Identification of a member of the MAPKKK family as a potential mediator of TGF-beta signal transduction

Signaling Cross Talk between TGF-β/Smad and Other Signaling Pathways

Cytokines of the transforming growth factor β (TGF-β) family, including TGF-βs, bone morphogenic proteins (BMPs), activins, and Nodal, play crucial roles in embryonic development and adult tissue homeostasis by regulating cell proliferation, survival, and differentiation, as well as stem-cell self-renewal and lineage-specific differentiation. Smad proteins are critical downstream mediators of these signaling activities. In addition to regulating the transcription of direct target genes of TGF-β, BMP, activin, or Nodal, Smad proteins also participate in extensive cross talk with other signaling pathways, often in a cell-type- or developmental stage-specific manner. These combinatorial signals often produce context-, time-, and location-dependent biological outcomes that are critical for development. This review discusses recent progress in our understanding of the cross talk between Smad proteins and signaling pathways of Wnt, Notch, Hippo, Hedgehog (Hh), mitogen-activated protein (MAP), kinase, phosphoinositide 3-kinase (PI3K)-Akt, nuclear factor κB (NF-κB), and Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathways.

NADPH oxidase 4 regulates vascular inflammation in aging and atherosclerosis

We recently reported that increased NADPH oxidase 4 (NOX4) expression and activity during aging results in enhanced cellular and mitochondrial oxidative stress, vascular inflammation, dysfunction, and atherosclerosis. The goal of the present study was to elucidate the molecular mechanism(s) for these effects and determine the importance of NOX4 modulation of proinflammatory gene expression in mouse vascular smooth muscle cells (VSMCs). A novel peptide-mediated siRNA transfection approach was used to inhibit Nox4 expression with minimal cellular toxicity. Using melittin-derived peptide p5RHH, we achieved significantly higher transfection efficiency (92% vs. 85% with Lipofectamine) and decreased toxicity (p<0.001 vs. Lipofectamine in MTT and p<0.0001 vs. Lipofectamine in LDH assays) in VSMCs. TGFβ1 significantly upregulates Nox4 mRNA (p<0.01) and protein (p<0.01) expression in VSMCs. p5RHH-mediated Nox4 siRNA transfection greatly attenuated TGFβ1-induced upregulation of Nox4 mRNA (p<0.01) and protein (p<0.0001) levels and decreased hydrogen peroxide production (p<0.0001). Expression of pro-inflammatory genes Ccl2, Ccl5, Il6, and Vcam1 was significantly upregulated in VSMCs in several settings cells isolated from aged vs. young wild-type mice, in atherosclerotic arteries of Apoe-/- mice, and atherosclerotic human carotid arteries and correlated with NOX4 expression. p5RHH-mediated Nox4 siRNA transfection significantly attenuated the expression of these pro-inflammatory genes in TGFβ1-treated mouse VSMCs, with the highest degree of inhibition in the expression of Il6. p5RHH peptide-mediated knockdown of TGFβ-activated kinase 1 (TAK1, also known as Map3k7), Jun, and Rela, but not Nfkb2, downregulated TGFβ1-induced Nox4 expression in VSMCs. Together, these data demonstrate that increased expression and activation of NOX4, which might result from increased TGFβ1 levels seen during aging, induces a proinflammatory phenotype in VSMCs, enhancing atherosclerosis.

TGF-β Down-regulates Apolipoprotein M Expression through the TAK-1-JNK-c-Jun Pathway in HepG2 Cells

Apolipoprotein M (apoM) is a relatively novel apolipoprotein that plays pivotal roles in many dyslipidemia-associated diseases; however, its regulatory mechanisms are poorly understood. Many cytokines have been identified that down-regulate apoM expression in HepG2 cells, among which transforming growth factor-β (TGF-β) exerts the most potent effects. In addition, c-Jun, a member of the activated protein 1 (AP-1) family whose activity is modulated by c-Jun N-terminal kinase (JNK), decreases apoM expression at the transcriptional level by binding to the regulatory element in the proximal apoM promoter. In this study, we investigated the molecular mechanisms through which TGF-β decreases the apoM level in HepG2 cells. The results revealed that TGF-β inhibited apoM expression at both the mRNA and protein levels in a dose- and time-dependent manner and that it suppressed apoM secretion. These effects were attenuated by treatment of cells with either SP600125 (JNK inhibitor) or c-Jun siRNA. 5Z-7-oxozeaenol [(a TGF-β-activated kinase 1 (TAK-1) inhibitor)] also attenuated the TGF-β-mediated inhibition of apoM expression and suppressed the activation of JNK and c-Jun. These results have demonstrated that TGF-β suppresses apoM expression through the TAK-1-JNK-c-Jun pathway in HepG2 cells.

Interplay between Inflammation and Stemness in Cancer Cells: The Role of Toll-Like Receptor Signaling

Cancer stem cells (CSCs) are a small population of cancer cells that exhibit stemness. These cells contribute to cancer metastasis, treatment resistance, and relapse following therapy; therefore, they may cause malignancy and reduce the success of cancer treatment. Nuclear factor kappa B- (NF-κB-) mediated inflammatory responses increase stemness in cancer cells, and CSCs constitutively exhibit higher NF-κB activation, which in turn increases their stemness. These opposite effects form a positive feedback loop that further amplifies inflammation and stemness in cancer cells, thereby expanding CSC populations in the tumor. Toll-like receptors (TLRs) activate NF-κB-mediated inflammatory responses when stimulated by carcinogenic microbes and endogenous molecules released from cells killed during cancer treatment. NF-κB activation by extrinsic TLR ligands increases stemness in cancer cells. Moreover, it was recently shown that increased NF-κB activity and inflammatory responses in CSCs may be caused by altered TLR signaling during the enrichment of stemness in cancer cells. Thus, the activation of TLR signaling by extrinsic and intrinsic factors drives a positive interplay between inflammation and stemness in cancer cells.

Structure-guided development of covalent TAK1 inhibitors

TAK1 (transforming growth factor-β-activated kinase 1) is an essential intracellular mediator of cytokine and growth factor signaling and a potential therapeutic target for the treatment of immune diseases and cancer. Herein we report development of a series of 2,4-disubstituted pyrimidine covalent TAK1 inhibitors that target Cys174, a residue immediately adjacent to the 'DFG-motif' of the kinase activation loop. Co-crystal structures of TAK1 with candidate compounds enabled iterative rounds of structure-based design and biological testing to arrive at optimized compounds. Lead compounds such as 2 and 10 showed greater than 10-fold biochemical selectivity for TAK1 over the closely related kinases MEK1 and ERK1 which possess an equivalently positioned cysteine residue. These compounds are smaller, more easily synthesized, and exhibit a different spectrum of kinase selectivity relative to previously reported macrocyclic natural product TAK1 inhibitors such as 5Z-7-oxozeanol.

TGF-β Signal Transduction in Oro-facial Health and Non-malignant Disease (Part I)

The transforming growth factor-beta (TGF-β) family of cytokines consists of multi-functional polypeptides that regulate a variety of cell processes, including proliferation, differentiation, apoptosis, extracellular matrix elaboration, angiogenesis, and immune suppression, among others. In so doing, TGF-β plays a key role in the control of cell behavior in both health and disease. In this report, we review what is known about the mechanisms of activation of the peptide, together with details of TGF-β signal transduction pathways. This review summarizes the evidence implicating TGF-β in normal physiological processes of the craniofacial complex—such as palatogenesis, tooth formation, wound healing, and scarring—and then evaluates its role in non-malignant disease processes such as scleroderma, submucous fibrosis, periodontal disease, and lichen planus.

Ginkgolides and bilobalide protect BV2 microglia cells against OGD/reoxygenation injury by inhibiting TLR2/4 signaling pathways

Ginkgolide and bilobalide are major trilactone constituent of Ginkgo biloba leaves and have been shown to exert powerful neuroprotective properties. The aims of this study were to observe the inhibitory effects of ginkgolide and bilobalide on the activation of microglial cells induced by oxygen-glucose deprivation and reoxygenation (OGD/R) and the specific mechanisms by which these effects are mediated. For detecting whether ginkgolide and bilobalide increased cell viability in a dose-dependent manner, BV2 cells were subjected to oxygen-glucose deprivation for 4 h followed by 3 h reoxygenation with various concentrations of drugs (6.25, 12.5, 25, 50, and 100 μg/ml). The extent of apoptosis effect of OGD/R with or without ginkgolide and bilobalide treatment were also measured by Annexin V-FITC/PI staining. Similarly, the levels of pro-inflammatory cytokines TNF-α, IL-1β, IL-6, IL-8, and IL-10 were detected using a specific Bio-Plex Pro™ Reagent Kit. The effects of ginkgolide and bilobalide on protein levels of TLR2/4, MyD88, p-TAK1, p-IKKβ, p-IkBα, NF-κB p65, Bcl-2, Bax, Bak, RIP3, cleaved-Caspase-3, cleaved PARP-1 and cellular localization of NF-κB p65 were evaluated by Western blot and double-labeled immunofluorescence staining, respectively. OGD/R significantly decreased the cell viability and increased the release of IL-1β, IL-6, IL-8, IL-10, TNF-α in BV2 microglia cells; these effects were suppressed by ginkgolide and bilobalide. Meanwhile, ginkgolide and bilobalide also attenuated the OGD/R-induced increases in TLR2, TLR4, MyD88, Bak, RIP3 levels and reversed cleaved caspase-3/caspase-3, Bax/Bcl-2 and cleaved PARP-1/PARP-1 ratio. Furthermore, ginkgolide and bilobalide also downregulated p-TAK1, p-IkBα, and p-IKKβ and inhibited the OGD/R-induced transfer of NF-κB p65 from cytoplasm to nucleus in BV2 microglia cells. The results showed that ginkgolide and bilobalide can inhibit OGD/R-induced production of inflammatory factors in BV2 microglia cells by regulating the TLRs/MyD88/NF-κB signaling pathways and attenuating inflammatory response. The possible mechanism of anti-inflammatory and neuroprotective effects of ginkgolides results from the synergistic reaction among each monomer constituents.

