, its expression and molecular mechanism in clear cell renal cell carcinoma (ccRCC) remain unclear. Runt-associated transcription factor 2 (RUNX2), a main transcription factor for osteoblast differentiation and chondrocyte maturation, has high expression in a number of tumours. In this study, the mRNA and protein levels of targeted genes in ccRCC tissues and adjacent tissues are analysed using the Cancer Genome Atlas (TCGA) database and western blotting. The ccRCC cell proliferation was measured with colony formation and EdU assay, and cell migration was examined through transwell assay. The interactive behaviour between proteins was detected with immunoprecipitation. Half-life period of RUNX2 protein was measured with cycloheximide chase assay. The results of the study indicated overexpression of MAPK11 and RUNX2 in ccRCC tissues and cell lines. MAPK11 and RUNX2 promoted the ccRCC cell proliferation and migration. Additionally, physical interaction took place between RUNX2 and P-MAPK11, which functioned to sustain the stability of RUNX2 protein. The high expression of RUNX2 could neutralize the functional degradation in MAPK11. And the outcomes of the study suggest that the P-MAPK11/RUNX2 axis may be used as a potential therapeutic target of ccRCC.

ABA-triggered ROS burst in rice developing anthers is critical for tapetal programmed cell death induction and heat stress-induced pollen abortion.

High temperatures (HT) cause pollen abortion and poor floret fertility in rice, which is closely associated with excessive accumulation of reactive oxygen species (ROS) in the developing anthers. However, the relationships between accumulation of abscisic acid (ABA) and ROS, and their effects on tapetum-specific programmed cell death (PCD) in HT-stressed anthers are poorly characterised. Here, we determined the spatiotemporal changes in ABA and ROS levels, and their relationships with tapetal PCD under HT exposure. Mutants lacking ABA-activated protein kinase 2 (SAPK2) functions and exogenous ABA treatments were used to explore the effects of ABA signalling on the induction of PCD and ROS accumulation during pollen development. HT-induced pollen abortion was tightly associated with ABA accumulation and oxidative stress. The higher ABA level in HT-stressed anthers resulted in the earlier initiation of PCD induction and subsequently abnormal tapetum degeneration by activating ROS accumulation in developing anthers. Interactions between SAPK2 and DEAD-box ATP-dependent RNA helicase elF4A-1 (RH4) were required for ABA-induced ROS generation in developing anthers. The OsSAPK2 knockout mutants showed the impaired PCD responses in the absence of HT. However, the deficiency of SAPK2 functions did not suppress the ABA-mediated ROS generation in HT-stressed anthers.

The role of MAPK11/12/13/14 (p38 MAPK) protein in dopamine agonist-resistant prolactinomas.

BACKGROUND: Prolactinoma is a functional pituitary adenoma that secretes excessive prolactin. Dopamine agonists (DAs) such as bromocriptine (BRC) are the first-line treatment for prolactinomas, but the resistance rate is increasing year by year, creating a clinical challenge. Therefore, it is urgent to explore the molecular mechanism of bromocriptine resistance in prolactinomas. Activation of the P38 MAPK pathway affects multidrug resistance in tumours. Our previous studies have demonstrated that inhibiting MAPK14 can suppress the occurrence of prolactinoma, but the role of MAPK11/12/13/14 (p38 MAPK) signalling in dopamine agonist-resistant prolactinomas is still unclear. METHODS: A prolactinoma rat model was established to determine the effect of bromocriptine on MAPK11/12/13/14 signalling. DA-resistant GH3 cells and DA-sensitive MMQ cells were used, and the role of MAPK11/12/13/14 in bromocriptine-resistant prolactinomas was preliminarily verified by western blot, RT-qPCR, ELISA, flow cytometry and CCK-8 experiments. The effects of MAPK11 or MAPK14 on bromocriptine-resistant prolactinomas were further verified by siRNA transfection experiments. RESULTS: Bromocriptine was used to treat rat prolactinoma by upregulating DRD2 expression and downregulating the expression level of MAPK11/12/13/14 in vivo experiments. The in vitro experiments showed that GH3 cells are resistant to bromocriptine and that MMQ cells are sensitive to bromocriptine. Bromocriptine could significantly reduce the expression of MAPK12 and MAPK13 in GH3 cells and MMQ cells. Bromocriptine could significantly reduce the expression of MAPK11, MAPK14, NF-κB p65 and Bcl2 in MMQ but had no effect on MAPK11, MAPK14, NF-κB p65 and Bcl2 in GH3 cells. In addition, knockdown of MAPK11 and MAPK14 in GH3 cells by siRNA transfection reversed the resistance of GH3 cells to bromocriptine, and haloperidol (HAL) blocked the inhibitory effect of bromocriptine on MAPK14, MAPK11, and PRL in MMQ cells. Our findings show that MAPK11 and MAPK14 proteins are involved in bromocriptine resistance in prolactinomas. CONCLUSION: Bromocriptine reduces the expression of MAPK11/12/13/14 in prolactinomas, and MAPK11 and MAPK14 are involved in bromocriptine resistance in prolactinomas by regulating apoptosis. Reducing the expression of MAPK11 or MAPK14 can reverse bromocriptine resistance in prolactinomas.

