Targeting of TAK1 in inflammatory disorders and cancer

Activation of toll-like receptor 2 promotes the expression of inflammatory mediators and cell proliferation of human polycystic kidney disease cells

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the progressive enlargement of fluid-filled cysts, leading to a decline in renal function. Toll-like receptors (TLR)-2 and TLR4 are pattern recognition receptors and components of the innate immune response. We found that mRNA levels for TLR2 and TLR4, an adaptor protein MyD88, and the transcription factor NF-κB were elevated in the kidneys of ADPKD patients and PKD mice. There was decreased expression of IκBα, an inhibitory protein sequestering NF-κB in the cytosol, and increased NF-κB nuclear translocation in human ADPKD kidneys compared with normal human kidneys (NHK). Pam3CSK4, a synthetic TLR2 agonist, increased the phosphorylation of IκBα, decreased its total levels, and caused NF-κB nuclear translocation and upregulation of pro-inflammatory mediators in cultured human ADPKD cells. Pam3CSK4 also increased phosphorylated ERK, a mitogen-activated protein kinase, and phosphorylated S6, a downstream target of the mTOR pathway, and accelerated ADPKD cell proliferation. By contrast, Pam3CSK4 did not affect NF-κB or ERK in NHK cells, but rather induced cytotoxicity, suggesting that TLR2 activation's effect was specific to ADPKD cells. Treatment with a TLR4 agonist did not affect NF-κB or ERK signaling in either ADPKD or NHK cells. Inhibition of TGF-β-activated kinase-1 (TAK1) effectively suppressed Pam3CSK4-induced NF-κB and ERK activation and the proliferation of ADPKD cells. These findings suggest that activation of TLR2 increases NF-κB-mediated-inflammatory mediators and ERK-dependent cell proliferation through TAK1 in ADPKD cells. We propose that the TLR2/TAK1 axis is a potential therapeutic target to reduce inflammation and cyst growth in ADPKD.

Naringenin alleviates heat stress-induced liver injury in Ningdu yellow chickens by decreasing RIPK3 and PDC binding

Naringenin, a flavonoid extract, possesses anti-inflammatory, antioxidant, hepatoprotective, antitumor, and antineurotoxic properties. This study investigated the antiheat stress effects in broilers by adding 200mg/kg naringenin to the diet of Ningdu yellow chicken under heat stress conditions. Heat stress conditions was controlled at 37±2°C (7:00 a.m.-7:00 p.m.) and 24±2°C (7:00 p.m.-7:00 a.m.) at humidity maintained at 60-65%. The results suggest that naringenin elevated the body weight and the ratio of liver mass to weight of Ningdu yellow chicken significantly. Additionally, naringenin significantly reduces heat stress level, improves liver function and antioxidant capacity. Meanwhile, the levels of necroptosis indexes (CYLD, RIPK1, RIPK3 and MLKL) and oxidative stress indexes (PDC, PYGL, GLUL and GLUD1) are downregulated by naringenin. Naringenin mitigated liver damage by decreasing inflammatory indexes caused by heat stress, including NF-κB, IL-1β, IL-18 and HMGB1. This anti-inflammatory effect arose through the downlink binding of the necroptosis index (RIPK3) and the oxidative stress index (PDC) as shown in results of fluorescence co-localization and co-immunoprecipitation. The use of naringenin in poultry may be a possible feed additive to address clinical heat stress.

TAK1-mediated phosphorylation of PLCE1 represses PIP2 hydrolysis to impede esophageal squamous cancer metastasis

TAK1 is a serine/threonine protein kinase that is a key regulator in a wide variety of cellular processes. However, the functions and mechanisms involved in cancer metastasis are still not well understood. Here, we found that TAK1 knockdown promoted esophageal squamous cancer carcinoma (ESCC) migration and invasion, whereas TAK1 overexpression resulted in the opposite outcome. These in vitro findings were recapitulated in vivo in a xenograft metastatic mouse model. Mechanistically, co-immunoprecipitation and mass spectrometry demonstrated that TAK1 interacted with phospholipase C epsilon 1 (PLCE1) and phosphorylated PLCE1 at serine 1060 (S1060). Functional studies revealed that phosphorylation at S1060 in PLCE1 resulted in decreased enzyme activity, leading to the repression of phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis. As a result, the degradation products of PIP2 including diacylglycerol (DAG) and inositol IP3 were reduced, which thereby suppressed signal transduction in the axis of PKC/GSK-3β/β-Catenin. Consequently, expression of cancer metastasis-related genes was impeded by TAK1. Overall, our data indicate that TAK1 plays a negative role in ESCC metastasis, which depends on the TAK1-induced phosphorylation of PLCE1 at S1060.

Dual signaling pathways of TGF-β superfamily cytokines in hepatocytes: balancing liver homeostasis and disease progression

The transforming growth factor-β (TGF-β) superfamily (TGF-β-SF) comprises over 30 cytokines, including TGF-β, activins/inhibins, bone morphogenetic proteins (BMPs), and growth differentiation factors (GDFs). These cytokines play critical roles in liver function and disease progression. Here, we discuss Smad-dependent (canonical) and non-Smad pathways activated by these cytokines in a hepatocellular context. We highlight the connection between the deregulation of these pathways or the balance between them and key hepatocellular processes (e.g., proliferation, apoptosis, and epithelial-mesenchymal transition (EMT)). We further discuss their contribution to various chronic liver conditions, such as metabolic dysfunction-associated steatotic liver disease (MASLD), metabolic dysfunction-associated steatohepatitis (MASH), and hepatocellular carcinoma (HCC). In MASLD and MASH, TGF-β signaling contributes to hepatocyte lipid accumulation, cell death and fibrosis progression through both Smad and non-Smad pathways. In HCC, TGF-β and other TGF-β-SF cytokines have a dual role, acting as tumor suppressors or promoters in early vs. advanced stages of tumor progression, respectively. Additionally, we review the involvement of non-Smad pathways in modulating hepatocyte responses to TGF-β-SF cytokines, particularly in the context of chronic liver diseases, as well as the interdependence with other key pathways (cholesterol metabolism, insulin resistance, oxidative stress and lipotoxicity) in MASLD/MASH pathogenesis. The perspectives and insights detailed in this review may assist in determining future research directions and therapeutic targets in liver conditions, including chronic liver diseases and cancer.

USP48 inhibits colorectal cancer progression and promotes M1-like macrophage polarization by stabilizing TAK1

Ubiquitination and deubiquitination have emerged as pivotal regulators of the development of colorectal cancer (CRC). However, the precise role of USP48 in CRC tumorigenesis is poorly understood. In this study, immunohistochemistry, protein blotting, MTT assays, plate cloning, scratch assays, transwell assays, and Hoechst 33258 staining were utilized to assess the expression level of USP48 and its involvement in CRC. The interaction between USP48 and Transforming growth factor-β activated kinase-1(TAK1) was confirmed using co-IP. Additionally, the impact of deubiquitination on downstream signaling was determined through qRT-PCR. Furthermore, the associations between USP48 and tumor-associated macrophages within the tumor microenvironment were investigated using flow cytometry. The findings of our study demonstrated that USP48 expression is downregulated in CRC patients. Through deubiquitination, USP48 interacts with and stabilizes TAK1, leading to the inhibition of TAK1-triggered NF-κB activation and effectively suppresses CRC tumorigenesis. Moreover, this study showed a positive correlation between USP48 expression and M1-type TAM polarization, revealed the potential of USP48 as a molecular target for the effective treatment of CRC in the future.

STING in cancer immunoediting: Modeling tumor-immune dynamics throughout cancer development

Cancer immunoediting is a dynamic process of tumor-immune system interaction that plays a critical role in cancer development and progression. Recent studies have highlighted the importance of innate signaling pathways possessed by both cancer cells and immune cells in this process. The STING molecule, a pivotal innate immune signaling molecule, mediates DNA-triggered immune responses in both cancer cells and immune cells, modulating the anti-tumor immune response and shaping the efficacy of immunotherapy. Emerging evidence has shown that the activation of STING signaling has dual opposing effects in cancer progression, simultaneously provoking and restricting anti-tumor immunity, and participating in every phase of cancer immunoediting, including immune elimination, equilibrium, and escape. In this review, we elucidate the roles of STING in the process of cancer immunoediting and discuss the dichotomous effects of STING agonists in the cancer immunotherapy response or resistance. A profound understanding of the sophisticated roles of STING signaling pathway in cancer immunoediting would potentially inspire the development of novel cancer therapeutic approaches and overcome the undesirable protumor effects of STING activation.

Targeting TAK1: Evolution of inhibitors, challenges, and future directions

The increasing incidence of inflammatory and malignant diseases signifies the need to develop first-in-class drugs with novel mechanisms of action. In this respect, the transforming growth factor (TGF)-β-activated kinase 1 (TAK1), an essential part of several signaling pathways, is considered relevant and promising. This manuscript provides a brief overview of the signal transduction orchestrated by TAK1 within these pathways, followed by an in-depth and thorough analysis of the chemical matter demonstrated to inhibit this kinase. Special attention is given to the selectivity profiling of inhibitors, as well as to the outcomes of their biological characterization. Because published TAK1 inhibitors differ significantly in their kinome selectivity, active-site binding, and biological activity, we hope that this review will allow a judicial estimation of their quality and usefulness for TAK1-addressing assays. Our thoughts on the perspectives and possible developments of the field are also provided to assist scientists who are involved in the design and development of TAK1-targeting modulators.