Deconstructing the Complexity of TGFβ Signaling in Hematopoietic Stem Cells: Quiescence and Beyond

The hematopoietic system is highly dynamic and must constantly produce new blood cells every day. Mature blood cells all derive from a pool of rare long-lived hematopoietic stem cells (HSCs) that are mostly quiescent but occasionally divide and self-renew in order to maintain the stem cell pool and continuous replenishment of mature blood cells throughout life. A tight control of HSC self-renewal, commitment to differentiation and maintenance of quiescence states is necessary for lifelong blood supply. Transforming growth factor-β (TGF-β) is a critical regulator hematopoietic cell functions. It is a potent inhibitor of hematopoietic cell growth. However, TGFβ functions are more complex and largely context-dependent. Emerging evidence suggests a role in aging, cell identity and cell fate decisions. Here, we will review the role of TGF-β and downstream signaling in normal HSC functions, in HSC quiescence and beyond.

Oocyte-somatic cell interactions in the human ovary-novel role of bone morphogenetic proteins and growth differentiation factors

BACKGROUND

Initially identified for their capability to induce heterotopic bone formation, bone morphogenetic proteins (BMPs) are multifunctional growth factors that belong to the transforming growth factor β superfamily. Using cellular and molecular genetic approaches, recent studies have implicated intra-ovarian BMPs as potent regulators of ovarian follicular function. The bi-directional communication of oocytes and the surrounding somatic cells is mandatory for normal follicle development and oocyte maturation. This review summarizes the current knowledge on the physiological role and molecular determinants of these ovarian regulatory factors within the human germline-somatic regulatory loop.

OBJECTIVE AND RATIONALE

The regulation of ovarian function remains poorly characterized in humans because, while the fundamental process of follicular development and oocyte maturation is highly similar across species, most information on the regulation of ovarian function is obtained from studies using rodent models. Thus, this review focuses on the studies that used human biological materials to gain knowledge about human ovarian biology and disorders and to develop strategies for preventing, diagnosing and treating these abnormalities.

SEARCH METHODS

Relevant English-language publications describing the roles of BMPs or growth differentiation factors (GDFs) in human ovarian biology and phenotypes were comprehensively searched using PubMed and the Google Scholar database. The publications included those published since the initial identification of BMPs in the mammalian ovary in 1999 through July 2016.

OUTCOMES

Studies using human biological materials have revealed the expression of BMPs, GDFs and their putative receptors as well as their molecular signaling in the fundamental cells (oocyte, cumulus/granulosa cells (GCs) and theca/stroma cells) of the ovarian follicles throughout follicle development. With the availability of recombinant human BMPs/GDFs and the development of immortalized human cell lines, functional studies have demonstrated the physiological role of intra-ovarian BMPs/GDFs in all aspects of ovarian functions, from follicle development to steroidogenesis, cell–cell communication, oocyte maturation, ovulation and luteal function. Furthermore, there is crosstalk between these potent ovarian regulators and the endocrine signaling system. Dysregulation or naturally occurring mutations within the BMP system may lead to several female reproductive diseases. The latest development of recombinant BMPs, synthetic BMP inhibitors, gene therapy and tools for BMP-ligand sequestration has made the BMP pathway a potential therapeutic target in certain human fertility disorders; however, further clinical trials are needed. Recent studies have indicated that GDF8 is an intra-ovarian factor that may play a novel role in regulating ovarian functions in the human ovary.

WIDER IMPLICATIONS

Intra-ovarian BMPs/GDFs are critical regulators of folliculogenesis and human ovarian functions. Any dysregulation or variations in these ligands or their receptors may affect the related intracellular signaling and influence ovarian functions, which accounts for several reproductive pathologies and infertility. Understanding the normal and pathological roles of intra-ovarian BMPs/GDFs, especially as related to GC functions and follicular fluid levels, will inform innovative approaches to fertility regulation and improve the diagnosis and treatment of ovarian disorders.

Wnt and BMP Signaling Crosstalk in Regulating Dental Stem Cells: Implications in Dental Tissue Engineering

Tooth is a complex hard tissue organ and consists of multiple cell types that are regulated by important signaling pathways such as Wnt and BMP signaling. Serious injuries and/or loss of tooth or periodontal tissues may significantly impact aesthetic appearance, essential oral functions and the quality of life. Regenerative dentistry holds great promise in treating oral/dental disorders. The past decade has witnessed a rapid expansion of our understanding of the biological features of dental stem cells, along with the signaling mechanisms governing stem cell self-renewal and differentiation. In this review, we first summarize the biological characteristics of seven types of dental stem cells, including dental pulp stem cells, stem cells from apical papilla, stem cells from human exfoliated deciduous teeth, dental follicle precursor cells, periodontal ligament stem cells, alveolar bone-derived mesenchymal stem cells (MSCs), and MSCs from gingiva. We then focus on how these stem cells are regulated by bone morphogenetic protein (BMP) and/or Wnt signaling by examining the interplays between these pathways. Lastly, we analyze the current status of dental tissue engineering strategies that utilize oral/dental stem cells by harnessing the interplays between BMP and Wnt pathways. We also highlight the challenges that must be addressed before the dental stem cells may reach any clinical applications. Thus, we can expect to witness significant progresses to be made in regenerative dentistry in the coming decade.

Inhibition of transforming growth factor β-activated kinase 1 prevents inflammation-related cartilage degradation in osteoarthritis

Osteoarthritis (OA) is a common debilitating joint disorder, there’s still no available disease-modifying drug for OA currently. This study aims to explore the role of TAK1 in OA pathogenesis and therapeutic efficiency of TAK1 inhibition for OA. The contribution of TAK1 to OA pathogenesis was investigated by intra-articular injection of TAK1-encoding adenovirus in rats. TAK1 inhibitor 5Z-7-induced expression changes of extracellular matrix (ECM)-related genes were detected by real-time PCR. The protective effect of 5Z-7 against OA progression was evaluated in a post-traumatic OA rat model. Our results showed that intra-articular injection of Ad-Tak1 induced cartilage destruction and OA-related cytokine secretion in rat joints. TAK1 inhibition by 5Z-7 efficiently blocked NF-κB, JNK and p38 pathways activation in OA chondrocytes and synoviocytes, Meanwhile, 5Z-7 significantly decreased the expression of matrix-degrading enzymes and pro-inflammatory cytokine, while increased ECM protein expression, which are all crucial components in OA. 5Z-7 also ameliorated ECM loss in OA cartilage explants. More importantly, 5Z-7 significantly protected against cartilage destruction in a rat model of OA. In conclusion, our findings provide the first in vivo evidence that TAK1 contributes to OA by disrupting cartilage homeostasis, thus represents an ideal target for OA treatment, with 5Z-7 as a candidate therapeutic.

TAK1 regulates caspase 8 activation and necroptotic signaling via multiple cell death checkpoints

Necroptosis has emerged as a new form of programmed cell death implicated in a number of pathological conditions such as ischemic injury, neurodegenerative disease, and viral infection. Recent studies indicate that TGFβ-activated kinase 1 (TAK1) is nodal regulator of necroptotic cell death, although the underlying molecular regulatory mechanisms are not well defined. Here we reported that TAK1 regulates necroptotic signaling as well as caspase 8-mediated apoptotic signaling through both NFκB-dependent and -independent mechanisms. Inhibition of TAK1 promoted TNFα-induced cell death through the induction of RIP1 phosphorylation/activation and necrosome formation. Further, inhibition of TAK1 triggered two caspase 8 activation pathways through the induction of RIP1-FADD-caspase 8 complex as well as FLIP cleavage/degradation. Mechanistically, our data uncovered an essential role for the adaptor protein TNF receptor-associated protein with death domain (TRADD) in caspase 8 activation and necrosome formation triggered by TAK1 inhibition. Moreover, ablation of the deubiqutinase CYLD prevented both apoptotic and necroptotic signaling induced by TAK1 inhibition. Finally, blocking the ubiquitin-proteasome pathway prevented the degradation of key pro-survival signaling proteins and necrosome formation. Thus, we identified new regulatory mechanisms underlying the critical role of TAK1 in cell survival through regulation of multiple cell death checkpoints. Targeting key components of the necroptotic pathway (e.g., TRADD and CYLD) and the ubiquitin-proteasome pathway may represent novel therapeutic strategies for pathological conditions driven by necroptosis.