p38ß - MAPK11 and its role in female cancers.

BACKGROUND: The p38MAPK family of Mitogen Activated Protein Kinases are a group of signalling molecules involved in cell growth, survival, proliferation and differentiation. The widely studied p38α isoform is ubiquitously expressed and is implicated in a number of cancer pathologies, as are p38γ and p38δ. However, the mechanistic role of the isoform, p38ß, remains fairly elusive. Recent studies suggest a possible role of p38ß in both breast and endometrial cancer with research suggesting involvement in bone metastasis and cancer cell survival. Female tissue specific cancers such as breast, endometrial, uterine and ovary account for over 3,000,000 cancer related incidents annually; advancements in therapeutics and treatment however require a deeper understanding of the molecular aetiology associated with these diseases. This study provides an overview of the MAPK signalling molecule p38ß (MAPK11) in female cancers using an in-silico approach. METHODS: A detailed gene expression and methylation analysis was performed using datasets from cBioportal, CanSar and MEXPRESS. Breast, Uterine Endometrial, Cervical, Ovarian and Uterine Carcinosarcoma TCGA cancer datasets were used and analysed. RESULTS: Data using cBioportal and CanSAR suggest that expression of p38ß is lower in cancers: BRCA, UCEC, UCS, CESC and OV compared to normal tissue. Methylation data from SMART and MEXPRESS indicate significant probe level variation of CpG island methylation status of the gene MAPK11. Analysis of the genes' two CpG islands shows that the gene was hypermethylated in the CpG1 with increased methylation seen in BRCA, CESC and UCEC cancer data sets with a slight increase of expression recorded in cancer samples. CpG2 exhibited hypomethylation with no significant difference between samples and high levels of expression. Further analysis from MEXPRESS revealed no significance between probe methylation and altered levels of expression. In addition, no difference in the expression of BRCA oestrogen/progesterone/HER2 status was seen. CONCLUSION: This data provides an overview of the expression of p38ß in female tissue specific cancers, showing a decrease in expression of the gene in BRCA, UCEC, CESC, UCS and OV, increasing the understanding of p38ß MAPK expression and offering insight for future in-vitro investigation and therapeutic application.

Phosphorylation of SNX27 by MAPK11/14 links cellular stress-signaling pathways with endocytic recycling.

Endocytosed proteins can be delivered to lysosomes for degradation or recycled to either the trans-Golgi network or the plasma membrane. It remains poorly understood how the recycling versus degradation of cargoes is determined. Here, we show that multiple extracellular stimuli, including starvation, LPS, IL-6, and EGF treatment, can strongly inhibit endocytic recycling of multiple cargoes through the activation of MAPK11/14. The stress-induced kinases in turn directly phosphorylate SNX27, a key regulator of endocytic recycling, at serine 51 (Ser51). Phosphorylation of SNX27 at Ser51 alters the conformation of its cargo-binding pocket and decreases the interaction between SNX27 and cargo proteins, thereby inhibiting endocytic recycling. Our study indicates that endocytic recycling is highly dynamic and can crosstalk with cellular stress-signaling pathways. Suppression of endocytic recycling and enhancement of receptor lysosomal degradation serve as new mechanisms for cells to cope with stress and save energy.

