Heat shock protein 90 (Hsp90) regulates the stability of transforming growth factor beta-activated kinase 1 (TAK1) in interleukin-1beta-induced cell signaling

Heat shock protein 90 is a chaperone regulator of HIV-1 latency

An estimated 32 million people live with HIV-1 globally. Combined antiretroviral therapy suppresses viral replication but therapy interruption results in viral rebound from a latent reservoir mainly found in memory CD4+ T cells. Treatment is therefore lifelong and not curative. Eradication of this viral reservoir requires hematopoietic stem cell transplantation from hemizygous or homozygous ΔCCR5 donors, which is not broadly applicable. Alternative cure strategies include the pharmacological reactivation of latently infected cells to promote their immune-mediated clearance, or the induction of deep latency. HIV-1 latency is multifactorial and linked to the activation status of the infected CD4+ T cell. Hence to perturb latency, multiple pathways need to be simultaneously targeted without affecting CD4+ T cell function. Hsp90 has been shown to regulate HIV-1 latency, although knowledge on the pathways is limited. Because Hsp90 promotes the proper folding of numerous cellular proteins required for HIV-1 gene expression, we hypothesized that Hsp90 might be a master regulator of latency. We tested this hypothesis using a polyclonal Jurkat cell model of latency and ex-vivo latently infected primary CD4+ T cells. We found that, in the Jurkat model, Hsp90 is required for HIV-1 reactivation mediated by the T-cell receptor, phorbol esters, TNF-α, inhibition of FOXO-1, and agonists of TLR-7 and TLR-8. In primary cells, Hsp90 regulates HIV-1 gene expression induced by stimulation of the T-cell receptor or in the presence of IL-7/IL-15 or a FOXO-1 inhibitor. Chemical inhibition of Hsp90 abrogated activation of the NF-kB, NFAT and AP-1 signal transduction pathways. Within the CD4+ T cell population, CDRA45+ CCR7+ "naïve" and CD45RA- CCR7- "effector memory" cells were most sensitive to Hsp90 inhibition, which did not perturb their phenotype or activation state. Our results indicate that Hsp90 is a master regulator of HIV-1 latency that can potentially be targeted in cure strategies.

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.

Native Size-Exclusion Chromatography-Based Mass Spectrometry Reveals New Components of the Early Heat Shock Protein 90 Inhibition Response Among Limited Global Changes

The molecular chaperone heat shock protein 90 (HSP90) works in concert with co-chaperones to stabilize its client proteins, which include multiple drivers of oncogenesis and malignant progression. Pharmacologic inhibitors of HSP90 have been observed to exert a wide range of effects on the proteome, including depletion of client proteins, induction of heat shock proteins, dissociation of co-chaperones from HSP90, disruption of client protein signaling networks, and recruitment of the protein ubiquitylation and degradation machinery-suggesting widespread remodeling of cellular protein complexes. However, proteomics studies to date have focused on inhibitor-induced changes in total protein levels, often overlooking protein complex alterations. Here, we use size-exclusion chromatography in combination with mass spectrometry (SEC-MS) to characterize the early changes in native protein complexes following treatment with the HSP90 inhibitor tanespimycin (17-AAG) for 8 h in the HT29 colon adenocarcinoma cell line. After confirming the signature cellular response to HSP90 inhibition (e.g., induction of heat shock proteins, decreased total levels of client proteins), we were surprised to find only modest perturbations to the global distribution of protein elution profiles in inhibitor-treated HT29 cells at this relatively early time-point. Similarly, co-chaperones that co-eluted with HSP90 displayed no clear difference between control and treated conditions. However, two distinct analysis strategies identified multiple inhibitor-induced changes, including known and unknown components of the HSP90-dependent proteome. We validate two of these-the actin-binding protein Anillin and the mitochondrial isocitrate dehydrogenase 3 complex-as novel HSP90 inhibitor-modulated proteins. We present this dataset as a resource for the HSP90, proteostasis, and cancer communities (https://www.bioinformatics.babraham.ac.uk/shiny/HSP90/SEC-MS/), laying the groundwork for future mechanistic and therapeutic studies related to HSP90 pharmacology. Data are available via ProteomeXchange with identifier PXD033459.

