RESUMO
CXCR5 is a hallmark of T follicular helper (Tfh) cells. The mechanism of CXCR5 induction, however, is still incompletely understood. In this study, we report that in mice with the absence of transcription factor Bach2, the Th17-inducing cytokines IL-6 and TGF-ß together induced CXCR5 expression in vitro. Mechanistically, IL-6/STAT3 drove Cxcr5 promoter activity via the upstream site 1 regulatory element, whereas TGF-ß enhanced permissive histone modifications, and the STAT3 binding to the site 1 regulatory element was higher in the absence of Bach2. Subsequently, despite previous studies showing enhanced Th17 cell differentiation in the absence of Bach2 in vitro, we found that in vivo, the Bach2 deficiency led to an enhanced Tfh cell response at the expense of the Th17 cell response. These findings suggest that Bach2 helps integrate cytokine signals to arbitrate differentiation decisions between Tfh and Th17 lineages.
Assuntos
Citocinas , Células Th17 , Camundongos , Animais , Citocinas/metabolismo , Linfócitos T Auxiliares-Indutores/metabolismo , Interleucina-6/metabolismo , Diferenciação Celular , Fator de Crescimento Transformador beta/metabolismo , Fatores de Transcrição de Zíper de Leucina Básica/genética , Fatores de Transcrição de Zíper de Leucina Básica/metabolismoRESUMO
BACKGROUND & AIMS: The metabolic features and function of intratumoral regulatory T cells (Tregs) are ambiguous in colorectal cancer. Tumor-infiltrating Tregs are reprogrammed to exhibit high glucose-depleting properties and adapt to the glucose-restricted microenvironment. The glucose-responsive transcription factor MondoA is highly expressed in Tregs. However, the role of MondoA in colorectal cancer-infiltrating Tregs in response to glucose limitation remains to be elucidated. METHODS: We performed studies using mice, in which MondoA was conditionally deleted in Tregs, and human colorectal cancer tissues. Seahorse and other metabolic assays were used to assess Treg metabolism. To study the role of Tregs in antitumor immunity, we used a subcutaneous MC38 colorectal cancer model and induced colitis-associated colorectal cancer in mice by azoxymethane and dextran sodium sulfate. RESULTS: Our analysis of single-cell RNA sequencing data of patients with colorectal cancer revealed that intratumoral Tregs featured low activity of the MondoA-thioredoxin-interacting protein (TXNIP) axis and increased glucose uptake. Although MondoA-deficient Tregs were less immune suppressive and selectively promoted T-helper (Th) cell type 1 (Th1) responses in a subcutaneous MC38 tumor model, Treg-specific MondoA knockout mice were more susceptible to azoxymethane-DSS-induced colorectal cancer. Mechanistically, suppression of the MondoA-TXNIP axis promoted glucose uptake and glycolysis, induced hyperglycolytic Th17-like Tregs, which facilitated Th17 inflammation, promoted interleukin 17A-induced of CD8+ T-cell exhaustion, and drove colorectal carcinogenesis. Blockade of interleukin 17A reduced tumor progression and minimized the susceptibility of MondoA-deficient mice to colorectal carcinogenesis. CONCLUSIONS: The MondoA-TXNIP axis is a critical metabolic regulator of Treg identity and function in the colorectal cancer microenvironment and a promising target for cancer therapy.