Astragaloside IV ameliorates atherosclerosis by targeting TAK1 to suppress endothelial cell proinflammatory activation

BACKGROUND

Atherosclerosis is a chronic inflammatory disease mainly characterized by the activation of endothelial cells and recruitment of macrophages, leading to plaque formation. Astragaloside IV (AS-IV), a natural saponin derived from Astragalus mongholicus Bunge, has been shown to confer protective effects against cardiovascular diseases.

PURPOSE

The purpose of this study is to explore the role of AS-IV on atherosclerosis and the underlying mechanism.

METHODS

Mice with atherosclerosis were administered with AS-IV by oral gavage. Atherosclerotic plaques and blood lipid profiles of these mice were assessed. Endothelial cell activation and macrophage infiltration were examined by immunofluorescent or immunohistochemical staining. The effects of AS-IV on endothelial cell activation, macrophage migration and adhesion were determined by transwell experiments, RT-qPCR, and Western blot.

RESULTS

Mice treated with AS-IV exhibited a dose-dependent reduction in atherosclerotic plaque size, with no concomitant change in blood lipid levels. It significantly suppressed endothelial cell activation and macrophage infiltration in the vasculature. AS-IV inhibited TNF-α-induced endothelial cell activation and macrophage migration and adhesion in vitro. Furthermore, AS-IV reduced the phosphorylation of key kinases in the MAPK pathways and their upstream regulator TAK1 in endothelial cells. The inhibitory effects of AS-IV on MAPK pathways and endothelial cell activation were counteracted by TAK1 deficiency or overexpression of TAK1. Molecular docking analysis suggested AS-IV binds to TAK1 with high affinity.

CONCLUSION

AS-IV exhibits anti-atherosclerotic effects by targeting TAK1 in endothelial cells, thereby inhibiting endothelial cell activation, and the subsequent adhesion and migration of macrophages, providing a prospective therapeutic strategy for the management of atherosclerosis.

Baicalin Decreases the LPS-Induced Intestine Inflammatory Responses by ROS/p-ERK/p-P38 Signal Pathways In Vivo and In Vitro

Background: This study aimed to investigate the role of ROS/MAPK signaling pathways and the effects of baicalin in LPS-induced inflammatory responses in mice and porcine intestinal epithelial cells (IPEC-J2). Methods: In vivo, 18 male C57BL/6J mice were randomly divided into three groups (n = 6): control, LPS (3.5 mg/kg LPS administered intraperitoneally [ip] on day 7), and baicalin (200 mg/kg orally for 7 days, with LPS ip on day 7). On day 8, mice were sacrificed, and jejunal tissues were collected for H&E staining. ROS levels in serum and cytokine protein expressions (TNF-α and IL-6) in the jejunum were measured via ELISA, while intestinal MAPK proteins were analyzed using Western blotting. In vitro, the study involved two experimental setups: NAC (a ROS scavenger) and baicalin. For the NAC experiment, IPEC-J2 cells were divided into three groups: control, LPS, and NAC. In the LPS group, cells were treated with LPS (40 μg/mL) for 1 h. In the NAC group, cells were pretreated with NAC prior to LPS exposure. For the baicalin experiment, IPEC-J2 cells were divided into five groups: control, LPS, and baicalin at low (10 μM), medium (20 μM), and high (40 μM) doses. Cells were pretreated with baicalin for 24 h before LPS exposure. ROS/LDH levels and cytokine expressions in the supernatant were determined via ELISA, and MAPK protein expressions were assessed using Western blotting. Results: In vivo, LPS-induced oxidative stress and inflammatory responses in the intestine, reduced the villus height-to-crypt ratio, and significantly increased protein expressions of p-ERK, p-P38, JNK, and p-JNK (p < 0.05). Baicalin treatment significantly inhibited serum ROS levels (p < 0.01), reduced jejunal cytokine expressions (TNF-α and IL-6, p < 0.05), improved intestinal structural damage, and decreased p-ERK, p-P38, and p-JNK protein expressions (p < 0.05). In vitro, NAC significantly reduced ROS levels (p < 0.01), cytokine expressions (TNF-α and IL-6), and MAPK activation (ERK, JNK, P38, and their phosphorylated forms, p < 0.05). Baicalin also significantly decreased ROS (p < 0.05), TNF-α (p < 0.05), IL-6 (p < 0.05), and MAPK protein expressions (ERK, p-ERK, and p-P38, p < 0.05). Molecular docking demonstrated that baicalin effectively bound to ERK and P38 proteins. Conclusions: Baicalin mitigated LPS-induced inflammatory responses via the ROS/p-ERK/p-P38 signaling pathway in vivo and in vitro.

Mapping Nanoscale-To-Single-Cell Phosphoproteomic Landscape by Chip-DIA

Protein phosphorylation plays a crucial role in regulating disease phenotypes and serves as a key target for drug development. Mapping nanoscale-to-single-cell samples can unravel the heterogeneity of cellular signaling events. However, it remains a formidable analytical challenge due to the low detectability, abundance, and stoichiometry of phosphorylation sites. Here, we present a Chip-DIA strategy, integrating a microfluidic-based phosphoproteomic chip (iPhosChip) with data-independent acquisition mass spectrometry (DIA-MS) for ultrasensitive nanoscale-to-single-cell phosphoproteomic profiling. The iPhosChip operates as an all-in-one station that accommodates both quantifiable cell capture/imaging and the entire phosphoproteomic workflow in a highly streamlined and multiplexed manner. Coupled with a sample size-comparable library-based DIA-MS strategy, Chip-DIA achieved ultra-high sensitivity, detecting 1076±158 to 15869±1898 phosphopeptides from 10±0 to 1013±4 cells, and revealed the first single-cell phosphoproteomic landscape comprising druggable sites and basal phosphorylation-mediated networks in lung cancer. Notably, the sensitivity and coverage enabled the illumination of heterogeneous cytoskeleton remodeling and cytokeratin signatures in patient-derived cells resistant to third-generation EGFR therapy, stratifying mixed-lineage adenocarcinoma-squamous cell carcinoma subtypes, and identifying alternative targeted therapy for late-stage patients. With flexibility in module design and functionalization, Chip-DIA can be adapted to other PTM-omics to explore dysregulated PTM landscapes, thereby guiding therapeutic strategies toward precision oncology.

The ethanolic extract of Rhaphidophora peepla prevents inflammation by inhibiting the activation of Syk/AKT/NF-κB and TAK1/MAPK/AP-1

BACKGROUND

Inflammation is the body's innate reaction to foreign pathogens and serves as a self-regulating mechanism. However, the immune system can mistakenly target the body's own tissues, triggering unnecessary inflammation. For millennia, medicinal plants have been employed for the treatment of diseases. One such plant, Rhaphidophora peepla, has demonstrated potential anti-inflammatory properties. However, the precise mechanism underlying its anti-inflammatory effects remains elusive.

STUDY DESIGN

For this study, validation of target molecules by different experimental approaches and employing two different in vivo experiments were tried to improve the immunopharmacological value of Rhaphidophora peepla.

PURPOSE

Our goal is to elucidate the mechanism through which the ethanol extract of Rhaphidophora peepla (Rp-EE) demonstrates anti-inflammatory properties, both in vivo and in vitro.

METHOD

Rp-EE was phytochemically analyzed with gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC). Bioinformatic analysis with protein-protein interaction (PPI) networks and Kyoto Encyclopedia of Genes and Genomes (KEGG), nitric oxide (NO) assay, MTT assay, RT-PCR, ELISA, luciferase assay, CETSA, hematoxylin and eosin (H&E) staining, and Western blotting analysis were used to evaluate anti-inflammatory activity of Rp-EE and its mechanism.

RESULTS

Rp-EE significantly reduced inflammatory responses including nitric oxide (NO) release induced by lipopolysaccharide (LPS) at the non-cytotoxic concentrations in vitro, and HCl/EtOH-induced gastritis and LPS-induced acute lung injury models in vivo. Mechanistically, it was revealed that Rp-EE can specifically target spleen tyrosine kinase (Syk) and transforming growth factor β-activated kinase 1 (TAK1) to suppress the phosphorylation levels of nuclear factor (NF)-κB subunits (p65 and p50) and activator protein (AP)-1 subunits (c-Jun and c-Fos).

CONCLUSION

Rp-EE can inhibit inflammatory reactions managed by Syk and TAK1, resulting in suppressing the Syk/AKT/NF-κB and TAK1/MAPK/AP-1 signaling pathways. These findings lead us to a possibility that Rp-EE can be developed as a promising anti-gastric ulcer and anti-lung injury remedy.

