A resorcylic acid lactone, 5Z-7-oxozeaenol, prevents inflammation by inhibiting the catalytic activity of TAK1 MAPK kinase kinase

AR loss in prostate cancer stroma mediated by NF-κB and p38-MAPK signaling disrupts stromal morphogen production

Androgen Receptor (AR) activity in prostate stroma is required to maintain prostate homeostasis. This is mediated through androgen-dependent induction and secretion of morphogenic factors that drive epithelial cell differentiation. However, stromal AR expression is lost in aggressive prostate cancer. The mechanisms leading to stromal AR loss and morphogen production are unknown. We identified TGFβ1 and TNFα as tumor-secreted factors capable of suppressing AR mRNA and protein expression in prostate stromal fibroblasts. Pharmacological and RNAi approaches identified NF-κB as the major signaling pathway involved in suppressing AR expression by TNFα. In addition, p38α- and p38δ-MAPK were identified as suppressors of AR expression independent of TNFα. Two regions of the AR promoter were responsible for AR suppression through TNFα. FGF10 and Wnt16 were identified as androgen-induced morphogens, whose expression was lost upon TNFα treatment and enhanced upon p38-MAPK inhibition. Wnt16, through non-canonical Jnk signaling, was required for prostate basal epithelial cell survival. These findings indicate that stromal AR loss is mediated by secreted factors within the TME. We identified TNFα/TGFβ as two possible factors, with TNFα mediating its effects through NF-κB or p38-MAPK to suppress AR mRNA transcription. This leads to loss of androgen-regulated stromal morphogens necessary to maintain normal epithelial homeostasis.

TAK1 inhibition mitigates intracerebral hemorrhage-induced brain injury through reduction of oxidative stress and neuronal pyroptosis via the NRF2 signaling pathway

Introduction

Intracerebral hemorrhage (ICH) often triggers oxidative stress through reactive oxygen species (ROS). Transforming growth factor-β-activated kinase 1 (TAK1) plays a pivotal role in regulating oxidative stress and inflammation across various diseases. 5Z-7-Oxozeaenol (OZ), a specific inhibitor of TAK1, has exhibited therapeutic effects in various conditions. However, the impact of OZ following ICH and its underlying molecular mechanisms remain elusive. This study aimed to explore the possible role of OZ in ICH and its underlying mechanisms by inhibiting oxidative stress-mediated pyroptosis.

Methods

Adult male Sprague-Dawley rats were subjected to an ICH model, followed by treatment with OZ. Neurobehavioral function, blood-brain barrier integrity, neuronal pyroptosis, and oxidative stress markers were assessed using various techniques including behavioral tests, immunofluorescence staining, western blotting, transmission electron microscopy, and biochemical assays.

Results

Our study revealed that OZ administration significantly inhibited phosphorylated TAK1 expression post-ICH. Furthermore, TAK1 blockade by OZ attenuated blood-brain barrier (BBB) disruption, neuroinflammation, and oxidative damage while enhancing neurobehavioral function. Mechanistically, OZ administration markedly reduced ROS production and oxidative stress by facilitating nuclear factor-erythroid 2-related factor 2 (NRF2) nuclear translocation. This was accompanied by a subsequent suppression of the NOD-like receptor protein 3 (NLRP3) activation-mediated inflammatory cascade and neuronal pyroptosis.

Discussion

Our findings highlight that OZ alleviates brain injury and oxidative stress-mediated pyroptosis via the NRF2 pathway. Inhibition of TAK1 emerges as a promising approach for managing ICH.

Loss of ESRP2 Activates TAK1-MAPK Signaling through the Fetal RNA-Splicing Program to Promote Hepatocellular Carcinoma Progression

Tumors usually display fetal-like characteristics, and many oncofetal proteins have been identified. However, fetal-like reprogramming of RNA splicing in hepatocellular carcinoma (HCC) is poorly understood. Here, it is demonstrated that the expression of epithelial splicing regulatory protein 2 (ESRP2), an RNA splicing factor, is suppressed in fetal hepatocytes and HCC, in parallel with tumor progression. By combining RNA-Seq with splicing analysis, it is identified that ESRP2 controls the fetal-to-adult switch of multiple splice isoforms in HCC. Functionally, ESRP2 suppressed cell proliferation and migration by specifically switching the alternative splicing (AS) of the TAK1 gene and restraining the expression of the fetal and oncogenic isoform, TAK1_ΔE12. Notably, aberrant TAK1 splicing led to the activation of p38MAPK signaling and predicted poor prognosis in HCC patients. Further investigation revealed that TAK1_ΔE12 protein interacted closely with TAB3 and formed liquid condensation in HCC cells, resulting in p38MAPK activation, enhanced cell migration, and accelerated tumorigenesis. Loss of ESRP2 sensitized HCC cells to TAK1 kinase inhibitor (TAK1i), promoting pyroptotic cell death and CD8+ T cell infiltration. Combining TAK1i with immune checkpoint therapy achieved potent tumor regression in mice. Overall, the findings reveal a previously unexplored onco-fetal reprogramming of RNA splicing and provide novel therapeutic avenues for HCC.

TGFβ1-driven SMAD2/3 phosphorylation and myofibroblast emergence are fully dependent on the TGFβ1 pre-activation of MAPKs and controlled by maternal leucine zipper kinase

Following wounding, endogenously secreted TGFβs drive resident and bone marrow-derived cells to convert into α-smooth actin (SMA)-rich, contractile myofibroblasts. The TGFβ effect is initiated by the phosphorylation of SMADs 2 and 3 (SMAD2/3). This event has been referred to as the canonical response to TGFβ. TGFβ also elicits other responses viewed as parallel events not directly connected to the SMAD activation, and thus referred to as noncanonical. A recognized response is the phosphorylation of the -activated kinase (TAK1/MAP3K), an upstream component of the mitogen-activated protein kinase (MAPK) cascade. We have now examined the relationship between these two effects of TGFβ1 at their earliest stages. The bulk of the studies were carried out with primary fibroblasts derived from the human cornea. The results' widespread relevance was confirmed in critical experiments with dermal-, and Tenon's capsule-derived fibroblasts. Cells were treated with kinase inhibitors or targeting siRNAs followed by induction by 2 ng/ml TGFβ1, and/or 10 ng/ml TNF-α. Cells were collected after 1 to 30 min for Western blot analysis and assayed for the accumulation of phosphorylated TAK1, ASK1, JNK1/2, p38, HPS27, MELK, SMAD2/3, and GAPDH. The effect of the kinase inhibitors on α-SMA expression and α-SMA stress fiber organization was also tested. For the immediate response to TGFβ1 we found that a) activation of the MAPK pathway was completed within 1 min after the addition of TGFβ1; b) phosphorylation of JNK1/2 was fully dependent on TAK1 and ASK1 activity, c) phosphorylation of MELK was fully dependent on JNK1/2 activity; d) phosphorylation of ASK1 depends on MELK activity, indicating the existence of an ASK1-MELK positive activation feedback loop; e) phosphorylation of SMAD2/3 started only after a 5 min period and reached a nadir after 10-15 min, f) the latter phosphorylation was fully blocked by inhibition of TAK1, ASK1, JNK1/2, and MELK, and siRNA-driven MELK downregulation; g) the inhibitors equally blocked the α-SMA protein expression, stress fiber development, and cell morphology changes at 72 h. These results demonstrate that the activation of the canonical pathway is fully subordinate to the activity of the MAPK pathway, challenging the concept of canonical and noncanonical TGFβ pathways and that SMAD2/3 activation is mediated by MELK, a kinase not previously associated with rapid pharmacological responses.

Resistance gene-guided genome mining reveals the roseopurpurins as inhibitors of cyclin-dependent kinases

With the significant increase in the availability of microbial genome sequences in recent years, resistance gene-guided genome mining has emerged as a powerful approach for identifying natural products with specific bioactivities. Here, we present the use of this approach to reveal the roseopurpurins as potent inhibitors of cyclin-dependent kinases (CDKs), a class of cell cycle regulators implicated in multiple cancers. We identified a biosynthetic gene cluster (BGC) with a putative resistance gene with homology to human CDK2. Using targeted gene disruption and transcription factor overexpression in Aspergillus uvarum, and heterologous expression of the BGC in Aspergillus nidulans, we demonstrated that roseopurpurin C (1) is produced by this cluster and characterized its biosynthesis. We determined the potency, specificity, and mechanism of action of 1 as well as multiple intermediates and shunt products produced from the BGC. We show that 1 inhibits human CDK2 with a Kiapp of 44 nM, demonstrates selectivity for clinically relevant members of the CDK family, and induces G1 cell cycle arrest in HCT116 cells. Structural analysis of 1 complexed with CDK2 revealed the molecular basis of ATP-competitive inhibition.

cFLIPS regulates alternative NLRP3 inflammasome activation in human monocytes

The innate immune responses, including inflammasome activation, are paramount for host defense against pathogen infection. In contrast to canonical and noncanonical inflammasome activation, in this study, heat-killed gram-negative bacteria (HK bacteria) were identified as single-step stimulators of the NLRP3 inflammasome in human monocytes, and they caused a moderate amount of IL-1β to be released from cells. Time course experiments showed that this alternative inflammasome response was finished within a few hours. Further analysis showed that the intrinsically limited NLRP3 inflammasome activation response was due to the negative regulation of caspase-8 by the short isoform of cFLIP (cFLIPs), which was activated by NF-κB. In contrast, overexpressed cFLIPS, but not overexpressed cFLIPL, inhibited the activation of caspase-8 and the release of IL-1β in response to HK bacteria infection in human monocytes. Furthermore, we demonstrated that TAK1 activity mediated the expression of cFLIPs and was upstream and essential for the caspase-8 cleavage induced by HK bacteria in human monocytes. The functional specificity of cFLIPs and TAK1 revealed unique responses of human monocytes to a noninvasive pathogen, providing novel insights into an alternative regulatory pathway of NLRP3 inflammasome activation.