Mitogen-activated protein kinase 11 (MAPK11) maintains growth and photosynthesis of potato plant under drought condition.

KEY MESSAGE: StMAPK11 overexpression promotes potato growth, physiological activities and photosynthesis under drought conditions. Mitogen-activated protein kinases (MAPKs) are import regulators of MAPK pathway in plants under drought condition. However, the critical role in potato (Solanum tuberosum L.) drought resistance is not fully understood. In this study, we aimed to explore the role of StMAPK11 under drought stress. The result of RT-qPCR for assay of StMAPKs expression demonstrated that 15 StMAPKs were differentially expressed in leaves, flowers, petioles, stamens, pistils, stems, stolons, roots, tubers and tuber peels of potato. StMAPKs was dynamically modulated by abiotic stresses and plant hormone treatments, and StMAPK11 was apparently up-regulated under drought conditions. Therefore, the vectors pCPB-StMAPK11 and pCPBI121-miRmapk11 for over-expression and down-regulation of StMAPK11 were constructed, respectively, and introduced into potato cultivar Atlantic. The result showed that StMAPK11 promoted potato growth under drought conditions, as well as the physiological activities evidenced by changes in SOD, CAT and POD activity and H2O2, proline and MDA content. StMAPK11 up-regulation intensified drought resistance of potato plant by elevating antioxidant activities and photosynthesis. Moreover, we consolidated the protective role of StMAPK11 in tobacco and Arabidopsis against drought stress. The result could provide new insights into the function of StMAPK11 in drought response and its possible mechanisms.

p38ß and Cancer: The Beginning of the Road.

The p38 mitogen-activated protein kinase (MAPK) signaling pathway is implicated in cancer biology and has been widely studied over the past two decades as a potential therapeutic target. Most of the biological and pathological implications of p38MAPK signaling are often associated with p38α (MAPK14). Recently, several members of the p38 family, including p38γ and p38δ, have been shown to play a crucial role in several pathologies including cancer. However, the specific role of p38ß (MAPK11) in cancer is still elusive, and further investigation is needed. Here, we summarize what is currently known about the role of p38ß in different types of tumors and its putative implication in cancer therapy. All evidence suggests that p38ß might be a key player in cancer development, and could be an important therapeutic target in several pathologies, including cancer.

Opposing Oncogenic Functions of p38 Mitogen-activated Protein Kinase Alpha and Beta in Human Pancreatic Cancer Cells.

BACKGROUND/AIM: The p38 family of mitogen-activated protein kinases (MAPK) includes four isoforms: p38α, -ß, -γ and -δ. The aim of this study was to elucidate possible functions of p38α and p38ß in human pancreatic cancer. MATERIALS AND METHODS: Isoform expression was determined in seven human pancreatic cancer cell lines. After shRNA based selective knockdown of p38α and p38ß, in vitro growth and migration as well as in vivo tumorigenicity were assessed. RESULTS: All pancreatic cancer cells expressed p38 isoforms. Knockdown of p38α and p38ß inhibited in vitro growth. Migration was markedly reduced in p38α shRNA expressing clones, but not altered by p38ß knockdown. While in vivo inhibition of p38ß decreased tumor formation and growth, the knockdown of p38α significantly enhanced tumorigenicity. CONCLUSION: p38 MAPKs may exert isoform specific functions in pancreatic cancer. Selective targeting may contribute to individualized treatment of pancreatic cancer in the future.

Propofol suppresses the progression of non­small cell lung cancer via downregulation of the miR­21­5p/MAPK10 axis.