Identification of TAK-756, A Potent TAK1 Inhibitor for the Treatment of Osteoarthritis through Intra-Articular Administration

Osteoarthritis (OA) is a chronic and degenerative joint disease affecting more than 500 million patients worldwide with no disease-modifying treatment approved to date. Several publications report on the transforming growth factor β-activated kinase 1 (TAK1) as a potential molecular target for OA, with complementary anti-catabolic and anti-inflammatory effects. We report herein on the development of TAK1 inhibitors with physicochemical properties suitable for intra-articular injection, with the aim to achieve high drug concentration at the affected joint, while avoiding severe toxicity associated with systemic inhibition. More specifically, reducing solubility by increasing crystallinity, while maintaining moderate lipophilicity proved to be a good compromise to ensure high and sustained free drug exposures in the joint. Furthermore, structure-based design allowed for an improvement of selectivity versus interleukin-1 receptor-associated kinases 1 and 4 (IRAK1/4). Finally, TAK-756 was discovered as a potent TAK1 inhibitor with good selectivity versus IRAK1/4 as well as excellent intra-articular pharmacokinetic properties.

Bibliometric and visualized analysis on global trends and hotspots of TAK1 in regulated cell death: 1999 to 2024

BACKGROUND

Regulated cell death (RCD) is a genetically controlled form of cell death that plays an important role in organogenesis, tissue remodeling, and pathogenesis of cancers. Transforming growth factor-beta-activation kinase 1 (TAK1) is a member of the serine/threonine protein kinase family, which can respond to internal and external stimuli and participate in inflammatory responses through multiple signaling pathways and cellular processes. In the last two decades, the regulatory roles of TAK1 at the crossroads of multiple RCD pathways, including apoptosis, necroptosis, pyroptosis, and PANoptosis were revealed by 801 articles retrieved from the Web of Science Core Collection database. To analyze global research trends and hotspots concerning the role of TAK1 in RCD, the bibliometric and visualized analysis were applied in the current study.

METHODS

The data for this bibliometrics study were retrieved from the Web of Science Core Collection database. The search formula was (TS=(Apoptosis) OR TS=(pyroptosis) OR TS=(Necroptosis) OR TS=(PANoptosis) OR TS=(Autophagy) OR TS=(Ferroptosis) OR TS=(cuproptosis)) AND ((TS=(TAK1)) OR TS=(MAP3K7)). The co-occurrence and co-cited analysis on basic bibliometric parameters were conducted by VOSviewer. The dual-map overlay of journals, citation bursts, keyword timelines, and keyword bursts were analyzed by CiteSpace.

RESULTS

A total of 801 articles from 46 countries have been included in the analysis. The number of publications demonstrates a consistent increase from 1999 to 2024. The primary research institutions driving this field are Osaka University Notably, the Journal of Biological Chemistry stands out as the most popular journal in this domain. These publications collectively involve contributions from 4663 authors, with Jun Tsuji emerging as a prolific author. Jun Tsuji also gains the highest co-citation frequency. Emerging research hotspots are encapsulated by keywords, including apoptosis, NF-κB, inflammation, autophagy, and TNFα.

CONCLUSION

This is the first bibliometric and visualized study to analyze the global trends and hotspots of TAK1 in RCD. Based on the analysis of 801 articles, the results provide a retrospective and comprehensive visualized view of the research hotspots and frontiers of TAK1 at the crossroads of multiple RCD signaling pathways and propose ideas for guiding their future investigations in molecular mechanisms and therapeutic strategies in this field.

The role of Pim-1 kinases in inflammatory signaling pathways

OBJECTIVE AND DESIGN

This observational study investigated the regulatory mechanism of Pim-1 in inflammatory signaling pathways.

MATERIALS

THP-1, RAW 264.7, BV2, and Jurkat human T cell lines were used.

TREATMENT

None.

METHODS

Lipopolysaccharide (LPS) was used to induce inflammation, followed by PIM1 knockdown. Western blot, immunoprecipitation, immunofluorescence, and RT-PCR assays were used to assess the effect of PIM1 knockdown on LPS-induced inflammation.

RESULTS

PIM1 knockdown in macrophage-like THP-1 cells suppressed LPS-induced upregulation of pro-inflammatory cytokines, inducible nitric oxide synthase, cyclooxygenase-2, phosphorylated Janus kinase, signal transducer and activator of transcription 3, extracellular signal-regulated kinase, c-Jun N-terminal kinase, p38, and nuclear factor kappa B p65 (NF-κB p65). It also suppressed upregulation of inhibitor of NF-κB kinase α/β and enhanced the nuclear translocation of NF-κB p65. Moreover, it inhibited the upregulation of Nod-like receptor family pyrin domain-containing 3 (NLRP3) and cleavage of caspase-1 induced by co-treatment of LPS with adenosine triphosphate. Additionally, p-transforming growth factor-β-activated kinase 1 (TAK1) interacted with Pim-1. All three members of Pim kinases (Pim-1, Pim-2, and Pim-3) were required for LPS-mediated inflammation in macrophages; however, unlike Pim-1 and Pim-3, Pim-2 functioned as a negative regulator of T cell activity.

CONCLUSIONS

Pim-1 interacts with TAK1 in LPS-induced inflammatory responses and is involved in MAPK/NF-κB/NLRP3 signaling pathways. Additionally, considering the negative regulatory role of Pim-2 in T cells, further in-depth studies on their respective functions are needed.

Overexpression of DUSP26 gene suppressed the proliferation, migration, and invasion of human prostate cancer cells

Prostate cancer (PCa) is threatening the health of millions of people, the pathological mechanism of prostate cancer has not been fully elaborated, and needs to be further explored. Here, we found that the expression of DUSP26 is dramatically suppressed, and a positive connection of its expression with PCa prognosis was also observed. In vitro, overexpression of DUSP26 significantly inhibited the proliferative, migrative, and invasive capacities of PC3 cells, DUSP26 silencing presented opposite results. Tumor formation experiments in subcutaneous nude mice demonstrated that DUSP26 overexpression could significantly suppress PC3 growth in vivo. Moreover, the mechanism of DUSP26 gene and PCa was discovered by RNA-Seq analysis. We found that DUSP26 significantly inhibited MAPK signaling pathway activation, and further experiments displayed that DUSP26 could impair TAK1, p38, and JNK phosphorylation. Interestingly, treatment with the TAK1 inhibitor (iTAK1) attenuated the effect of DUSP26 on PC3 cells. Together, these results suggested that DUSP26 may serve as a novel therapeutic target for PC3 cell type PCa, the underlying mechanism may be through TAK1-JNK/p38 signaling.

The deubiquitinase OTUD1 deubiquitinates TIPE2 and plays a protective role in sepsis-induced lung injury by targeting TAK1-mediated MAPK and NF-κB signaling

Ovarian tumor domain-containing protease 1 (OTUD1) is a critical negative regulator that promotes innate immune homeostasis and is extensively involved in the pathogenesis of sepsis. In this study, we performed a powerful integration of multiomics analysis and an experimental mechanistic investigation to elucidate the immunoregulatory role of OTUD1 in sepsis at the clinical, animal and cellular levels. Our study revealed the upregulation of OTUD1 expression and the related distinctive alterations observed via multiomics profiling in clinical and experimental sepsis. Importantly, in vivo and in vitro, OTUD1 was shown to negatively regulate inflammatory responses and play a protective role in sepsis-induced pathological lung injury by mechanistically inhibiting the activation of the transforming growth factor-beta-activated kinase 1 (TAK1)-mediated mitogen-activated protein kinase (MAPK) and nuclear factor kappa-B (NF-κB) signaling pathways in the present study. Subsequently, we probed the molecular mechanisms underlying OTUD1's regulation of NF-κB and MAPK pathways by pinpointing the target proteins that OTUD1 can deubiquitinate. Drawing upon prior research conducted in our laboratory, it has been demonstrated that tumor necrosis factor-α-induced protein 8-like 2 (TIPE2) performs a protective function in septic lung injury and septic encephalopathy by suppressing the NF-κB and MAPK pathways. Hence, we hypothesized that TIPE2 might be a target protein of OTUD1. Additional experiments, including Co-IP, immunofluorescence co-localization, and Western blotting, revealed that OTUD1 indeed has the ability to deubiquitinate TIPE2. In summary, OTUD1 holds potential as an immunoregulatory and inflammatory checkpoint agent, and could serve as a promising therapeutic target for sepsis-induced lung injury.

The journey of STING: Guiding immune signaling through membrane trafficking

Stimulator of Interferon Genes (STING) serves as a pivotal mediator in the innate immune signaling pathway, transducing signals from various DNA receptors and playing a crucial role in natural immune processes. During cellular quiescence, STING protein resides in the endoplasmic reticulum (ER), and its activation typically occurs through the cGAS-STING signaling pathway. Upon activation, STING protein is transported to the Golgi apparatus, thereby initiating downstream signaling cascades. Vesicular transport serves as the primary mechanism for STING protein trafficking between the ER and Golgi apparatus, with COPII mediating anterograde transport from the ER to Golgi apparatus, while COPI is responsible for retrograde transport. Numerous factors influence these transport processes, thereby exerting either promoting or inhibitory effects on STING protein expression. Upon reaching the Golgi apparatus, to prevent over-activation, STING protein is transported to post-Golgi compartments for degradation. In addition to the conventional lysosomal degradation pathway, ESCRT has also been identified as one of the degradation pathways for STING protein. This review summarizes the recent findings on the membrane trafficking pathways of STING, highlighting their contributions to the regulation of cytokine production, the activation of immune cells, and the coordination of immune signaling pathways.

