RESUMO
Proteasome-mediated degradation of chromatin-bound NF-κB is critical in terminating the transcription of pro-inflammatory genes and can be triggered by Set9-mediated lysine methylation of the RelA subunit. However, the E3 ligase targeting methylated RelA remains unknown. Here, we find that two structurally similar substrate-recognizing components of Cullin-RING E3 ligases, WSB1 and WSB2, can recognize chromatin-bound methylated RelA for polyubiquitination and proteasomal degradation. We showed that WSB1/2 negatively regulated a subset of NF-κB target genes via associating with chromatin where they targeted methylated RelA for ubiquitination, facilitating the termination of NF-κB-dependent transcription. WSB1/2 specifically interacted with methylated lysines (K) 314 and 315 of RelA via their N-terminal WD-40 repeat (WDR) domains, thereby promoting ubiquitination of RelA. Computational modeling further revealed that a conserved aspartic acid (D) at position 158 within the WDR domain of WSB2 coordinates K314/K315 of RelA, with a higher affinity when either of the lysines is methylated. Mutation of D158 abolished WSB2's ability to bind to and promote ubiquitination of methylated RelA. Together, our study identifies a novel function and the underlying mechanism for WSB1/2 in degrading chromatin-bound methylated RelA and preventing sustained NF-κB activation, providing potential new targets for therapeutic intervention of NF-κB-mediated inflammatory diseases.
Assuntos
Cromatina , Complexo de Endopeptidases do Proteassoma , Fator de Transcrição RelA , Ubiquitinação , Humanos , Cromatina/metabolismo , Células HEK293 , Lisina/metabolismo , Metilação , NF-kappa B/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Ligação Proteica , Proteólise , Fator de Transcrição RelA/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Ubiquitina-Proteína Ligases/genéticaRESUMO
The innate immune sensor NLRP3 assembles an inflammasome complex with NEK7 and ASC to activate caspase-1 and drive the maturation of proinflammatory cytokines IL-1ß and IL-18. NLRP3 inflammasome activity must be tightly controlled, as its over-activation is involved in the pathogenesis of inflammatory diseases. Here, we show that NLRP3 inflammasome activation is suppressed by a centrosomal protein Spata2. Spata2 deficiency enhances NLRP3 inflammasome activity both in the macrophages and in an animal model of peritonitis. Mechanistically, Spata2 recruits the deubiquitinase CYLD to the centrosome for deubiquitination of polo-like kinase 4 (PLK4), the master regulator of centrosome duplication. Deubiquitination of PLK4 facilitates its binding to and phosphorylation of NEK7 at Ser204. NEK7 phosphorylation in turn attenuates NEK7 and NLRP3 interaction, which is required for NLRP3 inflammasome activation. Pharmacological or shRNA-mediated inhibition of PLK4, or mutation of the NEK7 Ser204 phosphorylation site, augments NEK7 interaction with NLRP3 and causes increased NLRP3 inflammasome activation. Our study unravels a novel centrosomal regulatory pathway of inflammasome activation and may provide new therapeutic targets for the treatment of NLRP3-associated inflammatory diseases.
Assuntos
Centrossomo/imunologia , Enzima Desubiquitinante CYLD/metabolismo , Inflamassomos/imunologia , Quinases Relacionadas a NIMA/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas/fisiologia , Animais , Centrossomo/metabolismo , Citocinas/metabolismo , Enzima Desubiquitinante CYLD/genética , Modelos Animais de Doenças , Inflamassomos/metabolismo , Macrófagos/imunologia , Macrófagos/metabolismo , Macrófagos/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Quinases Relacionadas a NIMA/genética , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Peritonite/imunologia , Peritonite/metabolismo , Peritonite/patologia , Fosforilação , Proteínas Serina-Treonina Quinases/genética , Transdução de Sinais , UbiquitinaçãoRESUMO
P-TEFb modulates RNA polymerase II elongation through alternative interaction with negative and positive regulation factors. While inactive P-TEFbs are mainly sequestered in the 7SK snRNP complex in a chromatin-free state, most of its active forms are in complex with its recruitment factors, Brd4 and SEC, in a chromatin-associated state. Thus, switching from inactive 7SK snRNP to active P-TEFb (Brd4/P-TEFb or SEC/P-TEFb) is essential for global gene expression. Although it has been shown that cellular signaling stimulates the disruption of 7SK snRNP, releasing dephosphorylated and catalytically inactive P-TEFb, little is known about how the inactive released P-TEFb is reactivated. Here, we show that the Cdk9/CycT1 heterodimer released from 7SK snRNP is completely dissociated into monomers in response to stress. Brd4 or SEC then recruits monomerized Cdk9 and CycT1 to reassemble the core P-TEFb. Meanwhile, the binding of monomeric dephosphorylated Cdk9 to either Brd4 or SEC induces the autophosphorylation of T186 of Cdk9. Finally, the same mechanism is employed during nocodazole released entry into early G1 phase of cell cycle. Therefore, our studies demonstrate a novel mechanism by which Cdk9 and CycT1 monomers are reassembled on chromatin to form active P-TEFb by its interaction with Brd4 or SEC to regulate transcription.