TAK1 inhibitor NG25 enhances doxorubicin-mediated apoptosis in breast cancer cells

Doxorubicin (Dox, Adriamycin) has been widely used in breast cancer treatment. But its severe cardio-toxic side effects limited the clinical use. Dox treatment can induce DNA damage and other accompanying effects in cancer cells, and subsequently activates nuclear factor κB (NF-κB) pathway which has a strong pro-survival role in different types of malignancy. We hypothesize that blocking NF-κB pathway may sensitize breast cancer cells to Dox chemotherapy. TGFβ-activated kinase-1 (TAK1) is a key intracellular molecule participating in genotoxic stresses-induced NF-κB activation. Targeting TAK1 as a strategy to enhance cancer treatment efficacy has been studied in several malignancies. We showed that NG25, a synthesized TAK1 inhibitor, greatly enhanced Dox treatment efficacy in a panel of breast cancer cell lines. In this pre-clinical study, we found that NG25 partially blocked Dox-induced p38 phosphorylation and IκBα degradation and enhanced Dox-induced cytotoxic effects and apoptosis in all breast cancer cell lines tested. Taken together, we provided clear evidence that NG25 sensitizes the breast cancer cells to Dox treatment in vitro. This combination may be an effective and feasible therapeutic option maximizing Dox efficacy and meanwhile minimizing Dox side effects in treating breast cancer.

Enhancement of hyperthermia-induced apoptosis by 5Z-7-oxozeaenol, a TAK1 inhibitor, in A549 cells

KRAS mutant lung cancers have long been considered as untreatable with drugs. Transforming growth factor-β-activated kinase 1 (TAK1) appears to play an anti-apoptotic role in response to multiple stresses and has been reported to be a responsive kinase that regulates cell survival in KRAS-dependent cells. In this study, in order to find a useful approach to treat KRAS mutant lung cancer, we focused on the combined effects of 5Z-7-oxozeaenol, a TAK1 inhibitor, with hyperthermia (HT) in KRAS mutant lung cancer cell line A549. Annexin V-FITC/PI assay, cell cycle analysis, and colony formation assay revealed a significant enhancement in apoptosis induced by HT treatment, when the cells were pre-incubated with 5Z-7-oxozeaenol in a dose-dependent manner. The enhanced apoptosis by 5Z-7-oxozeaenol was accompanied by a significant increase in reactive oxygen species (ROS) generation and loss of mitochondrial membrane potential (MMP). In addition, western blot showed that 5Z-7-oxozeaenol enhanced HT-induced expressions of cleaved caspase-3, cleaved caspase-8, and HSP70 and decreased HT-induced expressions of Bcl-2, p-p38, p-JNK, and LC3. Moreover, 5Z-7-oxozeaenol pre-treatment resulted in a marked elevation of intracellular calcium level which might be associated with endoplasmic reticulum (ER) stress-related pathway. Taken together, our data provides further insights of the mechanism of action of 5Z-7-oxozeaenol and HT treatment, and their potential application as a novel approache to treat patients with KRAS mutant lung cancer.

Modification of TAK1 by O-linked N-acetylglucosamine facilitates TAK1 activation and promotes M1 macrophage polarization

Macrophages play many different roles in tissue inflammation and immunity, and the plasticity of macrophage polarization is closely associated with acute inflammatory responses. O-GlcNAcylation is an important type of post-translational modification, which subtly modulates inflammation responses. Transforming growth factor (TGF)-β-activated kinase 1 (TAK1) is a key serine/threonine protein kinase that mediates signals transduced by pro-inflammatory cytokines such as TGF-β, tumor necrosis factor (TNF), and interleukin-1 (IL-1). It is here reported that TGFβ-activated kinase (TAK1) is modified with N-acetylglucosamine (O-GlcNAc) on S427. Both IL-1 and osmotic stress, which are known as the TAK1-signaling inducers, significantly trigger the O-GlcNAcylation of TAK1 in macrophages. By overexpressing wild-type (WT) or S427A TAK1 mutant into macrophages, it was determined that O-GlcNAcylation of TAK1 on S427 is required for T187/S192 phosphorylation and full activation of TAK1 upon stimulation with IL-1α and NaCl. Aborting O-GlcNAcylation of TAK1 on S427 was found to inhibit the downstream JNK and nuclear factor-κB activation and reduce the final amount of cytokines produced in activated macrophages to a great extent. Results also showed that overexpression of the O-GlcNAcylation-deficient mutant of TAK1 promotes LPS-mediated apoptosis in macrophages. Importantly, TAK1 O-GlcNAcylation was found to promote M1 macrophage polarization in activated macrophages. Taken together, these data demonstrate that O-GlcNAcylation of TAK1 on S427 critically regulates the pro-inflammatory activation and M1 polarization of macrophages via modulation of the TAK1/JNK/NF-κB signaling pathway.

Effects of Maternal Chromium Restriction on the Long-Term Programming in MAPK Signaling Pathway of Lipid Metabolism in Mice

It is now broadly accepted that the nutritional environment in early life is a key factor in susceptibility to metabolic diseases. In this study, we evaluated the effects of maternal chromium restriction in vivo on the modulation of lipid metabolism and the mechanisms involved in this process. Sixteen pregnant C57BL mice were randomly divided into two dietary treatments: a control (C) diet group and a low chromium (L) diet group. The diet treatment was maintained through gestation and lactation period. After weaning, some of the pups continued with either the control diet or low chromium diet (CC or LL), whereas other pups switched to another diet (CL or LC). At 32 weeks of age, serum lipid metabolism, proinflammatory indexes, oxidative stress and anti-oxidant markers, and DNA methylation status in adipose tissue were measured. The results indicated that the maternal low chromium diet increased body weight, fat pad weight, serum triglyceride (TG), low-density lipoprotein cholesterol (LDL), tumor necrosis factor-α (TNF-α), malondialdehyde (MDA), and oxidized glutathione (GSSG). There was a decrease in serum reduced/oxidized glutathione (GSH/GSSG) ratio at 32 weeks of age in female offspring. From adipose tissue, we identified 1214 individual hypomethylated CpG sites and 411 individual hypermethylated CpG sites in the LC group when compared to the CC group. Pathway analysis of the differential methylation genes revealed a significant increase in hypomethylated genes in the mitogen-activated protein kinase (MAPK) signaling pathway in the LC group. Our study highlights the importance of the MAPK signaling pathway in epigenetic changes involved in the lipid metabolism of the offspring from chromium-restricted dams.

Heterozygous Mutations in MAP3K7, Encoding TGF-β-Activated Kinase 1, Cause Cardiospondylocarpofacial Syndrome

Cardiospondylocarpofacial (CSCF) syndrome is characterized by growth retardation, dysmorphic facial features, brachydactyly with carpal-tarsal fusion and extensive posterior cervical vertebral synostosis, cardiac septal defects with valve dysplasia, and deafness with inner ear malformations. Whole-exome sequencing identified heterozygous MAP3K7 mutations in six distinct CSCF-affected individuals from four families and ranging in age from 5 to 37 years. MAP3K7 encodes transforming growth factor β (TGF-β)-activated kinase 1 (TAK1), which is involved in the mitogen-activated protein kinase (MAPK)-p38 signaling pathway. MAPK-p38 signaling was markedly altered when expression of non-canonical TGF-β-driven target genes was impaired. These findings support the loss of transcriptional control of the TGF-β-MAPK-p38 pathway in fibroblasts obtained from affected individuals. Surprisingly, although TAK1 is located at the crossroad of inflammation, immunity, and cancer, this study reports MAP3K7 mutations in a developmental disorder affecting mainly cartilage, bone, and heart.

Mutations in MAP3K7 that Alter the Activity of the TAK1 Signaling Complex Cause Frontometaphyseal Dysplasia

Frontometaphyseal dysplasia (FMD) is a progressive sclerosing skeletal dysplasia affecting the long bones and skull. The cause of FMD in some individuals is gain-of-function mutations in FLNA, although how these mutations result in a hyperostotic phenotype remains unknown. Approximately one half of individuals with FMD have no identified mutation in FLNA and are phenotypically very similar to individuals with FLNA mutations, except for an increased tendency to form keloid scars. Using whole-exome sequencing and targeted Sanger sequencing in 19 FMD-affected individuals with no identifiable FLNA mutation, we identified mutations in two genes-MAP3K7, encoding transforming growth factor β (TGF-β)-activated kinase (TAK1), and TAB2, encoding TAK1-associated binding protein 2 (TAB2). Four mutations were found in MAP3K7, including one highly recurrent (n = 15) de novo mutation (c.1454C>T [ p.Pro485Leu]) proximal to the coiled-coil domain of TAK1 and three missense mutations affecting the kinase domain (c.208G>C [p.Glu70Gln], c.299T>A [p.Val100Glu], and c.502G>C [p.Gly168Arg]). Notably, the subjects with the latter three mutations had a milder FMD phenotype. An additional de novo mutation was found in TAB2 (c.1705G>A, p.Glu569Lys). The recurrent mutation does not destabilize TAK1, or impair its ability to homodimerize or bind TAB2, but it does increase TAK1 autophosphorylation and alter the activity of more than one signaling pathway regulated by the TAK1 kinase complex. These findings show that dysregulation of the TAK1 complex produces a close phenocopy of FMD caused by FLNA mutations. Furthermore, they suggest that the pathogenesis of some of the filaminopathies caused by FLNA mutations might be mediated by misregulation of signaling coordinated through the TAK1 signaling complex.