Therapeutic efficacy of the resorcylic acid lactone LL-Z1640-2 for adult T-cell leukaemia/lymphoma

Adult T-cell leukaemia/lymphoma (ATL) remains incurable. The NF-κB and interferon regulatory factor 4 (IRF4) signalling pathways are among the critical survival pathways for the progression of ATL. TGF-β-activated kinase 1 (TAK1), an IκB kinase-activating kinase, triggers the activation of NF-κB. The resorcylic acid lactone LL-Z1640-2 is a potent irreversible inhibitor of TAK1/extracellular signal-regulated kinase 2 (ERK2). We herein examined the therapeutic efficacy of LL-Z1640-2 against ATL. LL-Z1640-2 effectively suppressed the in vivo growth of ATL cells. It induced in vitro apoptosis and inhibited the nuclear translocation of p65/RelA in ATL cells. The knockdown of IRF4 strongly induced ATL cell death while downregulating MYC. LL-Z1640-2 as well as the NF-κB inhibitor BAY11-7082 decreased the expression of IRF4 and MYC at the protein and mRNA levels, indicating the suppression of the NF-κB-IRF4-MYC axis. The treatment with LL-Z1640-2 also mitigated the phosphorylation of p38 MAPK along with the expression of CC chemokine receptor 4. Furthermore, the inhibition of STAT3/5 potentiated the cytotoxic activity of LL-Z1640-2 against IL-2-responsive ATL cells in the presence of IL-2. Therefore, LL-Z1640-2 appears to be an effective treatment for ATL. Further studies are needed to develop more potent compounds that retain the active motifs of LL-Z1640-2.

EPRS1 Controls the TGF- Signaling Pathway via Interaction with TβRI in Hepatic Stellate Cell

Glutamyl-prolyl-tRNA synthetase 1 (EPRS1) is known to associated with fibrosis through its catalytic activity to produce prolyl-tRNA. Although its catalytic inhibitor halofuginone (HF) has been known to inhibit the TGF-β pathway as well as to reduce prolyl-tRNA production for the control of fibrosis, the underlying mechanism how EPRS1 regulates the TGF-β pathway was not fully understood. Here, we show a noncatalytic function of EPRS1 in controlling the TGF-β pathway and hepatic stellate cell activation via its interaction with TGF-β receptor I (TβRI). Upon stimulation with TGF-β, EPRS1 is phosphorylated by TGF-β-activated kinase 1 (TAK1), leading to its dissociation from the multi-tRNA synthetase complex and subsequent binding with TβRI. This interaction increases the association of TβRI with SMAD2/3 while decreases that of TβRI with SMAD7. Accordingly, EPRS1 stabilizes TβRI by preventing the ubiquitin-mediated degradation of TβRI. HF disrupts the interaction between EPRS1 and TβRI, and reduces TβRI protein levels, leading to inhibition of the TGF-β pathway. In conclusion, this work suggests the novel function of EPRS1 involved in the development of fibrosis by regulating the TGF-β pathway and the antifibrotic effects of HF by controlling both of EPRS1 functions.

Cross-activation of FGF, NODAL, and WNT pathways constrains BMP-signaling-mediated induction of the totipotent state in mouse embryonic stem cells

Embryonic stem cells (ESCs) are an attractive model to study the relationship between signaling and cell fates. Cultured mouse ESCs can exist in multiple states resembling distinct stages of early embryogenesis, such as totipotent, pluripotent, primed, and primitive endoderm. The signaling mechanisms regulating the totipotent state and coexistence of these states are poorly understood. Here we identify bone morphogenetic protein (BMP) signaling as an inducer of the totipotent state. However, we discover that BMP's role is constrained by the cross-activation of FGF, NODAL, and WNT pathways. We exploit this finding to enhance the proportion of totipotent cells by rationally inhibiting the cross-activated pathways. Single-cell mRNA sequencing reveals that induction of the totipotent state is accompanied by suppression of primed and primitive endoderm states. Furthermore, reprogrammed totipotent cells we generate in culture resemble totipotent cells of preimplantation embryo. Our findings reveal a BMP signaling mechanism regulating both the totipotent state and heterogeneity of ESCs.

Total synthesis of (3R, 4S)-4-hydroxylasiodiplodin

An efficient stereoselective total synthesis of (3R, 4S)-4-hydroxylasiodiplodin has been accomplished starting from known starting materials. The key steps involved in this synthesis are Stille cross coupling, alkylation of 1,3-dithiane and Yamaguchi macrolactonization.

Impact of a TAK-1 inhibitor as a single or as an add-on therapy to riociguat on the metabolic reprograming and pulmonary hypertension in the SUGEN5416/hypoxia rat model

Background: Despite increasing evidence suggesting that pulmonary arterial hypertension (PAH) is a complex disease involving vasoconstriction, thrombosis, inflammation, metabolic dysregulation and vascular proliferation, all the drugs approved for PAH mainly act as vasodilating agents. Since excessive TGF-β signaling is believed to be a critical factor in pulmonary vascular remodeling, we hypothesized that blocking TGFβ-activated kinase 1 (TAK-1), alone or in combination with a vasodilator therapy (i.e., riociguat) could achieve a greater therapeutic benefit.

Methods: PAH was induced in male Wistar rats by a single injection of the VEGF receptor antagonist SU5416 (20 mg/kg) followed by exposure to hypoxia (10%O2) for 21 days. Two weeks after SU5416 administration, vehicle, riociguat (3 mg/kg/day), the TAK-1 inhibitor 5Z-7-oxozeaenol (OXO, 3 mg/kg/day), or both drugs combined were administered for 7 days. Metabolic profiling of right ventricle (RV), lung tissues and PA smooth muscle cells (PASMCs) extracts were performed by magnetic resonance spectroscopy, and the differences between groups analyzed by multivariate statistical methods.

Results:In vitro, riociguat induced potent vasodilator effects in isolated pulmonary arteries (PA) with negligible antiproliferative effects and metabolic changes in PASMCs. In contrast, 5Z-7-oxozeaenol effectively inhibited the proliferation of PASMCs characterized by a broad metabolic reprogramming but had no acute vasodilator effects. In vivo, treatment with riociguat partially reduced the increase in pulmonary arterial pressure (PAP), RV hypertrophy (RVH), and pulmonary vascular remodeling, attenuated the dysregulation of inosine, glucose, creatine and phosphocholine (PC) in RV and fully abolished the increase in lung IL-1β expression. By contrast, 5Z-7-oxozeaenol significantly reduced pulmonary vascular remodeling and attenuated the metabolic shifts of glucose and PC in RV but had no effects on PAP or RVH. Importantly, combined therapy had an additive effect on pulmonary vascular remodeling and induced a significant metabolic effect over taurine, amino acids, glycolysis, and TCA cycle metabolism via glycine-serine-threonine metabolism. However, it did not improve the effects induced by riociguat alone on pulmonary pressure or RV remodeling. None of the treatments attenuated pulmonary endothelial dysfunction and hyperresponsiveness to serotonin in isolated PA.

Conclusion: Our results suggest that inhibition of TAK-1 induces antiproliferative effects and its addition to short-term vasodilator therapy enhances the beneficial effects on pulmonary vascular remodeling and RV metabolic reprogramming in experimental PAH.