Assuntos
Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/metabolismo , Proteínas de Transporte/metabolismo , Neoplasias Associadas a Colite/metabolismo , Neoplasias Colorretais/metabolismo , Linfócitos do Interstício Tumoral/metabolismo , Linfócitos T Reguladores/metabolismo , Tiorredoxinas/metabolismo , Microambiente Tumoral , Animais , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Proteínas de Transporte/genética , Linhagem Celular Tumoral , Neoplasias Associadas a Colite/genética , Neoplasias Associadas a Colite/imunologia , Neoplasias Associadas a Colite/patologia , Neoplasias Colorretais/genética , Neoplasias Colorretais/imunologia , Neoplasias Colorretais/patologia , Modelos Animais de Doenças , Regulação Neoplásica da Expressão Gênica , Glicólise , Humanos , Linfócitos do Interstício Tumoral/imunologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fenótipo , Transdução de Sinais , Linfócitos T Reguladores/imunologia , Células Th17/imunologia , Células Th17/metabolismo , Tiorredoxinas/genéticaRESUMO
The androgen receptor (AR) pathway is critical for prostate cancer carcinogenesis and development; however, after 18-24 months of AR blocking therapy, patients invariably progress to castration-resistant prostate cancer (CRPC), which remains an urgent problem to be solved. Therefore, finding key molecules that interact with AR as novel strategies to treat prostate cancer and even CRPC is desperately needed. In the current study, we focused on the regulation of RNA-binding proteins (RBPs) associated with AR and determined that the mRNA and protein levels of AR were highly correlated with Musashi2 (MSI2) levels. MSI2 was upregulated in prostate cancer specimens and significantly correlated with advanced tumor grades. Downregulation of MSI2 in both androgen sensitive and insensitive prostate cancer cells inhibited tumor formation in vivo and decreased cell growth in vitro, which could be reversed by AR overexpression. Mechanistically, MSI2 directly bound to the 3'-untranslated region (UTR) of AR mRNA to increase its stability and, thus, enhanced its transcriptional activity. Our findings illustrate a previously unknown regulatory mechanism in prostate cancer cell proliferation regulated by the MSI2-AR axis and provide novel evidence towards a strategy against prostate cancer.
Assuntos
Neoplasias da Próstata/patologia , Proteínas de Ligação a RNA/metabolismo , Receptores Androgênicos/genética , Receptores Androgênicos/metabolismo , Regiões 3' não Traduzidas , Animais , Linhagem Celular Tumoral , Progressão da Doença , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Camundongos , Gradação de Tumores , Transplante de Neoplasias , Neoplasias da Próstata/genética , Neoplasias da Próstata/metabolismo , Estabilidade de RNA , Receptores Androgênicos/química , Regulação para CimaRESUMO
The CD4+CD25+FOXP3+ regulatory T (Treg) cells are critical for maintaining immune tolerance in healthy individuals and are reported to restrict anti-inflammatory responses and thereby promote tumor progression, suggesting them as a target in the development of antitumor immunotherapy. Forkhead box P3 (FOXP3) is a key transcription factor governing Treg lineage differentiation and their immune-suppressive function. Here, using Treg cells, as well as HEK-293T and Jurkat T cells, we report that the stability of FOXP3 is directly and positively regulated by the E3 ubiquitin ligase ring finger protein 31 (RNF31), which catalyzes the conjugation of atypical ubiquitin chains to the FOXP3 protein. We observed that shRNA-mediated RNF31 knockdown in human Treg cells decreases FOXP3 protein levels and increases levels of interferon-γ, resulting in a Th1 helper cell-like phenotype. Human Treg cells that ectopically expressed RNF31 displayed stronger immune-suppressive capacity, suggesting that RNF31 positively regulates both FOXP3 stability and Treg cell function. Moreover, we found that RNF31 is up-regulated in Treg cells that infiltrate human gastric tumor tissues compared with their counterparts residing in peripheral and normal tissue. We also found that elevated RNF31 expression in intratumoral Treg cells is associated with poor survival of gastric cancer patients, suggesting that RNF31 supports the immune-suppressive functions of Treg cells. Our results suggest that RNF31 could be a potential therapeutic target in immunity-based interventions against human gastric cancer.