Rewiring of the apoptotic TGF-β-SMAD/NFκB pathway through an oncogenic function of p27 in human papillary thyroid cancer

Papillary thyroid carcinoma (PTC), the most frequent thyroid cancer, is characterized by low proliferation but no apoptosis, presenting frequent lymph-node metastasis. Papillary thyroid carcinoma overexpress transforming growth factor-beta (TGF-β). In human cells, TGF-β has two opposing actions: antitumoral through pro-apoptotic and cytostatic activities, and pro-tumoral promoting growth and metastasis. The switch converting TGF-β from a tumor-suppressor to tumor-promoter has not been identified. In the current study, we have quantified a parallel upregulation of TGF-β and nuclear p27, a CDK2 inhibitor, in samples from PTC. We established primary cultures from follicular epithelium in human homeostatic conditions (h7H medium). TGF-β-dependent cytostasis occurred in normal and cancer cells through p15/CDKN2B induction. However, TGF-β induced apoptosis in normal and benign but not in carcinoma cultures. In normal thyroid cells, TGF-β/SMAD repressed the p27/CDKN1B gene, activating CDK2-dependent SMAD3 phosphorylation to induce p50 NFκB-dependent BAX upregulation and apoptosis. In thyroid cancer cells, oncogene activation prevented TGF-β/SMAD-dependent p27 repression, and CDK2/SMAD3 phosphorylation, leading to p65 NFκB upregulation which repressed BAX, induced cyclin D1 and promoted TGF-β-dependent growth. In PTC samples from patients, upregulation of TGF-β, p27, p65 and cyclin D1 mRNA were significantly correlated, while the expression of the isoform BAX-β, exclusively transcribed in apoptotic cells, was negatively correlated. Additionally, combined ERK and p65 NFκB inhibitors reduced p27 expression and potentiated apoptosis in thyroid cancer cells while not affecting survival in normal thyroid cells. Our results therefore suggest that the oncoprotein p27 reorganizes the effects of TGF-β in thyroid cancer, explaining the slow proliferation but lack of apoptosis and metastatic behavior of PTC.

Transforming Growth Factor-β-Activated Kinase 1 Is Required for Human FcγRIIIb-Induced Neutrophil Extracellular Trap Formation

Neutrophils (PMNs) are the most abundant leukocytes in the blood. PMN migrates from the circulation to sites of infection where they are responsible for antimicrobial functions. PMN uses phagocytosis, degranulation, and formation of neutrophil extracellular traps (NETs) to kill microbes. Several stimuli, including bacteria, fungi, and parasites, and some pharmacological compounds, such as Phorbol 12-myristate 13-acetate (PMA), are efficient inducers of NETs. Antigen-antibody complexes are also capable of inducing NET formation. Recently, it was reported that FcγRIIIb cross-linking induced NET formation similarly to PMA stimulation. Direct cross-linking of FcγRIIA or integrins did not promote NET formation. FcγRIIIb-induced NET formation presented different kinetics from PMA-induced NET formation, suggesting differences in signaling. Because FcγRIIIb also induces a strong activation of extracellular signal-regulated kinase (ERK) and nuclear factor Elk-1, and the transforming growth factor-β-activated kinase 1 (TAK1) has recently been implicated in ERK signaling, in the present report, we explored the role of TAK1 in the signaling pathway activated by FcγRIIIb leading to NET formation. FcγRIIIb was stimulated by specific monoclonal antibodies, and NET formation was evaluated in the presence or absence of pharmacological inhibitors. The antibiotic LL Z1640-2, a selective inhibitor of TAK1 prevented FcγRIIIb-induced, but not PMA-induced NET formation. Both PMA and FcγRIIIb cross-linking induced phosphorylation of ERK. But, LL Z1640-2 only inhibited the FcγRIIIb-mediated activation of ERK. Also, only FcγRIIIb, similarly to transforming growth factor-β-induced TAK1 phosphorylation. A MEK (ERK kinase)-specific inhibitor was able to prevent ERK phosphorylation induced by both PMA and FcγRIIIb. These data show for the first time that FcγRIIIb cross-linking activates TAK1, and that this kinase is required for triggering the MEK/ERK signaling pathway to NETosis.

The Discovery and Early Days of TGF-β: A Historical Perspective

Transforming growth factors (TGFs) were discovered as activities that were secreted by cancer cells, and later by normal cells, and had the ability to phenotypically and reversibly transform immortalized fibroblasts. TGF-β distinguished itself from TGF-α because it did not bind to the same epidermal growth factor (EGF) receptor as TGF-α and, therefore, acted through different cell-surface receptors and signaling mediators. This review summarizes the discovery of TGF-β, the early developments in its molecular and biological characterization with its many biological activities in different cell and tissue contexts and its roles in disease, the realization that there is a family of secreted TGF-β-related proteins with many differentiation functions in development and activities in normal cell and tissue physiology, and the subsequent identification and characterization of the receptors and effectors that mediate TGF-β family signaling responses.

BMP-TAK1 (MAP3K7) Induces Adipocyte Differentiation Through PPARγ Signaling

BMPs have been shown to promote adipocyte differentiation through SMAD-dependent signaling. However, the role of TGF-β-activated kinase 1 (TAK1) in non-canonical BMP signaling in adipocyte differentiation remains unclear. Here, we show that TAK1 inhibition decreases lipid accumulation in C3H10T1/2 mesenchymal stem cells (MSCs) induced to differentiate into adipocytes. TAK1 knockdown by siRNA further confirms that TAK1 is required for adipocyte commitment of MSCs. Additionally, TAK1 knockdown inhibits adipogenesis of 3T3-L1 preadipocytes, indicating that TAK1 is not only needed for adipocyte commitment, but also required for adipocyte terminal differentiation. Furthermore, TAK1 ablation specifically in adipocytes reduced high fat diet-induced weight gain and improved glucose tolerance. Mechanistically, we demonstrate that TAK1 is required for PPARγ transactivation and promotes PPARγ transcriptional activity synergistically with TAK1 binding protein 1 (TAB1). Collectively, our results demonstrate that TAK1 plays a critical role in BMP-mediated adipocyte differentiation. J. Cell. Biochem. 118: 204-210, 2017. © 2016 Wiley Periodicals, Inc.

Inflammatory conditions partly impair the mechanically mediated activation of Smad2/3 signaling in articular cartilage

Background

Joint trauma, which is frequently related with mechanical overloading of articular cartilage, is a well-established risk for osteoarthritis (OA) development. Additionally, reports show that trauma leads to synovial joint inflammation. In consequence, after joint trauma, cartilage is influenced by deleterious excessive loading combined with the catabolic activity of proinflammatory mediators. Since the activation of TGF-β signaling by loading is considered to be a key regulatory pathway for maintaining cartilage homeostasis, we tested the effect of proinflammatory conditions on mechanically mediated activation of TGF-β/Smad2/3P signaling in cartilage.

Methods

Cartilage explants were subjected to dynamic mechanical compression in the presence of interleukin-1 beta (IL-1β) or osteoarthritic synovium-conditioned medium (OAS-CM). Subsequently, the activation of the Smad2/3P pathway was monitored with QPCR analysis of reporter genes and additionally the expression of receptors activating the Smad2/3P pathway was analyzed. Finally, the ability for mechanically mediated activation of Smad2/3P was tested in human OA cartilage.

Results

IL-1β presence during compression did not impair the upregulation of Smad2/3P reporter genes, however the results were affected by IL-1β-mediated upregulations in unloaded controls. OAS-CM significantly impaired the compression-mediated upregulation of bSmad7 and Tgbfb1. IL-1β suppressed the compression-mediated bAlk5 upregulation where 12 MPa compression applied in the presence of OAS-CM downregulated the bTgfbr2. Mechanically driven upregulation of Smad2/3P reporter genes was present in OA cartilage.

Conclusions

Proinflammatory conditions partly impair the mechanically mediated activation of the protective TGF-β/Smad2/3P pathway. Additionally, the excessive mechanical compression, applied in the presence of proinflammatory conditions diminishes the expression of the type II TGF-β receptor, a receptor critical for maintenance of articular cartilage.

Regulation of Transforming Growth Factor β-Activated Kinase Activation by Epigallocatechin-3-Gallate in Rheumatoid Arthritis Synovial Fibroblasts: Suppression of K(63) -Linked Autoubiquitination of Tumor Necrosis Factor Receptor-Associated Factor 6

OBJECTIVE

Transforming growth factor β-activated kinase 1 (TAK1) is a key MAPKKK family protein in interleukin-1β (IL-1β), tumor necrosis factor (TNF), and Toll-like receptor signaling. This study was undertaken to examine the posttranslational modification of TAK1 and its therapeutic regulation in rheumatoid arthritis (RA).

