Jun N-terminal Kinase Signaling Research Articles

A Tumor-Specific Molecular Network Promotes Tumor Growth in Drosophila by Enforcing a Jun N-Terminal Kinase-Yorkie Feedforward Loop.

Cancer cells expand rapidly in response to altered intercellular and signaling interactions to achieve the hallmarks of cancer. Impaired cell polarity combined with activated oncogenes is known to promote several hallmarks of cancer, e.g., activating invasion by increased activity of Jun N-terminal kinase (JNK) and sustained proliferative signaling by increased activity of Hippo effector Yorkie (Yki). Thus, JNK, Yki, and their downstream transcription factors have emerged as synergistic drivers of tumor growth through pro-tumor signaling and intercellular interactions like cell competition. However, little is known about the signals that converge onto JNK and Yki in tumor cells and enable tumor cells to achieve the hallmarks of cancer. Here, using mosaic models of cooperative oncogenesis (RasV12,scrib-) in Drosophila, we show that RasV12,scrib- tumor cells grow through the activation of a previously unidentified network comprising Wingless (Wg), Dronc, JNK, and Yki. We show that RasV12,scrib- cells show increased Wg, Dronc, JNK, and Yki signaling, and all these signals are required for the growth of RasV12,scrib- tumors. We report that Wg and Dronc converge onto a JNK-Yki self-reinforcing positive feedback signal-amplification loop that promotes tumor growth. We found that the Wg-Dronc-Yki-JNK molecular network is specifically activated in polarity-impaired tumor cells and not in normal cells, in which apical-basal polarity remains intact. Our findings suggest that the identification of molecular networks may provide significant insights into the key biologically meaningful changes in signaling pathways and paradoxical signals that promote tumorigenesis.

S100 calcium‑binding protein A16 suppresses the osteogenic differentiation of rat bone marrow mesenchymal stem cells by inhibiting SMAD family member 4 signaling.

Osteogenesis is a complex process of bone formation regulated by various factors, yet its underlying molecular mechanisms remain incompletely understood. The present study aimed to investigate the role of S100A16, a novel member of the S100 protein family, in the osteogenic differentiation of rat bone marrow mesenchymal stem cells (BMSCs) and uncover a novel Smad4-mitogen-activated protein kinase (MAPK)/Jun N-terminal kinase (JNK) signaling axis. In the present study, the expression level of S100A16 in bone tissues and BMSCs from ovariectomized rats was evaluated and then the impact of S100A16 silencing on osteogenic differentiation was examined. Increased S100A16 expression was observed in bone tissues and BMSCs from ovariectomized rats, and S100A16 silencing promoted osteogenic differentiation. Further transcriptomic sequencing revealed that the Smad4 pathway was involved in S100A16 silencing-induced osteogenesis. The results of western blot analysis revealed that S100A16 overexpression not only downregulated Smad4 but also activated MAPK/JNK signaling, which was validated by treatment with MAPK and JNK inhibitors U0126 and SP600125. Overall, in the present study, the novel regulatory factors influencing osteogenic differentiation were elucidated and mechanistic insights that could aid in the development of targeted therapeutic strategies for patients with osteoporosis were provided.