Influenza virus infection activates TAK1 to suppress RIPK3-independent apoptosis and RIPK1-dependent necroptosis

Many DNA viruses develop various strategies to inhibit cell death to facilitate their replication. However, whether influenza A virus (IAV), a fast-replicating RNA virus, attenuates cell death remains unknown. Here, we report that IAV infection induces TAK1 phosphorylation in a murine alveolar epithelial cell line (LET1) and a murine fibroblastoma cell line (L929). The TAK1-specific inhibitor 5Z-7-Oxzeneonal (5Z) and TAK1 knockout significantly enhance IAV-induced apoptosis, as evidenced by increased PARP, caspase-8, and caspase-3 cleavage. TAK1 inhibition also increases necroptosis as evidenced by increased RIPK1S166, RIPK3T231/S232, and MLKLS345 phosphorylation. Mechanistically, TAK1 activates IKK, which phosphorylates RIPK1S25 and inhibits its activation. TAK1 also activates p38 and its downstream kinase MK2, which phosphorylates RIPK1S321 but does not affect RIPK1 activation. Further investigation revealed that the RIPK1 inhibitor Nec-1 and RIPK1 knockout abrogate IAV-induced apoptosis and necroptosis; re-expression of wild-type but not kinase-dead (KD)-RIPK1 restores IAV-induced cell death. ZBP1 knockout abrogates IAV-induced cell death, whereas RIPK3 knockout inhibits IAV-induced necroptosis but not apoptosis. 5Z treatment enhances IAV-induced cell death and slightly reduces the inflammatory response in the lungs of H1N1 virus-infected mice and prolongs the survival of IAV-infected mice. Our study provides evidence that IAV activates TAK1 to suppress RIPK1-dependent apoptosis and necroptosis, and that RIPK3 is required for IAV-induced necroptosis but not apoptosis in epithelial cells.

USP13 ameliorates nonalcoholic fatty liver disease through inhibiting the activation of TAK1

BACKGROUND

The molecular mechanisms underlying nonalcoholic fatty liver disease (NAFLD) remain to be fully elucidated. Ubiquitin specific protease 13 (USP13) is a critical participant in inflammation-related signaling pathways, which are linked to NAFLD. Herein, the roles of USP13 in NAFLD and the underlying mechanisms were investigated.

METHODS

L02 cells and mouse primary hepatocytes were subjected to free fatty acid (FFA) to establish an in vitro model reflective of NAFLD. To prepare in vivo model of NAFLD, mice fed a high-fat diet (HFD) for 16 weeks and leptin-deficient (ob/ob) mice were used. USP13 overexpression and knockout (KO) strategies were employed to study the function of USP13 in NAFLD in mice.

RESULTS

The expression of USP13 was markedly decreased in both in vitro and in vivo models of NAFLD. USP13 overexpression evidently inhibited lipid accumulation and inflammation in FFA-treated L02 cells in vitro. Consistently, the in vivo experiments showed that USP13 overexpression ameliorated hepatic steatosis and metabolic disorders in HFD-fed mice, while its deficiency led to contrary outcomes. Additionally, inflammation was similarly attenuated by USP13 overexpression and aggravated by its deficiency in HFD-fed mice. Notably, overexpressing of USP13 also markedly alleviated hepatic steatosis and inflammation in ob/ob mice. Mechanistically, USP13 bound to transforming growth factor β-activated kinase 1 (TAK1) and inhibited K63 ubiquitination and phosphorylation of TAK1, thereby dampening downstream inflammatory pathways and promoting insulin signaling pathways. Inhibition of TAK1 activation reversed the exacerbation of NAFLD caused by USP13 deficiency in mice.

CONCLUSIONS

Our findings indicate the protective role of USP13 in NAFLD progression through its interaction with TAK1 and inhibition the ubiquitination and phosphorylation of TAK1. Targeting the USP13-TAK1 axis emerges as a promising therapeutic strategy for NAFLD treatment.

Inflammatory Cytokine-Induced Muscle Atrophy and Weakness Can Be Ameliorated by an Inhibition of TGF-β-Activated Kinase-1

Chronic inflammation causes muscle wasting. Because most inflammatory cytokine signals are mediated via TGF-β-activated kinase-1 (TAK1) activation, inflammatory cytokine-induced muscle wasting may be ameliorated by the inhibition of TAK1 activity. The present study was undertaken to clarify whether TAK1 inhibition can ameliorate inflammation-induced muscle wasting. SKG/Jcl mice as an autoimmune arthritis animal model were treated with a small amount of mannan as an adjuvant to enhance the production of TNF-α and IL-1β. The increase in these inflammatory cytokines caused a reduction in muscle mass and strength along with an induction of arthritis in SKG/Jcl mice. Those changes in muscle fibers were mediated via the phosphorylation of TAK1, which activated the downstream signaling cascade via NF-κB, p38 MAPK, and ERK pathways, resulting in an increase in myostatin expression. Myostatin then reduced the expression of muscle proteins not only via a reduction in MyoD1 expression but also via an enhancement of Atrogin-1 and Murf1 expression. TAK1 inhibitor, LL-Z1640-2, prevented all the cytokine-induced changes in muscle wasting. Thus, TAK1 inhibition can be a new therapeutic target of not only joint destruction but also muscle wasting induced by inflammatory cytokines.

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.

SMAD4-Dependent Signaling Pathway Involves in the Pathogenesis of TGFBR2-Related CE-like Phenotype

(1) Background: Our previous data indicated that disturbance of the Transforming Growth Factor beta (TGFB) signaling pathway via its Type-2 Receptor (TGFBR2) can cause a Corneal Ectasia (CE)-like phenotype. The purpose of this study is to elucidate whether the SMAD4-dependent signaling pathway is involved in the TGFBR2-related CE-like pathogenesis. (2) Methods: Smad4 was designed to be conditionally knocked out from keratocytes. Novel triple transgenic mice, KerartTA; Tet-O-Cre; Smad4flox/flox (Smad4kera-cko), were administered with doxycycline (Dox). Optical Coherence Tomography (OCT) was performed to examine Central Corneal Thickness (CCT), Corneal Radius, Anterior Chamber and CE-like phenotype and compared to the littermate Control group (Smad4Ctrl). (3) Results: The OCT revealed normal cornea in the Smad4Ctrl and a CE-like phenotype in the Smad4kera-cko cornea, in which the overall CCT in Smad4kera-cko was thinner than that of Smad4Ctrl at P42 (n = 6, p < 0.0001) and showed no significant difference when compared to that in Tgfbr2kera-cko. Furthermore, the measurements of the Anterior Chamber and Corneal Radius indicated a substantial ectatic cornea in the Smad4kera-cko compared to Smad4Ctrl. The H&E staining of Smad4kera-cko mimics the finding in the Tgfbr2kera-cko. The positive immunostaining of cornea-specific marker K12 indicating the cell fate of cornea epithelium remained unchanged in Smad4kera-cko and the Proliferating Cell Nuclear Antigen (PCNA) immunostaining further indicated an enhanced proliferation in the Smad4kera-cko. Both immunostainings recapitulated the finding in Tgfbr2kera-cko. The Masson's Trichrome staining revealed decreased collagen formation in the corneal stroma from both Smad4kera-cko and Tgfbr2kera-cko. The collagen type 1 (Col1a1) immunostaining further confirmed the reduction in collagen type 1 formation in Smad4kera-cko. (4) Conclusions: The aforementioned phenotypes in the Smad4kera-cko strain indicated that the SMAD4-dependent signaling pathway is involved in the pathogenesis of the CE-like phenotype observed in Tgfbr2kera-cko.

5Z-7-Oxozaenol attenuates cuprizone-induced demyelination in mice through microglia polarization regulation

INTRODUCTION

Demyelination is a key factor in axonal degeneration and neural loss, leading to disability in multiple sclerosis (MS) patients. Transforming growth factor beta activated kinase 1 (TAK1) is a critical molecule involved in immune and inflammatory signaling pathways. Knockout of microglia TAK1 can inhibit autoimmune inflammation of the brain and spinal cord and improve the outcome of MS. However, it is unclear whether inhibiting TAK1 can alleviate demyelination.

METHODS

Eight-week-old male c57bl/6j mice were randomly divided into five groups: (a) the control group, (b) the group treated with cuprizone (CPZ) only, (c) the group treated with 5Z-7-Oxozaenol (OZ) only, and (d) the group treated with both cuprizone and 15 μg/30 μg OZ. Demyelination in the mice of this study was induced by administration of CPZ (ig) at a daily dose of 400 mg/kg for consecutive 5 weeks. OZ was intraperitoneally administered at mentioned doses twice a week, starting from week 3 after beginning cuprizone treatment. Histology, rotarod test, grasping test, pole test, Western blot, RT-PCR, and ELISA were used to evaluate corpus callosum demyelination, behavioral impairment, oligodendrocyte differentiation, TAK1 signaling pathway expression, microglia, and related cytokines.