The Heat Shock Protein 90 (HSP90) Is Required for the IL-33-Induced Cytokine Production in Mast Cells (MCs)

The alarmin interleukin-33 (IL-33) is released upon cell stress and damage in peripheral tissues. The receptor for IL-33 is the Toll/Interleukin-1 receptor (TIR)-family member T1/ST2 (the IL-33R), which is highly and constitutively expressed on MCs. The sensing of IL-33 by MCs induces the MyD88-TAK1-IKK2-dependent activation of p65/RelA and MAP-kinases, which mediate the production of pro-inflammatory cytokines and amplify FcεRI-mediated MC-effector functions and the resulting allergic reactions. Therefore, the investigation of IL-33-induced signaling is of interest for developing therapeutic interventions effective against allergic reactions. Importantly, beside the release of IL-33, heat shock proteins (HSPs) are upregulated during allergic reactions. This maintains the biological functions of signaling molecules and/or cytokines but unfortunately also strengthens the severity of inflammatory reactions. Here, we demonstrate that HSP90 does not support the IL-33-induced and MyD88-TAK1-IKK2-dependent activation of p65/RelA and of mitogen-activated protein (MAP)-kinases. We found that HSP90 acts downstream of these signaling pathways, mediates the stability of produced cytokine mRNAs, and therefore facilitates the resulting cytokine production. These data show that IL-33 enables MCs to perform an effective cytokine production by the upregulation of HSP90. Consequently, HSP90 might be an attractive therapeutic target for blocking IL-33-mediated inflammatory reactions.

Regulation of Mitogen-Activated Protein Kinase Signaling Pathways by the Ubiquitin-Proteasome System and Its Pharmacological Potential

Mitogen-activated protein kinase (MAPK) cascades are evolutionarily conserved signaling pathways that play essential roles in transducing extracellular environmental signals into diverse cellular responses to maintain homeostasis. These pathways are classically organized into an architecture of three sequentially acting protein kinases: a MAPK kinase kinase that phosphorylates and activates a MAPK kinase, which in turn phosphorylates and activates the effector MAPK. The activity of MAPKs is tightly regulated by phosphorylation of their activation loop, which can be modulated by positive and negative feedback mechanisms to control the amplitude and duration of the signal. The signaling outcomes of MAPK pathways are further regulated by interactions of MAPKs with scaffolding and regulatory proteins. Accumulating evidence indicates that, in addition to these mechanisms, MAPK signaling is commonly regulated by ubiquitin-proteasome system (UPS)-mediated control of the stability and abundance of MAPK pathway components. Notably, the biologic activity of some MAPKs appears to be regulated mainly at the level of protein turnover. Recent studies have started to explore the potential of targeted protein degradation as a powerful strategy to investigate the biologic functions of individual MAPK pathway components and as a new therapeutic approach to overcome resistance to current small-molecule kinase inhibitors. Here, we comprehensively review the mechanisms, physiologic importance, and pharmacological potential of UPS-mediated protein degradation in the control of MAPK signaling. SIGNIFICANCE STATEMENT: Accumulating evidence highlights the importance of targeted protein degradation by the ubiquitin-proteasome system in regulating and fine-tuning the signaling output of mitogen-activated protein kinase (MAPK) pathways. Manipulating protein levels of MAPK cascade components may provide a novel approach for the development of selective pharmacological tools and therapeutics.

Molecular and functional characterization of HtrA protein in Actinobacillus pleuropneumoniae

Actinobacillus pleuropneumoniae (A.pleuropneumoniae) causes serious economic loss for the swine industry. A high-temperature requirements A (HtrA)-like protease and its homologs have been reported to be involved in protein quality control and expression of important immunoprotective antigens in many pathogens. In this study, we showed that HtrA of A.pleuropneumoniae exhibited both chaperone and proteolytic activities. Moreover, Outer membrane protein P5 (OmpP5) in A.pleuropneumoniae and Heat shock protein 90 (Hsp90) in porcine lung tissues were first discovered and identified as specific proteolytic substrates for rHtrA. The maximum cleavage activity occurs at 50 ℃ in a time-dependent manner. In addition, rHtrA mainly induced IgG 2a subtype of IgG and Th1 (IFN-γ, IL-2) response in a mice model, and promoted a significant proliferation of spleen lymphocytes compare with negative control (P < 0.05). The survival rates of 37.5 % were observed against A.pleuropneumoniae strain. Together, these data demonstrate that rHtrA plays a multi-functional role in A.pleuropneumoniae.