Aberrantly activated TAK1 links neuroinflammation and neuronal loss in Alzheimer's disease mouse models

Neuroinflammation is causally associated with Alzheimer's disease (AD) pathology. Reactive glia cells secrete various neurotoxic factors that impair neuronal homeostasis eventually leading to neuronal loss. Although the glial activation mechanism in AD has been relatively well studied, how it perturbs intraneuronal signaling, which ultimately leads to neuronal cell death, remains poorly understood. Here, we report that compound stimulation with the neurotoxic factors TNF and glutamate aberrantly activates neuronal TAK1 (also known as MAP3K7), which promotes the pathogenesis of AD in mouse models. Glutamate-induced Ca2+ influx shifts TNF signaling to hyper-activate TAK1 enzymatic activity through Ca2+/calmodulin-dependent protein kinase II, which leads to necroptotic cellular damage. Genetic ablation and pharmacological inhibition of TAK1 ameliorated AD-associated neuronal loss and cognitive impairment in the AD model mice. Our findings provide a molecular mechanism linking cytokines, Ca2+ signaling and neuronal necroptosis in AD.

TAK1 blockade as a therapy for retinal neovascularization

Retinal neovascularization, or pathological angiogenesis in the retina, is a leading cause of blindness in developed countries. Transforming growth factor-β-activated kinase 1 (TAK1) is a mitogen-activated protein kinase kinase kinase (MAPKKK) activated by TGF-β1 and other proinflammatory cytokines. TAK1 is also a key mediator of proinflammatory signals and plays an important role in maintaining vascular integrity upon proinflammatory cytokine stimulation such as TNFα. However, its role in pathological angiogenesis, particularly in retinal neovascularization, remains unclear. Here, we investigate the regulatory role of TAK1 in human endothelial cells responding to inflammatory stimuli and in a rat model of oxygen-induced retinopathy (OIR) featured retinal neovascularization. Using TAK1 knockout human endothelial cells that subjected to inflammatory stimuli, transcriptome analysis revealed that TAK1 is required for activation of NFκB signaling and mediates its downstream gene expression related to endothelial activation and angiogenesis. Moreover, pharmacological inhibition of TAK1 by 5Z-7-oxozeaenol attenuated angiogenic activities of endothelial cells. Transcriptome analysis also revealed enrichment of TAK1-mediated NFκB signaling pathway in the retina of OIR rats and retinal neovascular membrane from patients with proliferative diabetic retinopathy. Intravitreal injection of 5Z-7-oxozeaenol significantly reduced hypoxia-induced inflammation and microglial activation, thus attenuating aberrant retinal angiogenesis in OIR rats. Our data suggest that inhibition of TAK1 may have therapeutic potential for the treatment of retinal neovascular pathologies.

Comprehensive Analysis of NABP2 as a Prognostic Biomarker and Its Correlation with Immune Infiltration in Hepatocellular Carcinoma

Background

The DNA binding protein NABP2 (nucleic acid binding protein 2) is a member of the SSB (single-stranded DNA-binding) protein family, which is involved in DNA damage repair. Its prognostic significance and relationship with immune infiltration in hepatocellular carcinoma (HCC), however, remain unknown.

Methods

The purpose of this study was to estimate the prognostic value of NABP2 and to investigate its possible immune function in HCC. By applying multiple bioinformatics methods, we gathered and analysed data from The Cancer Genome Atlas (TCGA), Cancer Cell Lineage Encyclopedia (CCLE), and Gene Expression Omnibus (GEO) to investigate the potential oncogenic and cancer-promoting role of NABP2, including the differential expression, prognostic value, immune cell infiltration association, and drug sensitivity of NABP2 in HCC. Immunohistochemistry and Western blotting were used to validate the expression of NABP2 in HCC. The knockdown of NABP2 expression by siRNA was further used to validate its role in hepatocellular carcinoma.

Results

Our findings indicated that NABP2 was overexpressed in HCC samples and was related to poor survival, clinical stage, and tumour grade in HCC patients. Analysis of functional enrichment indicated that NABP2 was potentially involved in the cell cycle, DNA replication, G2M checkpoint, E2F targets, apoptosis, P53 signalling, TGFA signalling via NF-κB, and so on. NABP2 was shown to be significantly linked to immune cell infiltration and immunological checkpoints in HCC. Analyses of drug sensitivity predict a number of drugs that could potentially be used to target NABP2. Moreover, in vitro experiments verified the promoting effect of NABP2 on the migration and proliferation of hepatocellular carcinoma cells.

Conclusion

Based on these findings, NABP2 appears to be a candidate biomarker for HCC prognosis and immunotherapy.

Patulin and LL‐Z1640 ‐2 induce apoptosis of cancer cells by decreasing endogenous protein levels of Zic family member 5

Zic family member 5 (ZIC5) is a transcription factor that promotes the survival of several cancer cell types. As ZIC5 is expressed at minimal levels in normal human adult tissues, it is a potential therapeutic target. In this study, we screened a chemical library containing 3398 compounds that includes pre‐existing drugs and compounds with known effects to identify ZIC5 inhibitors. In the first screening, 18 hit compounds decreased GFP intensity in melanoma A375 cells overexpressing GFP‐tagged ZIC5. In the second screening, five compounds that attenuated ZIC5 protein levels in A375 cells were identified. Among them, LL‐Z1640‐2 and patulin selectively induced apoptosis in melanoma cells expressing ZIC5, while only inducing very low levels of apoptosis in normal human melanocytes, which have no detectable ZIC5 expression. LL‐Z1640‐2 and patulin also induced apoptosis in BRAF inhibitor‐resistant melanoma, pancreatic cancer, cholangiocarcinoma and colorectal cancer cells. LL‐Z1640‐2‐ and patulin‐mediated suppression of melanoma proliferation were rescued by ZIC5 overexpression. These results suggest that LL‐Z1640‐2 and patulin are promising compounds that decrease ZIC5 expression to induce apoptosis in cancer cells.

TAK1 protein kinase activity is required for TLR signalling and cytokine production in myeloid cells

A conditional knock-in mouse was generated in which the TAK1 catalytic subunit was largely replaced by the kinase-inactive TAK1[D175A] mutant in immune cells. The activation of p38α MAP kinase, c-Jun N-terminal kinases 1 and 2 (JNK1/2) and the canonical IKK complex induced by stimulation with several TLR-activating ligands was reduced in bone marrow-derived macrophages (BMDM) from TAK1[D175A] mice. TLR signalling in TAK1[D175A] BMDM was catalysed by the residual wild-type TAK1 in these cells because it was abolished by either of two structurally unrelated TAK1 inhibitors (NG25 and 5Z-7-oxozeaenol) whose off-target effects do not overlap. The secretion of inflammatory mediators and production of the mRNAs encoding these cytokines induced by TLR ligation was greatly reduced in peritoneal neutrophils or BMDM from TAK1[D175A] mice. The Pam3CSK4- or LPS-stimulated activation of MAP kinases and the canonical IKK complex, as well as cytokine secretion, was also abolished in TAK1 knock-out human THP1 monocytes or macrophages. The results establish that TAK1 protein kinase activity is required for TLR-dependent signalling and cytokine secretion in myeloid cells from mice. We discuss possible reasons why other investigators, studying myeloid mice with a conditional knock-out of TAK1 or a different conditional kinase-inactive knock-in of TAK1, reported TAK1 to be a negative regulator of LPS-signalling and cytokine production in mouse macrophages and neutrophils.

Adult fibroblasts use aggresomes only in distinct cell-states

The aggresome is a protein turnover system in which proteins are trafficked along microtubules to the centrosome for degradation. Despite extensive focus on aggresomes in immortalized cell lines, it remains unclear if the aggresome is conserved in all primary cells and all cell-states. Here we examined the aggresome in primary adult mouse dermal fibroblasts shifted into four distinct cell-states. We found that in response to proteasome inhibition, quiescent and immortalized fibroblasts formed aggresomes, whereas proliferating and senescent fibroblasts did not. Using this model, we generated a resource to provide a characterization of the proteostasis networks in which the aggresome is used and transcriptomic features associated with the presence or absence of aggresome formation. Using this resource, we validate a previously reported role for p38 MAPK signaling in aggresome formation and identify TAK1 as a novel driver of aggresome formation upstream of p38 MAPKs. Together, our data demonstrate that the aggresome is a non-universal protein degradation system which can be used cell-state specifically and provide a resource for studying aggresome formation and function.

Semisynthesis of Hypothemycin Analogues Targeting the C8-C9 Diol

Hypothemycin, an epoxide derivative of (5Z)-7-oxozeaenol, was used in the semisynthesis of a series of C8-C9 diol derivatives, with many inhibiting TAK1 at submicromolar concentrations. A step-economical approach was chosen, whereby nonselective reactions functionalized the diol to generate multiple analogues in a single reaction. Using this approach, 35 analogues were synthesized using 12 reactions, providing a wealth of information about the role that the C8-C9 diol plays in TAK1 inhibition and cytotoxicity in ovarian and breast cancer cell lines. Monofunctionalized analogues exhibited strong inhibition of TAK1, showing potential for modification of this section of the molecule to assist with solubility, formulation, and other desirable properties. Most analogues were cytotoxic, and three compounds had similar or slightly increased potency with >100-fold improvement in solubility profiles.

