Stress-activated Mitogen-activated Protein Kinase Research Articles

STEAP2 promotes hepatocellular carcinoma progression via increased copper levels and stress-activated MAP kinase activity

Six Transmembrane Epithelial Antigen of Prostate 2 (STEAP2) belongs to a family of metalloreductases, which indirectly aid in uptake of iron and copper ions. Its role in hepatocellular carcinoma (HCC) remains to be characterized. Here, we report that STEAP2 expression was upregulated in HCC tumors compared with paired adjacent non-tumor tissues by RNA sequencing, RT-qPCR, Western blotting, and immunostaining. Public HCC datasets demonstrated upregulated STEAP2 expression in HCC and positive association with tumor grade. Transient and stable knockdown (KD) of STEAP2 in HCC cell lines abrogated their malignant phenotypes in vitro and in vivo, while STEAP2 overexpression showed opposite effects. STEAP2 KD in HCC cells led to significant alteration of genes associated with extracellular matrix organization, cell adhesion/chemotaxis, negative enrichment of an invasiveness signature gene set, and inhibition of cell migration/invasion. STEAP2 KD reduced intracellular copper levels and activation of stress-activated MAP kinases including p38 and JNK. Treatment with copper rescued the reduced HCC cell migration due to STEAP2 KD and activated p38 and JNK. Furthermore, treatment with p38 or JNK inhibitors significantly inhibited copper-mediated cell migration. Thus, STEAP2 plays a malignant-promoting role in HCC cells by driving migration/invasion via increased copper levels and MAP kinase activities. Our study uncovered a novel molecular mechanism contributing to HCC malignancy and a potential therapeutic target for HCC treatment.

JNK inhibition enhances cell-cell adhesion impaired by desmoglein3 gene disruption in keratinocytes.

c-Jun NH2-terminal protein kinase (JNK) and p38 are stress-activated mitogen-activated protein kinases (MAPK) that are phosphorylated by various stimuli. It has been reported that the loss of desmoglein (DSG) 3, a desmosomal transmembrane core molecule, in keratinocytes impairs cell-cell adhesion accompanied by p38 MAPK activation. To understand the biological role of DSG3 in desmosomes and its relationship with stress-activated MAPKs, we established DSG3 knockout keratinocytes (KO cells). Wild-type cells showed a linear localization of DSG1 to cell-cell contacts, whereas KO cells showed a remarkable reduction despite the increased protein levels of DSG1. Cell-cell adhesion in KO cells was impaired over time, as demonstrated by dispase-based dissociation assays. The linear localization of DSG1 to cell-cell contacts and the strength of cell-cell adhesion were promoted by the pharmacological inhibition of JNK. Conversely, pharmacological activation of JNK, but not p38 MAPK, in wild-type cells reduced the linear localization of DSG1 in cell-cell contacts. Our data indicate that DSG1 and DSG2 in KO cells cannot compensate for the attenuation of cell-cell adhesion strength caused by DSG3 deficiency and that JNK inhibition restores the strength of cell-cell adhesion by increasing the linear localization of DSG1 in cell-cell contacts in KO cells. Inhibition of JNK signaling may improve cell-cell adhesion in diseases in which DSG3 expression is impaired.

Synergistic Anti-Tumor Effects in RAS Mut Multiple Myeloma By Targeting MAP4K2 and RAS Pathways