Non­small cell lung cancer (NSCLC) accounts for >80% of lung cancer cases and is the leading cause of cancer­associated mortality worldwide. Propofol is an anesthetic drug frequently used during tumor resection. It is also known to exert inhibitory effects on cancer. Although the role of propofol in NSCLC has been reported, its underlying mechanisms remain unknown. The present study aimed therefore to investigate the mechanisms of propofol action on NSCLC. Starbase V3.0 project was used to analyze the expression levels of microRNA­21­5p (miR­21­5p) and mitogen­activated protein kinase 10 (MAPK10) in NSCLC and adjacent normal tissues from patients with NSCLC and the association between miR­21­5p and MAPK10 expression level in NSCLC tissues. The correlation between MAPK10 expression and disease­free survival (DFS) in patients with NSCLC was analyzed using GEPIA software version 1.0. miR­21­5p and MAPK10 expression in tumor and adjacent normal tissues from patients with NSCLC was evaluated by reverse transcription­quantitative (RT­q) PCR and western blotting. Cell viability and apoptosis were assessed by using Cell Counting Kit­8 assay and flow cytometry, respectively. The interaction between miR­21­5p and MAPK10 was predicted by TargetScan/miRanda and verified by dual luciferase assay. The regulatory effect of propofol on miR­21­5p and MAPK10 expression in NSCLC cell lines was examined by RT­qPCR and western blotting. Starbase V3.0 project and the results of the present study indicated that tumor tissues presented a significantly lower MAPK10 level and a higher miR­21­5p level compared with the normal samples, and that miR­21­5p expression was negatively correlated with MAPK10 expression in the tumor tissues of patients with NSCLC. Furthermore, miR­21­5p targeted the 3'­untranslated region of MAPK10. In addition, compared with BEAS­2B cells, a higher miR­21­5p and a lower MAPK10 expression was observed in the NSCLC cell lines A549 and H1299, which was reversed by propofol. The overexpression of miR­21­5p abrogated the effects of propofol on A549 and H1299 cell viability and apoptosis by targeting MAPK10. Taken together, these findings demonstrated that propofol inhibited the viability and promoted the apoptosis of NSCLC cells by downregulating the miR­21­5p/MAPK10 axis.

Roles of p38α and p38ß mitogen­activated protein kinase isoforms in human malignant melanoma A375 cells.

Skin cancer is one of the most common cancers worldwide. Melanoma accounts for ~5% of skin cancers but causes the large majority of skin cancer­related deaths. Recent discoveries have shown that the mitogen­activated protein kinase (MAPK) signaling pathway is critical for melanoma development and progression. Many oncogenic pathways that cause melanoma tumorigenesis have been identified, most of which are due to RAF/MEK/ERK (MAPK) pathway activation. However, the precise role of p38 remains unclear. Using specific short hairpin (sh) RNA to silence p38α and p38ß, the present findings demonstrated that p38α was a crucial factor in regulating cell migration in the A375 melanoma cell line. Silencing p38α downregulated the expression of epithelial­mesenchymal transition markers, such as matrix metallopeptidase (MMP) 2, MMP9, twist family bHLH transcription factor 1, snail family transcriptional repressor 1 and vimentin, while mesenchymal­epithelial transition markers, such as E­cadherin, were upregulated. Of note, the results also demonstrated that p38α silencing impaired vascular endothelial growth factor expression, which regulates tumor angiogenesis. Furthermore, p38α knockdown inhibited cell proliferation in melanoma cells. In addition, silencing p38α induced senescence­like features, but not cell cycle arrest. Expression of the senescence markers p16, p21, p53 and ß­galactosidase was upregulated, and an increase in the number of senescence­associated ß­galactosidase­positive cells was observed in a p38α knockdown stable clone. However, no significant difference was found between control and p38ß stable knockdown cells. Taken together, the present results suggested that p38α knockdown impaired migration and proliferation, and increased senescence, in A375 melanoma cells. However, p38ß may not be involved in melanoma tumorigenesis. Therefore, targeting p38α may be a valuable approach towards inhibiting tumor growth and metastasis in patients with melanoma.