Assuntos
Proteínas de Ciclo Celular/metabolismo , Ciclina T/metabolismo , Quinase 9 Dependente de Ciclina/metabolismo , Proteínas de Ligação a DNA/metabolismo , Fator B de Elongação Transcricional Positiva/metabolismo , Ribonucleoproteínas Nucleares Pequenas/metabolismo , Fatores de Transcrição/metabolismo , Fatores de Elongação da Transcrição/metabolismo , Ciclo Celular , Linhagem Celular , Ciclina T/química , Quinase 9 Dependente de Ciclina/química , Ativação Enzimática , Humanos , Modelos Biológicos , Fosforilação , Ligação Proteica , Multimerização Proteica , Proteínas Recombinantes , Ribonucleoproteínas Nucleares Pequenas/química , Estresse FisiológicoRESUMO
Bromodomain-containing factor Brd4 has emerged as an important transcriptional regulator of NF-κB-dependent inflammatory gene expression. However, the in vivo physiological function of Brd4 in the inflammatory response remains poorly defined. We now demonstrate that mice deficient for Brd4 in myeloid-lineage cells are resistant to LPS-induced sepsis but are more susceptible to bacterial infection. Gene-expression microarray analysis of bone marrow-derived macrophages (BMDMs) reveals that deletion of Brd4 decreases the expression of a significant amount of LPS-induced inflammatory genes while reversing the expression of a small subset of LPS-suppressed genes, including MAP kinase-interacting serine/threonine-protein kinase 2 (Mknk2). Brd4-deficient BMDMs display enhanced Mnk2 expression and the corresponding eukaryotic translation initiation factor 4E (eIF4E) activation after LPS stimulation, leading to an increased translation of IκBα mRNA in polysomes. The enhanced newly synthesized IκBα reduced the binding of NF-κB to the promoters of inflammatory genes, resulting in reduced inflammatory gene expression and cytokine production. By modulating the translation of IκBα via the Mnk2-eIF4E pathway, Brd4 provides an additional layer of control for NF-κB-dependent inflammatory gene expression and inflammatory response.
Assuntos
Imunidade Inata , Inibidor de NF-kappaB alfa/metabolismo , NF-kappa B/metabolismo , Proteínas Nucleares/fisiologia , Fatores de Transcrição/fisiologia , Animais , Fator de Iniciação 4E em Eucariotos/metabolismo , Regulação da Expressão Gênica , Lipopolissacarídeos , Pulmão/patologia , Sistema de Sinalização das MAP Quinases , Macrófagos/metabolismo , Camundongos Knockout , Proteínas Serina-Treonina Quinases/metabolismo , Choque Séptico/imunologia , Choque Séptico/patologiaRESUMO
Current clinical treatment of Helicobacter pylori infection, the main etiological factor in the development of gastritis, gastric ulcers, and gastric carcinoma, requires a combination of at least two antibiotics and one proton pump inhibitor. However, such triple therapy suffers from progressively decreased therapeutic efficacy due to the drug resistance and undesired killing of the commensal bacteria due to poor selectivity. Here, we report the development of antimicrobial polypeptide-based monotherapy, which can specifically kill H. pylori under acidic pH in the stomach while inducing minimal toxicity to commensal bacteria under physiological pH. Specifically, we designed a class of pH-sensitive, helix-coil conformation transitionable antimicrobial polypeptides (HCT-AMPs) (PGA)m-r-(PHLG-MHH)n, bearing randomly distributed negatively charged glutamic acid and positively charged poly(γ-6-N-(methyldihexylammonium)hexyl-l-glutamate) (PHLG-MHH) residues. The HCT-AMPs showed unappreciable toxicity at physiological pH when they adopted random coiled conformation. Under acidic condition in the stomach, they transformed to the helical structure and exhibited potent antibacterial activity against H. pylori, including clinically isolated drug-resistant strains. After oral gavage, the HCT-AMPs afforded comparable H. pylori killing efficacy to the triple-therapy approach while inducing minimal toxicity against normal tissues and commensal bacteria, in comparison with the remarkable killing of commensal bacteria by 65% and 86% in the ileal contents and feces, respectively, following triple therapy. This strategy renders an effective approach to specifically target and kill H. pylori in the stomach while not harming the commensal bacteria/normal tissues.