Mitogen-activated protein kinase kinase kinase kinase 2 (MAP4K2) is an important key regulator of the stress-activated MAPK core signaling pathways. Our previous work demonstrated that MAP4K2 is highly expressed in multiple myeloma (MM) cells, and MM cells carrying a RAS mutation are more vulnerable to MAP4K2 inhibition, associated with the downregulation of critical transcriptional factors including IKZF1/3, BCL-6, and c-MYC proteins ( Li et al. Blood 2021). Targeting the aberrant RAS/MAPK signaling, MEK inhibitors have been shown to induce cytotoxicity in MM (De la Puente, P. et al. Blood Cancer J. 2016). Thus, we used a recently developed MEK inhibitor (MEKi) Trametinib to investigate the therapeutic potential of combined MEK and MAP4K2 signaling inhibition in RAS-driven MM. Tet-on sh-MAP4K2 lentivirus was introduced into RAS Mut MM cells to establish the inducible MAP4K2 knockdown cells upon doxycycline treatment. To examine the combined effects, Tet-on sh-MAP4K2 RAS Mut MM cells were treated with doxycycline to silence MAP4K2 expression, followed by treatment of MEKi Trametinib at different dosages. Cell proliferation, apoptosis, and cell cycle were analyzed five days later. Data showed that MAP4K2 silencing combined with MEK inhibition significantly decreased cell proliferation to 10% compared with MEKi alone 32% ( p<0.01) by MTS assays, and enhanced cell apoptosis (MEKi alone vs. with MAP4K2 silencing: 26% vs 91%, p<0.01). Cell cycle assay demonstrated that MEKi induced G1 arrest in RAS Mut MM cells (MEKi alone:76% vs vehicle control: 54%, p<0.01), which was also significantly higher in combination with MAP4K2 silencing (92%). Western blot assay confirmed that MAP4K2 silencing combined with MEKi significantly enhanced the downregulation of IKZF1 and c-MYC compared to the MEKi treatment alone. These data suggest that the MEKi and MAP4K2 inhibition combination has synergetic anti-MM effects. To further confirm the synergetic effects, we tested the combined effects of MEKi with the MAP4K2 kinase inhibitor TL4-12. H929 (N-Ras Mut) cells were treated by vehicle control, TL4-12 (2 uM) alone, MEKi (200 nM) alone, or TL4-12 + MEKi for 4 days, followed by an apoptosis assay. The combination of TL4-12 and MEKi strongly enhanced the cytotoxicity effects compared to the single-agent treatments. Consistently, the carboxyfluorescein diacetate succinimidyl ester (CFSE) cell proliferation assay confirmed that dual treatment significantly delayed H929 cell proliferation compared to the single-agent treatments (percentage of proliferating cells: TL4-12 alone: 86.2%; MEKi alone: 89.03%; dual treatment: 18.9%. p<0.01). Western blotting assay further confirmed that dual treatment of MEKi and MAP4K2i enhanced the decrease in MEK1/2 and ERK1/2 phosphorylation and downregulation of transcriptional factors IKZF1 and c-MYC. Taken together, our findings demonstrate that the combination of MAP4K2 inhibition with MEKi results in synergetic anti-MM effects in RAS mutation myeloma, therefore could be a potent novel therapeutic regimen for patients with relapsed/refractory multiple myeloma.

Stress-induced nuclear speckle reorganization is linked to activation of immediate early gene splicing.

Current models posit that nuclear speckles (NSs) serve as reservoirs of splicing factors and facilitate posttranscriptional mRNA processing. Here, we discovered that ribotoxic stress induces a profound reorganization of NSs with enhanced recruitment of factors required for splice-site recognition, including the RNA-binding protein TIAR, U1 snRNP proteins and U2-associated factor 65, as well as serine 2 phosphorylated RNA polymerase II. NS reorganization relies on the stress-activated p38 mitogen-activated protein kinase (MAPK) pathway and coincides with splicing activation of both pre-existing and newly synthesized pre-mRNAs. In particular, ribotoxic stress causes targeted excision of retained introns from pre-mRNAs of immediate early genes (IEGs), whose transcription is induced during the stress response. Importantly, enhanced splicing of the IEGs ZFP36 and FOS is accompanied by relocalization of the corresponding nuclear mRNA foci to NSs. Our study reveals NSs as a dynamic compartment that is remodeled under stress conditions, whereby NSs appear to become sites of IEG transcription and efficient cotranscriptional splicing.

Expression and clinical significance of miR-8078 in patients with congenital heart disease-associated pulmonary arterial hypertension