Knocking down of LINC01220 inhibits proliferation and induces apoptosis of endometrial carcinoma through silencing MAPK11.

Background: Endometrial carcinoma (EC) still threatens the health of women. Thus, to explore how long intergenic non-protein coding RNA 01220 regulates the development of EC.Methods: Whole genome expression profile data of EC and paracancerous tissues in TCGA database were downloaded. LINC01220 expression in EC and paracancerous tissues of patients in our hospital were detected by qRT-PCR. Furthermore, the relationship between LINC01220 expression and clinicopathological features of EC patients was analyzed. After transfection with sh-LINC01220 and pcDNA-MAPK11 (mitogen-activated protein kinase) in EC cells, proliferative, colony formation abilities and apoptosis were determined by cell counting kit-8 (CCK-8), colony formation assay and flow cytometry, respectively. Western blot was conducted to determine the regulatory role of LINC01220 on MAPK11.Results: TCGA data showed that LINC01220 expression is markedly higher in EC tissues than that of paracancerous tissues, which was consistent without detection in EC patients of our hospital. LINC01220 expression was positively correlated to pathological grade and International Federation of Gynecology and Obstetrics (FIGO) stage of EC patients. After knockdown of LINC01220 in EC cells, proliferative and colony formation abilities decreased, whereas apoptotic rate increased. Cor function analysis revealed the positive correlation between LINC01220 and MAPK11 in EC. MAPK11 expression was regulated by LINC01220 in EC cells. Overexpression of MAPK11 can reverse the tumor suppressing effect of LINC01220 on EC.Conclusions: LINC01220 promotes EC development by stimulating proliferation and inhibiting apoptosis of EC cells through up-regulating MAPK11.

Activator protein-1 and caspase 8 mediate p38α MAPK-dependent cardiomyocyte apoptosis induced by palmitic acid.

Lipoapoptosis of cardiomyocytes may underlie diabetic cardiomyopathy. Numerous forms of cardiomyopathies share a common end-pathway in which apoptotic loss of cardiomyocytes is mediated by p38α mitogen activated protein kinase (MAPK). Although we have previously shown that palmitic acid (PA), a saturated fatty acid (SFA) elevated in plasma of type 2 diabetes mellitus and morbid obesity, induces apoptosis in cardiomyocytes via p38α MAPK-dependent signaling, the downstream cascade events that cause cell death remain unknown. The objective of this study was to investigate mechanisms involved in palmitic acid-induced cardiomyocyte apoptosis. Human adult ventricular cardiomyocyte line (AC16 cells) exposed to high physiological levels of PA for 16 h showed enhanced transcription and phosphorylation of c-fos and c-jun subunits of AP-1 and transcription of caspase 8. When AC16 cells were transfected with small interfering RNA specific against p38α MAPK (si-p38α) for 24 or 48 h, the amplified phosphorylation of c-fos was dose-dependently attenuated, and procaspase 8 was dose-dependently reduced. With translational knockdown of c-fos, PA-induced apoptosis was diminished. Inhibition of caspase 8 for 24 h reduced apoptosis in PA-treated cardiomyocytes. These findings provide evidence for induction of apoptosis in cardiomyocytes exposed to high SFA by a novel pathway requiring activation of c-fos/AP-1 and caspase 8. These results demonstrate how elevated plasma SFA may lead to continual and cumulative loss of cardiomyocytes and potentially contribute to the development of diabetic cardiomyopathy.

Beneficial Effect of Silymarin in Pressure Overload Induced Experimental Cardiac Hypertrophy.