RESULTS

Our results demonstrated that OZ protected against myelin loss and behavior impairment caused by CPZ. Additionally, OZ rescued the loss of oligodendrocytes in CPZ-induced mice. OZ inhibited the activation of JNK, p65, and p38 pathways, transformed M1 polarized microglia into M2 phenotype, and increased brain-derived neurotrophic factor (BDNF) expression to attenuate demyelination in CPZ-treated mice. Furthermore, OZ reduced the expression of proinflammatory cytokines and increases anti-inflammatory cytokines in CPZ-treated mice.

CONCLUSION

These findings suggest that inhibiting TAK1 may be an effective approach for treating demyelinating diseases.

TIPE2: A Candidate for Targeting Antitumor Immunotherapy

TNF-α-induced protein 8-like 2 (TIPE2 or TNFAIP8L2) is a recently discovered negative regulator of innate and adaptive immunity. TIPE2 is expressed in a wide range of tissues, both immune and nonimmune, and is implicated in the maintenance of immune homeostasis within the immune system. Furthermore, TIPE2 has been shown to play a pivotal role in the regulation of inflammation and the development of tumor. This review focuses on the structural characteristics, expression patterns, and functional roles of TIPE proteins, with a particular emphasis on the role and underlying mechanisms of TIPE2 in immune regulation and its involvement in different diseases. However, the current body of evidence is still limited in providing a comprehensive understanding of the complex role of TIPE2 in the human body, warranting further investigation to elucidate the possible mechanisms and functions of TIPE2 in diverse disease contexts.

Precision treatment of viral pneumonia through macrophage-targeted lipid nanoparticle delivery

Macrophages are integral components of the innate immune system, playing a dual role in host defense during infection and pathophysiological states. Macrophages contribute to immune responses and aid in combatting various infections, yet their production of abundant proinflammatory cytokines can lead to uncontrolled inflammation and worsened tissue damage. Therefore, reducing macrophage-derived proinflammatory cytokine release represents a promising approach for treating various acute and chronic inflammatory disorders. However, limited macrophage-specific delivery vehicles have hindered the development of macrophage-targeted therapies. In this study, we screened a pool of 112 lipid nanoparticles (LNPs) to identify an optimal LNP formulation for efficient siRNA delivery. Subsequently, by conjugating the macrophage-specific antibody F4/80 to the LNP surface, we constructed MacLNP, an enhanced LNP formulation designed for targeted macrophage delivery. In both in vitro and in vivo experiments, MacLNP demonstrated a significant enhancement in targeting macrophages. Specifically, delivery of siRNA targeting TAK1, a critical kinase upstream of multiple inflammatory pathways, effectively suppressed the phosphorylation/activation of NF-kB. LNP-mediated inhibition of NF-kB, a key upstream regulator in the classic inflammatory signaling pathway, in the murine macrophage cell line RAW264.7 significantly reduced the release of proinflammatory cytokines after stimulation with the viral RNA mimic Poly(I:C). Finally, intranasal administration of MacLNP-encapsulated TAK1 siRNA markedly ameliorated lung injury induced by influenza infection. In conclusion, our findings validate the potential of targeted macrophage interventions in attenuating inflammatory responses, reinforcing the potential of LNP-mediated macrophage targeting to treat pulmonary inflammatory disorders.

Discovery of imidazo[1,2-b]pyridazine-containing TAK1 kinase inhibitors with excellent activities against multiple myeloma

Current treatment options for patients with multiple myeloma (MM) include proteasome inhibitors, anti-CD38 antibodies, and immunomodulatory agents. However, if patients have continued disease progression after administration of these treatments, there are limited options. There is a need for effective targeted therapies of MM. Recent studies have shown that the transforming growth factor-β activated kinase (TAK1) is upregulated and overexpressed in MM. We have discovered that 6-substituted morpholine or piperazine imidazo[1,2-b]pyridazines, with an appropriate aryl substituent at position-3, inhibit TAK1 at nanomolar concentrations. The lead compound, 26, inhibits the enzymatic activity of TAK1 with an IC50 of 55 nM. Under similar conditions, the known TAK1 inhibitor, takinib, inhibits the kinase with an IC50 of 187 nM. Compound 26 and analogs thereof inhibit the growth of multiple myeloma cell lines MPC-11 and H929 with GI50 values as low as 30 nM. These compounds have the potential to be translated into anti-MM therapeutics.

Targeting TRIM29 As a Negative Regulator of CAR-NK Cell Effector Function to Improve Antitumor Efficacy of these Cells: A Perspective

Natural killer (NK) cells are among the most important cells in innate immune defense. In contrast to T cells, the effector function of NK cells does not require prior stimulation and is not MHC restricted. Therefore, chimeric antigen receptor (CAR)-NK cells are superior to CAR-T cells. The complexity of the tumor microenvironment (TME) makes it necessary to explore various pathways involved in NK cell negative regulation. CAR-NK cell effector function can be improved by inhibiting the negative regulatory mechanisms. In this respect, the E3 ubiquitin ligase tripartite motif containing 29 (TRIM29) is known to be involved in reducing NK cell cytotoxicity and cytokine production. Also, targeting TRIM29 may enhance the antitumor efficacy of CAR-NK cells. The present study discusses the negative effects of TRIM29 on NK cell activity and proposes genomic deletion or suppression of the expression of TRIM29 as a novel approach to optimize CAR-NK cell-based immunotherapy.

Highly cyto- and immune compatible new synthetic fluorapatite nanomaterials co-doped with rubidium(I) and europium(III) ions

In the present study, biocompatible luminescent of nanosized fluorapatite doped with rubidium(I) (Rb+ ion) and europium(III) (Eu3+ ion) ions were synthesized via hydrothermal method. It was investigated the influence of co-doped Rb+ and Eu3+ ions on the structural, and morphological characteristics of the obtained fluorapatite materials. The characterization techniques utilized included: X-ray powder diffraction (XRPD), infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). Moreover, to establish the influence of the co-doped Rb+ and Eu3+ ions on the luminescence properties of the lanthanide ion, emission excitation, emission spectrum and luminescence decays were measured. This confirmed a distinct red emission originating from Eu3+ ions and an increased emission lifetime. To determine the biocompatibility of the obtained fluorapatite compounds, in vitro studies using normal dermal human fibroblasts were performed. The results of these studies clearly demonstrate the remarkable biocompatibility of our compounds. This discovery opens exciting prospects for the use of synthetic fluorapatites doped with Eu3+ and Rb+ ions in various biomedical contexts. In particular, these materials hold great promise for potential applications in regenerative engineering, but also serve as innovative and practical solutions as bone scaffolds and dental implants containing nano-fluorapatite. Further discussion of these properties can be found in this article, along with a discussion of their importance and potential in the field of biomedical applications. However, according to our pervious study and based on our current investigations but also based on available scientific records, it was proposed potential molecular mechanism of Rb+ ions in the process of osteoclastogenesis.

Microglia and Multiple Sclerosis

Multiple sclerosis (MS) is a devastating autoimmune disease that leads to profound disability. This disability arises from the stochastic, regional loss of myelin-the insulating sheath surrounding neurons-in the central nervous system (CNS). The demyelinated regions are dominated by the brain's resident macrophages: microglia. Microglia perform a variety of functions in MS and are thought to initiate and perpetuate demyelination through their interactions with peripheral immune cells that traffic into the brain. However, microglia are also likely essential for recruiting and promoting the differentiation of cells that can restore lost myelin in a process known as remyelination. Given these seemingly opposing functions, an overarching beneficial or detrimental role is yet to be ascribed to these immune cells. In this chapter, we will discuss microglia dynamics throughout the MS disease course and probe the apparent dichotomy of microglia as the drivers of both demyelination and remyelination.

TAK1 is an essential kinase for STING trafficking

The translocation of stimulator of interferon genes (STING) from the endoplasmic reticulum (ER) to the ER-Golgi intermediate compartment (ERGIC) enables its activation. However, the mechanism underlying the regulation of STING exit from the ER remains elusive. Here, we found that STING induces the activation of transforming growth factor beta-activated kinase 1 (TAK1) prior to STING trafficking in a TAK1 binding protein 1 (TAB1)-dependent manner. Intriguingly, activated TAK1 directly mediates STING phosphorylation on serine 355, which facilitates its interaction with STING ER exit protein (STEEP) and thereby promotes its oligomerization and translocation to the ERGIC for subsequent activation. Importantly, activation of TAK1 by monophosphoryl lipid A, a TLR4 agonist, boosts cGAMP-induced antitumor immunity dependent on STING phosphorylation in a mouse allograft tumor model. Taken together, TAK1 was identified as a checkpoint for STING activation by promoting its trafficking, providing a basis for combinatory tumor immunotherapy and intervention in STING-related diseases.