ObjectivesThis study aimed to analyze the plasma levels of miR-8078 in patients with congenital heart disease-associated pulmonary arterial hypertension (CHD-PAH) and to explore the diagnostic value and potential mechanisms of miR-8078 in CHD-PAH. MethodsPlasma samples were collected from 110 patients with congenital heart disease. Subsequently, based on the mean pulmonary artery pressure (PAPm) measured via right heart catheterization, the patients were divided into three groups: no-PAH group (Group W, PAPm < 25 mmHg), mild group (Group M, 25 mmHg ≤ PAPm < 35 mmHg), and moderate-to-severe group (Group H, PAPm ≥ 35 mmHg). The study also involved a control group (Group C) comprised of 40 healthy individuals. The miR-8078 expression levels were determined by means of reverse transcription-polymerase chain reaction (RT-PCR). The target genes and biological functions of miR-8078 were predicted using TargetScan, PicTar, and miRDB software. Statistical analysis was performed to evaluate the correlation between miR-8078 and hemodynamic parameters in CHD-PAH, in addition to its diagnostic value. ResultsThe plasma miR-8078 expression levels were significantly higher in the moderate-to-severe group when compared with the control group, no-PAH group, and mild group (p < 0.05). Furthermore, the mild group and no-PAH group showed significantly higher miR-8078 expression levels when compared with the control group (p < 0.05). Both results were consistent with the high-throughput sequencing results. KEGG pathway analysis of the miR-8078 target genes revealed associations with morphine addiction, ubiquitin-mediated proteolysis, and parathyroid hormone synthesis and secretion. GO enrichment analysis indicated the involvement of miR-8078 in the regulation of transcription by RNA polymerase II, the positive regulation of stress-activated MAPK cascade, the transmembrane transport of CI- and K+ ions, chromatin organization, and atrioventricular valve morphogenesis. Correlation analysis showed that the miR-8078 expression levels were positively correlated with the pulmonary artery systolic pressure, mean pulmonary artery pressure, and pulmonary vascular resistance (correlation coefficients of 0.404, 0.397, and 0.283, respectively; all p < 0.05). Univariate and multivariate regression analyses revealed plasma miR-8078 (odds ratio: 1.475, 95 % confidence interval: 1.053–2.065, p < 0.05) to be an independent risk factor for CHD-PAH. Receiver operating characteristic curve analysis revealed that the area under the curve (AUC) for miR-8078 alone and for B-type natriuretic peptide alone in diagnosing CHD-PAH was 0.686 and 0.851, respectively, while the AUC for a combined diagnosis was 0.874, which was higher than that associated with the individual diagnoses (p < 0.05). ConclusionThe findings of this study suggest that miR-8078 is upregulated in CHD-PAH, while the results of the bioinformatics analysis indicate its involvement in the pathogenesis of CHD-PAH, suggesting it to be a potential therapeutic target or biomarker.

Impact of curcumin on p38 MAPK: therapeutic implications.

Curcumin (diferuloylmethane) is a herbal remedy which possesses numerous biological attributes including anti-inflammatory, anti-oxidant and anti-cancer properties. Curcumin has been shown to impact a number of signaling pathways including nuclear factor kappa B (NF-KB), reactive oxygen species (ROS), Wingless/Integrated (Wnt), Janus kinase-signal transducer and activator of mitogen-activated protein kinase (MAPK) and transcription (JAK/STAT). P38 belongs to the MAPKs, is known as a stress-activated MAPK and is involved in diverse biological responses. P38 is activated in various signaling cascades. P38 plays a role in inflammation, cell differentiation, proliferation, motility and survival. This cascade can serve as a therapeutic target in many disorders. Extensive evidence confirms that curcumin impacts the P38 MAPK signaling pathway, through which it exerts anti-inflammatory, neuroprotective, and apoptotic effects. Hence, curcumin can positively affect inflammatory disorders and cancers, as well as to increase glucose uptake in cells. This review discusses the pharmacological and therapeutic effects of curcumin as effected through p38 MAPK.

Fungal plant pathogen "mutagenomics" reveals tagged and untagged mutations in Zymoseptoria tritici and identifies SSK2 as key morphogenesis and stress-responsive virulence factor.