Assuntos
Aminas/química , Antibacterianos/farmacologia , Peptídeos Catiônicos Antimicrobianos/farmacologia , Ácido Glutâmico/farmacologia , Infecções por Helicobacter/tratamento farmacológico , Helicobacter pylori/efeitos dos fármacos , Animais , Antibacterianos/síntese química , Peptídeos Catiônicos Antimicrobianos/síntese química , Modelos Animais de Doenças , Feminino , Ácido Glutâmico/análogos & derivados , Ácido Glutâmico/síntese química , Infecções por Helicobacter/microbiologia , Infecções por Helicobacter/patologia , Helicobacter pylori/patogenicidade , Helicobacter pylori/fisiologia , Concentração de Íons de Hidrogênio , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos ICR , Especificidade de Órgãos , Conformação Proteica em alfa-Hélice , Eletricidade Estática , Estômago/efeitos dos fármacos , Estômago/microbiologia , Estômago/patologiaRESUMO
Acetylation of transcriptional regulators is normally dynamically regulated by nutrient status but is often persistently elevated in nutrient-excessive obesity conditions. We investigated the functional consequences of such aberrantly elevated acetylation of the nuclear receptor FXR as a model. Proteomic studies identified K217 as the FXR acetylation site in diet-induced obese mice. In vivo studies utilizing acetylation-mimic and acetylation-defective K217 mutants and gene expression profiling revealed that FXR acetylation increased proinflammatory gene expression, macrophage infiltration, and liver cytokine and triglyceride levels, impaired insulin signaling, and increased glucose intolerance. Mechanistically, acetylation of FXR blocked its interaction with the SUMO ligase PIASy and inhibited SUMO2 modification at K277, resulting in activation of inflammatory genes. SUMOylation of agonist-activated FXR increased its interaction with NF-κB but blocked that with RXRα, so that SUMO2-modified FXR was selectively recruited to and trans-repressed inflammatory genes without affecting FXR/RXRα target genes. A dysregulated acetyl/SUMO switch of FXR in obesity may serve as a general mechanism for diminished anti-inflammatory response of other transcriptional regulators and provide potential therapeutic and diagnostic targets for obesity-related metabolic disorders.
Assuntos
Regulação da Expressão Gênica , Inflamação/patologia , Hepatopatias/patologia , Obesidade/complicações , Receptores Citoplasmáticos e Nucleares/metabolismo , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/metabolismo , Acetilação , Sequência de Aminoácidos , Animais , Western Blotting , Citocinas/genética , Citocinas/metabolismo , Ensaio de Desvio de Mobilidade Eletroforética , Perfilação da Expressão Gênica , Técnicas Imunoenzimáticas , Imunoprecipitação , Inflamação/etiologia , Inflamação/metabolismo , Hepatopatias/etiologia , Hepatopatias/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Obesos , Dados de Sequência Molecular , NF-kappa B/genética , NF-kappa B/metabolismo , Obesidade/fisiopatologia , Conformação Proteica , Processamento de Proteína Pós-Traducional , Proteômica , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Receptores Citoplasmáticos e Nucleares/química , Receptores Citoplasmáticos e Nucleares/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Homologia de Sequência de Aminoácidos , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/química , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/genética , Sumoilação , Espectrometria de Massas em TandemRESUMO
Helicobacter pylori infection causes chronic gastritis and peptic ulceration. H. pylori-initiated chronic gastritis is characterized by enhanced expression of many NF-κB-regulated inflammatory cytokines. Brd4 has emerged as an important NF-κB regulator and regulates the expression of many NF-κB-dependent inflammatory genes. In this study, we demonstrated that Brd4 was not only actively involved in H. pylori-induced inflammatory gene mRNA transcription but also H. pylori-induced inflammatory gene enhancer RNA (eRNA) synthesis. Suppression of H. pylori-induced eRNA synthesis impaired H. pylori-induced mRNA synthesis. Furthermore, H. pylori stimulated NF-κB-dependent recruitment of Brd4 to the promoters and enhancers of inflammatory genes to facilitate the RNA polymerase II-mediated eRNA and mRNA synthesis. Inhibition of Brd4 by JQ1 attenuated H. pylori-induced eRNA and mRNA synthesis for a subset of NF-κB-dependent inflammatory genes. JQ1 also inhibited H. pylori-induced interaction between Brd4 and RelA and the recruitment of Brd4 and RNA polymerase II to the promoters and enhancers of inflammatory genes. Finally, we demonstrated that JQ1 suppressed inflammatory gene expression, inflammation, and cell proliferation in H. pylori-infected mice. These studies highlight the importance of Brd4 in H. pylori-induced inflammatory gene expression and suggest that Brd4 could be a potential therapeutic target for the treatment of H. pylori-triggered inflammatory diseases and cancer.