Phellinus linteus activates Treg cells via FAK to promote M2 macrophage polarization in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most prevalent malignant tumor worldwide. Within HCC's tumor microenvironment, focal adhesion kinase (FAK) plays a critical role. Regulatory T cells (Treg) modulate the polarization of tumor-associated macrophages , but the relationship between FAK, Treg cells, and macrophages remains underexplored. Phellinus linteus (PL) shows promise as a treatment for HCC due to its pharmacological effects. This study aimed to explore the relationship between FAK and Treg-macrophages and to assess whether PL could exert a protective effect through the FAK process in HCC. Initially, C57BL/6-FAK−/− tumor-bearing mice were utilized to demonstrate that FAK stimulates HCC tumor development. High dosages (200 μM) of FAK and the FAK activator ZINC40099027 led to an increase in Treg (CD4+CD25+) cells, a decrease in M1 macrophages (F4/80+CD16/32+, IL-12, IL-2, iNOS), and an increase in M2 macrophages (F4/80+CD206+, IL-4, IL-10, Arg1, TGF-β1). Additionally, FAK was found to encourage cell proliferation, migration, invasion, and epithelial-mesenchymal transition while inhibiting apoptosis in HepG2 and SMMC7721 cells. These effects were mediated by the PI3K/AKT1/Janus Kinase (JAK)/ signal transducer and activator of transcription 3 (STAT3), and mitogen-activated protein kinase (p38 MAPK)/Jun N-terminal Kinase (JNK) signaling pathways. Furthermore, PL exhibited a potent antitumor effect in vivo in a dose-dependent manner, reducing FAK, Treg cells, and M2 macrophages, while increasing M1 macrophages. This effect was achieved through the inhibition of the PI3K/AKT/JAK/STAT3, and p38/JNK pathways. Overall, our findings suggest that FAK promotes HCC via Treg cells that polarize macrophages toward the M2 type through specific signaling pathways. PL, acting through FAK, could be a protective therapy against HCC.

Osteolectin Promotes Odontoblastic Differentiation in Human Dental Pulp Cells

IntroductionOsteolectin is a secreted glycoprotein of the C-type lectin domain superfamily, expressed in bone tissues and is reported as a novel osteogenic factor that promotes bone regeneration. However, the effect of osteolectin on human dental pulp cells (hDPCs) has not been reported. Therefore, we aimed to investigate the odontoblastic differentiation of osteolectin in hDPCs and further attempt to reveal its underlying mechanism. MethodsCytotoxicity assays were used to detect the cytotoxicity of osteolectin. The odontoblastic differentiation of hDPCs and its underlying mechanisms were measured by the alkaline phosphatase (ALP) activity, mineralized spots formation, and the gene and protein expression of odontoblastic differentiation through ALP staining, Alizarin red S staining, quantitative real-time polymerase chain reaction, and Western blot analysis, respectively. ResultsWST-1 assay showed osteolectin at concentrations below 300 ng/ml was noncytotoxic and safe for hDPCs. The following experiment demonstrated that osteolectin could increase ALP activity, accelerate the mineralization process, and up-regulate the odontogenic differentiation markers in both gene and protein levels (P < .05). Osteolectin stimulated the phosphorylation of ERK, JNK, and Protein kinase B (AKT) in hDPCs. Extracellular signal-regulated kinase (ERK), Jun N-terminal kinase (JNK), and AKT inhibitors decreased ALP activity and mineralization capacity and suppressed the expression of dentin sialophosphoprotein and dentin matrix protein-1. ConclusionOsteolectin can promote odontoblastic differentiation of hDPCs, and the whole process may stimulate ERK, JNK, and AKT signaling pathways by increasing p-ERK, p-JNK, and p-AKT signals.

PLEKHA4 is Associated with Tumour Microenvironment, Stemness, Proliferation and Poor Prognosis of Gliomas.

Glioma is the most common intracranial malignancy. Immune-infiltration and tumour stemness are associated with the prognosis of glioma. Although pleckstrin homology containing family A, number 4 (PLEKHA4) is widely expressed in various human cancers, its role in glioma remains unclear. We examined the features and clinical significance of PLEKHA4 in gliomas by analysing relevant data from the Chinese Glioma Genome Atlas (CGGA) and The Cancer Genome Atlas (TCGA) databases. Gene set enrichment analysis (GSEA) was performed to determine the possible functions and pathways involving PLEKHA4 in glioma. The relationship between PLEKHA4 expression and the degree of oncogenic dedifferentiation was analysed using stemness scores (ss) calculated from epigenetic and transcriptomic features. We also explored the relationship between PLEKHA4 expression and immune cell infiltration in gliomas using the CIBERSORT databases. Furthermore, drug sensitivity analysis was performed using datasets from the GDSC and GTRP databases. In addition, we performed relevant in vitro experimental studies. PLEKHA4 DNA hypomethylation status was associated with its high expression in glioma tissues as well as poor prognoses. Univariate and multivariate Cox analyses indicated that PLEKHA4 expression may be considered as an independent prognostic factor in patients with glioma. GSEA indicated that high PLEKHA4 expression was associated with Janus kinase (JAK)/signal transducer and activator of transcription (STAT), Wingless-Type MMTV Integration Site Family (Wnt), JUN N-terminal kinase (JNK) signalling pathways and involved in apoptotic, cytoskeletal, and cell adhesion biological processes (BPs). In addition, increased PLEKHA4 expression was associated with higher glioma stemness scores than lower PLEKHA4 expression levels. Furthermore, the expression of PLEKHA4 was shown to be associated with glioma infiltration by CD4+ T cells, B cells, neutrophils, macrophages, and dendritic cells. Drug sensitivity analysis also showed that PLEKHA4 expression was negatively correlated with the sensitivity of several small molecule kinase inhibitors. Furthermore, in vitro experiments confirmed that PLEKHA4 knockdown inhibited the proliferation of glioma cells. PLEKHA4 is highly expressed in glioma tissues and correlated with tumour stemness, immune cell infiltration and proliferation, suggesting its potential as a novel prognostic biomarker and therapeutic target in glioma.