Association of XIST/miRNA155/Gab2/TAK1 cascade with the pathogenesis of anti-phospholipid syndrome and its effect on cell adhesion molecules and inflammatory mediators

Anti-phospholipid syndrome (APS) is an autoimmune disease characterized by thrombosis and miscarriage events. Still, the molecular mechanisms underlying APS, which predisposes to a wide spectrum of complications, are being explored. Seventy patients with primary and secondary APS were recruited, in addition to 35 healthy subjects. Among APS groups, the gene expression levels of XIST, Gab2, and TAK1 were higher along with declined miRNA155 level compared with controls. Moreover, the sera levels of ICAM-1, VCAM-1, IL-1ꞵ, and TNF-α were highly elevated among APS groups either primary or secondary compared with controls. The lncRNA XIST was directly correlated with Gab2, TAK1, VCAM-1, ICAM-1, IL-1ꞵ, and TNF-α. The miRNA155 was inversely correlated with XIST, Gab2, and TAK1. Moreover, ROC curve analyses subscribed the predictive power of the lncRNA XIST and miRNA155, to differentiate between primary and secondary APS from control subjects. The lncRNA XIST and miRNA155 are the upstream regulators of the Gab2/TAK1 axis among APS patients via influencing the levels of VCAM-1, ICAM-1, IL1ꞵ, and TNF-α which propagates further inflammatory and immunological streams. Interestingly, the study addressed that XIST and miRNA155 may be responsible for the thrombotic and miscarriage events associated with APS and provides new noninvasive molecular biomarkers for diagnosing the disease and tracking its progression.

Methyl lucidone inhibits airway inflammatory response by reducing TAK1 activity in human bronchial epithelial NCI-H292 cells

Background

Methyl lucidone (ML), a methyl derivative of lucidone, has anti-inflammatory properties. However, the molecular mechanisms that reduce the inflammatory effect of ML in human lung epithelial cells remain unkown. This study aimed to elucidate the molecular mechanisms underlying the anti-inflammatory effect of ML.

Methods

Four compounds (ML, methyl linderone, kanakugiol, and linderone) from Lindera erythrocarpa Makino were evaluated for their ability to reduce MUC5AC secretion levels in phorbol-12-myristate-13-acetate (PMA)-stimulated NCI-H292 cells using ELISA. The expression and secretion levels of inflammatory response-related proteins were analyzed using quantitative reverse transcription-PCR, ELISA, and western blotting. To determine whether ML directly regulates TGF-β-activated kinase 1 (TAK1), we performed an in vitro kinase assay.

Results

ML treatment effectively reduced the levels of inflammatory cytokines, including interleukin-1β and TNF-α, increased by stimulation. Furthermore, ML downregulated the pathway cascade of both IκB kinase (IKK)/NF-κB and p38 mitogen-activated protein (MAP) kinase/CREB by inhibiting the upstream kinase TAK1. An in vitro kinase analysis confirmed that ML treatment significantly reduced the kinase activity of TAK1.

Conclusion

ML pretreatment repressed the PMA-stimulated inflammation reaction by reducing the TAK1-mediated IKK/NF-κB and p38 MAP kinase/CREB signaling. These findings suggest that ML may improve respiratory health and can be used as a dietary supplement or functional food to prevent inflammatory lung diseases.

Knockdown of CPEB1 and CPEB4 Inhibits Scar Formation via Modulation of TAK1 and SMAD Signaling

BACKGROUND

Cytoplasmic polyadenylation element binding (CPEB) proteins are sequence-specific RNA-binding proteins that control translation via cytoplasmic polyadenylation. We previously reported that CPEB1 or CPEB4 knockdown suppresses TAK1 and SMAD signaling in an in vitro study.

OBJECTIVE

This study aimed to investigate whether suppression of CPEB1 or CPEB4 expression inhibits scar formation in a mice model of acute dermal wound healing.

METHODS

CPEB1 and CPEB4 expression levels were suppressed by siRNA treatment. Skin wounds were created by pressure-induced ulcers in mice. Images of the wound healing were obtained using a digital camera and contraction was measured by ImageJ. mRNA and protein expression was analyzed using quantitative real time polymerase chain reaction and western blotting, respectively.

RESULTS

Wound contraction was significantly decreased by pre-treatment with CPEB1 or CPEB4 siRNA compared to the control. Suppression of CPEB1 or CPEB4 expression decreased TAK1 signaling by reducing the levels of TLR4 and TNF-α, phosphorylated TAK1, p38, ERK, JNK, and NF-κB-p65. Decreased levels of phosphorylated SMAD2 and SMAD3 indicated a reduction in SMAD signaling as well. Consequently, the expression of α-SMA, fibronectin, and type I collagen decreased.

CONCLUSION

CPEB1 siRNA or CPEB4 siRNA inhibit scar formation by modulating the TAK1 and SMAD signaling pathways. Our study highlights CPEB1 and CPEB4 as potential therapeutic targets for the treatment of scar formation.

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.

CTRP12 ameliorates post-myocardial infarction heart failure through down-regulation of cardiac apoptosis, oxidative stress and inflammation by influencing the TAK1-p38 MAPK/JNK pathway

OBJECTIVE

C1q/tumour necrosis factor-related protein 12 (CTRP12) is closely related to coronary artery disease and has an outstanding cardioprotective effect. However, whether CTRP12 participates in heart failure (HF) has not been well studied. This work aimed to explore the role and mechanism of CTRP12 in post-myocardial infarction (MI) HF.

METHODS

Rats were subjected to left anterior descending artery ligation and then raised for six weeks to establish post-MI HF. Recombinant adeno-associated virus-mediated gene transfer was applied to overexpress or silence CTRP12 in rat hearts. RT-qPCR, Immunoblot, Echocardiography, Haematoxylin-eosin (HE) staining, Masson's trichrome staining, TUNEL staining and ELISA were carried out.

RESULTS

CTRP12 levels were decreased in the hearts of rats with post-MI HF. The overexpression of CTRP12 improved cardiac function and attenuated cardiac hypertrophy and fibrosis in rats with post-MI HF. CTRP12 silencing exacerbated cardiac dysfunction, hypertrophy and fibrosis in rats with post-MI HF. The cardiac apoptosis, oxidative stress and inflammatory response induced by post-MI HF were weakened by CTRP12 overexpression or aggravated by CTRP12 silencing. CTRP12 inhibited the activation of the transforming growth factor-β activated kinase 1 (TAK1)-p38 mitogen-activated protein kinase (MAPK)/c-Jun N-terminal kinase (JNK) pathway in the hearts of rats with post-MI HF. Treatment with the TAK1 inhibitor reversed the adverse effects of CTRP12 silencing on post-MI HF.

CONCLUSIONS

CTRP12 protects against post-MI HF by modulating the TAK1-p38 MAPK/JNK pathway. CTRP12 may be a therapeutic target for the treatment of post-MI HF.

PSMD13 inhibits NF-κB pathway by targeting TAK1 for K63-linked ubiquitination in miiuy croaker (Miichthys miiuy)

ransforming growth factor-β activated kinase (TAK) 1 is an adaptor molecular in the TLR-mediated NF-κB pathway which has been implicated in the regulation of a wide range of physiological and pathological processes. Proteasome 26S subunit, non-ATPases (PSMD) 13 is essential for the structural maintenance and function of the 26S proteasome. However, the mechanism of PSMD13 in innate immune regulation is not clear. In this study, the expression of PSMD13 mRNA was significantly increased under Vibrio harveyi stimulation, and PSMD13 inhibited the NF-κB pathway by targeting TAK1. Mechanically, PSMD13 significantly inhibited the K63-linked ubiquitination of TAK1, thereby inhibiting the expression of TAK1. Moreover, this discovery enriches the research of the PSMD family regulating the innate immune response and provides a new idea for the study of the mammalian innate immune regulation mechanism.

New Insights into NF-κB Signaling in Innate Immunity: Focus on Immunometabolic Crosstalks

The nuclear factor kappa B (NF-κB) is a family of transcription factors that, beyond their numberless functions in various cell processes, play a pivotal role in regulating immune cell activation. Two main pathways-canonical and non-canonical-are responsible for NF-κB activation and heterodimer translocation into the nucleus. A complex crosstalk between NF-κB signaling and metabolism is emerging in innate immunity. Metabolic enzymes and metabolites regulate NF-κB activity in many cases through post-translational modifications such as acetylation and phosphorylation. On the other hand, NF-κB affects immunometabolic pathways, including the citrate pathway, thereby building an intricate network. In this review, the emerging findings about NF-κB function in innate immunity and the interplay between NF-κB and immunometabolism have been discussed. These outcomes allow for a deeper comprehension of the molecular mechanisms underlying NF-κB function in innate immune cells. Moreover, the new insights are important in order to perceive NF-κB signaling as a potential therapeutic target for inflammatory/immune chronic diseases.