METHODS

The effect of TAK1, IL-1 receptor-associated kinase 1 (IRAK-1), and TNF receptor-associated factor 6 (TRAF6) inhibition was evaluated in IL-1β-stimulated human RA synovial fibroblasts (RASFs). Western blotting, immunoprecipitation, and 20S proteasome assay were used to study the ubiquitination process in RASFs. The efficacy of epigallocatechin-3-gallate (EGCG), a potent antiinflammatory molecule, in regulating these processes in RASFs was evaluated. Molecular docking was performed to examine the interaction of EGCG with human TAK1, IRAK-1, and TRAF6. These findings were confirmed using a rat model of adjuvant-induced arthritis (AIA).

RESULTS

Inhibition of TAK1, but not IRAK-1 or TRAF6, completely abrogated IL-1β-induced IL-6 and IL-8 synthesis in RASFs. EGCG inhibited TAK1 phosphorylation at Thr(184/187) and occupied the C(174) position, an ATP-binding site, to inhibit its kinase activity. EGCG pretreatment also inhibited K(63) -linked autoubiquitination of TRAF6, a posttranslational modification essential for TAK1 autophosphorylation, by forming a stable H bond at the K(124) position on TRAF6. Furthermore, EGCG enhanced proteasome-associated deubiquitinase expression to rescue proteins from proteasomal degradation. Western blot analyses of joint homogenates from rats with AIA showed a significant increase in K(48) -linked polyubiquitination, TAK1 phosphorylation, and TRAF6 expression when compared to naive rats. Administration of EGCG (50 mg/kg/day) for 10 days ameliorated AIA in rats by reducing TAK1 phosphorylation and K(48) -linked polyubiquitination.

CONCLUSION

Our findings provide a rationale for targeting TAK1 for the treatment of RA with EGCG.

Combination treatment with flavonoid morin and telomerase inhibitor MST‑312 reduces cancer stem cell traits by targeting STAT3 and telomerase

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers worldwide. The malignant CRC that undergoes metastasis in the advanced stage is usually refractory to existing chemotherapy and shows a poor prognosis. However, to date, efficient targeted-therapy for metastatic CRC is ill-defined. We tested the hypothesis that combined treatment of flavonoid morin and telomerase inhibitor MST‑312 may reduce the cancer stem cell (CSC) traits. To characterize CSC phenotype, we performed the CD133/CD44 subpopulation profiling, tumorsphere formation assay, cell invasion assay and wound healing assay. We have examined the augmenting effects of the combined treatment of morin and MST‑312 for 5-FU (5-fluorouracil) efficacy in human colorectal cancer. Morin and MST‑312 combined treatment reduced CD133 (+) and CD44 (+) subpopulations in human colorectal and breast cancer cells, respectively. Tumorsphere formation and cell invasiveness were decreased with the morin and MST‑312 combination treatment. Consistent with these data, morin and MST‑312 treatment decreased the wound healing capacity of human breast cancer cells. Stress and apoptosis antibody arrays revealed that there were specific upregulated and downregulated proteins resulting from different treatments. Phosphorylation levels of BAD, p53 and Chk1 were enhanced upon morin/MST‑312 treatments in HT-29 cells, whereas caspase-3 cleavage level and expression of IκBα were downregulated by combined morin/MST‑312 treatment in SW620 cells. Finally, morin and MST‑312 co-treatment further augmented the 5-FU efficacy, chemosensitizing the 5-FU resistant human colorectal cancer cells. Taken together, our study suggests that novel targeted-therapy can be implemented by using flavonoid morin and telomerase inhibitor MST‑312 for improved cancer prognosis.

A-Raf and C-Raf differentially regulate mechanobiological response of osteoblasts to guide mechanical stress-induced differentiation

Regulation of osteoblast activity by mechanical stress is important for bone remodeling. However, the precise mechanotransduction mechanism that triggers the anabolic reaction of osteoblasts is largely unknown. In this study, we performed RNA interference (RNAi) screening to identify the signaling molecules upstream of ERK, which was responsible for osteogenesis. Of twenty-two mitogen-activated protein kinase (MAPK) kinase kinases (MAP3Ks), we identified A-Raf and C-Raf as upstream MAP3Ks of the mechanical stretch-activated ERK pathway. Subsequently we screened the mechanosensitive cation channel, and identified P2X7 as an upstream molecule of the ERK pathway. Intriguingly, P2X7 functioned as an upstream activator of A-Raf but not of C-Raf. Furthermore, A-Raf contributed to mechanical stretch-induced osteoblast differentiation. In contrast, C-Raf but not A-Raf protected osteoblasts from mechanical stretch-induced apoptosis. These results suggested that A-Raf and C-Raf were involved in mechanobiological osteogenesis in a distinct way: A-Raf was responsible for osteogenesis while C-Raf for anti-apoptotic protection and promotion.

Orchestrating the Tumor Microenvironment to Improve Survival for Patients With Pancreatic Cancer: Normalization, Not Destruction

Pancreatic cancer is the fourth leading cause of cancer death in the United States. The microenvironment of pancreatic cancer could be one of the "perfect storms" that support the growth of a cancer. Indeed, pancreatic cancer may be the poster child of a problem with the microenvironment. In this article, we review the rationale and attempts to date on modifying or targeting structural proteins in the microenvironment including hyaluronan (HA) (in primary and metastases), collagen, and SPARC (secreted protein, acidic, and rich in cysteine). Indeed, working in this area has produced a regimen that improves survival for patients with advanced pancreatic cancer (nab-paclitaxel + gemcitabine). In addition, in initial clinical trials, PEGylated hyaluronidase appears promising. We also review a new approach that is different than targeting/destroying the microenvironment and that is orchestrating, reengineering, reprogramming, or normalizing the microenvironment (including normalizing structural proteins, normalizing an immunologically tumor-friendly environment to a less friendly environment, reversing epithelial-to-mesenchymal transition, and so on). We believe this will be most effectively done by agents that have global effects on transcription. There is initial evidence that this can be done by agents such as vitamin D derivatives and other new agents. There is no doubt these opportunities can now be tried in the clinic with hopefully beneficial effects.

Evaluation of bone morphogenic proteins in periodontal practice

Forty years ago Marshal R. Urist discovered a substance in bone matrix that had inductive properties for the development of bone and cartilage, until date, at least 20 bone morphogenetic proteins (BMPs) have been identified, some of which have been shown in vitro to stimulate the process of stem cell differentiation into osteoblasts in human and animal models. The purpose of this paper is to give a brief overview of BMPs and to review critically the clinical data currently available on the use of BMPs in various periodontal applications. The literature on BMPs was reviewed. A comprehensive search was designed. The articles were independently screened for eligibility. Articles with authentic controls and proper randomization and pertaining specifically to their role in periodontal applications were included. The available literature was analyzed and compiled. The analysis indicates BMPs to be a promising, as well as an effective novel approach to reconstruct and engineer the periodontal apparatus. Here, we represent several articles, as well as recent texts that make up a special and an in-depth review on the subject. On the basis of the data provided in the studies that were reviewed BMPs provide revolutionary therapies in periodontal practice.

Identification and characterization of transforming growth factor β-activated kinase 1 from Litopenaeus vannamei involved in anti-bacterial host defense

LvTAK1, a member of transforming growth factor β-activated kinase 1 (TAK1) families, has been identified from Litopenaeus vannamei in this study. The full length of LvTAK1 is 2670 bp, including a 2277 bp open reading frame (ORF) that encoded a putative protein of 758 amino acids with a calculated molecular weight of ∼83.4 kDa LvTAK1 expression was most abundant in muscles and was up-regulated in gills after LPS, Vibrio parahaemolyticus, Staphylococcus aureus, Poly (I:C) and WSSV challenge. Both in vivo and in vitro experiments indicated that LvTAK1 could activate the expression of several antimicrobial peptide genes (AMPs). In addition, the dsRNA-mediated knockdown of LvTAK1 enhanced the susceptibility of shrimps to Vibrio parahaemolyticus, a kind of Gram-negative bacteria. These results suggested LvTAK1 played important roles in anti-bacterial infection. CoIP and subcellular localization assay demonstrated that LvTAK1 could interact with its binding protein LvTAB2, a key component of IMD pathway. Moreover, over-expression of LvTAK1 in Drosophila S2 cell could strongly induce the promoter activity of Diptericin (Dpt), a typical AMP which is used to read out of the activation of IMD pathway. These findings suggested that LvTAK1 could function as a component of IMD pathway. Interestingly, with the over-expression of LvTAK1 in S2 cell, the promoter activity of Metchnikowin (Mtk), a main target gene of Toll/Dif pathway, was up-regulated over 30 times, suggesting that LvTAK1 may also take part in signal transduction of the Toll pathway. In conclusion, we provided some evidences that the involvement of LvTAK1 in the regulation of both Toll and IMD pathways, as well as innate immune against bacterial infection in shrimp.