Osmotic pressure induces translocation of aquaporin-8 by P38 and JNK MAPK signaling pathways in patients with functional constipation.

Aquaporins (AQPs) maintain fluid homeostasis in the colon. The role of colonic AQPs in the pathophysiology of functional constipation (FC) remains largely unknown. To explore variations in aquaporins and investigate their underlying mechanisms. Colonic biopsies were collected from patients with FC and healthy controls. The expression and localization of AQPs were evaluated using quantitative real-time polymerase chain reaction (qRT-PCR), western blot analysis, and immunofluorescence assays. Furthermore, osmotic pressure-induced cell model was used in vitro to investigate the potential relationship between AQP8 and osmotic pressure, and to reveal the underlying mechanisms. Upregulation of AQP3 and AQP8, and downregulation of AQP1, AQP7, AQP9, AQP10, and AQP11 were observed in the patients with functional constipation. Furthermore, cellular translocation of AQP8 from the cytoplasm to the plasma membrane was observed in patients with FC. Mechanistically, the increase in osmotic pressure could activate the Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK) signaling pathways, and subsequently promote the upregulation and translocation of AQP8. Upregulation of AQP8 and AQP3, and translocation of AQP8 were observed in colon biopsies from patients with FC. The p38 and JNK MAPK signaling pathways are involved in the regulation of osmotic pressure-induced AQP8 variation.

Croquemort elicits activation of the immune deficiency pathway in ticks

The immune deficiency (IMD) pathway directs host defense in arthropods upon bacterial infection. In Pancrustacea, peptidoglycan recognition proteins sense microbial moieties and initiate nuclear factor-κB-driven immune responses. Proteins that elicit the IMD pathway in non-insect arthropods remain elusive. Here, we show that an Ixodes scapularis homolog of croquemort (Crq), a CD36-like protein, promotes activation of the tick IMD pathway. Crq exhibits plasma membrane localization and binds the lipid agonist 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol. Crq regulates the IMD and jun N-terminal kinase signaling cascades and limits the acquisition of the Lyme disease spirochete B. burgdorferi. Additionally, nymphs silenced for crq display impaired feeding and delayed molting to adulthood due to a deficiency in ecdysteroid synthesis. Collectively, we establish a distinct mechanism for arthropod immunity outside of insects and crustaceans.

Heat shock protein 40 of Streptococcus pneumoniae induces immune response of human dendritic cells via TLR4-dependent p38 MAPK and JNK signaling pathways.