Calcineurin Immune Signaling in Response to Zinc Challenge in the Naked Carp Gymnocypris eckloni

Zinc pollution impairs neural processes and protein function and also effects calcium-related transcriptional regulation and enzyme activity. In this study, we investigated pathways that potentially respond to calcium signaling under Zn²⁺ stress. Specifically we measured relative expressions of GeCNAα, GeCNB, GeMT, GeTNF-α, GeIL-1β, and GeHsp90 in gills, livers, and kidneys of the indicator species Gymnocypris eckloni and found wide variation in their expression between tissues during the course of Zn²⁺ exposure. Notably, GeCNAα, GeCNB, GeTNF-α, GeIL-1β, and GeMT were rapidly and strongly up-regulated in gills; GeIL-1β and GeHsp90 transcription was quickly induced in kidneys; and GeCNB, GeTNF-α, GeIL-1β, and GeHsp90 were most rapidly up-regulated in livers. GeCNAα and GeMT showed a contrasting late transcriptional up-regulation. These results suggest independent branches for chelation and immune responses during self-protection against Zn²⁺ toxicity, and the immune response appears to be faster than metal chelation.

Montelukast inhibits inflammatory response in rheumatoid arthritis fibroblast-like synoviocytes

Montelukast, a potent selective antagonist of cysteinyl leukotriene (cysLT) receptors, has displayed its important anti-oxidative and anti-inflammatory effects in various tissues and organs. Rheumatoid arthritis (RA) is an immune disease defined by hyperplastic synovitis and joint destruction. Fibroblast-like synoviocytes in RA (RA-FLSs) are the main cell component of the hyperplastic synovium. Whether montelukast can protect against the inflammatory milieu of RA remains unclear. Here, it is shown that cysLT1R is present in FLSs and unregulated in RA-FLSs. Montelukast has an inhibitory effect on the inflammatory microenvironment of RA by decreasing the secretion of IL-6, IL-8, MMP-3 and MMP-13 in FLSs induced by IL-1β. Notably, treatment with montelukast attenuated IL-1β-induced phosphorylation of IκBα, IκBα degradation, nuclear translocation of p65 and NF-κB activity to express a luciferase reporter gene in FLSs. The findings of the current study provide evidence for a novel therapeutic strategy for RA using montelukast.

Interactome analysis of transforming growth factor-β-activated kinase 1 in Helicobacter pylori-infected cells revealed novel regulators tripartite motif 28 and CDC37

Transforming growth factor-β (TGFβ)-activated kinase 1 (TAK1) plays a central role in controlling the cellular pro-inflammatory response via the activation of the nuclear factor κB (NF-κB)- and mitogen-activated protein (MAP) kinases-dependent transcriptional programs. Here, we show that depletion of TAK1 and the TAK1-binding proteins TAB1 and TAB2 affects NF-κB, JNK and p38 phosphorylation and suppresses NF-κB activity in AGS cells infected with Helicobacter pylori or stimulated with the cytokines TNF and IL-1β. To increase our understanding of TAK1 regulation and function, we performed mass spectrometry (MS)-based TAK1 interactomics. In addition to the identification of known and novel TAK1 interacting proteins, including TRIM28, CDC37 and STOML2, analysis of the MS data revealed various post-translational modifications within the TAK1/TAB complex. By applying siRNAs, TRIM28 and CDC37 were found to regulate phosphorylations of TAK1, IκB kinases IKKα/IKKβ and MAP kinases, NF-κB transactivation activity and IL-8 expression in the infected epithelial cells.

Role of aryl hydrocarbon receptor in mesenchymal stromal cell activation: A minireview

Mesenchymal stromal cells (MSCs) possess great therapeutic advantages due to their ability to produce a diverse array of trophic/growth factors related to cytoprotection and immunoregulation. MSC activation via specific receptors is a crucial event for these cells to exert their immunosuppressive response. The aryl-hydrocarbon receptor (AhR) is a sensitive molecule for external signals and it is expressed in MSCs and, upon positive activation, may potentially regulate the MSC-associated immunomodulatory function. Consequently, signalling pathways linked to AhR activation can elucidate some of the molecular cascades involved in MSC-mediated immunosuppression. In this minireview, we have noted some important findings concerning MSC regulation via AhR, highlighting that its activation is associated with improvement in migration and immunoregulation, as well as an increase in pro-regenerative potential. Thus, AhR-mediated MSC activation can contribute to new perspectives on MSC-based therapies, particularly those directed at immune-associated disorders.