Live imaging of transforming growth factor-β activated kinase 1 activation in Lewis lung carcinoma 3LL cells implanted into syngeneic mice and treated with polyinosinic:polycytidylic acid

Transforming growth factor‐β activated kinase 1 (TAK1) has been shown to play a crucial role in cell death, differentiation, and inflammation. Here, we live‐imaged robust TAK1 activation in Lewis lung carcinoma 3LL cells implanted into the s.c. tissue of syngeneic C57BL/6 mice and treated with polyinosinic:polycytidylic acid (PolyI:C). First, we developed and characterized a Förster resonance energy transfer‐based biosensor for TAK1 activity. The TAK1 biosensor, named Eevee‐TAK1, responded to stress‐inducing reagents such as anisomycin, tumor necrosis factor‐α, and interleukin1‐β. The anisomycin‐induced increase in Förster resonance energy transfer was abolished by the TAK1 inhibitor (5z)‐7‐oxozeaenol. Activity of TAK1 in 3LL cells was markedly increased by PolyI:C in the presence of macrophages. 3LL cells expressing Eevee‐TAK1 were implanted into mice and observed through imaging window by two‐photon excitation microscopy. During the growth of tumor, the 3LL cells at the periphery of the tumor showed higher TAK1 activity than the 3LL cells located at the center of the tumor, suggesting that cells at the periphery of the tumor mass were under stronger stress. Injection of PolyI:C, which is known to induce regression of the implanted tumors, induced marked and homogenous TAK1 activation within the tumor tissues. The effect of PolyI:C faded within 4 days. These observations suggest that Eevee‐TAK1 is a versatile tool to monitor cellular stress in cancer tissues.

Dephosphorylation of Tak1 at Ser412 greatly contributes to the spermatocyte-specific testis toxicity induced by (5R)-5-hydroxytriptolide in C57BL/6 mice

(5R)-5-Hydroxytriptolide (LLDT-8), a novel triptolide derivative, will proceed to phase II clinical trials for the treatment of rheumatoid arthritis and cancer. However, the selection of disease and patients is largely limited by the testis toxicity, yet toxicity mechanisms are still poorly understood. In this study, LLDT-8 dose and time-dependently decreased the testes weight, germinal cell layers and induced abnormal spermatid development. Analysis of the germ cell-specific marker showed that spermatocytes were more sensitive to LLDT-8, which was confirmed by the in vitro sensitivity assay with spermatocyte-like GC-2spd and sertoli-like TM4 cells. In GC-2spd, LLDT-8 induced G1/S arrest and apoptosis. MAPK activity screening identified that TGF-β activated kinase 1 (Tak1) is critical in LLDT-8 induced apoptosis. LLDT-8 reduced the Tak1 protein and dephosphorylated Tak1 at Ser412 in GC-2spd and the testes, but not in TM4. RNAi mediated depletion or pharmacologic inhibition of Tak1 induced apoptosis in GC-2spd. Meanwhile, activating Tak1 rescued up to 50% of the GC-2spd cells from the apoptosis induced by LLDT-8. Altogether, our study firstly revealed the important role of Tak1 in the survival of spermatocytes, and dephosphorylation of Tak1 at Ser412 may contribute to the spermatocyte-specific testis toxicity induced by LLDT-8.

TGF-beta-induced early gene-1 overexpression promotes oxidative stress protection and actin cytoskeleton rearrangement in human skin fibroblasts

BACKGROUND

Transforming growth factor beta inducible early gene-1 (TIEG-1), a member of the Krüppel-like factor, was identified as a primary response gene for TGF-β. The role of TIEG-1 in skin repair has been mainly addressed in vivo on TIEG-1 null mice model and the mechanism remains unexplored.

METHODS

We investigated the modulation of TIEG-1 expression in normal human skin fibroblasts by either down-expressing or overexpressing the gene. We evaluated reactive oxygen species production and the cell viability of treated cells. The effect of TIEG-1 overexpression was monitored by wound healing assay and immunofluorescence staining of actin fibers organization and alpha-smooth muscle actin (α-SMA). Western blots were carried out to identify the level of expression or phosphorylation of key proteins such as cofilin, Rho GTPases, and p38 mitogen-activated protein kinase (p38 MAPK).

RESULTS

TIEG-1 down-regulation had a deleterious effect on the cell viability. It was significantly reduced (65±5%) and exposure to ultraviolet further increased this effect (47±3%). By contrast, cells overexpressing TIEG-1 had a reduced reactive oxygen species production (75%) compared to control and mock-transfected cells. This overexpression also resulted in formation of actin stress fibers and increased α-SMA expression and an enhanced wound healing feature. RhoB GTPase was upregulated and phosphorylation of cofilin and p38 MAPK was observed.

CONCLUSION

TIEG-1 overexpression in normal human skin fibroblasts results in improved resistance to oxidative stress, myofibroblast-like conversion that involved RhoB signaling pathway with cofilin and p38 MAPK proteins activation.

GENERAL SIGNIFICANCE

This study enlightens the role of TIEG-1 role in skin biology.

Dual-specificity phosphatase 14 protects the heart from aortic banding-induced cardiac hypertrophy and dysfunction through inactivation of TAK1-P38MAPK/-JNK1/2 signaling pathway

Dual-specificity phosphatase 14 (Dusp14), an important negative modulator of mitogen-activated protein kinase (MAPK) signaling pathways, has been implicated in inflammatory immune response, cancers, cell differentiation and proliferation. The role of Dusp14 in chronic pressure overload-induced cardiac hypertrophy has not been explored. Here we have shown that Dusp14-/- knockout mice and cardiac-specific Dusp14 transgenic mice were generated and subjected to aortic banding (AB) for 4 weeks. Our results demonstrated that genetic loss of Dusp14 significantly aggravated cardiac hypertrophy, fibrosis, ventricular dilation and dysfunction, whereas transgenic cardiac-specific Dusp14 overexpression significantly attenuated AB-induced cardiac dysfunction and remodeling. In vitro, adenoviral overexpression of constitutive Dusp14 blocked angiotensin II-induced hypertrophic growth of cardiomyocytes, while Dusp14 knockdown led to opposite effects. Mechanistically, excessive phosphorylation of TAK1, P38MAPK and JNK1/2 was evidenced in Dusp14-/- knockout mice post-AB and inactivation of TAK1-P38MAPK and -JNK1/2 signaling using TAK1 inhibitor 5Z-7-ox shares similar antihypertrophic effect as Dusp14 overexpression. Moreover, we show that Dusp14 directly interacted with TAK1. Results from present experiments indicate that Dusp14 protects the heart from AB-induced cardiac hypertrophy and dysfunction possibly through inactivation of TAK1-P38MAPK/-JNK1/2 signaling pathway. Future studies are warranted to test the feasibility of overexpressing Dusp14 as a therapeutic strategy to attenuate cardiac hypertrophy and failure.

The matricellular protein CCN1 enhances TGF-β1/SMAD3-dependent profibrotic signaling in fibroblasts and contributes to fibrogenic responses to lung injury

Matricellular proteins mediate pleiotropic effects during tissue injury and repair. CCN1 is a matricellular protein that has been implicated in angiogenesis, inflammation, and wound repair. In this study, we identified CCN1 as a gene that is differentially up-regulated in alveolar mesenchymal cells of human subjects with rapidly progressive idiopathic pulmonary fibrosis (IPF). Elevated levels of CCN1 mRNA were confirmed in lung tissues of IPF subjects undergoing lung transplantation, and CCN1 protein was predominantly localized to fibroblastic foci. CCN1 expression in ex vivo IPF lung fibroblasts correlated with gene expression of the extracellular matrix proteins, collagen (Col)1a1, Col1a2, and fibronectin as well as the myofibroblast marker, α-smooth muscle actin. RNA interference (RNAi)-mediated knockdown of CCN1 down-regulated the constitutive expression of these profibrotic genes in IPF fibroblasts. TGF-β1, a known mediator of tissue fibrogenesis, induces gene and protein expression of CCN1 via a mothers against decapentaplegic homolog 3 (SMAD3)-dependent mechanism. Importantly, endogenous CCN1 potentiates TGF-β1-induced SMAD3 activation and induction of profibrotic genes, supporting a positive feedback loop leading to myofibroblast activation. In vivo RNAi-mediated silencing of CCN1 attenuates fibrogenic responses to bleomycin-induced lung injury. These studies support previously unrecognized, cooperative interaction between the CCN1 matricellular protein and canonical TGF-β1/SMAD3 signaling that promotes lung fibrosis.-Kurundkar, A. R., Kurundkar, D., Rangarajan, S., Locy, M. L., Zhou, Y., Liu, R.-M., Zmijewski, J., Thannickal, V. J. The matricellular protein CCN1 enhances TGF-β1/SMAD3-dependent profibrotic signaling in fibroblasts and contributes to fibrogenic responses to lung injury.

A20 Mutation Is Not a Prognostic Marker for Activated B-Cell-Like Diffuse Large B-Cell Lymphoma

Background

Constitutive activation of nuclear factor κB (NF-κB) is a hallmark of activated B-cell-like diffuse large B-cell lymphoma (ABC-DLBCL). Mutations in the A20 gene activate NF-κB, but the prognostic value of A20 mutations in ABC-DLBLC is unclear.