Heat shock protein 40 (HSP40) is a vaccine adjuvant candidate for Streptococcus pneumoniae. The mechanism by which HSP40 activates the human dendritic cells (DCs) is unclear. DCs were isolated from human peripheral blood and their markers (HLA-DR, CD86, CD83, and CD80) were detected by flow cytometry. The messengerRNA (mRNA) and secretion levels of inflammary cytokines were measured after DCs were stimulated with recombinant HSP40 (rHSP40). Short hairpin RNAs were used to knock down toll-like receptor 2 (TLR2) and TLR4. The TLR2- or TLR4-deficient DCs were treated with lipopolysaccharides, rHSP40, or peptidoglycan, and then the secretion levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were measured. Moreover, the secretion levels of TNF-α and IL-6 were measured after DCs were treated with mitogen-activated protein kinase (MAPK) inhibitors including SB203580, SP600125, and U0126. In addition, the phosphorylation levels of p38 MAPK and Jun N-terminal kinase (JNK) in DC cells were determined using western blot analysis after treatment with rHSP40 for different times. DCs were successfully isolated and cultured. rHSP40 treatment significantly increased cytokine levels in a concentration-dependent manner. TLR4 deficiency, but not TLR2 deficiency, significantly suppressed the rHSP40-induced secretion of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). SB203580 and SP600125 significantly inhibited the rHSP40-induced secretion of TNF-α and IL-6. rHSP40 significantly enhanced the phosphorylation of p38 MAPK and JNK. HPS40 stimulates the immune response of DCs via the p38 MAPK and JNK signaling pathways, which depend on TLR4.

Exposure to bisphenol A induced oxidative stress, cell death and impaired epithelial homeostasis in the adult Drosophila melanogaster midgut

Recently, the chemical compound Bisphenol A (BPA) has been attracting worldwide attention due to its various toxic effects in animals, including reprotoxicity, neurotoxicity, hepatoxicity, and nephrotoxicity. Here, the midgut of adult Drosophila melanogaster (D. melanogaster), an invertebrate model organism, was employed to investigate the gastrointestinal toxicity of BPA in D. melanogaster and explore its underlying mechanisms of action in insects. As a result, exposure of flies to 0.5 mM BPA resulted in a dramatic morphological alteration of D. melanogaster midgut and decrease in survival rates and climbing ability of flies. Further study indicated that BPA induced high levels of oxidative stress in D. melanogaster midgut due to the imbalance between the production of reactive oxygen species and the activities of cellular antioxidant enzymes, including glutathione-S-transferase, catalase and superoxide dismutase. Oxidative stress induced by BPA then caused intestinal epithelial cell death and gut barrier dysfunction and elevated gut permeability, leading to oxidative injury of midgut epithelium. Antioxidant vitamin E alleviated midgut injury induced by BPA. Subsequently, BPA-induced oxidative injury of midgut further stimulated the proliferation of intestinal stem cell (ISC) and ISC-mediated midgut regeneration, but did not alter cell fate determination of ISCs in Drosophila midgut. Meanwhile, activation of Jun N-terminal kinase signal pathway was found to be required for BPA-induced cell death and tissue regeneration in midgut. Collectively, the present study provided additional evidence from an invertebrate model organism that BPA exposure induced gastrointestinal toxicity in D. melanogaster and further extended our understanding of the molecular mechanisms mediating BPA toxicity in insects.

Inhibition of TNF-α and JNK Signaling Pathway Can Reduce Paclitaxel-Induced Apoptosis of Mouse Cardiomyocytes.

Paclitaxel (PTX) is a widely used chemotherapeutic drug for treating tumors. However, studies have shown that it can cause cardiac problems such as arrhythmia, myocarditis, chronic cardiomyopathy, and heart failure. Therefore, it is essential to study the mechanism behind the cardiotoxicity of PTX in tumor treatment. In this study, we initially injected PTX into mice to establish a myocardial cell apoptosis model to observe the degree of damage to mouse myocardium caused by PTX. Upon determining the levels of mouse myocardial creatine phosphokinase (CK), myokinase isoenzyme (CK-MB), aspartate transaminase (AST), and lactate dehydrogenase (LDH), we found that all of these levels showed apparent increases in mice treated with PTX. Further analyses of the TNF-α level and the expression of Jun N-terminal kinase (JNK) and Bcl-2 family-related proteins in myocardial tissue were performed. It was found that PTX increased the protein levels of TNF-α, Bax, p-JNK, and JNK in myocardial tissue but decreased the protein level of Bcl-2. After 1 month of PTX treatment in mice, we inhibited the expression of TNF-α and JNK proteins, which reduced the effect of paclitaxel on the apoptosis of mouse cardiomyocytes. The protein levels of Bax, p-JNK, and TNF-α in cardiomyocytes were reduced, while there was a relative increase in the Bcl-2 protein level. The findings suggested that inhibition of the NK signaling pathway and TNF-α can lessen the effect of PTX on mouse cardiomyocytes.