Assuntos
Fatores de Transcrição Forkhead/imunologia , Regulação Enzimológica da Expressão Gênica/imunologia , Linfócitos T Reguladores/imunologia , Ubiquitina-Proteína Ligases/imunologia , Ubiquitinação/imunologia , Regulação para Cima/imunologia , Intervalo Livre de Doença , Células HEK293 , Humanos , Células Jurkat , Estabilidade Proteica , Neoplasias Gástricas/imunologia , Neoplasias Gástricas/mortalidade , Neoplasias Gástricas/patologia , Taxa de Sobrevida , Linfócitos T Reguladores/patologiaRESUMO
T cells play critical roles in immune responses to pathogens, autoimmunity, and antitumor immunity. During the past few decades, increasing numbers of studies have demonstrated the significance of protein ubiquitination in T cell-mediated immunity. Several E3 ubiquitin ligases and deubiquitinases (DUBs) have been identified as either positive or negative regulators of T cell development and function. In this review, we mainly focus on the roles of DUBs (especially ubiquitin-specific proteases (USPs)) in modulating T cell differentiation and function, as well as the molecular mechanisms. Understanding how T cell development and function is regulated by ubiquitination and deubiquitination will provide novel strategies for treating infection, autoimmune diseases, and cancer.
Assuntos
Doenças Autoimunes/imunologia , Enzimas Desubiquitinantes/genética , Neoplasias/imunologia , Processamento de Proteína Pós-Traducional , Linfócitos T/imunologia , Ubiquitina-Proteína Ligases/genética , Animais , Doenças Autoimunes/enzimologia , Doenças Autoimunes/genética , Doenças Autoimunes/patologia , Diferenciação Celular , Proliferação de Células , Enzimas Desubiquitinantes/imunologia , Humanos , Tolerância Imunológica , Imunidade Celular , Isoenzimas/genética , Isoenzimas/imunologia , Camundongos , Neoplasias/enzimologia , Neoplasias/genética , Neoplasias/patologia , Transdução de Sinais , Linfócitos T/enzimologia , Linfócitos T/patologia , Ubiquitina-Proteína Ligases/imunologia , UbiquitinaçãoRESUMO
An unconventional organic molecule (TBBU) showing obvious long-lived room temperature phosphorescence (RTP) is reported. X-ray single crystal analysis demonstrates that TBBU molecules are packed in a unique fashion with side-by-side arranged intermolecular aromatic rings, which is entirely different from the RTP molecules reported to date. Theoretical calculations verify that the extraordinary intermolecular interaction between neighboring molecules plays an important role in RTP of TBBU crystals. More importantly, the polymer film doped with TBBU inherits its distinctive RTP property, which is highly sensitive to oxygen. The color of the doped film changes and its RTP lifetime drops abruptly through a dynamic collisional quenching mechanism with increasing oxygen fraction, enabling visual and quantitative detection of oxygen. Through analyzing the grayscale of the phosphorescence images, a facile method is developed for rapid, visual, and quantitative detection of oxygen in the air.
RESUMO
Nickel complexes bearing amine-imine ligands with various backbone substituents were synthesized and employed as ethylene polymerization catalysts on activation with Et2 AlCl. The substituent on the backbone carbon atom of the amine moiety is decisive for the living nature of ethylene polymerization. A bulky amine-imine nickel precursor with a tert-butyl group on the carbon atom of the amine group can polymerize ethylene in a living fashion at an elevated temperature of 65 °C, which is the highest temperature of living polymerization of ethylene with late transition-metal catalysts. The wide applicable temperature range for living polymerization and sensitivity of the branch structure of the polyethylene to temperature enable precise synthesis of di- and triblock polyethylenes featuring different branched segments by sequential tuning of the polymerization temperature.
RESUMO
A class of new amphiphilic nanocapsules entangled with organometallic coordination polymers has been developed for the first time. Poly(2-(N,N-dimethyl amino)ethyl methacrylate)-b-polystyrene capped with ß-cyclodextrin (ß-CD) (CD-PDMAEMA-b-PS) is first synthesized using sequent RAFT polymerization of styrene and 2-(N,N-dimethyl amino)ethyl methacrylate with xanthate modified ß-CD as chain transfer agent. The end group of ß-CD is allowed to include 4,4'-bipyridine through host-guest inclusion to yield PDMAEMA-b-PS terminated with an inclusion complex of ß-CD and bipyridine (bpy-PDMAEMA-b-PS), which is then used as surfactant to prepare emulsion droplets in toluene/water mixture. Upon addition of Ni(II), bipyridine coordinates with Ni(II) to form coordination polymers in the periphery of emulsion droplets, affording amphiphilic capsules entangled with organometallic coordination polymers, as confirmed by GPC, (1)H NMR, SEM, TEM, DLS, and so on. The organometallic coordination polymer capsules are capable of encapsulating organic cargoes. Interestingly, encapsulated cargoes can be extracted from the capsules without damaging the capsules. Such capsules are potential candidates for encapsulating and controlled release of organic cargoes.