"Mutagenomics" is the combination of random mutagenesis, phenotypic screening, and whole-genome re-sequencing to uncover all tagged and untagged mutations linked with phenotypic changes in an organism. In this study, we performed a mutagenomics screen on the wheat pathogenic fungus Zymoseptoria tritici for altered morphogenetic switching and stress sensitivity phenotypes using Agrobacterium-mediated "random" T-DNA mutagenesis (ATMT). Biological screening identified four mutants which were strongly reduced in virulence on wheat. Whole genome re-sequencing defined the positions of the T-DNA insertion events and revealed several unlinked mutations potentially affecting gene functions. Remarkably, two independent reduced virulence mutant strains, with similarly altered stress sensitivities and aberrant hyphal growth phenotypes, were found to have a distinct loss of function mutations in the ZtSSK2 MAPKKK gene. One mutant strain had a direct T-DNA insertion affecting the predicted protein's N-terminus, while the other possessed an unlinked frameshift mutation towards the C-terminus. We used genetic complementation to restore both strains' wild-type (WT) function (virulence, morphogenesis, and stress response). We demonstrated that ZtSSK2 has a non-redundant function with ZtSTE11 in virulence through the biochemical activation of the stress-activated HOG1 MAPK pathway. Moreover, we present data suggesting that SSK2 has a unique role in activating this pathway in response to specific stresses. Finally, dual RNAseq-based transcriptome profiling of WT and SSK2 mutant strains revealed many HOG1-dependent transcriptional changes in the fungus during early infection and suggested that the host response does not discriminate between WT and mutant strains during this early phase. Together these data define new genes implicated in the virulence of the pathogen and emphasise the importance of a whole genome sequencing step in mutagenomic discovery pipelines.

Maresin-1 improves LPS-induced depressive-like behavior by inhibiting hippocampal microglial activation

Maresin-1 is an antiphlogistic agonist synthesized by macrophages from docosahexaenoic acid (DHA). It has both anti-inflammatory and pro-inflammatory properties and has been found to enhance neuroprotection and cognitive function. However, there is limited knowledge of its effects on depression and the potential mechanism remains unclear. In this study, the effects of Maresin-1 on lipopolysaccharide (LPS)-induced depressive symptoms and neuroinflammation were investigated in mice and the possible cellular and molecular mechanisms were further clarified. Maresin-1 treatment (5 μg/kg, i.p.) led to improved tail suspension times, as well as distances moved in an open-field test but it did not improve reductions in sugar-water consumption in mice with depressive-like behaviors induced by LPS (1 mg/kg, i.p.); TSPO PETCT scanning showed that Maresin-1 reduced the standardized uptake value (SUV) of [18 F] DPA-714 in brain regions associated with depression (e.g., hippocampus and pre-frontal cortex), while immunofluorescence of hippocampal and indicated that Maresin-1 inhibited microglial activation reducing the expression of the pro-inflammatory cytokine IL-1β and NLRP3. The RNA sequencing of mouse hippocampi showed that genes expressed differentially between Maresin-1-treated and LPS-treated tissue were associated with tight connections between cells and the stress-activated MAPK cascade negative regulatory pathways. Overall, this study demonstrates that peripheral application of Maresin-1 could partially relieve LPS-induced depressive-like behaviors and showed for the first time that this effect was related to its anti-inflammatory action on microglia, thus providing new clues for the pharmacological mechanism underlying the anti-depression properties of Maresin-1.

Stress-induced cell depolarization through the MAP kinase-Cdc42 axis.

General stress responses, which sense environmental or endogenous signals, aim at promoting cell survival and fitness during adverse conditions. In eukaryotes, mitogen-activated protein (MAP) kinase-driven cascades trigger a shift in the cell's gene expression program as a cellular adaptation to stress. Here, we review another aspect of activated MAP kinase cascades reported in fission yeast: the transient inhibition of cell polarity in response to oxidative stress. The phosphorylation by a stress-activated MAP kinase of regulators of the GTPase cell division cycle 42 (Cdc42) causes a transient inhibition of polarized cell growth. The formation of growth sites depends on limiting and essential polarity components. We summarize here some processes in which inhibition of Cdc42 may be a general mechanism to regulate polarized growth also under physiological conditions.

Identification of key genes involved in neural regeneration and the repairing effect of BDNF-overexpressed BMSCs on spinal cord ischemia-reperfusion injury in rats