Glutamine exerts a protective effect on osteoarthritis development by inhibiting the Jun N-terminal kinase and nuclear factor kappa-B signaling pathways

Strategies for treating osteoarthritis (OA) have become a research focus because an effective treatment for OA is unavailable. The objective of this study was to explore the effects and underlying mechanisms of glutamine (Gln) in OA. First, the chondrocytes were identified and a standard IL-1β-induced OA model was established. After treatment with Gln or saline, the viability and apoptosis of chondrocytes were evaluated using a CCK-8 assay and flow cytometry analysis, which revealed that Gln can improve the IL-1β-induced OA cells. Meanwhile, Gln can enhance the expression of aggrecan and collagen II, which are protective proteins for articular cartilage. Instead, Gln inhibited the expression of matrix metalloproteinase-1 (MMP-1) and matrix metalloproteinase-13 (MMP-13), which can degrade cartilage. To better understand the underlying mechanisms of Gln in IL-1β-induced chondrocytes, the classical OA pathways of JNK and NF-κB were examined at the protein and mRNA levels using western blot and qRT–PCR analyses. We found that JNK and NF-κB were downregulated gradually depending on the Gln dose and protective and destructive factors changed based on changes of JNK and NF-κB. The effects of high-dose Gln were more effective than low-dose. Moreover, Gln was applied to the animal OA model to check the effects in vivo. The results showed that Gln attenuated cartilage degeneration and decreased OARSI scores, which demonstrated that Gln can improve OA. The experiments showed that Gln can benefit mice with OA by inhibiting the JNK and NF-κB signaling pathways.

Synaptotagmin 11 scaffolds MKK7–JNK signaling process to promote stem-like molecular subtype gastric cancer oncogenesis

BackgroundIdentifying biomarkers related to the diagnosis and treatment of gastric cancer (GC) has not made significant progress due to the heterogeneity of tumors. Genes involved in histological classification and genetic correlation studies are essential to develop an appropriate treatment for GC.MethodsIn vitro and in vivo lentiviral shRNA library screening was performed. The expression of Synaptotagmin (SYT11) in the tumor tissues of patients with GC was confirmed by performing Immunohistochemistry, and the correlation between the expression level and the patient’s survival rate was analyzed. Phospho-kinase array was performed to detect Jun N-terminal kinase (JNK) phosphorylation. SYT11, JNK, and MKK7 complex formation was confirmed by western blot and immunoprecipitation assays. We studied the effects of SYT11 on GC proliferation and metastasis, real-time cell image analysis, adhesion assay, invasion assay, spheroid formation, mouse xenograft assay, and liver metastasis.ResultsSYT11 is highly expressed in the stem-like molecular subtype of GC in transcriptome analysis of 527 patients with GC. Moreover, SYT11 is a potential prognostic biomarker for histologically classified diffuse-type GC. SYT11 functions as a scaffold protein, binding both MKK7 and JNK1 signaling molecules that play a role in JNK1 phosphorylation. In turn, JNK activation leads to a signaling cascade resulting in cJun activation and expression of downstream genes angiopoietin-like 2 (ANGPTL2), thrombospondin 4 (THBS4), Vimentin, and junctional adhesion molecule 3 (JAM3), which play a role in epithelial-mesenchymal transition (EMT). SNU484 cells infected with SYT11 shRNA (shSYT11) exhibited reduced spheroid formation, mouse tumor formation, and liver metastasis, suggesting a pro-oncogenic role of SYT11. Furthermore, SYT11-antisense oligonucleotide (ASO) displayed antitumor activity in our mouse xenograft model and was conferred an anti-proliferative effect in SNU484 and MKN1 cells.ConclusionSYT11 could be a potential therapeutic target as well as a prognostic biomarker in patients with diffuse-type GC, and SYT11-ASO could be used in therapeutic agent development for stem-like molecular subtype diffuse GC.