Assuntos
Gastrite/imunologia , Infecções por Helicobacter/imunologia , Helicobacter pylori/fisiologia , Proteínas Nucleares/metabolismo , RNA Mensageiro/biossíntese , Fatores de Transcrição/metabolismo , Azepinas/farmacologia , Proteínas de Ciclo Celular , Linhagem Celular Tumoral , Elementos Facilitadores Genéticos/genética , Gastrite/etiologia , Regulação da Expressão Gênica , Infecções por Helicobacter/complicações , Humanos , Mediadores da Inflamação/metabolismo , NF-kappa B/metabolismo , Proteínas Nucleares/genética , Regiões Promotoras Genéticas/genética , Ligação Proteica/efeitos dos fármacos , RNA Polimerase II/genética , RNA Polimerase II/metabolismo , Fatores de Transcrição/genética , Triazóis/farmacologiaRESUMO
The association of DSIF and NELF with initiated RNA Polymerase II (Pol II) is the general mechanism for inducing promoter-proximal pausing of Pol II. However, it remains largely unclear how the paused Pol II is released in response to stimulation. Here, we show that the release of the paused Pol II is cooperatively regulated by multiple P-TEFbs which are recruited by bromodomain-containing protein Brd4 and super elongation complex (SEC) via different recruitment mechanisms. Upon stimulation, Brd4 recruits P-TEFb to Spt5/DSIF via a recruitment pathway consisting of Med1, Med23 and Tat-SF1, whereas SEC recruits P-TEFb to NELF-A and NELF-E via Paf1c and Med26, respectively. P-TEFb-mediated phosphorylation of Spt5, NELF-A and NELF-E results in the dissociation of NELF from Pol II, thereby transiting transcription from pausing to elongation. Additionally, we demonstrate that P-TEFb-mediated Ser2 phosphorylation of Pol II is dispensable for pause release. Therefore, our studies reveal a co-regulatory mechanism of Brd4 and SEC in modulating the transcriptional pause release by recruiting multiple P-TEFbs via a Mediator- and Paf1c-coordinated recruitment network.
Assuntos
Fator B de Elongação Transcricional Positiva/metabolismo , Regiões Promotoras Genéticas , RNA Polimerase II/metabolismo , Acetamidas/farmacologia , Proteínas de Ciclo Celular , Células HCT116 , Células HeLa , Humanos , Modelos Biológicos , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Fosforilação/efeitos dos fármacos , RNA Interferente Pequeno/metabolismo , Elongação da Transcrição Genética/efeitos dos fármacos , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Fatores de Elongação da Transcrição/metabolismoRESUMO
α-Helical antimicrobial peptides (AMPs) generally have facially amphiphilic structures that may lead to undesired peptide interactions with blood proteins and self-aggregation due to exposed hydrophobic surfaces. Here we report the design of a class of cationic, helical homo-polypeptide antimicrobials with a hydrophobic internal helical core and a charged exterior shell, possessing unprecedented radial amphiphilicity. The radially amphiphilic structure enables the polypeptide to bind effectively to the negatively charged bacterial surface and exhibit high antimicrobial activity against both gram-positive and gram-negative bacteria. Moreover, the shielding of the hydrophobic core by the charged exterior shell decreases nonspecific interactions with eukaryotic cells, as evidenced by low hemolytic activity, and protects the polypeptide backbone from proteolytic degradation. The radially amphiphilic polypeptides can also be used as effective adjuvants, allowing improved permeation of commercial antibiotics in bacteria and enhanced antimicrobial activity by one to two orders of magnitude. Designing AMPs bearing this unprecedented, unique radially amphiphilic structure represents an alternative direction of AMP development; radially amphiphilic polypeptides may become a general platform for developing AMPs to treat drug-resistant bacteria.