Gedunin Binds to Myeloid Differentiation Protein 2 and Impairs Lipopolysaccharide-Induced Toll-Like Receptor 4 Signaling in Macrophages

Recognition of bacterial lipopolysaccharide (LPS) by innate immune system is mediated by the cluster of differentiation 14/Toll-like receptor 4/myeloid differentiation protein 2 (MD-2) complex. In this study, we investigated the modulatory effect of gedunin, a limonoid from species of the Meliaceae family described as a heat shock protein Hsp90 inhibitor, on LPS-induced response in immortalized murine macrophages. The pretreatment of wild-type (WT) macrophages with gedunin (0.01-100 µM, noncytotoxic concentrations) inhibited LPS (50 ng/ml)-induced calcium influx, tumor necrosis factor-α, and nitric oxide production in a concentration-dependent manner. The selective effect of gedunin on MyD88-adapter-like/myeloid differentiation primary response 88- and TRIF-related adaptor molecule/TIR domain-containing adapter-inducing interferon-β-dependent signaling pathways was further investigated. The pretreatment of WT, TIR domain-containing adapter-inducing interferon-β knockout, and MyD88 adapter-like knockout macrophages with gedunin (10 µM) significantly inhibited LPS (50 ng/ml)-induced tumor necrosis factor-α and interleukin-6 production, at 6 hours and 24 hours, suggesting that gedunin modulates a common event between both signaling pathways. Furthermore, gedunin (10 µM) inhibited LPS-induced prostaglandin E2 production, cyclooxygenase-2 expression, and nuclear factor κB translocation into the nucleus of WT macrophages, demonstrating a wide-range effect of this chemical compound. In addition to the ability to inhibit LPS-induced proinflammatory mediators, gedunin also triggered anti-inflammatory factors interleukin-10, heme oxygenase-1, and Hsp70 in macrophages stimulated or not with LPS. In silico modeling studies revealed that gedunin efficiently docked into the MD-2 LPS binding site, a phenomenon further confirmed by surface plasmon resonance. Our results reveal that, in addition to Hsp90 modulation, gedunin acts as a competitive inhibitor of LPS, blocking the formation of the Toll-like receptor 4/MD-2/LPS complex.

Activation of the heat shock response attenuates the interleukin 1β-mediated inhibition of the amiloride-sensitive alveolar epithelial ion transport

Acute lung injury (ALI) is a clinical syndrome characterized by hypoxia, which is caused by the breakdown of the alveolar capillary barrier. Interleukin 1β (IL-1β), a cytokine released within the airspace in ALI, downregulates the α subunit of the epithelial sodium channel (αENaC) transcription and protein expression via p38 MAP kinase-dependent signaling. Although induction of the heat shock response can restore alveolar fluid clearance compromised by IL-1β following the onset of severe hemorrhagic shock in rats, the mechanisms are not fully understood. In this study, we report that the induction of the heat shock response prevents IL-1β-dependent inhibition of αENaC mRNA expression and subsequent channel function. Heat shock results in IRAK1 detergent insolubility and a disruption of Hsp90 binding to IRAK1. Likewise, TAK1, another client protein of Hsp90 and signaling component of the IL-1β pathway, is also detergent insoluble after heat shock. Twenty-four hours after heat shock, both IRAK1 and TAK1 are again detergent soluble, which correlates with the IL-1β-dependent p38 activation. Remarkably, IL-1β-dependent p38 activation 24 h after heat shock did not result in an inhibition of αENaC mRNA expression and channel function. Further analysis demonstrates prolonged preservation of αENaC expression by the activation of the heat shock response that involves inducible Hsp70. Inhibition of Hsp70 at 24 h after heat shock results in p38-dependent IL-1β inhibition of αENaC mRNA expression, whereas overexpression of Hsp70 attenuates the p38-dependent IL-1β inhibition of αENaC mRNA expression. These studies demonstrate new mechanisms by which the induction of the heat shock response protects the barrier function of the alveolar epithelium in ALI.

A conceptually new treatment approach for relapsed glioblastoma: coordinated undermining of survival paths with nine repurposed drugs (CUSP9) by the International Initiative for Accelerated Improvement of Glioblastoma Care