Regulation of the p38-MAPK pathway by hyperosmolarity and by WNK kinases

p38-MAPK is a stress-response kinase activated by hyperosmolarity. Here we interrogated the pathways involved. We show that p38-MAPK signaling is activated by hyperosmotic stimulation in various solutions, cell types and colonic organoids. Hyperosmolarity sensing is detected at the level of the upstream activators of p38-MAPK: TRAF2/ASK1 (but not Rac1) and MKK3/6/4. While WNK kinases are known osmo-sensors, we found, unexpectedly, that short (2 h) inhibition of WNKs (with WNK463) led to elevated p38-MAPK activity under hyperosmolarity, which was mediated by WNK463-dependent stimulation of TAK1 or TRAF2/ASK1, the upstream activators of MKK3/6/4. However, this effect was temporary and was reversed by long-term (2 days) incubation with WNK463. Accordingly, 2 days (but not 2 h) inhibition of p38-MAPK or its upstream activators ASK1 or TAK1, or WNKs, diminished regulatory volume increase (RVI) following cell shrinkage under hyperosmolarity. We also show that RVI mediated by the ion transporter NKCC1 is dependent on p38-MAPK. Since WNKs are known activators of NKCC1, we propose a WNK- > NKCC1- > p38-MAPK pathway that controls RVI. This pathway is augmented by NHE1. Additionally, hyperosmolarity inhibited mTORC1 activation and cell proliferation. Thus, activation of p38-MAPK and WNKs is important for RVI and for cell proliferation.

Numb-associated kinases are required for SARS-CoV-2 infection and are cellular targets for antiviral strategies

The coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to pose serious threats to global health. We previously reported that AAK1, BIKE and GAK, members of the Numb-associated kinase family, control intracellular trafficking of multiple RNA viruses during viral entry and assembly/egress. Here, using both genetic and pharmacological approaches, we probe the functional relevance of NAKs for SARS-CoV-2 infection. siRNA-mediated depletion of AAK1, BIKE, GAK, and STK16, the fourth member of the NAK family, suppressed SARS-CoV-2 infection in human lung epithelial cells. Both known and novel small molecules with potent AAK1/BIKE, GAK or STK16 activity suppressed SARS-CoV-2 infection. Moreover, combination treatment with the approved anti-cancer drugs, sunitinib and erlotinib, with potent anti-AAK1/BIKE and GAK activity, respectively, demonstrated synergistic effect against SARS-CoV-2 infection in vitro. Time-of-addition experiments revealed that pharmacological inhibition of AAK1 and BIKE suppressed viral entry as well as late stages of the SARS-CoV-2 life cycle. Lastly, suppression of NAKs expression by siRNAs inhibited entry of both wild type and SARS-CoV-2 pseudovirus. These findings provide insight into the roles of NAKs in SARS-CoV-2 infection and establish a proof-of-principle that pharmacological inhibition of NAKs can be potentially used as a host-targeted approach to treat SARS-CoV-2 with potential implications to other coronaviruses.

The role of BMP4 signaling in trophoblast emergence from pluripotency

The Bone Morphogenetic Protein (BMP) signaling pathway has established roles in early embryonic morphogenesis, particularly in the epiblast. More recently, however, it has also been implicated in development of extraembryonic lineages, including trophectoderm (TE), in both mouse and human. In this review, we will provide an overview of this signaling pathway, with a focus on BMP4, and its role in emergence and development of TE in both early mouse and human embryogenesis. Subsequently, we will build on these in vivo data and discuss the utility of BMP4-based protocols for in vitro conversion of primed vs. naïve pluripotent stem cells (PSC) into trophoblast, and specifically into trophoblast stem cells (TSC). PSC-derived TSC could provide an abundant, reproducible, and ethically acceptable source of cells for modeling placental development.

Deficiency of PPP6C protects TNF-induced necroptosis through activation of TAK1

Necroptotic cell death is mediated by a super-molecular complex called necrosome which consists of receptor-interacting protein kinase 1 and 3 (RIPK1, RIPK3) and mixed-lineage kinase domain-like protein (MLKL). The role of these kinases has been extensively investigated in the regulation of necroptosis. However, whether the protein phosphatase is involved in necroptosis is still largely unknown. Here, we identified protein phosphatase 6 catalytic subunit (PPP6C) promotes TNF-induced necroptosis by genome-wide CRISPR/Cas9 library screening. We found that PPP6C deficiency protects cells from TNF-induced necroptosis in a phosphatase-activity-dependent manner. Mechanistically, PPP6C acts as a TGF-β activated kinase 1 (TAK1) phosphatase to inactivate its kinase activity. Deletion of PPP6C leads to hyperactivation of TAK1 and reduced RIPK1 kinase activity upon TNF stimulation. We further showed that heterozygous deletion of Ppp6c in mouse gastrointestinal tract alleviates necroptosis-related tissue injury and inflammation. Thus, our study identifies PPP6C as an important regulator of necroptosis and highlights a central role of phosphatase in the regulation of necroptosis-related diseases.

Breviscapine alleviates NASH by inhibiting TGF-β-activated kinase 1-dependent signaling

BACKGROUND AND AIMS

NAFLD is a key component of metabolic syndrome, ranging from nonalcoholic fatty liver to NASH, and is now becoming the leading cause of cirrhosis and HCC worldwide. However, due to the complex and unclear pathophysiological mechanism, there are no specific approved agents for treating NASH. Breviscapine, a natural flavonoid prescription drug isolated from the traditional Chinese herb Erigeron breviscapus, exhibits a wide range of pharmacological properties, including effects on metabolism. However, the anti-NASH efficacy and mechanisms of breviscapine have not yet been characterized.

APPROACH AND RESULTS

We evaluated the effects of breviscapine on the development of hepatic steatosis, inflammation, and fibrosis in vivo and in vitro under metabolic stress. Breviscapine treatment significantly reduced lipid accumulation, inflammatory cell infiltration, liver injury, and fibrosis in mice fed a high-fat diet, a high-fat/high-cholesterol diet, or a methionine- and choline-deficient diet. In addition, breviscapine attenuated lipid accumulation, inflammation, and lipotoxicity in hepatocytes undergoing metabolic stress. RNA-sequencing and multiomics analyses further indicated that the key mechanism linking the anti-NASH effects of breviscapine was inhibition of TGF-β-activated kinase 1 (TAK1) phosphorylation and the subsequent mitogen-activated protein kinase signaling cascade. Treatment with the TAK1 inhibitor 5Z-7-oxozeaenol abrogated breviscapine-mediated hepatoprotection under metabolic stress. Molecular docking illustrated that breviscapine directly bound to TAK1.

CONCLUSION

Breviscapine prevents metabolic stress-induced NASH progression through direct inhibition of TAK1 signaling. Breviscapine might be a therapeutic candidate for the treatment of NASH.

Tripartite Motif 38 Attenuates Cardiac Fibrosis after Myocardial Infarction by Suppressing TAK1 Activation via TAB2/3 Degradation

The role of tripartite motif (TRIM) 38, a ubiquitin E3 ligase regulating various pathophysiological processes, in cardiac fibrosis remains unclear. Here, a model of angiotensin II and myocardial infarction (MI)-induced fibrosis was established to explore its role in cardiac fibrosis and its underlying mechanisms. Cardiac fibrosis in the mouse MI model was mitigated by TRIM38 overexpression, but aggravated by its depletion. Consistently, in vitro overexpression or knockdown of TRIM38 ameliorated or aggravated the proliferation and secretion of cardiac fibroblasts (CFs) exposed to fibrotic stimulation, respectively. Mechanistically, TRIM38 suppressed cardiac fibrosis progression by attenuating TAK1/MAPK signaling. Inhibiting TAK1/MAPK signaling with a pharmacological inhibitor greatly reversed the effects of TRIM38 knockdown on CF secretion. Specifically, TRIM38 interacted with and “targeted” TAB2 and TAB3 for degradation, subsequently inhibiting TAK1 phosphorylation and negatively regulating MAPK signaling. These findings can help develop therapeutic strategies to treat and prevent cardiac fibrosis.