Assuntos
Peptídeos Catiônicos Antimicrobianos/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Testes de Sensibilidade MicrobianaRESUMO
Aesculin (AES), a coumarin compound derived from Aesculus hippocasanum L, is reported to exert protective role against inflammatory diseases, gastric disease and cancer. However, direct effect of AES in bone metabolism is deficient. In this study, we examined the effects of AES on osteoclast (OC) differentiation in receptor activator of NF-κB ligand (RANKL)-induced RAW264.7 cells. AES inhibits the OC differentiation in both dose- and time-dependent manner within non-toxic concentrations, as analyzed by Tartrate Resistant Acid Phosphatase (TRAP) staining. The actin ring formation manifesting OC function is also decreased by AES. Moreover, expressions of osteoclastogenesis related genes Trap, Atp6v0d2, Cathepsin K and Mmp-9 are decreased upon AES treatment. Mechanistically, AES attenuates the activation of MAPKs and NF-κB activity upon RANKL induction, thus leading to the reduction of Nfatc1 mRNA expression. Moreover, AES inhibits Rank expression, and RANK overexpression markedly decreases AES's effect on OC differentiation and NF-κB activity. Consistently, AES protects against bone mass loss in the ovariectomized and dexamethasone treated rat osteoporosis model. Taken together, our data demonstrate that AES can modulate bone metabolism by suppressing osteoclastogenesis and related transduction signals. AES therefore could be a promising agent for the treatment of osteoporosis.
Assuntos
Osso e Ossos/efeitos dos fármacos , Osso e Ossos/metabolismo , Esculina/farmacologia , Osteogênese/efeitos dos fármacos , Ligante RANK/antagonistas & inibidores , Transdução de Sinais/efeitos dos fármacos , Animais , Células Cultivadas , Relação Dose-Resposta a Droga , Esculina/administração & dosagem , Esculina/química , Camundongos , Conformação Molecular , Ligante RANK/metabolismo , Células RAW 264.7 , Relação Estrutura-AtividadeRESUMO
DNA repair helicases function in the cell to separate DNA duplexes or remodel nucleoprotein complexes. These functions are influenced by sensing and signaling; the cellular pool of a DNA helicase may contain subpopulations of enzymes carrying different post-translational modifications and performing distinct biochemical functions. Here, we report a novel experimental strategy, single-molecule sorting, which overcomes difficulties associated with comprehensive analysis of heterologously modified pool of proteins. This methodology was applied to visualize human DNA helicase F-box-containing DNA helicase (FBH1) acting on the DNA structures resembling a stalled or collapsed replication fork and its interactions with RAD51 nucleoprotein filament. Individual helicase molecules isolated from human cells with their native post-translational modifications were analyzed using total internal reflection fluorescence microscopy. Separation of the activity trajectories originated from ubiquitylated and non-ubiquitylated FBH1 molecules revealed that ubiquitylation affects FBH1 interaction with the RAD51 nucleoprotein filament, but not its translocase and helicase activities.
Assuntos
DNA Helicases/metabolismo , Proteínas de Ligação a DNA/metabolismo , Ubiquitinação , Sítios de Ligação , DNA/metabolismo , DNA Helicases/química , Replicação do DNA , Proteínas de Ligação a DNA/química , Células HEK293 , Humanos , Estrutura Terciária de Proteína , Rad51 Recombinase/metabolismoRESUMO
The etiology of human T cell leukemia virus 1 (HTLV-1)-mediated adult T cell leukemia is associated with the ability of viral oncoprotein Tax to induce sustained NF-κB activation and the expression of many NF-κB target genes. Acetylation of the RelA subunit of NF-κB and the subsequent recruitment of bromodomain-containing factor Brd4 are important for the expression of NF-κB target genes in response to various stimuli. However, their contributions to Tax-mediated NF-κB target gene expression and tumorigenesis remain unclear. Here we report that Tax induced the acetylation of lysine 310 of RelA and the binding of Brd4 to acetylated RelA to facilitate Tax-mediated transcriptional activation of NF-κB. Depletion of Brd4 down-regulated Tax-mediated NF-κB target gene expression and cell proliferation. Inhibiting the interaction of Brd4 and acetylated RelA with the bromodomain extraterminal protein inhibitor JQ1 suppressed the proliferation of Tax-expressing rat fibroblasts and Tax-positive HTLV-1-infected cells and Tax-mediated cell transformation and tumorigenesis. Moreover, JQ1 attenuated the Tax-mediated transcriptional activation of NF-κB, triggering the polyubiquitination and proteasome-mediated degradation of constitutively active nuclear RelA. Our results identify Brd4 as a key regulator for Tax-mediated NF-κB gene expression and suggest that targeting epigenetic regulators such as Brd4 with the bromodomain extraterminal protein inhibitor might be a potential therapeutic strategy for cancers and other diseases associated with HTLV-1 infection.