LncRNA SNHG14 contributes to proinflammatory cytokine production in rheumatoid arthritis via the regulation of the miR-17-5p/MINK1-JNK pathway.

Rheumatoid arthritis (RA) is a widespread autoimmune disorder of the joints. Long noncoding RNAs (lncRNAs) have been reported to participate in the pathogenesis of RA by serving as competitive endogenous RNAs. LncRNA small nucleolar RNA host gene 14 (SNHG14) is involved in the development of various diseases. Here, we found that high expression of SNHG14 in RA was closely related to the disease activity. Functional assays indicated that SNHG14 knockdown obviously hampered phorbol myristate acetate-activated THP-1 (pTHP-1) cell proliferation and proinflammatory cytokines production. In mechanism, SNHG14 served as a sponge of microRNA-17-5p (miR-17-5p), and misshapen like kinase 1 (MINK1) was a target of miR-17-5p. SNHG14 depletion-induced inhibitory effects on cell proliferation and inflammatory response were reversed by MINK1 overexpression in macrophages. Moreover, SNHG14 promoted the jun N-terminal kinase (JNK) signaling via the miR-17-5p/MINK1 axis. Overall, SNHG14 boosted the process of RA by MINK1 activating the JNK pathway.

Long non-coding RNA CASC2 restrains high glucose-induced proliferation, inflammation and fibrosis in human glomerular mesangial cells through mediating miR-135a-5p/TIMP3 axis and JNK signaling

BackgroundDiabetic nephropathy (DN) is a common complication of diabetes. Long non-coding RNA (lncRNA) cancer susceptibility candidate 2 (CASC2) is reported to exert a protective role in DN by a previous study. The working mechanism underlying the protective role of CASC2 in DN progression was further explored in this study.MethodsThe expression of CASC2 and microRNA-135a-5p (miR-135a-5p) was determined by real-time quantitative polymerase chain reaction (RT-qPCR). Cell proliferation ability was assessed by Cell Counting Kit-8 (CCK8) assay and 5-ethynyl-29-deoxyuridine (EDU) assay. Enzyme-linked immunosorbent assay (ELISA) was conducted to analyze the production of inflammatory cytokines in the supernatant. Western blot assay was performed to analyze protein expression. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were performed to verify the target relationship between miR-135a-5p and CASC2 or tissue inhibitors of metalloproteinase 3 (TIMP3).ResultsHigh glucose (HG) treatment reduced the expression of CASC2 in human glomerular mesangial cells (HMCs) in a time-dependent manner. CASC2 overexpression suppressed HG-induced proliferation, inflammation and fibrosis in HMCs. miR-135a-5p was validated as a target of CASC2, and CASC2 restrained HG-induced influences in HMCs partly by down-regulating miR-135a-5p. miR-135a-5p bound to the 3ʹ untranslated region (3ʹUTR) of TIMP3, and CASC2 positively regulated TIMP3 expression by sponging miR-135a-5p in HMCs. miR-135a-5p silencing inhibited HG-induced effects in HMCs partly by up-regulating its target TIMP3. CASC2 overexpression suppressed HG-induced activation of Jun N-terminal Kinase (JNK) signaling partly through mediating miR-135a-5p/TIMP3 signaling.ConclusionsIn conclusion, CASC2 alleviated proliferation, inflammation and fibrosis in DN cell model by sponging miR-135a-5p to induce TIMP3 expression.

Active elimination of intestinal cells drives oncogenic growth in organoids.

SummaryCompetitive cell interactions play a crucial role in quality control during development and homeostasis. Here, we show that cancer cells use such interactions to actively eliminate wild-type intestine cells in enteroid monolayers and organoids. This apoptosis-dependent process boosts proliferation of intestinal cancer cells. The remaining wild-type population activates markers of primitive epithelia and transits to a fetal-like state. Prevention of this cell-state transition avoids elimination of wild-type cells and, importantly, limits the proliferation of cancer cells. Jun N-terminal kinase (JNK) signaling is activated in competing cells and is required for cell-state change and elimination of wild-type cells. Thus, cell competition drives growth of cancer cells by active out-competition of wild-type cells through forced cell death and cell-state change in a JNK-dependent manner.