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TRIM38 expression is negatively correlated with cardiac fibrosis progression

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TRIM38 ameliorates the proliferation and secretion of CFs post fibrotic stimulation

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TRIM38 overexpression attenuates cardiac fibrosis progression in MI mice

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TRIM38 inhibits the TAK1/MAPK pathway by targeting the degradation of TAB2 and TAB3

Supraphysiological activation of TAK1 promotes skeletal muscle growth and mitigates neurogenic atrophy

Skeletal muscle mass is regulated through coordinated activation of multiple signaling pathways. TAK1 signalosome has been found to be activated in various conditions of muscle atrophy and hypertrophy. However, the role and mechanisms by which TAK1 regulates skeletal muscle mass remain less understood. Here, we demonstrate that supraphysiological activation of TAK1 in skeletal muscle of adult mice stimulates translational machinery, protein synthesis, and myofiber growth. TAK1 causes phosphorylation of elongation initiation factor 4E (eIF4E) independent of mTOR. Inactivation of TAK1 disrupts neuromuscular junction morphology and causes deregulation of Smad signaling. Using genetic approaches, we demonstrate that TAK1 prevents excessive loss of muscle mass during denervation. TAK1 favors the nuclear translocation of Smad4 and cytoplasmic retention of Smad6. TAK1 is also required for the phosphorylation of eIF4E in denervated skeletal muscle. Collectively, our results demonstrate that TAK1 supports skeletal muscle growth and prevents neurogenic muscle atrophy in adult mice.

TGF-β-activated kinase 1 (TAK1) is essential for the maintenance of skeletal muscle mass through incompletely understood mechanisms. Here the authors show that supraphysiological activation of TAK1 leads to muscle hypertrophy through the elongation initiation factor 4E (eIF4E) involved in protein synthesis, and prevents denervation-induced atrophy in mice.

Black Ginseng Extract Suppresses Airway Inflammation Induced by Cigarette Smoke and Lipopolysaccharides In Vivo

Cigarette smoke (CS) is a risk factor that can induce airway enlargement, airway obstruction, and airway mucus hypersecretion. Although studies have shown that Korean black ginseng extract (BGE) has potent anti-inflammatory and antioxidant activities, the CS-induced inflammatory responses and molecular mechanisms are yet to be examined. The aim of this study was to examine the effect of BGE on the airway inflammatory response and its molecular mechanisms, using CS/lipopolysaccharides (LPS)-exposed animals and PMA-stimulated human airway epithelial NCI-H292 cells. The results show that BGE inhibited the recruitment of immune cells and the release of inflammatory mediators, such as tumor necrosis factor (TNF)-α and interleukin (IL)-6, monocyte chemoattractant protein (MCP)-1, elastase, and reactive oxygen species (ROS) in the airways of CS/LPS-exposed animals. BGE inhibited mucus secretion and the expression of Mucin 5AC (MUC5AC). Furthermore, BGE exhibited an anti-inflammatory effect by downregulating a signaling pathway mediated by transforming growth factor-β-activated kinase (TAK) 1, an important protein that accelerates inflammation by cigarette smoke (CS). Overall, the findings show that BGE inhibits lung inflammation and mucus secretion by decreasing the activation of TAK1 both in human epithelial cells and in CS/LPS-exposed animals, and could be a potential adjuvant in the treatment and prevention of airway inflammatory diseases caused by airway irritants such as CS.

Discovery of Anticancer Agents of Diverse Natural Origin

Research progress from mainly over the last five years is described for a multidisciplinary collaborative program project directed toward the discovery of potential anticancer agents from a broad range of taxonomically defined organisms. Selected lead compounds with potential as new antitumor agents that are representative of considerable structural diversity have continued to be obtained from each of tropical plants, terrestrial and aquatic cyanobacteria, and filamentous fungi. Recently, a new focus has been on the investigation of the constituents of U.S. lichens and their fungal mycobionts. A medicinal chemistry and pharmacokinetics component of the project has optimized structurally selected lead natural products, leading to enhanced cytotoxic potencies against selected cancer cell lines. Biological testing has shown several compounds to have in vivo activity, and relevant preliminary structure-activity relationship and mechanism of action studies have been performed. Several promising lead compounds worthy of further investigation have been identified from the most recent collaborative work performed.

Ginsenoside Rg2 Ameliorates Myocardial Ischemia/Reperfusion Injury by Regulating TAK1 to Inhibit Necroptosis

Necroptosis contribute to the pathogenesis of myocardial ischemia/reperfusion (MI/R) injury. Ginsenoside Rg2 has been reported to have cardioprotective effects against MI/R injury; however, the underlying mechanism remains unclear. This work aimed to investigate the effect of ginsenoside Rg2 on necroptosis induced by MI/R and to explore the mechanism. In this study, hypoxia/reoxygenation (H/R) injury model was established in H9c2 cells. In vivo, male C57/BL6 mice were subjected to myocardial ischemia 30 min/reperfusion 4 h. Rg2 (50 mg/kg) or vehicle was intravenously infused 5 min before reperfusion. Cardiac function and the signaling pathway involved in necroptosis were investigated. Compared with H/R group, Rg2 significantly inhibited H/R-induced cardiomyocyte death. Rg2 treatment effectively inhibited the phosphorylation of RIP1, RIP3, and MLKL in H/R cardiomyocytes, and inhibited RIP1/RIP3 complex (necrosome) formation. In mice, Rg2 treatment manifested significantly lower ischemia/reperfusion (I/R)-induced myocardial necroptosis, as evidenced by decrease in phosphorylation of RIP1, RIP3, and MLKL, inhibited lactate dehydrogenase (LDH) release and Evans blue dye (EBD) penetration. Mechanically, an increased level of tumor necrosis factor α (TNFα), interleukin (IL)-1β, IL-6, and MCP-1 were found in MI/R hearts, and Rg2 treatment significantly inhibit the expression of these factors. We found that TNFα-induced phosphorylation of RIP1, RIP3, and MLKL was negatively correlated with transforming growth factor-activated kinase 1 (TAK1) phosphorylation, and inhibition of TAK1 phosphorylation led to necroptosis enhancement. More importantly, Rg2 treatment significantly increased TAK1 phosphorylation, enhanced TAK1 binding to RIP1 while inhibiting RIP1/RIP3 complex, ultimately reducing MI/R-induced necroptosis. These findings highlight a new mechanism of Rg2-induced cardioprotection: reducing the formation of RIP1/RIP3 necrosome by regulating TAK1 phosphorylation to block necroptosis induced by MI/R.

Topical application of TAK1 inhibitor encapsulated by gelatin particle alleviates corneal neovascularization

Rationale: Corneal neovascularization (CoNV) is a severe complication of various types of corneal diseases, that leads to permanent visual impairment. Current treatments for CoNV, such as steroids or anti-vascular endothelial growth factor agents, are argued over their therapeutic efficacy and adverse effects. Here, we demonstrate that transforming growth factor-β (TGF-β)-activated kinase 1 (TAK1) plays an important role in the pathogenesis of CoNV. Methods: Angiogenic activities were assessed in ex vivo and in vitro models subjected to TAK1 inhibition by 5Z-7-oxozeaenol, a selective inhibitor of TAK1. RNA-Seq was used to examine pathways that could be potentially affected by TAK1 inhibition. A gelatin-nanoparticles-encapsulated 5Z-7-oxozeaenol was developed as the eyedrop to treat CoNV in a rodent model. Results: We showed that 5Z-7-oxozeaenol reduced angiogenic processes through impeding cell proliferation. Transcriptome analysis suggested 5Z-7-oxozeaenol principally suppresses cell cycle and DNA replication, thereby restraining cell proliferation. In addition, inhibition of TAK1 by 5Z-7-oxozeaenol blocked TNFα-mediated NFκB signalling, and its downstream genes related to angiogenesis and inflammation. 5Z-7-oxozeaenol also ameliorated pro-angiogenic activity, including endothelial migration and tube formation. Furthermore, topical administration of the gelatin-nanoparticles-encapsulated 5Z-7-oxozeaenol led to significantly greater suppression of CoNV in a mouse model compared to the free form of 5Z-7-oxozeaenol, likely due to extended retention of 5Z-7-oxozeaenol in the cornea. Conclusion: Our study shows the potential of TAK1 as a therapeutic target for pathological angiogenesis, and the gelatin nanoparticle coupled with 5Z-7-oxozeaenol as a promising new eyedrop administration model in treatment of CoNV.

Resorcylic acid lactones from a Podospora sp. that induce apoptosis in activated T cells through MAPKs/AKT pathway

Podomycins A-L (1-12), 12 undescribed hypothemycin-type resorcylic acid lactones (RALs), were characterized from Podospora sp. G214, an endophyte harbored in the roots of Sanguisorba officinalis L. Their structures were addressed by spectroscopic data, X-ray crystallography, the modified Mosher's method, together with Mo₂(OAc)₄- and Rh₂(OCOCF₃)₄-induced electronic circular dichroism (ICD) experiments. Podomycins A-C (1-3) represent the first class of natural RALs with a 13-membered macrolactone ring, while 4-12 are rearranged methoxycarbonyl substituted RALs. Biologically, compounds 2, 6, 8, 10, and 12 displayed immunosuppressive activities against T cell proliferation with IC₅₀ values of 14.5-21.9 μM, and B cell proliferation with IC₅₀ values of 22.3-36.5 μM, respectively. Further mechanism of action research demonstrated that podomycin F (6) distinctly induced apoptosis in activated T cells via MAPKs/AKT pathway.