Extracellular Vesicles Released from Macrophages Infected with Mycoplasma pneumoniae Stimulate Proinflammatory Response via the TLR2-NF-κB/JNK Signaling Pathway

Mycoplasma pneumoniae (M. pneumoniae, Mp) is an intracellular pathogen that causes pneumonia, tracheobronchitis, pharyngitis, and asthma in humans and can infect and survive in the host cells leading to excessive immune responses. Extracellular vesicles (EVs) from host cells carry components of pathogens to recipient cells and play a role in intercellular communication during infection. However, there is limited knowledge on whether EVs derived from M. pneumoniae-infected macrophages play as intercellular messengers and functional mechanisms. In this study, we establish a cell model of M. pneumoniae-infected macrophages that continuously secrete EVs to further asses their role as intercellular messengers and their functional mechanisms. Based on this model, we determined a method for isolating the pure EVs from M. pneumoniae-infected macrophages, which employs a sequence of operations, including differential centrifugation, filtering, and ultracentrifugation. We identified EVs and their purity using multiple methods, including electron microscopy, nanoparticle tracking analysis, Western blot, bacteria culture, and nucleic acid detection. EVs from M. pneumoniae-infected macrophages are pure, with a 30-200 nm diameter. These EVs can be taken up by uninfected macrophages and induce the production of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and IL-8 through the nuclear factor (NF)-κB, and mitogen-activated protein kinases (MAPK) signals pathway. Moreover, the expression of inflammatory cytokines induced by EVs relies on TLR2-NF-κB/JNK signal pathways. These findings will help us better understand a persistent inflammatory response and cell-to-cell immune modulation in the context of M. pneumoniae infection.

Cellular stress induces non-canonical activation of the receptor tyrosine kinase EphA2 through the p38-MK2-RSK signaling pathway

The receptor tyrosine kinase EphA2 is overexpressed in malignant tumors. We previously reported that non-canonical EphA2 phosphorylation at Ser-897 was catalyzed by p90 ribosomal S6 kinase (RSK) via the MEK-ERK pathway in ligand- and tyrosine kinase-independent manners. Non-canonical EphA2 activation plays a key role in tumor progression; however, its activation mechanism remains unclear. In the present study, we focused on cellular stress signaling as a novel inducer of non-canonical EphA2 activation. p38, instead of ERK in the case of epidermal growth factor signaling, activated RSK-EphA2 under cellular stress conditions, including anisomycin, cisplatin and high osmotic stress. Notably, p38 activated the RSK-EphA2 axis via downstream MAPK-activated protein kinase 2 (MK2). Furthermore, MK2 directly phosphorylated both RSK1 Ser-380 and RSK2 Ser-386, critical residues for the activation of their N-terminal kinases, which is consistent with the result showing that the C-terminal kinase domain of RSK1 was dispensable for MK2-mediated EphA2 phosphorylation. Moreover, the p38-MK2-RSK-EphA2 axis promoted glioblastoma cell migration induced by temozolomide, a chemotherapeutic agent for the treatment of glioblastoma patients. Collectively, the present results reveal a novel molecular mechanism for non-canonical EphA2 activation under stress conditions in the tumor microenvironment.

Emerging role of TAK1 in the regulation of skeletal muscle mass

Maintenance of skeletal muscle mass and strength throughout life is crucial for heathy living and longevity. Several signaling pathways have been implicated in the regulation of skeletal muscle mass in adults. TGF-β-activated kinase 1 (TAK1) is a key protein, which coordinates the activation of multiple signaling pathways. Recently, it was discovered that TAK1 is essential for the maintenance of skeletal muscle mass and myofiber hypertrophy following mechanical overload. Forced activation of TAK1 in skeletal muscle causes hypertrophy and attenuates denervation-induced muscle atrophy. TAK1-mediated signaling in skeletal muscle promotes protein synthesis, redox homeostasis, mitochondrial health, and integrity of neuromuscular junctions. In this article, we have reviewed the role and potential mechanisms through which TAK1 regulates skeletal muscle mass and growth. We have also proposed future areas of research that could be instrumental in exploring TAK1 as therapeutic target for improving muscle mass in various catabolic conditions and diseases.

RNF207 exacerbates pathological cardiac hypertrophy via post-translational modification of TAB1

AIMS

The heart undergoes pathological remodelling, featured by the hypertrophic growth of cardiomyocytes and increased cardiac fibrosis, under biomechanical stress such as haemodynamic overload. Ring Finger Protein 207 (RNF207) is an E3 ubiquitin ligase that is predominantly expressed in the heart, but its function remains elusive. In this study, we aimed to explore the role of RNF207 in the development of pathological cardiac hypertrophy and dysfunction.

METHODS AND RESULTS

Transverse aortic constriction (TAC) surgery was performed on mice to induce cardiac hypertrophy. Cardiac function and remodelling were evaluated by echocardiography, histological assessment, and molecular analyses. Our data indicated that RNF207 overexpression (OE) exacerbated cardiac hypertrophy, fibrosis, and systolic dysfunction. In contrast, TAC-induced cardiac remodelling was profoundly blunted in RNF207 knockdown (KD) hearts. In line with the in vivo findings, RNF207 OE augmented, whereas RNF207 KD alleviated, phenylephrine-induced cardiomyocyte hypertrophy in vitro. Mechanistically, we demonstrated that RNF207 elicited detrimental effects by promoting K63-linked ubiquitination of TAK1-binding protein 1 (TAB1), which triggered the autophosphorylation of transforming growth factor-β activated kinase 1 (TAK1) and the activation of downstream p38 and c-Jun N-terminal kinase (JNK)1/2 signalling pathways. In the TAB1-KD cardiomyocytes, RNF207-OE-induced cell hypertrophy was significantly attenuated, indicating that RNF207-induced hypertrophy is, at least in part, TAB1-dependent.

CONCLUSIONS

This study demonstrates that RNF207 exacerbates pressure overload-induced cardiac hypertrophy and dysfunction via post-translational modification of TAB1.

The Ninj1/Dusp1 Axis Contributes to Liver Ischemia Reperfusion Injury by Regulating Macrophage Activation and Neutrophil Infiltration

BACKGROUND & AIMS

Liver ischemia-reperfusion (IR) injury represents a major risk factor in both partial hepatectomy and liver transplantation. Nerve injury-induced protein 1 (Ninj1) is widely recognized as an adhesion molecule in leukocyte trafficking under inflammatory conditions, but its role in regulating sterile inflammation during liver IR injury remains unclear.

METHODS

Myeloid Ninj1-deficient mice were generated by bone marrow chimeric models using Ninj1 knockout mice and wild-type mice. In vivo, a liver partial warm ischemia model was applied. Liver injury and hepatic inflammation were investigated. In vitro, primary Kupffer cells (KCs) isolated from Ninj1 knockout and wild-type mice were used to explore the function and mechanism of Ninj1 in modulating KC inflammation upon lipopolysaccharide stimulation.

RESULTS

Ninj1 deficiency in KCs protected mice against liver IR injury during the later phase of reperfusion, especially in neutrophil infiltration, intrahepatic inflammation, and hepatocyte apoptosis. This prompted ischemia-primed KCs to decrease proinflammatory cytokine production. In vitro and in vivo, using small-interfering RNA against dual-specificity phosphatase 1 (DUSP1), we found that Ninj1 deficiency diminished the inflammatory response in KCs and neutrophil infiltration through DUSP1-dependent deactivation of the c-Jun-N-terminal kinase and p38 pathways. Sivelestat, a neutrophil elastase inhibitor, functioned similarly to Ninj1 deficiency, resulting in both mitigated hepatic IR injury in mice and a more rapid recovery of liver function in patients undergoing liver resection.

CONCLUSIONS

The Ninj1/Dusp1 axis contributes to liver IR injury by regulating the proinflammatory response of KCs, and influences neutrophil infiltration, partly by subsequent regulation of C-X-C motif chemokine ligand 1 (CXCL1) production after IR.

Assessment of sulfamethoxazole toxicity to marine mussels (Mytilus galloprovincialis): Combine p38-MAPK signaling pathway modulation with histopathological alterations

Sulfamethoxazole (SMX), is a ubiquitous antibiotic in the aquatic environment and received concerns on its health hazards, especially its sub-lethal effects on non-target organisms which were remained largely unknown. In the present study, in order to investigate SMX induced tissue damages and reveal underlying mechanisms, marine mussels, Mytilus galloprovincialis were challenged to SMX series (0.5, 50 and 500 μg/L) for six-days followed by six-day-recovery. Comprehensive histopathological alteration (including qualitative, semi-quantitative and quantitative indices), together with transcriptional and (post-) translational responses of key factors (p38, NFκB and p53) in the p38-MAPK signaling pathway were analyzed in gills and digestive glands. Tissue-specific responses were clearly investigated with gills showing more prompt responses and digestive glands showing higher tolerance to SMX. The histopathology showed that SMX triggered inflammatory damages in both tissues and quantitative analysis revealed more significant responses, suggesting its potential as a valuable health indicator. SMX activated expressions of p38, NFκB and p53 at transcriptional and (post-) translational levels, especially after exposed to low level SMX, evidenced by p38 coupled with NFκB/p53 regulation on immunity defense in mussels. Less induction of targeted molecules under severe SMX exposure indicated such signaling transduction may not be efficient enough and can result in inflammatory damages. Taken together, this study expanded the understanding of aquatic SMX induced health risk in marine mussels and the underlying regulation mechanism through p38 signaling transduction.