Assuntos
Carcinogênese , Produtos do Gene tax/metabolismo , Vírus Linfotrópico T Tipo 1 Humano/fisiologia , Proteínas Nucleares/metabolismo , Transdução de Sinais , Fator de Transcrição RelA/metabolismo , Fatores de Transcrição/metabolismo , Acetilação/efeitos dos fármacos , Animais , Azepinas/farmacologia , Carcinogênese/efeitos dos fármacos , Proteínas de Ciclo Celular , Linhagem Celular , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Proliferação de Células/efeitos dos fármacos , Regulação para Baixo/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Vírus Linfotrópico T Tipo 1 Humano/metabolismo , Humanos , Lisina/metabolismo , Camundongos , Transdução de Sinais/efeitos dos fármacos , Fator de Transcrição RelA/química , Triazóis/farmacologiaRESUMO
Absent, small, or homeotic1-like (ASH1L) is a histone lysine methyltransferase that generally functions as a transcriptional activator in controlling cell fate. So far, its physiological relevance in bone homeostasis and osteoclast differentiation remains elusive. Here, by conditional deleting Ash1l in osteoclast progenitors of mice, we found ASH1L deficiency resulted in osteoporosis and potentiation of osteoclastogenesis in vivo and in vitro. Mechanistically, ASH1L binds the promoter of the Src homology 3 and cysteine-rich domain 2 (Stac2) and increases the gene's transcription via histone 3 lysine 4 (H3K4) trimethylation modification, thus augmenting the STAC2's protection against receptor activator of nuclear factor kB ligand (RANKL)-initiated inflammation during osteoclast formation. Collectively, we demonstrate the first piece of evidence to prove ASH1L as a critical checkpoint during osteoclastogenesis. The work sheds new light on our understanding about the biological function of ASH1L in bone homeostasis, therefore providing a valuable therapeutic target for the treatment of osteoporosis or inflammatory bone diseases.
Assuntos
Histona-Lisina N-Metiltransferase , Osteoclastos , Osteogênese , Animais , Camundongos , Reabsorção Óssea/metabolismo , Reabsorção Óssea/patologia , Diferenciação Celular , Proteínas de Ligação a DNA/metabolismo , Proteínas de Ligação a DNA/genética , Histona-Lisina N-Metiltransferase/metabolismo , Histona-Lisina N-Metiltransferase/genética , Histonas/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Osteoclastos/metabolismo , Osteoporose/metabolismo , Osteoporose/patologia , Osteoporose/genética , Ligante RANK/metabolismo , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genéticaRESUMO
BACKGROUND & AIMS: Metabolic reprogramming is essential for the activation and functions of macrophages, including bacterial killing and cytokine production. Bromodomain-containing protein 4 (BRD4) has emerged as a critical regulator of innate immune response. However, the potential role of BRD4 in the metabolic reprogramming of macrophage activation upon Helicobacter pylori infection remains unclear. METHODS: Bone marrow-derived macrophages (BMDMs) from wild-type (WT) and Brd4-myeloid deletion conditional knockout (Brd4-CKO) mice were infected with H pylori. RNA sequencing was performed to evaluate the differential gene expression between WT and Brd4-deficient BMDMs upon infection. An in vivo model of H pylori infection using WT and Brd4-CKO mice was used to confirm the role of BRD4 in innate immune response to infection. RESULTS: Depletion of Brd4 in BMDMs showed impaired H pylori-induced glycolysis. In addition, H pylori-induced expression of glycolytic genes, including Slc2a1 and Hk2, was decreased in Brd4-deficient BMDMs. BRD4 was recruited to the promoters of Slc2a1 and Hk2 via hypoxia-inducible factor-1α, facilitating their expression. BRD4-mediated glycolysis stabilized H pylori-induced nitric oxide synthase (Nos2) messenger RNA to produce nitric oxide. The NO-mediated killing of H pylori decreased in Brd4-deficient BMDMs, which was rescued by pyruvate. Furthermore, Brd4-CKO mice infected with H pylori showed reduced gastric inflammation and increased H pylori colonization with reduced inducible NO synthase expression in gastric macrophages. CONCLUSIONS: Our study identified BRD4 as a key regulator of hypoxia-inducible factor-1α-dependent glycolysis and macrophage activation. Furthermore, we show a novel regulatory role of BRD4 in innate immunity through glycolysis to stabilize Nos2 messenger RNA for NO production to eliminate H pylori infection.