Role of autocrine bone morphogenetic protein Signaling in trophoblast stem cells

The Bone Morphogenetic Protein (BMP) pathway is involved in numerous developmental processes, including cell growth, apoptosis, and differentiation. In mouse embryogenesis, BMP signaling is a well-known morphogen for both mesoderm induction and germ cell development. Recent evidence points to a potential role in development of the extra-embryonic compartment, including trophectoderm-derived tissues. In this study, we investigated the effect of BMP signaling in both mouse and human trophoblast stem cells (TSC) in vitro, evaluating the expression and activation of the BMP signaling response machinery, and the effect of BMP signaling manipulation during TSC maintenance and differentiation. Both mTSC and hTSC expressed various BMP ligands and the receptors BMPR1A and BMPR2, necessary for BMP response, and displayed maximal active BMP signaling when undifferentiated. We also observed a conserved modulatory role of BMP signaling during trophoblast differentiation, whereby maintenance of active BMP signaling blunted differentiation of TSC in both species. Conversely, the effect of BMP signaling on the undifferentiated state of TSC appeared to be species-specific, with SMAD-independent signaling important in maintenance of mTSC, and a more subtle role for both SMAD-dependent and -independent BMP signaling in hTSC. Altogether, these data establish an autocrine role for the BMP pathway in the trophoblast compartment. As specification and correct differentiation of the extra-embryonic compartment are fundamental for implantation and early placental development, insights on the role of the BMP signaling in early development might prove useful in the setting of in vitro fertilization as well as targeting trophoblast-associated placental dysfunction.

Natural resorcylic acid lactones: A chemical biology approach for anticancer activity

Resorcylic acid lactones (RALs) are fungal polyketides that consist of a β-resorcylic acid residue (2,4-dihydroxybenzoic acid) embedded in a macrolactone ring. RALs exhibit a broad range of biological activities, including anticancer activities. Following discovery of the selective Hsp90 inhibition activity of radicicol, the kinase inhibition activity of hypothemycin, monocillin II, 5Z-7-oxo-zeaenol, and L-783,277 RALs, and the nuclear factor kappa B (NF-κB) inhibition activity of the RAL zearalenone, have attracted great attention as potential therapeutics for cancer treatment. In this minireview, we focus on natural RALs that possess cytotoxic activities [IC₅₀ values < 10 μM (or 4-5 μg/ml)], discussing their structures, isolation, occurrence, biological activities, and anticancer molecular mechanisms.

Inhibition of the MAP2K7-JNK pathway with 5Z-7-oxozeaenol induces apoptosis in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive pediatric leukemia with a worse prognosis than most frequent B-cell ALL due to a high incidence of treatment failures and relapse. Our previous work showed that loss of the pioneer factor KLF4 in a NOTCH1-induced T-ALL mouse model accelerated the development of leukemia through expansion of leukemia-initiating cells and activation of the MAP2K7 pathway. Similarly, epigenetic silencing of the KLF4 gene in children with T-ALL was associated with MAP2K7 activation. Here, we showed the small molecule 5Z-7-oxozeaenol (5Z7O) induces dose-dependent cytotoxicity in a panel of T-ALL cell lines mainly through inhibition of the MAP2K7-JNK pathway, which further validates MAP2K7 as a therapeutic target. Mechanistically, 5Z7O-mediated apoptosis was caused by the downregulation of regulators of the G2/M checkpoint and the inhibition of survival pathways. The anti-leukemic capacity of 5Z7O was evaluated using leukemic cells from two mouse models of T-ALL and patient-derived xenograft cells generated using lymphoblasts from pediatric T-ALL patients. Finally, a combination of 5Z7O with dexamethasone, a drug used in frontline therapy, showed synergistic induction of cytotoxicity. In sum, we report here that MAP2K7 inhibition thwarts survival mechanisms in T-ALL cells and warrants future pre-clinical studies for high-risk and relapsed patients.

TAK1 mediates neuronal pyroptosis in early brain injury after subarachnoid hemorrhage

BACKGROUND

Innate immunity can facilitate early brain injury (EBI) following subarachnoid hemorrhage (SAH). Numerous studies suggest that pyroptosis could exacerbate extracellular immune responses by promoting secretion of inflammatory cytokines. Transforming growth factor-β-activated kinase 1 (TAK1) is a quintessential kinase that positively regulates inflammation through NF-κB and MAPK signaling cascades. However, the effects of TAK1 on neuroinflammation in EBI following SAH are largely unknown.

METHODS

Two hundred and forty-six male C57BL/6J mice were subjected to the endovascular perforation model of SAH. A selective TAK1 inhibitor, 5Z-7-oxozeaenol (OZ) was administered by intracerebroventricular (i.c.v) injection at 30 min after SAH induction. To genetic knockdown of TAK1, small interfering RNA (siRNA) was i.c.v injected at 48 h before SAH induction. SAH grade, brain water content, BBB permeability, neurological score, western blot, real-time PCR, ELISA, transmission electron microscope, and immunofluorescence staining were performed. Long-term behavioral sequelae were evaluated by the rotarod and Morris water maze tests. Furthermore, OZ was added to the culture medium with oxyhemoglobin (OxyHb) to mimic SAH in vitro. The reactive oxygen species level was detected by DCFH-DA staining. Lysosomal integrity was assessed by Lyso-Tracker Red staining and Acridine Orange staining.

RESULTS

The neuronal phosphorylated TAK1 expression was upregulated following SAH. Pharmacologic inhibition of TAK1 with OZ could alleviate neurological deficits, brain edema, and brain-blood barrier (BBB) disruption at 24 h after SAH. In addition, OZ administration restored long-term neurobehavioral function. Furthermore, blockade of TAK1 dampened neuronal pyroptosis by downregulating the N-terminal fragment of GSDMD (GSDMD-N) expression and IL-1β/IL-18 production. Mechanistically, both in vivo and in vitro, we demonstrated that TAK1 can induce neuronal pyroptosis through promoting nuclear translocation of NF-κB p65 and activating nucleotide-binding oligomerization domain (NOD)-like receptor pyrin domain containing 3 (NLRP3) inflammasome. TAK1 siRNA treatment mitigated SAH-induced neurobehavioral deficits and restrained phosphorylated NF-κB p65 expression and NLRP3 inflammasome activation. TAK1 blockade also ameliorated reactive oxygen species (ROS) production and prevented lysosomal cathepsin B releasing into the cytoplasm.

CONCLUSIONS

Our findings demonstrate that TAK1 modulates NLRP3-mediated neuronal pyroptosis in EBI following SAH. Inhibition of TAK1 may serve as a potential candidate to relieve neuroinflammatory responses triggered by SAH.

Tripartite motif 16 ameliorates nonalcoholic steatohepatitis by promoting the degradation of phospho-TAK1

Nonalcoholic steatohepatitis (NASH)-related hepatocellular carcinoma and liver disorders have become the leading causes for the need of liver transplantation in developed countries. Lipotoxicity plays a central role in NASH progression by causing endoplasmic reticulum stress and disrupting protein homeostasis. To identify key molecules that mitigate the detrimental consequences of lipotoxicity, we performed integrative multiomics analysis and identified the E3 ligase tripartite motif 16 (TRIM16) as a candidate molecule. In particular, we found that lipid accumulation and inflammation in a mouse NASH model is mitigated by TRIM16 overexpression but aggravated by its depletion. Multiomics analysis showed that TRIM16 suppressed NASH progression by attenuating the activation of the mitogen-activated protein kinase (MAPK) signaling pathway; specifically, by preferentially interacting with phospho-TAK1 to promote its degradation. Together, these results identify TRIM16 as a promising therapeutic target for the treatment of NASH.

Sensing of mycobacterial arabinogalactan by galectin-9 exacerbates mycobacterial infection

Mycobacterial arabinogalactan (AG) is an essential cell wall component of mycobacteria and a frequent structural and bio-synthetical target for anti-tuberculosis (TB) drug development. Here, we report that mycobacterial AG is recognized by galectin-9 and exacerbates mycobacterial infection. Administration of AG-specific aptamers inhibits cellular infiltration caused by Mycobacterium tuberculosis (Mtb) or Mycobacterium bovis BCG, and moderately increases survival of Mtb-infected mice or Mycobacterium marinum-infected zebrafish. AG interacts with carbohydrate recognition domain (CRD) 2 of galectin-9 with high affinity, and galectin-9 associates with transforming growth factor β-activated kinase 1 (TAK1) via CRD2 to trigger subsequent activation of extracellular signal-regulated kinase (ERK) as well as induction of the expression of matrix metalloproteinases (MMPs). Moreover, deletion of galectin-9 or inhibition of MMPs blocks AG-induced pathological impairments in the lung, and the AG-galectin-9 axis aggravates the process of Mtb infection in mice. These results demonstrate that AG is an important virulence factor of mycobacteria and galectin-9 is a novel receptor for Mtb and other mycobacteria, paving the way for the development of novel effective TB immune modulators.