The present investigation was undertaken to study the effect of silymarin on cardiac hypertrophy induced by partial abdominal aortic constriction (PAAC) in Wistar rats. Silymarin was administered for 9 weeks at the end of which we evaluated hypertrophic, hemodynamic, non-specific cardiac markers, oxidative stress parameters, and determined mitochondrial DNA concentration. Hypertrophic control animals exhibited cardiac hypertrophy, altered hemodynamics, oxidative stress, and decreased mitochondrial DNA (mtDNA) concentration. Treatment with silymarin prevented cardiac hypertrophy, improved hemodynamic functions, prevented oxidative stress and increased mitochondrial DNA concentration. Docking studies revealed that silymarin produces maximum docking score with mitogen-activated protein kinases (MAPK) p38 as compared to other relevant proteins docked. Moreover, PAAC-control rats exhibited significantly increased expression of MAPK p38ß mRNA levels which were significantly decreased by the treatment of silymarin. Our data suggest that silymarin produces beneficial effects on cardiac hypertrophy which are likely to be mediated through inhibition of MAPK p38ß.

The sucrose non-fermenting-1-related protein kinases SAPK1 and SAPK2 function collaboratively as positive regulators of salt stress tolerance in rice.

BACKGROUND: The sucrose non-fermenting-1-related protein kinase 2 family (SnRK2s) unifies different abiotic stress signals in plants. To date, the functions of two rice SnRK2s, osmotic stress/ABA-activated protein kinase 1 (SAPK1) and SAPK2, have been unknown. We investigated their roles in response to salt stress by generating loss-of-function lines using the CRISPR/Cas9 system and by overexpressing these proteins in transgenic rice plants. RESULTS: Expression profiling revealed that SAPK1 and SAPK2 expression were strongly induced by drought, NaCl, and PEG treatment, but not by ABA. SAPK2 expression was highest in the leaves, followed by the roots, whereas SAPK1 was highest expressed in roots followed by leaves. Both proteins were localized to the nucleus and the cytoplasm. Under salt stress, sapk1, sapk2 and, in particular, sapk1/2 mutants, exhibited reduced germination rates, more severe growth inhibition, more distinct chlorosis, reduced chlorophyll contents, and reduced survival rates in comparison with the wild-type plants. In contrast, SAPK1- and SAPK2-overexpression lines had increased germination rates and reduced sensitivities to salt; including mild reductions in growth inhibition, reduced chlorosis, increased chlorophyll contents and improved survival rates in comparison with the wild-type plants. These results suggest that SAPK1 and SAPK2 may function collaboratively as positive regulators of salt stress tolerance at the germination and seedling stages. We also found that SAPK1 and SAPK2 affected the osmotic potential following salt stress by promoting the generation of osmotically active metabolites such as proline. SAPK1 and SAPK2 also improved reactive oxygen species (ROS) detoxification following salt stress by promoting the generation of ROS scavengers such as ascorbic acid, and by increasing the expression levels of proteins such as superoxide dismutase (SOD) and catalase (CAT). SAPK1 and SAPK2 may function collaboratively in reducing Na+ toxicity by affecting the Na+ distribution between roots and shoots, Na+ exclusion from the cytoplasm, and Na+ sequestration into the vacuoles. These effects may be facilitated through the expression of Na+-and K+-homeostasis-related genes. CONCLUSION: SAPK1 and SAPK2 may function collaboratively as positive regulators of salt stress tolerance at the germination and seedling stages in rice. SAPK1 and SAPK2 may be useful to improve salt tolerance in crop plants.

p38b and JAK-STAT signaling protect against Invertebrate iridescent virus 6 infection in Drosophila.

The fruit fly Drosophila melanogaster is a powerful model system for the study of innate immunity in vector insects as well as mammals. For vector insects, it is particularly important to understand all aspects of their antiviral immune defenses, which could eventually be harnessed to control the transmission of human pathogenic viruses. The immune responses controlling RNA viruses in insects have been extensively studied, but the response to DNA virus infections is poorly characterized. Here, we report that infection of Drosophila with the DNA virus Invertebrate iridescent Virus 6 (IIV-6) triggers JAK-STAT signaling and the robust expression of the Turandots, a gene family encoding small secreted proteins. To drive JAK-STAT signaling, IIV-6 infection more immediately induced expression of the unpaireds, a family of IL-6-related cytokine genes, via a pathway that required one of the three Drosophila p38 homologs, p38b. In fact, both Stat92E and p38b were required for the survival of IIV-6 infected flies. In addition, in vitro induction of the unpaireds required an NADPH-oxidase, and in vivo studies demonstrated Nox was required for induction of TotA. These results argue that ROS production, triggered by IIV-6 infection, leads to p38b activation and unpaired expression, and subsequent JAK-STAT signaling, which ultimately protects the fly from IIV-6 infection.