Purpose

To investigate the prognostic value of A20 mutation in ABC-DLBCL patients.

Methods

The somatic mutation of A20 was investigated in 68 de novo ABC-DLBCLs by PCR/sequencing. The Kaplan-Meier method was used to estimate median overall survival (OS) and progression-free survival (PFS).

Results

The A20 mutation rate in ABC-DLBCL patients was 29.4%. Complete remission rates were 35% and 45.8% in patients with and without A20 mutations, respectively (P = 0.410). In patients with and without A20 mutations, the median OS was 24.0 and 30.6 months, respectively (P = 0.58), and the median PFS was 15 and 17.4 months, respectively (P = 0.52). None of the differences between the patient groups were significant.

Conclusions

Our findings suggested that the A20 mutation is a frequent event in ABC-DLBCLs. However, there was no significant difference in PFS and OS in patients with or without A20 mutations. Further study is required to completely exclude A20 somatic mutation as a prognostic marker in the ABC subtype of DLBLC.

TAK1 modulates satellite stem cell homeostasis and skeletal muscle repair

Satellite cells are resident adult stem cells that are required for regeneration of skeletal muscle. However, signalling mechanisms that regulate satellite cell function are less understood. Here we demonstrate that transforming growth factor-β-activated kinase 1 (TAK1) is important in satellite stem cell homeostasis and function. Inactivation of TAK1 in satellite cells inhibits muscle regeneration in adult mice. TAK1 is essential for satellite cell proliferation and its inactivation causes precocious differentiation. Moreover, TAK1-deficient satellite cells exhibit increased oxidative stress and undergo spontaneous cell death, primarily through necroptosis. TAK1 is required for the activation of NF-κB and JNK in satellite cells. Forced activation of NF-κB improves survival and proliferation of TAK1-deficient satellite cells. Furthermore, TAK1-mediated activation of JNK is essential to prevent oxidative stress and precocious differentiation of satellite cells. Collectively, our study suggests that TAK1 is required for maintaining the pool of satellite stem cells and for regenerative myogenesis.

Docosahexaenoic acid inhibits inflammation via free fatty acid receptor FFA4, disruption of TAB2 interaction with TAK1/TAB1 and downregulation of ERK-dependent Egr-1 expression in EA.hy926 cells

SCOPE

Inflammation is intimately associated with many cardiovascular events and docosahexaenoic acid (DHA) has been shown to protect against CVD. Egr-1 has emerged as a key regulator in the development of atherosclerosis. Free fatty acid receptor 4 (FFA4) is an n-3 FA membrane receptor. Tumor necrosis factor alpha (TNF-α) is an inflammatory mediator and transforming growth factor-β-activated kinase 1 (TAK1) is essential in the TNF-α-mediated activation of NF-κB. We examined the mechanisms underlying DHA inhibition of inflammation in human EA.hy926 cells.

METHODS AND RESULTS

TNF-α markedly induced the interaction between TAK1 binding protein (TAB) 2 and TAK1/TAB1, the phosphorylation of ERK, p38 MAPK and Akt, the expression of Egr-1 and ICAM-1, and HL-60 (monocyte-like) cell adhesion. Pretreatment with DHA attenuated TNF-α-induced phosphorylation of ERK, expression of Egr-1 and ICAM-1 and HL-60 cell adhesion. Transfection with siFFA4 reversed the DHA-mediated inhibition of TNF-α-induced Egr-1 and ICAM-1 expression, HL-60 cell adhesion and NF-κB and DNA-binding activity.

CONCLUSION

Our results suggest that the anti-inflammatory effect of DHA on the endothelium is at least partially linked to FFA4, disruption of TAB2 interaction with TAK1/TAB1 and downregulation of ERK-dependent Egr-1 and ICAM-1 expression, which leads to less HL-60 cell adhesion to TNF-α-stimulated EA.hy926 cells.

Concurrent BMP7 and FGF9 signalling governs AP-1 function to promote self-renewal of nephron progenitor cells

Self-renewal of nephron progenitor cells (NPCs) is governed by BMP, FGF and WNT signalling. Mechanisms underlying cross-talk between these pathways at the molecular level are largely unknown. Here we delineate the pathway through which the proliferative BMP7 signal is transduced in NPCs in the mouse. BMP7 activates the MAPKs TAK1 and JNK to phosphorylate the transcription factor JUN, which in turn governs transcription of AP-1-element containing G1-phase cell cycle regulators such as Myc and Ccnd1 to promote NPC proliferation. Conditional inactivation of Tak1 or Jun in cap mesenchyme causes identical phenotypes characterized by premature depletion of NPCs. While JUN is regulated by BMP7, we find that its partner FOS is regulated by FGF9. We demonstrate that BMP7 and FGF9 coordinately regulate AP-1 transcription to promote G1-S cell cycle progression and NPC proliferation. Our findings identify a molecular mechanism explaining the important cooperation between two major NPC self-renewal pathways.

The growth factors BMP and FGF both stimulate the self-renewal of nephron progenitor cells (NPCs), but how these signals overlap is unclear. Here in the mouse, Muthukrishnan et al. find BMP7 and FGF9 coordinately regulate AP-1 transcriptional activity, promoting G1-S cell cycle progression and NPC proliferation.

Targeting of TGF-β-activated protein kinase 1 inhibits chemokine (C-C motif) receptor 7 expression, tumor growth and metastasis in breast cancer

TGF-β-activated protein kinase 1 (TAK1) is a critical mediator in inflammation, immune response and cancer development. Our previous study demonstrated that activation of TAK1 increases the expression of chemokine (C-C motif) receptor 7 (CCR7) and promotes lymphatic invasion ability of breast cancer cells. However, the expression and association of activated TAK1 and CCR7 in breast tumor tissues is unknown and the therapeutic effect by targeting TAK1 is also unclear. We showed that activated TAK1 (as indicated by phospho-TAK1) and its binding protein TAB1 are strongly expressed in breast tumor tissues (77% and 74% respectively). In addition, increase of phospho-TAK1 or TAB1 is strongly associated with over-expression of CCR7. TAK1 inhibitor 5Z-7-Oxozeaenol (5Z-O) inhibited TAK1 activity, suppressed downstream signaling pathways including p38, IκB kinase (IKK) and c-Jun N-terminal kinase (JNK) and reduced CCR7 expression in metastatic MDA-MB-231 cells. In addition, 5Z-O repressed NF-κB- and c-JUN-mediated transcription of CCR7 gene. Knockdown of TAB1 attenuated CCR7 expression and tumor growth in an orthotopic animal study. More importantly, lymphatic invasion and lung metastasis were suppressed. Collectively, our results demonstrate that constitutive activation of TAK1 is frequently found in human breast cancer and this kinase is a potential therapeutic target for this cancer.

Bone morphogenetic proteins in tumour associated angiogenesis and implication in cancer therapies

Bone morphogenetic protein (BMP) belongs to transforming growth factor-β superfamily. To date, more than 20 BMPs have been identified in humans. BMPs play a critical role in embryonic and postnatal development, and also in maintaining homeostasis in different organs and tissues by regulating cell differentiation, proliferation, survival and motility. They play important roles in the development and progression of certain malignancies, including prostate cancer, breast cancer, lung cancer, etc. Recently, more evidence shows that BMPs are also involved in tumour associated angiogenesis. For example BMP can either directly regulate the functions of vascular endothelial cells or indirectly influence the angiogenesis via regulation of angiogenic factors, such as vascular endothelial growth factor (VEGF). Such crosstalk can also be reflected in the interaction with other angiogenic factors, like hepatocyte growth factor (HGF) and basic fibroblast growth factor (bFGF). All these factors are involved in the orchestration of the angiogenic process during tumour development and progression. Review of the relevant studies will provide a comprehensive prospective on current understanding and shed light on the corresponding therapeutic opportunity.

TAK1 Regulates Myocardial Response to Pathological Stress via NFAT, NFκB, and Bnip3 Pathways

TAK1 (TGFβ-activated kinase-1) signaling is essential in regulating a number of important biological functions, including innate immunity, inflammatory response, cell growth and differentiation, and myocardial homeostasis. The precise role of TAK1 in the adult heart under pathological conditions remains largely unknown. Importantly, we observed that TAK1 is upregulated during compensatory hypertrophy but downregulated in end-stage heart failure. Here we generated transgenic mice with inducible expression of an active TAK1 mutant (TAK1ΔN) in the adult heart. TAK1ΔN transgenic mice developed greater cardiac hypertrophy compared with control mice after transverse aortic constriction (TAC), which was largely blocked by ablation of calcineurin Aβ. Expression of TAK1ΔN also promoted NFAT (nuclear factor of activated T-cells) transcriptional activity in luciferase reporter mice at baseline, which was further enhanced after TAC. Our results revealed that activation of TAK1 promoted adaptive cardiac hypertrophy through a cross-talk between calcineurin-NFAT and IKK-NFκB pathways. More significantly, adult-onset inducible expression of TAK1ΔN protected the myocardium from adverse remodeling and heart failure after myocardial infarction or long-term pressure overload, by preventing cardiac cell death and fibrosis. Mechanistically, TAK1 exerts its cardioprotective effect through activation of NFAT/NFκB, downregulation of Bnip3, and inhibition of cardiac cell death.