Assuntos
Infecções por Helicobacter , Helicobacter pylori , Animais , Camundongos , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Infecções por Helicobacter/microbiologia , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Helicobacter pylori/metabolismo , Macrófagos/metabolismo , Óxido Nítrico Sintase/metabolismo , RNA Mensageiro/metabolismo , Glicólise , Óxido Nítrico Sintase Tipo II/metabolismoRESUMO
Helicobacter pylori (H. pylori) infection causes chronic gastritis and peptic ulceration and is the strongest risk factor for the development of gastric cancer. The pathogenesis of H. pylori is believed to be associated with infection-initiated chronic gastritis, which is characterized by enhanced expression of many inflammatory genes. H. pylori utilizes various virulence factors, targeting different cellular proteins, to modulate the host inflammatory response. In this review, we explore the many different ways by which H. pylori initiates inflammation, leveling many "hits" on the gastric mucosa which can lead to the development of cancer. We also discuss some recent findings in understanding the pathogen-host interactions and the role of transcription factor NF-κB in H. pylori-induced inflammation.
Assuntos
Gastrite/microbiologia , Infecções por Helicobacter/imunologia , Helicobacter pylori/patogenicidade , NF-kappa B/metabolismo , Neoplasias Gástricas/etiologia , Neoplasias Gástricas/microbiologia , Antígenos de Bactérias/metabolismo , Proteínas de Bactérias/metabolismo , Ativação Enzimática , Mucosa Gástrica/microbiologia , Mucosa Gástrica/patologia , Gastrite/complicações , Infecções por Helicobacter/complicações , Infecções por Helicobacter/microbiologia , Helicobacter pylori/imunologia , Interações Hospedeiro-Patógeno , Humanos , MAP Quinase Quinase Quinases/metabolismo , Neoplasias Gástricas/complicações , Neoplasias Gástricas/imunologiaRESUMO
The Helicobacter pylori virulence factor CagA targets a variety of host proteins to alter different cellular responses, including the induction of pro-inflammatory cytokines. We have previously shown that CagA-facilitated lysine 63-linked ubiquitination of TAK1 is essential for the H. pylori-induced NF-κB activation and the expression of proinflammatory cytokines. However, the molecular mechanism for TAK1 ubiquitination and activation in H. pylori-mediated NF-κB activation remains elusive. Here, we identify lysine 158 of TAK1 as the key residue undergoing lysine 63-linked ubiquitination in response to H. pylori infection. Mutation of lysine 158 to arginine prevents the ubiquitination of TAK1 and impairs H. pylori-induced TAK1 and NF-κB activation. Moreover, we demonstrate that E2 ubiquitin conjugating enzyme Ubc13 is involved in H. pylori-mediated TAK1 ubiquitination. Suppressing the activity of Ubc13 by a dominant-negative mutant or siRNA abolishes CagA-facilitated and H. pylori-induced TAK1 and NF-κB activation. These findings further underscore the importance of lysine 63-linked ubiquitination of TAK1 in H. pylori-induced NF-κB activation and NF-κB-mediated inflammatory response.
Assuntos
Helicobacter pylori/patogenicidade , Lisina/metabolismo , MAP Quinase Quinase Quinases/metabolismo , NF-kappa B/metabolismo , Enzimas de Conjugação de Ubiquitina/metabolismo , Ubiquitinação/fisiologia , Linhagem Celular , Linhagem Celular Tumoral , Interações Hospedeiro-Patógeno , Humanos , Immunoblotting , Imunoprecipitação , Reação em Cadeia da Polimerase em Tempo Real , Enzimas de Conjugação de Ubiquitina/genética , Ubiquitinação/genéticaRESUMO
Proper regulation of NF-kappaB activity is critical to maintain and balance the inflammatory response. Inactivation of the NF-kappaB complex relies in part on the proteasome-mediated degradation of promoter-bound NF-kappaB, but the detailed molecular mechanism initiating this process remains elusive. Here, we show that the methylation of the RelA subunit of NF-kappaB has an important function in this process. Lysine methyltransferase Set9 physically associates with RelA in vitro and in vivo in response to TNF-alpha stimulation. Mutational and mass spectrometric analyses reveal that RelA is monomethylated by Set9 at lysine residues 314 and 315 in vitro and in vivo. Methylation of RelA inhibits NF-kappaB action by inducing the proteasome-mediated degradation of promoter-associated RelA. Depletion of Set9 by siRNA or mutation of the RelA methylation sites prolongs DNA binding of NF-kappaB and enhances TNF-alpha-induced expression of NF-kappaB target genes. Together, these findings unveil a novel mechanism by which methylation of RelA dictates the turnover of NF-kappaB and controls the NF-kappaB-mediated inflammatory response.