Media and strain studies for the scaled production of cis-enone resorcylic acid lactones as feedstocks for semisynthesis

Resorcylic acid lactones (RALs) with a cis-enone moiety, represented by hypothemycin (1) and (5Z)-7-oxozeaenol (2), are fungal secondary metabolites with irreversible inhibitory activity against protein kinases, with particularly selective activity for inhibition of TAK1 (transforming growth factor beta-activated kinase 1). Gram-scale quantities of these compounds were needed as feedstock for semi-synthesizing RAL-analogues in a step-economical fashion. To do so, this study had three primary goals: identifying fungi that biosynthesized 1 and 2, enhancing their production by optimizing the fermentation conditions on the lab scale, and developing straight forward purification processes. After evaluating 536 fungal extracts via an in-house dereplication protocol, three strains were identified as producing cis-enone RALs (i.e., MSX78495, MSX63935, MSX45109). Screening these fungal strains on three grain-based media revealed enhanced production of 1 by strain MSX78495 on oatmeal medium, while rice medium increased the biosynthesis of 2 by strain MSX63935. Furthermore, the purification processes were improved, moving away from HPLC purification to utilizing two to four cycles of resuspension and centrifugation in small volumes of organic solvents, generating gram-scale quantities of these metabolites readily. In addition, studying the chemistry profiles of strains MSX78495 and MSX63935 resulted in the isolation of ten other RALs (3-12), two radicinin analogues (13-14), and six benzopyranones (15-20), with 19 and 20 being newly described chlorinated benzopyranones.

TAK1 inhibition elicits mitochondrial ROS to block intracellular bacterial colonization

Mitogen-activated protein kinase kinase kinase 7 (MAP3K7), known as TAK1, is an intracellular signaling intermediate of inflammatory responses. However, a series of mouse Tak1 gene deletion analyses have revealed that ablation of TAK1 does not prevent but rather elicits inflammation, which is accompanied by elevation of reactive oxygen species (ROS). This has been considered a consequence of impaired TAK1-dependent maintenance of tissue integrity. Contrary to this view, here we propose that TAK1 inhibition-induced ROS are an active cellular process that targets intracellular bacteria. Intracellular bacterial effector proteins such as Yersinia's outer membrane protein YopJ are known to inhibit TAK1 to circumvent the inflammatory host responses. We found that such TAK1 inhibition induces mitochondrial-derived ROS, which effectively destroys intracellular bacteria. Two cell death-signaling molecules, caspase 8 and RIPK3, cooperatively participate in TAK1 inhibition-induced ROS and blockade of intracellular bacterial growth. Our results reveal a previously unrecognized host defense mechanism, which is initiated by host recognition of pathogen-induced impairment in a host protein, TAK1, but not directly of pathogens.

Synthesis and biological activity of 2-cyanoacrylamide derivatives tethered to imidazopyridine as TAK1 inhibitors

The importance of transforming growth factor beta-activated kinase 1 (TAK1) to cell survival has been demonstrated in many studies. TAK1 regulates signalling cascades, the NF-κB pathway and the mitogen-activated protein kinase (MAPK) pathway. TAK1 inhibitors can induce the apoptosis of cancerous cells, and irreversible inhibitors such as (5Z)-7-oxozeaenol are highly potent. However, they can react non-specifically with cysteine residues in proteins, which may have serious adverse effects. Reversible covalent inhibitors have been suggested as alternatives. We synthesised imidazopyridine derivatives as novel TAK1 inhibitors, which have 2-cyanoacrylamide moiety that can form reversible covalent bonding. A derivative with 2-cyano-3-(6-methylpyridin-2-yl)acrylamide (13h) exhibited potent TAK1 inhibitory activity with an IC₅₀ of 27 nM. It showed a reversible reaction with β-mercaptoethanol, which supports its potential as a reversible covalent inhibitor.

A Multi-target Drug Designing for BTK, MMP9, Proteasome and TAK1 for the Clinical Treatment of Mantle Cell Lymphoma

BACKGROUND

Mantle cell lymphoma (MCL) is a type of non-Hodgkin lymphoma characterized by the mutation and overexpression of the cyclin D1 protein by the reciprocal chromosomal translocation t(11;14)(q13:q32).

AIM

The present study aims to identify potential inhibition of MMP9, Proteasome, BTK, and TAK1 and determine the most suitable and effective protein target for the MCL.

METHODOLOGY

Nine known inhibitors for MMP9, 24 for proteasome, 15 for BTK and 14 for TAK1 were screened. SB-3CT (PubChem ID: 9883002), oprozomib (PubChem ID: 25067547), zanubrutinib (PubChem ID: 135565884) and TAK1 inhibitor (PubChem ID: 66760355) were recognized as drugs with high binding capacity with their respective protein receptors. 41, 72, 102 and 3 virtual screened compounds were obtained after the similarity search with compound (PubChem ID:102173753), PubChem compound SCHEMBL15569297 (PubChem ID:72374403), PubChem compound SCHEMBL17075298 (PubChem ID:136970120) and compound CID: 71814473 with best virtual screened compounds.

RESULT

MMP9 inhibitors show commendable affinity and good interaction profile of compound holding PubChem ID:102173753 over the most effective established inhibitor SB-3CT. The pharmacophore study of the best virtual screened compound reveals its high efficacy based on various interactions. The virtual screened compound's better affinity with the target MMP9 protein was deduced using toxicity and integration profile studies.

CONCLUSION

Based on the ADMET profile, the compound (PubChem ID: 102173753) could be a potent drug for MCL treatment. Similar to the established SB-3CT, the compound was non-toxic with LD50 values for both the compounds lying in the same range.

TAK1 signaling is a potential therapeutic target for pathological angiogenesis

Angiogenesis plays a critical role in both physiological responses and disease pathogenesis. Excessive angiogenesis can promote neoplastic diseases and retinopathies, while inadequate angiogenesis can lead to aberrant perfusion and impaired wound healing. Transforming growth factor β activated kinase 1 (TAK1), a member of the mitogen-activated protein kinase kinase kinase family, is a key modulator involved in a range of cellular functions including the immune responses, cell survival and death. TAK1 is activated in response to various stimuli such as proinflammatory cytokines, hypoxia, and oxidative stress. Emerging evidence has recently suggested that TAK1 is intimately involved in angiogenesis and mediates pathogenic processes related to angiogenesis. Several detailed mechanisms by which TAK1 regulates pathological angiogenesis have been clarified, and potential therapeutics targeting TAK1 have emerged. In this review, we summarize recent studies of TAK1 in angiogenesis and discuss the crosstalk between TAK1 and signaling pathways involved in pathological angiogenesis. We also discuss the approaches for selectively targeting TAK1 and highlight the rationales of therapeutic strategies based on TAK1 inhibition for the treatment of pathological angiogenesis.

TAK1 Is a Novel Target in Hepatocellular Carcinoma and Contributes to Sorafenib Resistance

BACKGROUND & AIMS

Identifying novel and actionable targets in hepatocellular carcinoma (HCC) remains an unmet medical need. TAK1 was originally identified as a transforming growth factor-β-activated kinase and was further proved to phosphorylate and activate numerous downstream targets and promote cancer progression. However, the role of TAK1 in developed HCC progression and targeted therapy resistance is poorly understood.

METHODS

The expression of TAK1 or MTDH in HCC cell lines, tumor tissues, and sorafenib-resistant models was analyzed by in silico analysis, quantitative real-time polymerase chain reaction, Western blotting, and immunohistochemistry. In vivo and in vitro experiments were introduced to examine the function of TAK1 or MTDH in HCC and sorafenib resistance using small interfering RNA and pharmacologic inhibitors in combination with or without sorafenib. Co-immunoprecipitation and RNA immunoprecipitation were carried out to determine the binding between TAK1 and FBXW2 or between MTDH and FBXW2 mRNA. Protein half-life and in vitro ubiquitination experiment was performed to validate whether FBXW2 regulates TAK1 degradation.

RESULTS

Our findings unraveled the clinical significance of TAK1 in promoting HCC and sorafenib resistance. We identified a novel E3 ubiquitin ligase, FBXW2, targeting TAK1 for K48-linked polyubiquitylation and subsequent degradation. We also found that MTDH contributes to TAK1 up-regulation in HCC and sorafenib resistance through binding to FBXW2 mRNA and accelerates its degradation. Moreover, combination of TAK1 inhibitor and sorafenib suppressed the growth of sorafenib-resistant HCCLM3 xenograft in mouse models.