Inhibition of TAK1/TAB2 complex formation by costunolide attenuates obesity cardiomyopathy via the NF-κB signaling pathway

BACKGROUND

Chronic and persistent obesity can lead to various complications, including obesity cardiomyopathy. Inhibition of the inflammatory response is an effective measure for the intervention of obesity cardiomyopathy. Numerous studies indicate that costunolide (Cos) can reduce inflammation. However, the role of Cos in obesity cardiomyopathy and its molecular targets remains unknown.

HYPOTHESIS/PURPOSE

We aimed to clarify potential cardioprotective effects and mechanism of Cos against obesity cardiomyopathy.

METHODS

The model of obesity cardiomyopathy was established by feeding mice with a high-fat diet for 24 weeks. Cos at 10 and 20 mg/kg or vehicle (1% CMCNa solution) was administered once every two days via oral gavage from the 17th to 24th week. Body weight, heart weight/tibia length, cardiac function, myocardial injury markers, pathological morphology of the heart, hypertrophic and fibrotic markers, inflammatory factors were assessed. The targets of Cos were predicted through molecular docking. Pull-down assay and biolayer interferometry were used to confirm the target of Cos.

RESULTS

Cos effectively reduces obesity-induced cardiomyocyte inflammation, cardiac hypertrophy and fibrosis, thereby improving cardiac function. We confirmed that Cos can interact with TAK1 and inhibit downstream NF-κB pathway activation by blocking the formation of the TAK1/TAB2 complex, thus inhibiting inflammatory cytokine release in cardiomyocytes.

CONCLUSION

Our results demonstrated that Cos significantly improved myocardial remodeling and cardiac dysfunction against obesity cardiomyopathy by reducing myocardial inflammation. Therefore, Cos may serve as a promising therapeutic agent in obesity cardiomyopathy.

Epoxymicheliolide prevents dextran sulfate sodium-induced colitis in mice by inhibiting TAK1-NF-κB pathway and activating Keap1-NRF2 signaling in macrophages

Ulcerative colitis (UC) is an unspecific colorectal inflammation associated with macrophages overactivation. Therefore, macrophage-targeted treatment has been considered a promising strategy for UC therapy. Epoxymicheliolide (EMCL) is a compound from Aucklandia lappa Decne, a TCM for treating gastrointestinal inflammatory diseases. The purpose of this study is to investigate the therapeutic effect of EMCL on DSS-induced mice colitis through the anti-inflammatory activity on macrophages and its underlying mechanisms. We found that EMCL inhibited the release of NO and PGE₂ by down-regulating the expression of iNOS and COX2, while suppressed the expression of IL-1β, IL-6, and TNF-α in LPS-stimulated RAW264.7 macrophages. EMCL also inhibited NO production in LPS-activated peritoneal macrophages and TNFα-stimulated RAW264.7 cells. Moreover, EMCL blocked the phosphorylation of TAK1, IKKα/β, and IκBα, as well as IκBα degradation, thereby inhibiting the NF-κB pro-inflammatory signaling. Furthermore, EMCL decreased the intracellular ROS, by activating the NRF2 antioxidant pathway. CETSA and molecular docking showed that EMCL might form a covalent bond with Cys174 of TAK1 or Cya151 of Keap1, which may contribute to EMCL-mediated actions. Additionally, a thiol donor β-mercaptoethanol obviously abolished EMCL-mediated actions in vitro, suggesting the crucial role of the α, γ-unsaturated lactone of EMCL on its anti-inflammatory effects. Furthermore, EMCL not only ameliorated symptoms of colitis and colon barrier injury, but also decreased the levels of pro-inflammatory cytokines, MPO, NO, and MDA in DSS-challenged mice. Thus, our study demonstrated that EMCL ameliorated UC by targeting NF-κB and Nrf2 pathways, indicating it may server as a promising drug candidate for UC therapy.

Tabersonine attenuates Angiotensin II-induced cardiac remodeling and dysfunction through targeting TAK1 and inhibiting TAK1-mediated cardiac inflammation

BACKGROUND

Angiotensin II (Ang II)-induced cardiac inflammation contribute to pathological cardiac remodeling and hypertensive heart failure (HF). Tabersonine (Tab) is an indole alkaloid mainly isolated from Catharanthus roseus and exhibits anti-inflammatory activity in various systems. However, the role of Tab in hypertensive HF and its molecular targets remains unknown.

HYPOTHESIS/PURPOSE

We aimed to investigate potential cardioprotective effects and mechanism of Tab against Ang II-induced cardiac injuries.

METHODS

C57BL/6 mice were administered Ang II (at 1000 ng/kg/min) by micro-osmotic pump infusion for 30 days to develop hypertensive HF. Tab at 20 and 40 mg/kg/day was administered during the last 2 weeks to elucidate the cardioprotective properties. Cultured cardiomyocyte-like H9c2 cells and rat primary cardiomyocytes were used for mechanistic studies of Tab.

RESULTS

We demonstrate for the first time that Tab provides protection against Ang II-induced cardiac dysfunction in mice, associated with reduced cardiac inflammation and fibrosis. Mechanistically, we show that Tab may interacts with TAK1 to inhibit Ang II-induced TAK1 ubiquitination and phosphorylation. Disruption of TAK1 activation by Tab blocked downstream NF-κB and JNK/P38 MAPK signaling activation and decreased cardiac inflammation and fibrosis both in vitro and in vivo. TAK1 knockdown also blocked Ang II-induced cardiomyocytes injuries and prevented the innately pharmacological effects of Tab.

CONCLUSION

Our results indicate that Tab protects hearts against Ang II-mediated injuries through targeting TAK1 and inhibiting TAK1-mediated inflammatory cascade and response. Thus, Tab may be a potential therapeutic candidate for hypertensive HF.

Exogenous TIPE2 Inhibit TAK1 to Improve Inflammation and Neuropathic Pain Induced by Sciatic Nerve Injury Through Inactivating NF-κB and JNK

Tumor necrosis factor-alpha-induced protein 8-like 2 (TIPE2) possesses potent anti-inflammatory effect. However, if TIPE2 ameliorates sciatic nerve injury (SNI)-induced inflammation and pain remains undiscussed, and the underlying role TAK1 in it were unknown. To verify our imagine, we performed SNI surgery, and analyzed expression and colocalization of TIPE2 and TAK1 in spinal cord and dorsal root neurons (DRG) by immunofluorescence staining and western blot. And the biological analysis, inflammatory factors, and pathological improvement were determined, and the regulation of TIPE2 in TAK1, phosphor-NF-κB, phospho-JNK was also tested by immunofluorescence staining and western blot. Experimental results showed the parabola-like change of TIPE2 and rising expression of TAK1 in spinal cord and DRG. And intrathecal TIPE2 injection could significantly improve the status of SNI rats, inhibit level of IL-6, IL-10 and TNF-α, raise the thermal withdrawal relax latency and mechanical withdrawal thresholds. Meanwhile, we also detected how TIPE2 regulated TAK1, and the downstream pathway NF-κB and JNK. The result indicated that TIPE2 could reduce TAK1 expression, and make NF-κB and JNK inactivated. To deeply discuss the potential mechanism, we injected TAK1 oligodeoxynucleotide into rats, and found that TIPE2 exerted the protective role against SNI through TAK1. In brief, TIPE2 reduced expression of TAK1, thereby inhibiting activation of NF-kB and JNK, further improving the neuroinflammation and neuropathic pain. TIPE2 played a protective role in sciatic nerve injury rats through regulating TAK1.

The Role of TAK1 in RANKL-Induced Osteoclastogenesis

Bone remodelling is generally a dynamic process orchestrated by bone-resorbing osteoclasts and bone-forming osteoblasts. Osteoclasts are the only cell type capable of bone resorption to maintain bone homeostasis in the human body. However, excessive osteoclastogenesis can lead to osteolytic diseases. The receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL) has been widely considered to be an important modulator of osteoclastogenesis thereby participating in the pathogenesis of osteolytic diseases. Transforming growth factor β-activated kinase 1 (TAK1), a member of the mitogen-activated protein kinase kinase kinase family, is an important intracellular molecule that regulates multiple signalling pathways, such as NF-κB and mitogen-activated protein kinase to mediate multiple physiological processes, including cell survival, inflammation, and tumourigenesis. Furthermore, increasing evidence has demonstrated that TAK1 is intimately involved in RANKL-induced osteoclastogenesis. Moreover, several detailed mechanisms by which TAK1 regulates RANKL-induced osteoclastogenesis have been clarified, and some potential approaches targeting TAK1 for the treatment of osteolytic diseases have emerged. In this review, we discuss how TAK1 functions in RANKL-mediated signalling pathways and highlight the significant role of TAK1 in RANKL-induced osteoclastogenesis. In addition, we discuss the potential clinical implications of TAK1 inhibitors for the treatment of osteolytic diseases.