The Emerging Roles of JNK Signaling in Drosophila Stem Cell Homeostasis.

The Jun N-terminal kinase (JNK) pathway is an evolutionary conserved kinase cascade best known for its roles during stress-induced apoptosis and tumor progression. Recent findings, however, have identified new roles for this pleiotropic pathway in stem cells during regenerative responses and in cellular plasticity. Here, we provide an overview of recent findings about the new roles of JNK signaling in stem cell biology using two well-established Drosophila models: the testis and the intestine. We highlight the pathway’s roles in processes such as proliferation, death, self-renewal and reprogramming, and discuss the known parallels between flies and mammals.

Evidences for the mechanism of Shenmai injection antagonizing doxorubicin-induced cardiotoxicity

BackgroundDoxorubicin (DOX) is a widely used antitumor drug. However, its clinical application is limited for its serious cardiotoxicity. The mechanism of DOX-induced cardiotoxicity is attributed to the increasing of cell stress in cardiomyocytes, then following autophagic and apoptotic responses. Our previous studies have demonstrated the protective effect of Shenmai injection (SMI) on DOX-induced cardiotoxicity via regulation of inflammatory mediators for releasing cell stress. PurposeTo further investigate whether SMI attenuates the DOX-induced cell stress in cardiomyocytes, we explored the mechanism underlying cell stress as related to Jun N-terminal kinase (JNK) activity and the regulation of autophagic flux to determine the mechanism by which SMI antagonizes DOX-induced cardiotoxicity. Study designThe DOX-induced cardiotoxicity model of autophagic cell death was established in vitro to disclose the protected effects of SMI on oxidative stress, autophagic flux and JNK signaling pathway. Then the autophagic mechanism of SMI antagonizing DOX cardiotoxicity was validated in vivo. ResultsSMI was able to reduce the DOX-induced cardiomyocyte apoptosis associated with inhibition of activation of the JNK pathway and the accumulation of reactive oxygen species (ROS). Besides, SMI antagonized DOX cardiotoxicity, regulated cardiomyocytes homeostasis by restoring DOX-induced cardiomyocytes autophagy. Under specific circumstances, SMI depressed autophagic process by reducing the Beclin 1-Bcl-2 complex dissociation which was activated by DOX via stimulating the JNK signaling pathway. At the same time, SMI regulated lysosomal pH to restore the autophagic flux which was blocked by DOX in cardiomyocytes. ConclusionSMI regulates cardiomyocytes apoptosis and autophagy by controlling JNK signaling pathway, blocking DOX-induced apoptotic pathway and autophagy formation. SMI was also found to play a key role in restoring autophagic flux for counteracting DOX-damaged cardiomyocyte homeostasis.

Yorkie-Cactus (IκBα)-JNK axis promotes tumor growth and progression in Drosophila.

Presence of inflammatory factors in the tumor microenvironment is well-documented yet their specific role in tumorigenesis is elusive. The core inflammatory pathways like the Toll-Like Receptor (TLR) and the Tumor Necrosis Factor (TNF) pathway are conserved in Drosophila. We induced GFP-marked epithelial tumors by expressing activated oncogenic forms of RasV12 or Yorkie (Yki3SA, mammalian YAP) in scribble deficient cells (scribRNAi, mammalian SCRIB) to study the role of inflammatory factors in tumorigenesis. Similar to RasV12scribRNAi, we found that Yki3SAscribRNAi form invasive neoplastic lethal tumors that induce a systemic inflammatory response. We identified Cactus (Cact, mammalian IκBα), the negative regulator of TLR, as a key player in tumor growth. Cact accumulates in the cytoplasm in Drosophila tumor models, similar to squamous cell carcinoma in mice models and human patients where cytoplasmic IκBα favors oncogenic transformation. Further, cact is transcriptionally upregulated in tumors, and downregulation of Cact affects tumor growth. We investigated if TLR or TNF pathway affect tumor growth through activation of Jun N-terminal Kinase (JNK) pathway and its target Matrix Metalloprotease1 (MMP1). Genetically manipulating levels of TLR components or TNF receptors showed that Cact acts upstream of JNK signaling and regulates JNK via a non-canonical mechanism during tumorigenesis. Further, Hippo coactivator Yki transcriptionally regulates cact expression, and downregulation of Yki or Cact is sufficient to cause downregulation of JNK-mediated signaling that promotes tumorigenesis. Here, we report a link between Hippo, IκBα and JNK signaling that may induce inflammation and innate immune response in tumorigenesis.