Isolation, semisynthesis, covalent docking and transforming growth factor beta-activated kinase 1 (TAK1)-inhibitory activities of (5Z)-7-oxozeaenol analogues

(5Z)-7-Oxozeanol and related analogues were isolated and screened to explore their activity as TAK1 inhibitors. Seven analogues were synthesized and more than a score of natural products isolated that examined the role that different areas of the molecule contribute to TAK1 inhibition. A novel nonaromatic difluoro-derivative was synthesized that had similar potency compared to the lead. This is the first example of a nonaromatic compound in this class to have TAK1 inhibition. Covalent docking for the isolated and synthesized analogues was carried out and found a strong correlation between the observed activities and the calculated binding.

TAK1 inhibition-induced RIP1-dependent apoptosis in murine macrophages relies on constitutive TNF-α signaling and ROS production

Background

Transforming growth factor-β (TGF-β)-activated kinase 1 (TAK1) is a key regulator of signal cascades of TNF-α receptor and TLR4, and can induce NF-κB activation for preventing cell apoptosis and eliciting inflammation response.

Results

TAK1 inhibitor (TAKI) can decrease the cell viability of murine bone marrow-derived macrophages (BMDM), RAW264.7 and BV-2 cells, but not dermal microvascular endothelial cells, normal human epidermal keratinocytes, THP-1 monocytes, human retinal pigment epithelial cells, microglia CHME3 cells, and some cancer cell lines (CL1.0, HeLa and HCT116). In BMDM, TAKI-induced caspase activation and cell apoptosis were enhanced by lipopolysaccharide (LPS). Moreover, TAKI treatment increased the cytosolic and mitochondrial reactive oxygen species (ROS) production, and ROS scavengers NAC and BHA can inhibit cell death caused by TAKI. In addition, RIP1 inhibitor (necrostatin-1) can protect cells against TAKI-induced mitochondrial ROS production and cell apoptosis. We also observed the mitochondrial membrane potential loss after TAKI treatment and deterioration of oxygen consumption upon combination with LPS. Notably TNF-α neutralization antibody and inhibitor enbrel can decrease the cell death caused by TAKI.

Conclusions

TAKI-induced cytotoxicity is cell context specific, and apoptosis observed in macrophages is dependent on the constitutive autocrine action of TNF-α for RIP1 activation and ROS production.

TAK1 is a key modulator of the profibrogenic phenotype of human ileal myofibroblasts in Crohn's disease

Transforming growth factor (TGF)-β-activated kinase 1 (TAK1) signaling can mediate inflammatory responses as well as tissue remodeling. Intestinal mucosal myofibroblast (IMF) activation drives gut fibrosis in Crohn's disease (CD); however, the molecular pathways involved are largely unknown. Thus we investigated the yet-unknown expression and function of TAK1 in human CD-associated fibrosis. Ileal surgical specimens, ileal biopsies, and IMF isolated from controls and CD patients were analyzed for TAK1 and its active phosphorylated form (pTAK1) by Western blotting, immunohistochemistry, and real-time quantitative PCR. TAK1 pharmacological inhibition and silencing were used to assess its role in collagen and inflammatory cytokine synthesis in IMF. TAK1 and pTAK1 levels increased in ileum specimens from CD patients compared with controls and correlated to tissue fibrosis. Similarly, TAK1 mRNA in ileal biopsies of CD patients correlated with fibrogenic marker expression but not inflammatory cytokines. CD-derived IMF showed higher TAK1 and pTAK1 expression associated with increased collagen1(α)1 mRNA levels compared with control IMF. TGF-β1 promoted pTAK1 nuclear translocation and collagen synthesis. TAK1 inhibition or silencing significantly reduced TGF-β1-stimulated collagen production and normalized the profibrogenic phenotype of CD-derived IMF. Taken together, these data suggest that TAK1 activation and nuclear translocation induce and maintain a fibrogenic phenotype in the IMF. Thus the TAK1 signaling pathway may represent a suitable target to design new, antifibrotic therapies.

MicroRNAs Enhance Keratinocyte Proliferative Capacity in a Stem Cell-Enriched Epithelium

MicroRNAs are critical regulators of stem cell behavior. The miR-103/107 family is preferentially expressed in the stem cell-enriched corneal limbal epithelium and plays an important role in coordinating several intrinsic characteristics of limbal epithelial stem cells. To elucidate further the mechanisms by which miRs-103/107 function in regulating limbal epithelial stem cells, we investigate the global effects of miRs-103/107 on gene expression in an unbiased manner. Using antagomirs-103/107, we knocked down endogenous miRs-103/107 in keratinocytes and conducted an mRNA profiling study. We show that miRs-103/107 target mitogen-activated protein kinase kinase kinase 7 (MAP3K7) and thereby negatively regulate the p38/AP-1 pathway, which directs epithelial cells towards a differentiated state. Pharmacological inhibition of p38 increases holoclone colony formation, a measure of proliferative capacity. This suggests that the negative regulation of p38 by miRs-103/107 contributes to enhanced proliferative capacity, which is a hallmark of stem cells. Since miRs-103/107 also promote increased holoclone colony formation by regulating JNK activation through non-canonical Wnt signaling, we believe that this microRNA family preserves “stemness” by mediating the crosstalk between the Wnt/JNK and MAP3K7/p38/AP-1 pathways.

Synergistic action of 5Z-7-oxozeaenol and bortezomib in inducing apoptosis of Burkitt lymphoma cell line Daudi

Treatment failure in cancer chemotherapy is largely due to the toxic effects of chemotherapeutic agents on normal cells/tissues. The proteasome inhibitor bortezomib has been successfully applied to treat multiple myeloma (MM), but there are some common adverse reactions in the clinic including peripheral neuropathy (PN). The TAK1 selective inhibitor 5Z-7-oxozeaenol has been widely studied in cancer therapy. Here, we investigated the potential synergy of bortezomib and 5Z-7-oxozeaenol in Burkitt's lymphoma (BL) cell lines. Cell viability assay showed that co-treatment of bortezomib at 8 nM, representing a one-eighth concentration for growth arrest, and 5Z-7-oxozeaenol at 2 μM, a dose that exhibited insignificant cytotoxic effects, synergistically induced apoptosis in the cell line Daudi. In parallel with the increasing dose of the bortezomib, and 5Z-7-oxozeaenol at 0.5 μM, lower colony formation efficiencies were seen in the cell line Daudi. Western blotting analysis verified that TAK1 inhibition by 5Z-7-oxozeaenol completely blocked JNK, p38, Erk, IKK, and IκB phosphorylation, which was almost instantly activated by TAK1 both directly or indirectly. Both agents synergistically prevented nuclear translocation of NF-κB, a characteristic of NF-κB inactivation. Moreover, a synergistic effect of bortezomib and 5Z-7-oxozeaenol on Western blotting analysis and flow cytometry was disclosed. Collectively, our results indicated that the proteasome inhibitor bortezomib and the TAK1 inhibitor 5Z-7-oxozeaenol displayed synergy on inhibiting BL cell apoptosis by inhibiting NF-κB activity.

Coordinate loss of MAP3K7 and CHD1 promotes aggressive prostate cancer

Prostate cancer subtypes are poorly defined and functional validation of drivers of ETS rearrangement-negative prostate cancer has not been conducted. Here, we identified an ETS(-) subtype of aggressive prostate cancer (ERG(-)MAP3K7(del)CHD1(del)) and used a novel developmental model and a cell line xenograft model to show that cosuppression of MAP3K7 and CHD1 expression promotes aggressive disease. Analyses of publicly available prostate cancer datasets revealed that MAP3K7 and CHD1 were significantly codeleted in 10% to 20% of localized tumors and combined loss correlated with poor disease-free survival. To evaluate the functional impact of dual MAP3K7-CHD1 loss, we suppressed Map3k7 and/or Chd1 expression in mouse prostate epithelial progenitor/stem cells (PrP/SC) and performed tissue recombination experiments in vivo. Dual shMap3k7-shChd1 PrP/SC recombinants displayed massive glandular atypia with regions of prostatic intraepithelial neoplasia and carcinoma apparent. Combined Map3k7-Chd1 suppression greatly disrupted normal prostatic lineage differentiation; dual recombinants displayed significant androgen receptor loss, increased neuroendocrine differentiation, and increased neural differentiation. Clinical samples with dual MAP3K7-CHD1 loss also displayed neuroendocrine and neural characteristics. In addition, dual Map3k7-Chd1 suppression promoted E-cadherin loss and mucin production in recombinants. MAP3K7 and CHD1 protein loss also correlated with Gleason grade and E-cadherin loss in clinical samples. To further validate the phenotype observed in the PrP/SC model, we suppressed MAP3K7 and/or CHD1 expression in LNCaP prostate cancer cells. Dual shMAP3K7-shCHD1 LNCaP xenografts displayed increased tumor growth and decreased survival compared with shControl, shMAP3K7, and shCHD1 xenografts. Collectively, these data identify coordinate loss of MAP3K7 and CHD1 as a unique driver of aggressive prostate cancer development.