Bone marrow mesenchymal stem cells (BMSCs) can repair spinal cord ischemia-reperfusion injury (SCII); however, only a few BMSCs are usually located in the injured spinal cord. Since the brain-derived neurotrophic factor (BDNF) can promote neural development and maturation, we hypothesised that BDNF-overexpressed BMSCs can ameliorate SCII more effectively than BMSCs alone. To determine the effect of BDNF overexpression on SCII repair, BDNF-overexpressed BMSCs and BMSCs were transplanted into SCII rats. Our results revealed that BDNF-overexpressed BMSCs can better promote the recovery of damaged spinal cords than BMSCs alone. Gene chip detection of spinal cord tissues showed 803 differentially expressed genes in all groups. BTG anti-proliferation factor 2 (Btg2), FOS like 2 (Fosl2), early growth response protein 1 (Egr1), and serpin family E member 1 (Serpine1) were identified as key interrelated genes based on their expression trends, as validated via quantitative PCR and protein–protein interaction network analysis. A co-expression network was constructed to further explore the role of the candidate key genes using Pearson correlation analysis. Cluster 5 was identified as the key cluster using community discovery algorithms. Functional analysis of Cluster 5 genes revealed that this cluster was mainly involved in the stress-activated MAPK cascade, p38MAPK cascade, and apoptosis. Notably, Egr1 may play an important role in SCII repair as the top hub gene in Cluster 5. Therefore, the repair activity of transplanted BDNF-overexpressed BMSCs in SCII rats is better than that of BMSCs alone, which may be regulated by the interactions between Btg2, Fosl2, Egr1, Serpine1, and BDNF.

Stress Activated MAP Kinases and Cyclin-Dependent Kinase 5 Mediate Nuclear Translocation of Nrf2 via Hsp90α-Pin1-Dynein Motor Transport Machinery

Non-lethal low levels of oxidative stress leads to rapid activation of the transcription factor nuclear factor-E2-related factor 2 (Nrf2), which upregulates the expression of genes important for detoxification, glutathione synthesis, and defense against oxidative damage. Stress-activated MAP kinases p38, ERK, and JNK cooperate in the efficient nuclear accumulation of Nrf2 in a cell-type-dependent manner. Activation of p38 induces membrane trafficking of a glutathione sensor neutral sphingomyelinase 2, which generates ceramide upon depletion of cellular glutathione. We previously proposed that caveolin-1 in lipid rafts provides a signaling hub for the phosphorylation of Nrf2 by ceramide-activated PKCζ and casein kinase 2 to stabilize Nrf2 and mask a nuclear export signal. We further propose a mechanism of facilitated Nrf2 nuclear translocation by ERK and JNK. ERK and JNK phosphorylation of Nrf2 induces the association of prolyl cis/trans isomerase Pin1, which specifically recognizes phosphorylated serine or threonine immediately preceding a proline residue. Pin1-induced structural changes allow importin-α5 to associate with Nrf2. Pin1 is a co-chaperone of Hsp90α and mediates the association of the Nrf2-Pin1-Hsp90α complex with the dynein motor complex, which is involved in transporting the signaling complex to the nucleus along microtubules. In addition to ERK and JNK, cyclin-dependent kinase 5 could phosphorylate Nrf2 and mediate the transport of Nrf2 to the nucleus via the Pin1-Hsp90α system. Some other ERK target proteins, such as pyruvate kinase M2 and hypoxia-inducible transcription factor-1, are also transported to the nucleus via the Pin1-Hsp90α system to modulate gene expression and energy metabolism. Notably, as malignant tumors often express enhanced Pin1-Hsp90α signaling pathways, this provides a potential therapeutic target for tumors.

Proteome-wide screening for mitogen-activated protein kinase docking motifs and interactors.

Essential functions of mitogen-activated protein kinases (MAPKs) depend on their capacity to selectively phosphorylate a limited repertoire of substrates. MAPKs harbor a conserved groove located outside of the catalytic cleft that binds to short linear sequence motifs found in substrates and regulators. However, the weak and transient nature of these "docking" interactions poses a challenge to defining MAPK interactomes and associated sequence motifs. Here, we describe a yeast-based genetic screening pipeline to evaluate large collections of MAPK docking sequences in parallel. Using this platform, we analyzed a combinatorial library based on the docking sequences from the MAPK kinases MKK6 and MKK7, defining features critical for binding to the stress-activated MAPKs JNK1 and p38α. Our screen of a library consisting of ~12,000 sequences from the human proteome revealed multiple MAPK-selective interactors, including many that did not conform to previously defined docking motifs. Analysis of p38α/JNK1 exchange mutants identified specific docking groove residues that mediate selective binding. Last, we verified that docking sequences identified in the screen functioned in substrate recruitment in vitro and in cultured cells. Together, these studies establish an approach to characterize MAPK docking sequences and provide a resource for future investigation of signaling downstream of p38 and JNK.