CONCLUSIONS

These results revealed novel mechanism underlying TAK1 protein degradation and highlighted the therapeutic value of targeting TAK1 in suppressing HCC and overcoming sorafenib resistance.

Discovery of 2,4-1H-Imidazole Carboxamides as Potent and Selective TAK1 Inhibitors

Herein we report the discovery of 2,4-1H-imidazole carboxamides as novel, biochemically potent, and kinome selective inhibitors of transforming growth factor β-activated kinase 1 (TAK1). The target was subjected to a DNA-encoded chemical library (DECL) screen. After hit analysis a cluster of compounds was identified, which was based on a central pyrrole-2,4-1H-dicarboxamide scaffold, showing remarkable kinome selectivity. A scaffold-hop to the corresponding imidazole resulted in increased biochemical potency. Next, X-ray crystallography revealed a distinct binding mode compared to other TAK1 inhibitors. A benzylamide was found in a perpendicular orientation with respect to the core hinge-binding imidazole. Additionally, an unusual amide flip was observed in the kinase hinge region. Using structure-based drug design (SBDD), key substitutions at the pyrrolidine amide and the glycine resulted in a significant increase in biochemical potency.

Olea europaea Suppresses Inflammation by Targeting TAK1-Mediated MAP Kinase Activation

Possessing a variety of medicinal functions, Olea europaea L. is widely cultivated across the world. However, the anti-inflammatory mechanism of Olea europaea is not yet fully elucidated. In this study, how the methanol extract of the leaves of Olea europaea (Oe-ME) can suppress in vitro inflammatory responses was examined in terms of the identification of the target protein. RAW264.7 and HEK293T cells were used to study macrophage-mediated inflammatory responses and to validate the target protein using PCR, immunoblotting, nuclear fraction, overexpression, and cellular thermal shift assay (CETSA) under fixed conditions. Oe-ME treatment inhibited the mRNA expression levels of cyclooxygenase (COX)-2, matrix metallopeptidase (MMP)-9, and intercellular adhesion molecule-1 (ICAM-1) in activated RAW264.7 cells. Oe-ME diminished the activation of activator protein (AP)-1 and the phosphorylation of its upstream signaling cascades, including extracellular signal regulated kinase (ERK), mitogen-activated protein kinase kinase 1/2 (MEK1/2), c-Jun N-terminal kinase (JNK), mitogen-activated protein kinase kinase 3/6 (MKK3/6), p38, MKK7, and transforming growth factor-β-activated kinase 1 (TAK1), in stimulated-RAW264.7 cells. Overexpression and CETSA were carried out to verify that TAK1 is the target of Oe-ME. Our results suggest that the anti-inflammatory effect of Oe-ME could be attributed to its control of posttranslational modification and transcription of TAK1.

Natural and Synthetic Lactones Possessing Antitumor Activities

Cancer is one of the leading causes of death globally, accounting for an estimated 8 million deaths each year. As a result, there have been urgent unmet medical needs to discover novel oncology drugs. Natural and synthetic lactones have a broad spectrum of biological uses including anti-tumor, anti-helminthic, anti-microbial, and anti-inflammatory activities. Particularly, several natural and synthetic lactones have emerged as anti-cancer agents over the past decades. In this review, we address natural and synthetic lactones focusing on their anti-tumor activities and synthetic routes. Moreover, we aim to highlight our journey towards chemical modification and biological evaluation of a resorcylic acid lactone, L-783277 (4). We anticipate that utilization of the natural and synthetic lactones as novel scaffolds would benefit the process of oncology drug discovery campaigns based on natural products.

Inhibition of TGFβ-activated kinase 1 promotes inflammation-resolving microglial/macrophage responses and recovery after stroke in ovariectomized female mice

TGFβ-activated kinase 1 (TAK1) is a master regulator that drives multiple cell death and proinflammatory signaling pathways, making it a promising therapeutic target to treat ischemic stroke. However, whether targeting TAK1 could improve stroke outcomes has never been tested in female subjects, hindering its potential translation into clinical use. Here we examined the therapeutic effect of 5Z-7-Oxozeaenol (OZ), a selective TAK1 inhibitor, in ovariectomized female mice after middle cerebral artery occlusion (MCAO). OZ significantly reduced neuronal cell death and axonal injury at the acute stage and mitigated neuroinflammation at the subacute stage after MCAO in ovariectomized female mice. Consistent with RNA sequencing analysis that TAK1 activation contributed to microglia/macrophage-mediated inflammatory responses in the post-stroke brain, inhibition of TAK1 with OZ caused phenotypic shift of microglia/macrophages toward an inflammation-resolving state. Furthermore, microglia/macrophage-specific TAK1 knockout (TAK1 mKO) reproduced OZ's effects, causally confirming the role of TAK1 in determining proinflammatory microglial/macrophage responses in post-stroke females. Post-stroke treatment with OZ for 5 days effectively promoted long-term neurological recovery and the integrity of both gray matter and white matter in female mice. Together, the TAK1 inhibitor OZ elicits long-lasting improvement of stroke outcomes in female mice, at least partially through enhancing beneficial microglial/macrophage responses and inflammation resolution. Given its therapeutic efficacy on both male and female rodents, TAK1 inhibitor is worth further investigation as a valid treatment to ischemic stroke.

Hepatic Regulator of G Protein Signaling 5 Ameliorates Nonalcoholic Fatty Liver Disease by Suppressing Transforming Growth Factor Beta-Activated Kinase 1-c-Jun-N-Terminal Kinase/p38 Signaling

BACKGROUND AND AIMS

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease, which has no specific pharmacological treatments partially because of the unclear pathophysiological mechanisms. Regulator of G protein signaling (RGSs) proteins are proteins that negatively regulate G protein-coupled receptor (GPCR) signaling. The members of the R4/B subfamily are the smallest RGS proteins in size, and RGS5 belongs to this family, which mediates pluripotent biological functions through canonical G protein-mediated pathways and non-GPCR pathways. This study combined a genetically engineered rodent model and a transcriptomics-sequencing approach to investigate the role and regulatory mechanism of RGS5 in the development of NAFLD.

APPROACH AND RESULTS

This study found that RGS5 protects against NAFLD and nonalcoholic steatohepatitis. Using RNA sequencing and an unbiased systematic investigative approach, this study found that the activation of mitogen-activated protein kinase signaling cascades in response to metabolic challenge is negatively associated with hepatic RGS5 expression. Mechanistically, we found that the 64-181 amino-acid-sequence (aa) fragment of RGS5 directly interacts with transforming growth factor beta-activated kinase 1 (TAK1) through the 1-300aa fragment and inhibits TAK1 phosphorylation and the subsequent c-Jun-N-terminal kinase (JNK)/p38 pathway activation.

CONCLUSIONS

In hepatocytes, RGS5 is an essential molecule that protects against the progression of NAFLD. RGS5 directly binds to TAK1, preventing its hyperphosphorylation and the activation of the downstream JNK/p38 signaling cascade. RGS5 is a promising target molecule for fine-tuning the activity of TAK1 and for the treatment of NAFLD.

Euodia pasteuriana Methanol Extract Exerts Anti-Inflammatory Effects by Targeting TAK1 in the AP-1 Signaling Pathway

Euodia pasteuriana A. Chev. ex Guillaumin, also known as Melicope accedens (Blume) T.G. Hartley, is a herbal medicinal plant native to Vietnam. Although Euodia pasteuriana is used as a traditional medicine to treat a variety of inflammatory diseases, the pharmacological mechanisms related to this plant are unclear. This study aimed to investigate the anti-inflammatory effects of a methanol extract of Euodia pasteuriana leaves (Ep-ME) on the production of inflammatory mediators, the mRNA expression of proinflammatory genes, and inflammatory signaling activities in macrophage cell lines. The results showed that Ep-ME strongly suppressed the release of nitric oxide (NO) in RAW264.7 cells induced with lipopolysaccharide (LPS), pam3CysSerLys4 (Pam3CSK), and polyinosinic-polycytidylic acid (poly I:C) without cytotoxicity. A reverse transcription-polymerase chain reaction further confirmed that Ep-ME suppressed the expression of interleukin 6 (IL-6), matrix metalloproteinase-1 (MMP1), matrix metalloproteinase-2 (MMP2), matrix metalloproteinase-3 (MMP3), tumor necrosis factor-α (TNF-α), and matrix metalloproteinase-9 (MMP9) at the transcriptional level and reduced the luciferase activities of activator protein 1 (AP-1) reporter promoters. In addition, immunoblotting analyses of the whole lysate and nuclear fraction, as well as overexpression assays demonstrated that Ep-ME decreased the translocation of c-Jun and suppressed the activation of transforming growth factor beta-activated kinase 1 (TAK1) in the AP-1 signaling pathways. These results imply that Ep-ME could be developed as an anti-inflammatory agent that targets TAK1 in the AP-1 signaling pathway.