To improve prognosis in recurrent glioblastoma we developed a treatment protocol based on a combination of drugs not traditionally thought of as cytotoxic chemotherapy agents but that have a robust history of being well-tolerated and are already marketed and used for other non-cancer indications. Focus was on adding drugs which met these criteria: a) were pharmacologically well characterized, b) had low likelihood of adding to patient side effect burden, c) had evidence for interfering with a recognized, well-characterized growth promoting element of glioblastoma, and d) were coordinated, as an ensemble had reasonable likelihood of concerted activity against key biological features of glioblastoma growth. We found nine drugs meeting these criteria and propose adding them to continuous low dose temozolomide, a currently accepted treatment for relapsed glioblastoma, in patients with recurrent disease after primary treatment with the Stupp Protocol. The nine adjuvant drug regimen, Coordinated Undermining of Survival Paths, CUSP9, then are aprepitant, artesunate, auranofin, captopril, copper gluconate, disulfiram, ketoconazole, nelfinavir, sertraline, to be added to continuous low dose temozolomide. We discuss each drug in turn and the specific rationale for use- how each drug is expected to retard glioblastoma growth and undermine glioblastoma's compensatory mechanisms engaged during temozolomide treatment. The risks of pharmacological interactions and why we believe this drug mix will increase both quality of life and overall survival are reviewed.

Inducible HSP70 antagonizes IL-1β cytocidal effects through inhibiting NF-kB activation via destabilizing TAK1 in HeLa cells

Background

Despite several reports describing the HSP70-mediated cytoprotection against IL-1, the precise mechanism for this phenomenon remains to be determined.

Methods/Principal Findings

Here we used HeLa cells, a human epithelial carcinoma cell line, to evaluate the role of inducible HSP70 in response of IL-1β stimulation. We found that inducible HSP70 antagonized the cytotoxicity of IL-1β and improved the survival of HeLa cells. Further investigation demonstrated that increased expression level of inducible HSP70 reduced the complex of TAK1 and HSP90, and promoted the degradation of TAK1 protein via proteasome pathway. By overexpression and RNAi knockdown, we showed that inducible HSP70 modulated the NF-kB but not MAPKs signalings through influencing the stability of TAK1 protein in HeLa cells. Moreover, overexpression of HSP70 attenuated the production of iNOS upon IL-1β stimulation, validating that inducible HSP70 serves as a cytopretective factor to antagonize the cytocidal effects of IL-1β in HeLa cells.

Conclusions/Significance

Our observations provide evidence for a novel signaling mechanism involving HSP70, TAK1, and NF-κB in the response of IL-1β cytocidal effects. This research also provides insight into mechanisms by which HSP70 exerts its cytoprotective action upon toxic stimuli in tumor cells.

Functional interaction of heat shock protein 90 and Beclin 1 modulates Toll-like receptor-mediated autophagy

Autophagy is one of the downstream effector mechanisms for elimination of intracellular microbes following activation of the Toll-like receptors (TLRs). Although the detailed molecular mechanism for this cellular process is still unclear, Beclin 1, a key molecule for autophagy, has been suggested to play a role. Heat shock protein 90 (Hsp90) is a molecular chaperone that regulates the stability of signaling proteins. Herein, we show that Hsp90 forms a complex with Beclin 1 through an evolutionarily conserved domain to maintain the stability of Beclin 1. In monocytic cells, geldanamycin (GA), an Hsp90 inhibitor, effectively promoted proteasomal degradation of Beclin 1 in a concentration-dependent (EC(50) 100 nM) and time-dependent (t(50) 2 h) manner. In contrast, KNK437/Hsp inhibitor I had no effect. Hsp90 specifically interacted with Beclin 1 but not with other adapter proteins in the TLR signalsome. Treatment of cells with GA inhibited TLR3- and TLR4-mediated autophagy. In addition, S. typhimurium infection-induced autophagy was blocked by GA treatment. This further suggested a role of the Hsp90/Beclin 1 in controlling autophagy in response to microbial infections. Taken together, our data revealed that by maintaining the homeostasis of Beclin 1, Hsp90 plays a novel role in TLR-mediated autophagy.

Comprehending the complex connection between PKCbeta, TAK1, and IKK in BCR signaling

The transcription factor nuclear factor-kappaB (NF-kappaB) contributes to many events in the immune system. Characterization of NF-kappaB has facilitated our understanding of immune cell differentiation, survival, proliferation, and effector functions. Intense research continues to elucidate the role of NF-kappaB, which is shared in several receptor signaling pathways, such as Toll-like receptors, the tumor necrosis factor receptor, and antigen receptors. The specificity of cellular responses emanating from stimulation of these receptors is determined by post-translational modification, or 'fine tuning', which regulates spatiotemporal dynamics of downstream signaling. Understanding the fine tuning mechanisms of NF-kappaB activation is crucial for insights into biological regulation and for understanding how cellular signaling pathways are tightly regulated to guide different cell fates. In this review, we focus on recent advances that illuminate the fine tuning mechanisms of NF-kappaB activation by BCR signaling and have increased our comprehension of complex signal systems.