Manganese Stress Tolerance Depends on Yap1 and Stress-Activated MAP Kinases

Understanding which intracellular signaling pathways are activated by manganese stress is crucial to decipher how metal overload compromise cellular integrity. Here, we unveil a role for oxidative and cell wall stress signaling in the response to manganese stress in yeast. We find that the oxidative stress transcription factor Yap1 protects cells against manganese toxicity. Conversely, extracellular manganese addition causes a rapid decay in Yap1 protein levels. In addition, manganese stress activates the MAPKs Hog1 and Slt2 (Mpk1) and leads to an up-regulation of the Slt2 downstream transcription factor target Rlm1. Importantly, Yap1 and Slt2 are both required to protect cells from oxidative stress in mutants impaired in manganese detoxification. Under such circumstances, Slt2 activation is enhanced upon Yap1 depletion suggesting an interplay between different stress signaling nodes to optimize cellular stress responses and manganese tolerance.

Identification of TSC22D3 As a Novel Immune-Related Prognostic Biomarker of Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is the most common type of hematological neoplasms in adults. TSC22 Domain Family Member 3 (TSC22D3) is one of glucocorticoid-induced genes and has an important regulatory role in immunosuppressive and cell proliferation. However, its prognostic value and immune infiltration effect in acute myeloid leukemia are remain elusive. Here, we investigated the association of TSC22D3 with immune infiltrates and its prognostic value in AML patients. We first analyzed 173 patients from the TCGA and 70 healthy controls from GTEx databases and found that TSC22D3 was highly expressed in AML (Figure A)and closely associated with various biological processes and signaling pathways, including stress-activated MAPK cascade and proteoglycans in cancer and cytokine-cytokine receptor interaction (Figure B). In addition, GESA analysis demonstrated that TSC22D3 was closely corelated with several critical signaling pathways including Toll-like receptor 4 (TLR4) pathway, EGFR pathway, NOTCH pathway, TNFR2 non-canonical NF-κB pathway (Figure C), which further highlighted the important role of TSC22D3 in the pathogenesis of AML. Immunogen analysis found positive associations with various immune cells, especially macrophages (Figure D), and TSC22D3 was also significantly associated with PD-1 and CTLA-4 expression in AML (Figure E). Our results suggest that TSC22D3 is closely associated with immune injectors and promotes immune escape in AML patients in the tumor microenvironment. High level of TSC22D3 was related with poor prognosis of AML in age, BM blasts and several gene mutation (IDH1 R132, FLT3) subgroups (Figure F), indicated that TSC22D3 can be identified as a prognostic molecule in these clinical feature subgroups. Subsequently, a calibration nomogram based on the age and genetic risk level of the clinical patient was conducted. There was a favorable consistency between the actual observed and predicted values for 1-, 3-, 5-year OS based on the calibration chart (Figure G). Based on the complementary perspective for respective tumors, the constructed model provided a personalized score for individual patients. Taken together, this study firstly reported that the high expression of TSC22D3 was significantly associated with the poor survival rate and immune infiltration in AML patients, which may promote the tumorigenesis of AML through enhancing the abnormal inflammation and immune escape. In particular, the immunomodulatory effects of TSC22D3 may play a crucial role in predicting the prognosis and have the potential to become a new biomarker of AML. Thus, this study identified that TSC22D3 may be useful as an immunomodulatory agent for AML clinical management and provided a new insight for further investigation on the clinicopathological significance and molecular pathogenesis of AML. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Mitogen-activated protein kinase kinase 7 in inflammatory, cancer, and neurological diseases.

Stress-activated mitogen-activated protein kinase kinase 7 (MKK7) is a member of the dual-specificity mitogen-activated protein kinase family. In the human body, MKK7 controls essential physiological processes, including but not limited to proliferation and differentiation in multiple tissues and organs. MKK7, along with the MKK4 pathway, has been implicated in stress-activated activities and biological events that are mediated by c-Jun N-terminal kinase (JNK) signaling. Although numerous studies have been performed to identify the role of JNK in multiple biological processes, there are limited publications that focus on dissecting the independent role of MKK7. Recent research findings have spurred testing via in vivo genetically deficient models, uncovering previously undocumented JNK-independent functions of MKK7. Here we discuss both JNK-dependent and-independent functions of MKK7 in vivo. This review summarizes the role of MKK7 in inflammation, cytokine production, cancer, and neurological diseases.