JNK Signaling Pathway Mediates Fluoride-Induced Upregulation of CK1α during Enamel Formation

Fluorosis is a defect in the enamel mineral content caused by excessive fluoride intake during amelogenesis; the interaction of various factors in the development and progression of fluorosis has not been defined. Casein kinase 1α (CK1α) is constitutively active in cells and is involved in diverse cellular processes; however, its expression in fluorosis has not been measured. This study aimed to investigate the effects of fluoride on CK1α expression and to assess the regulation of molecular signaling involving fluoride and CK1α during enamel development. Kunming mice were randomly divided into the control and F groups with induced clinical features of fluorosis. The F group mice, including mothers and newborns, were treated with 50 ppm fluoridated water. Immunohistochemical staining of the sections of the embryonic mandible regions was performed at the bell stage. Protein expression and signaling pathways in a mouse-derived ameloblast-like cell line (LS8) exposed to fluoride or a Jun N-terminal kinase (JNK) inhibitor were compared to those in control cells without exposure. CK1α and proteins of the JNK signaling pathways were assayed by quantitative real-time PCR and Western blotting. Mice of the F group developed dental fluorosis. Scanning electron microscopy showed a significant reduction in the degree of mineralization in the F group mice, which manifested as thin, loosely arranged, and disorganized enamel rods. Additional analysis revealed that the expression of CK1α in the F group was significantly elevated compared with that in the control group; LS8 cells responded to fluoride by upregulation of CK1α expression through the JNK pathway. Our findings identified the potential effects of CK1α on fluorosis using a mouse model and revealed that a high fluoride level increases the expression of CK1α and that JNK can be a key regulatory factor in CK1α expression.

Leptin Is Associated with Poor Clinical Outcomes and Promotes Clear Cell Renal Cell Carcinoma Progression.

Emerging evidence has shown the oncogenic roles of leptin in modulating cancer progression in addition to its original roles. Analyses of transcriptomic data and patients’ clinical information have revealed leptin’s prognostic significance in renal cell carcinoma (RCC). However, its biological effects on RCC progression have not yet been explored. Clinical and transcriptomic data of a RCC cohort of 603 patients were retrieved from The Cancer Genome Atlas (TCGA) and analyzed to reveal the correlation of leptin with clinical outcomes and the hierarchical clustering of gene signatures based on leptin levels. In addition, cox univariate and multivariate regression analyses, cell migration upon leptin treatment, identification of putative leptin-regulated canonical pathways via ingenuity pathway analysis (IPA), and the investigation of induction of Wnt5a, ROR2, and Jun N-terminal Kinases (JNK) phosphorylation activation were performed. We first observed a correlation of high leptin levels and poor outcomes in RCC patients. Knowledge-based analysis by IPA indicated the induction of cancer cell migration by leptin, which was manifested via direct leptin treatment in the RCC cell lines. In RCC patients with high leptin levels, the planar cell polarity (PCP)/JNK signaling pathway was shown to be activated, and genes in the axis, including CTHRC1, FZD2, FZD10, ROR2, WNT2, WNT4, WNT10B, WNT5A, WNT5B, and WNT7B, were upregulated. All of these genes were associated with unfavorable clinical outcomes. WNT5A and ROR2 are pivotal upstream regulators of PCP/JNK signaling, and their correlations with leptin expression levels were displayed by a Pearson correlation analysis. The inhibition of signal transduction by SP600125 reversed leptin-mediated cell migration properties in RCC cell lines. The results indicate the prognostic impact of leptin on RCC patients and uncover its ability to promote cell migration via PCP/JNK signaling.