Intrathecal administration of antisense oligonucleotide against p38α but not p38ß MAP kinase isoform reduces neuropathic and postoperative pain and TLR4-induced pain in male mice.

p38 mitogen-activated protein kinase (MAPK) consists of two major isoforms: p38α and p38ß; however, it remains unclear which isoform is more important for chronic pain development. Recently, we developed potent, long-lasting, and p38 MAPK subtype-specific antisense oligonucleotides (ASOs). We examined the therapeutic effects of isoform-specific ASOs in several chronic pain models following single intrathecal injection (300 µg/10 µl) in CD1 mice. In the chronic constriction injury (CCI) model, p38α MAPK ASO, given on post-operative day 5, reduced CCI-induced mechanical allodynia in male but not female mice. In contrast, mechanical allodynia after CCI in both sexes was not affected by p38ß MAPK ASO. Intrathecal injection of p38α or p38ß ASO resulted in a partial reduction (≈ 50%) of spinal p38α or p38ß mRNA level, respectively, in both sexes at two weeks. In contrast, intrathecal injection of the ASOs did not affect p38α and p38ß MAPK mRNA levels in dorsal root ganglia. Intrathecal p38α ASO also reduced postoperative pain (mechanical and cold allodynia) in male mice after tibia fracture. However, intrathecal p38α ASO had no effect on mechanical allodynia in male mice after paclitaxel treatment. Intrathecal p38α MAPK ASO pre-treatment also prevented TLR4-mediated mechanical allodynia and downregulated levels of p38α MAPK and phosphorylated p38 MAPK following intrathecal treatment of lipopolysaccharide. In summary, our findings suggest that p38α MAPK is the major p38 MAPK isoform in the spinal cord and regulates chronic pain in a sex and model-dependent manner. Intrathecal p38α MAPK ASO may offer a new treatment for some chronic pain conditions.

p38α regulates cytokine-induced IFNγ secretion via the Mnk1/eIF4E pathway in Th1 cells.

The p38 mitogen-activated protein kinase (MAPK) pathway is involved in the regulation of immune and inflammatory processes. We used p38α-conditional, p38ß-deficient and p38α/ß double-null mouse models to address the role of these two p38 MAPK in CD4+ T cells, and found that p38α deficiency causes these cells to hyperproliferate. Our studies indicate that both p38α and p38ß are dispensable for T helper cell type 1 (Th1) differentiation but, by controlling interferon (IFN)γ and tumor necrosis factor (TNF)α production, are critical for normal Th1 effector function. We found that both p38α and p38ß modulate T-cell receptor-induced IFNγ and TNFα production, whereas only p38α regulates cytokine-induced IFNγ production. The lack of p38α and p38ß did not affect transcription and mRNA stability of Ifng. However, the absence of p38α in Th1 cells resulted in a decreased MNK1 phosphorylation after cytokine activation, and MNK1 inhibition blocked IFNγ production. Our results indicate that p38α regulates IFNγ secretion through the activation of the MNK1/eIF4E pathway of translation initiation and identify specific functions for p38α and p38ß in T-cell proliferation.

Loss of Functionally Redundant p38 Isoforms in T Cells Enhances Regulatory T Cell Induction.