CAMP-Protein kinase A and stress-activated MAP kinase signaling mediate transcriptional control of autophagy in fission yeast during glucose limitation or starvation

ABSTRACT Macroautophagy/autophagy is an essential adaptive physiological response in eukaryotes induced during nutrient starvation, including glucose, the primary immediate carbon and energy source for most cells. Although the molecular mechanisms that induce autophagy during glucose starvation have been extensively explored in the budding yeast Saccharomyces cerevisiae, little is known about how this coping response is regulated in the evolutionary distant fission yeast Schizosaccharomyces pombe. Here, we show that S. pombe autophagy in response to glucose limitation relies on mitochondrial respiration and the electron transport chain (ETC), but, in contrast to S. cerevisiae, the AMP-activated protein kinase (AMPK) and DNA damage response pathway components do not modulate fission yeast autophagic flux under these conditions. In the presence of glucose, the cAMP-protein kinase A (PKA) signaling pathway constitutively represses S. pombe autophagy by downregulating the transcription factor Rst2, which promotes the expression of respiratory genes required for autophagy induction under limited glucose availability. Furthermore, the stress-activated protein kinase (SAPK) signaling pathway, and its central mitogen-activated protein kinase (MAPK) Sty1, positively modulate autophagy upon glucose limitation at the transcriptional level through its downstream effector Atf1 and by direct in vivo phosphorylation of Rst2 at S292. Thus, our data indicate that the signaling pathways that govern autophagy during glucose shortage or starvation have evolved differently in S. pombe and uncover the existence of sophisticated and multifaceted mechanisms that control this self-preservation and survival response.

P-448 Changes in gene transcription induced by cyclophosphamide treatment in an experimental ovarian culture model

Abstract Study question How does cyclophosphamide (CPA) treatment impact at transcriptional level on mouse ovarian tissue? Summary answer Cultured murine ovarian tissue with CPA versus control showed up-regulated intrinsic and extrinsic apoptotic signaling pathways, associated with DNA damage, DNA repair and oxidative response. What is known already Alkylating chemotherapeutic treatment depletes the ovarian pool and induces infertility in women. The suggested mechanisms behind these adverse effects include apoptosis and/or over-activation of the dormant primordial follicle pool. However, there is a lack of knowledge about the pathways that lead to these outcomes and previous researches have been inconclusive. The investigation of changes in the ovarian transcriptomic profiling following the alkylating drug CPA treatment can be useful to identify new potential targets for fertility preservation in women treated for cancer. Study design, size, duration Controlled experimental study using 20 female B6CBA/F1 4-day-old mice. Ovaries were collected and randomly assigned to CPA (4-hydroperoxycyclophosphamide) treated group (n = 20) or control group (n = 20). Five ovaries/group were collected at 8, 12, 24 and 36 h to investigate the dynamic of the changes. RNA extraction and RNA sequencing analysis were carried out. Participants/materials, setting, methods Ovaries were cultured on Millicell cell culture inserts floating on 0.25 mL culture medium in a 24-well plate. Freshly prepared 4-hydroperoxycyclophosphamide solution was added to the wells of CPA group (final concentration = 5 µM). Equal amount of solvent was added to the wells of control group. Culture medium was refreshed at 48 h with culture medium only. RNA sequencing data were processed for subsequent differentially expressed genes (DEGs) and gene set enrichment analysis (GSEA). Main results and the role of chance At 8 h, CPA treatment induced the up-regulation of biological processes related to hypoxia, cell growth and embryonic organ development. At 12 h, DNA damage and the ovarian cell responses were evidenced by an increased activity of DNA damage response, DNA damage checkpoint, DNA repair (double-strand break, mismatch, single strand binding), stress-activated MAPK cascade, antioxidant activity and intrinsic apoptotic signaling pathway. The representative genes of these processes there were Bbc3, Bax, Trp73, Cdkn1a, Trp53inp1 and Mdm2. A dramatic increase in the number of DEGs was found at 24 h (8 h, n = 209; 12 h, n = 239; 24 h, n = 2013). Also at 24 h DNA repair, intrinsic and extrinsic apoptotic signaling pathways were the most representative processes evidenced by the addition of Rad9a, H2afx, Casp3, Bak1 and Casp8 genes to the above mentioned. Whereas, germ cell related genes Ybx2, Nobox and Ddx4 were all down-regulated. At 36 h, the number of DEGs (n = 3804) still increased, the up-regulated pathways were similar to 24 h, while meiosis and microtubule-based movements pathways were observed in the down-regulated set too. Limitations, reasons for caution Although the age of the mice chosen for the experiment ensured a high and representative content of primordial follicles in the ovary, whole ovaries were used for RNA sequencing analysis containing a heterogeneous composition of cells other than follicles. Wider implications of the findings Our results provide evidence of dynamic sequential changes in transcriptional level where apoptosis was involved in CPA-induced ovarian follicle depletion. Our research indicates a time frame before the occurrence of DNA definitive damage following CPA-treatment, where application of possible treatments in order to prevent the following apoptosis would be possible. Trial registration number Not Applicable