Assuntos
Lisina/metabolismo , NF-kappa B/metabolismo , Proteínas Metiltransferases/metabolismo , Subunidades Proteicas/metabolismo , Fator de Transcrição RelA/metabolismo , Sequência de Aminoácidos , Histona Metiltransferases , Histona-Lisina N-Metiltransferase , Humanos , Metilação , Dados de Sequência Molecular , NF-kappa B/genética , Regiões Promotoras Genéticas , Proteínas Metiltransferases/genética , Subunidades Proteicas/genética , Interferência de RNA , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Fator de Transcrição RelA/genética , Ativação Transcricional , Fator de Necrose Tumoral alfa/metabolismoRESUMO
RUNX3 is a transcription factor with regulatory roles in cell proliferation and development. While largely characterized as a tumor suppressor, RUNX3 can also be oncogenic in certain cancers. Many factors account for the tumor suppressor function of RUNX3, which is reflected by its ability to suppress cancer cell proliferation after expression-restoration, and its inactivation in cancer cells. Ubiquitination and proteasomal degradation represent a major mechanism for the inactivation of RUNX3 and the suppression of cancer cell proliferation. On the one hand, RUNX3 has been shown to facilitate the ubiquitination and proteasomal degradation of oncogenic proteins. On the other hand, RUNX3 can be inactivated through the ubiquitin-proteasome system. This review encapsulates two facets of RUNX3 in cancer: how RUNX3 suppresses cell proliferation by facilitating the ubiquitination and proteasomal degradation of oncogenic proteins, and how RUNX3 is degraded itself through interacting RNA-, protein-, and pathogen-mediated ubiquitination and proteasomal degradation.
Assuntos
Neoplasias , Complexo de Endopeptidases do Proteassoma , Humanos , Complexo de Endopeptidases do Proteassoma/metabolismo , Ubiquitina/metabolismo , Ubiquitinação , Subunidade alfa 3 de Fator de Ligação ao Core/genética , Subunidade alfa 3 de Fator de Ligação ao Core/metabolismoRESUMO
Background: Systemic lupus erythematosus (SLE) is characterized by poor regulation of the immune response leading to chronic inflammation and multiple organ dysfunction. Glucocorticoid (GC) is currently one of the main treatments. However, a high dose or prolonged use of GC may result in glucocorticoid-induced osteoporosis (GIOP). Jiedu Quyu Ziyin decoction (JP) is effective in treating SLE and previous clinical studies have proved that JP can prevent and treat SLE steroid osteoporosis (SLE-GIOP). We aim to examine JPs main mechanism on SLE-GIOP through network pharmacology and molecular docking. Methods: TCMSP and TCMID databases were used to screen potential active compounds and targets of JP. The SLE-GIOP targets are collected from GeneCards, OMIM, PharmGkb, TTD, and DrugBank databases. R software was used to obtain the cross-targets of JP and SLE-GIOP and to perform GO and KEGG enrichment analysis. Cytoscape software was used to make the Chinese Medicines-Active Ingredient-Intersection Targets network diagram. STRING database construct protein-protein interaction network and obtain the core targets. Auto Dock Tools and Pymol software were used for docking. Results: Fifty eight targets overlapped between JP and SLE-GIOP were suggested as potential targets of JP in the treatment of SLE-GIOP. Network topology analysis identified five core targets. GO enrichment analysis was obtained 1,968 items, and the top 10 biological process, closeness centrality, and molecular function were displayed. A total of 154 signaling pathways were obtained by KEGG enrichment analysis, and the top 30 signaling pathways were displayed. JP was well bound by MAPK1, TP53, and MYC according to the molecular docking results. Conclusion: We investigated the potential targets and signaling pathways of JP against SLE-GIOP in this study. It shows that JP is most likely to achieve the purpose of treating SLE-GIOP by promoting the proliferation and differentiation of osteoblasts. A solid theoretical foundation will be provided for the future study of clinical and experimental topics.
Assuntos
Medicamentos de Ervas Chinesas , Lúpus Eritematoso Sistêmico , Osteoporose , Humanos , Simulação de Acoplamento Molecular , Farmacologia em Rede , Glucocorticoides , Lúpus Eritematoso Sistêmico/tratamento farmacológico , Osteoporose/tratamento farmacológico , Medicamentos de Ervas Chinesas/farmacologia , Medicamentos de Ervas Chinesas/uso terapêuticoRESUMO
Emerging evidence indicates that RUNX3 is a tumor suppressor in breast cancer. RUNX3 is frequently inactivated in human breast cancer cell lines and cancer samples by hemizygous deletion of the Runx3 gene, hypermethylation of the Runx3 promoter, or cytoplasmic sequestration of RUNX3 protein. Inactivation of RUNX3 is associated with the initiation and progression of breast cancer. Female Runx3(+/-) mice spontaneously develop ductal carcinoma, and overexpression of RUNX3 inhibits the proliferation, tumorigenic potential, and invasiveness of breast cancer cells. This review is intended to summarize these findings and discuss the tumor suppressor function of RUNX3 in breast cancer.