The evolutionarily conserved protein kinase p38 mediates innate resistance to environmental stress and microbial infection. Four p38 isoforms exist in mammals and may have been co-opted for new roles in adaptive immunity. Murine T cells deficient in p38α, the ubiquitously expressed p38 isoform, showed no readily apparent cell-autonomous defects while expressing elevated amounts of another isoform, p38ß. Mice with T cells simultaneously lacking p38α and p38ß displayed lymphoid atrophy and elevated Foxp3+ regulatory T cell frequencies. Double deficiency of p38α and p38ß in naïve CD4+ T cells resulted in an attenuation of MAPK-activated protein kinase (MK)-dependent mTOR signaling after T cell receptor engagement, and enhanced their differentiation into regulatory T cells under appropriate inducing conditions. Pharmacological inhibition of the p38-MK-mTOR signaling module produced similar effects, revealing potential for therapeutic applications.

Activin A induces skeletal muscle catabolism via p38ß mitogen-activated protein kinase.

BACKGROUND: Activation of type IIB activin receptor (ActRIIB) in skeletal muscle leads to muscle atrophy because of increased muscle protein degradation. However, the intracellular signalling mechanism that mediates ActRIIB-activated muscle catabolism is poorly defined. METHODS: We investigated the role of p38ß mitogen-activated protein kinases (MAPK) in mediating ActRIIB ligand activin A-activated muscle catabolic pathways in C2C12 myotubes and in mice with perturbation of this kinase pharmacologically and genetically. RESULTS: Treatment of C2C12 myotubes with activin A or myostatin rapidly activated p38 MAPK and its effector C/EBPß within 1 h. Paradoxically, Akt was activated at the same time through a p38 MAPK-independent mechanism. These events were followed by up-regulation of ubiquitin ligases atrogin1 (MAFbx) and UBR2 (E3α-II), as well as increase in LC3-II, a marker of autophagosome formation, leading to myofibrillar protein loss and myotube atrophy. The catabolic effects of activin A were abolished by p38α/ß MAPK inhibitor SB202190. Using small interfering RNA-mediated gene knockdown, we found that the catabolic activity of activin A was dependent on p38ß MAPK specifically. Importantly, systemic administration of activin A to mice similarly activated the catabolic pathways in vivo, and this effect was blocked by SB202190. Further, activin A failed to activate the catabolic pathways in mice with muscle-specific knockout of p38ß MAPK. Interestingly, activin A up-regulated MuRF1 in a p38 MAPK-independent manner, and MuRF1 did not appear responsible for activin A-induced myosin heavy chain loss and muscle atrophy. CONCLUSIONS: ActRIIB-mediated activation of muscle catabolism is dependent on p38ß MAPK-activated signalling.

Complex genetics architecture contributes to Salmonella resistance in AcB60 mice.

Human infection with Salmonella is of global public health concern. In low- and middle-income countries, Salmonella infection is a major source of disease in terms of both mortality and morbidity, while in high-income nations, the pathogen is an ongoing threat to food security. The outcome of infection with Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) in mouse models is dependent upon a coordinated and complex immune response. A panel of recombinant congenic strains (RCS) derived from the reciprocal double backcross of A/J and C57BL/6J mice has been screened for their susceptibility to Salmonella infection, and the RCS AcB60 was identified to be the most resistant strain to Salmonella infection, more resistant than the parental strain A/J. These mice are known to carry resistant alleles at three well-defined Salmonella susceptibility loci, Slc11a1 Ity (solute carrier family 11 member 1; Immunity to Typhimurium locus), Pklr Ity4 (pyruvate kinase liver and red blood cell; Ity4 locus), and Ity5. In the current study, we used interval mapping to validate a locus on Chr 15, named Ity8, linked to Salmonella resistance in AcB60 mice. Global gene expression analysis during infection identified AcB60-specific expression of genes involved in Ccr7 signaling, including downstream effector Mapk11 (mitogen-activated protein kinase 11), located within the Ity8 interval, and representing a potential positional candidate gene. An additional region on Chr 18 of C57BL/6J descent was shown to be associated with increase resistance in AcB60. These observations provide an opportunity to achieve new insight into the complex genetics of resistance to Salmonella infection in the context of mouse models of human infection with Salmonella Typhimurium.