The transcription factor Atf1 lowers the transition barrier for nucleosome-mediated establishment of heterochromatin.

Transcription factors can exert opposite effects depending on the chromosomal context. The fission yeast transcription factor Atf1 both activates numerous genes in response to stresses and mediates heterochromatic gene silencing in the mating-type region. Investigating this context dependency, we report here that the establishment of silent heterochromatin in the mating-type region occurs at a reduced rate in the absence of Atf1 binding. Quantitative modeling accounts for the observed establishment profiles by a combinatorial recruitment of histone-modifying enzymes: locally by Atf1 at two binding sites and over the whole region by dynamically appearing heterochromatic nucleosomes, a source of which is the RNAi-dependent cenH element. In the absence of Atf1 binding, the synergy is lost, resulting in a slow rate of heterochromatin formation. The system shows how DNA-binding proteins can influence local nucleosome states and thereby potentiate long-range positive feedback on histone-modification reactions to enable heterochromatin formation over large regions in a context-dependent manner.

RNA-Seq Reveals the Role of miR-29c in Regulating Inflammation and Oxidative Stress of Bovine Mammary Epithelial Cells.

Healthy mammary gland is essential for milk performance in dairy cows. MicroRNAs (miRNAs) are the key molecules to regulate the steady state of mammary gland in dairy cows. This study investigated the potential role of miR-29c in bovine mammary epithelial cells (bMECs). RNA sequencing (RNA-seq) was used to measure the transcriptome profile of bovine mammary epithelial cells line (MAC-T) transfected with miR-29c inhibitor or negative control (NC) inhibitor, and then differentially expressed genes (DEGs) were screened. The results showed that a total of 42 up-regulated and 27 down-regulated genes were found in the miR-29c inhibitor group compared with the NC inhibitor group. The functional enrichment of the above DEGs indicates that miR-29c is a potential regulator of oxidative stress and inflammatory response in bMECs through multiple genes, such as forkhead box O1 (FOXO1), tumor necrosis factor-alpha (TNF-α), and major histocompatibility complex, class II, DQ alpha 5 (BoLA-DQA5) in the various biological process and signaling pathways of stress-activated mitogen-activated protein kinase (MAPK) cascade, Epstein-Barr virus infection, inflammatory bowel disease, etc. The results imply that miR-29c plays an important role in a steady state of bMECs or cow mammary gland and may be a potential therapeutic target for mastitis in dairy cows.

A Simple and Low-Cost Strategy to Improve Conidial Yield and Stress Resistance of Trichoderma guizhouense through Optimizing Illumination Conditions.

Light is perceived by photoreceptors in fungi and further integrated into the stress-activated MAPK HOG pathway, and thereby potentially activates the expression of genes for stress responses. This indicates that the precise control of light conditions can likely improve the conidial yield and stress resistance to guarantee the low cost and long shelf life of Trichoderma-based biocontrol agents and biofertilizers. In this study, effects of wavelengths and intensities of light on conidial yield and stress tolerance to osmotic, oxidative and pH stresses in Trichoderma guizhouense were investigated. We found that 2 μmol photons/(m2 × s) of blue light increased the conidial yield more than 1000 folds as compared to dark condition and simultaneously enhanced conidial stress resistance. The enhanced conidial stress resistance is probably due to the upregulated stress-related genes in blue light, which is under the control of the blue light receptor BLR1 and the MAP kinase HOG1.