Assuntos
Sistemas de Liberação de Medicamentos , Metacrilatos/química , Nanocápsulas/química , Nanotecnologia/métodos , Nylons/química , Polímeros/química , Espectroscopia de Ressonância Magnética , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Peso Molecular , Níquel/química , Compostos Orgânicos/química , Oxazinas/química , Poliestirenos/química , Piridinas/química , Tensoativos , beta-Ciclodextrinas/químicaRESUMO
Surfactant-free nanospheres and latex nanospheres of poly(methyl methacrylate) (PMMA) with diameter ranging from 20 to 220 nm are prepared by atom transfer radical polymerization (ATRP) in microemulsions and subsequent dialysis against deionized water. The glass transitions of these PMMA nanospheres are characterized using nano differential scanning calorimetry (nano-DSC) in aqueous dispersions. The glass transition temperature (Tg) of the surfactant-free PMMA nanospheres and nonionic PMMA latex nanospheres with diameters below 150 nm is less than that of the PMMA bulk, and Tg decreases with the decrease of the diameter. In contrast, Tg of the anionic PMMA latex nanospheres is size-independent and is near to that of the PMMA bulk. The influence of the environment surrounding the PMMA nanospheres on glass transitions as well as comparisons to our prior studies with polystyrene (PS) nanospheres in aqueous dispersions are discussed.
RESUMO
We present a numerical investigation of terahertz channel plasmon polaritons (CPPs) propagating in a semiconductor InSb. It is shown that these CPPs can simultaneously exhibit subwavelength field confinement and relatively long propagation length. Moreover, single-mode propagation is available for terahertz CPPs in a certain frequency range.
RESUMO
MXenes as an emerging class of 2D materials have great potential in fabricating functional polymer nanocomposites. In this study, Ti3C2T x MXene as a representative MXene filler was employed to prepare sPS nanocomposites. The abundant surface groups (mainly -OH) on MXene allowed facile modification, and thus MXene nanosheets bearing -C12H25 groups were prepared using dodecyl triethoxysiloxane (DCTES) as a modifier. Grafting -C12H25 long alkyl chains onto the surface of MXene strongly affected its affinity towards hydrophobic solvent and the sPS matrix. The rheological threshold concentration (Ï c,G' = 0.033 vol%) and exponent (ß G' = 1.51) and the conductivity threshold concentration (Ï c,σ = 0.259 vol%) and exponent (ß σ = 2.92) were determined by applying percolation scaling laws. The influences of DCTES-modified MXene on the polymorphism, mechanical, thermal and flammability properties of nanocomposites were studied. The obtained nanocomposites displayed not only enhanced mechanical properties, but also improved thermal stability and flame retardancy to some extent. Moreover, the higher the loading level of DCTES-modified MXene, the better was the improved effect.
RESUMO
Herein, we develop a new intelligent moisture-sensitive hybrid aerogel by evenly embedding a proton-conductive covalent organic framework (COF-2SO3H) into a carboxylated cellulose nanofiber network (CNF-C) for water harvesting and spontaneous sustained electricity production from ambient humidity and human respiration. Our strategy first exploits the "suspending agent" role of CNF-C to stably disperse COF materials in water for forming uniform hierarchical hybrid structures. By utilizing the synergy of COF-2SO3H and CNF-C together with their inherent structure merits and surface group effects, the hybrid aerogel displays increased water uptake and ion conductivity. Upon asymmetric moisturization, it can create a self-maintained moisture gradient to engender a concentration difference for mobile Na+ and H+, resulting in efficient charge separation and diffusion. Thus, the hybrid aerogel-based coin-type generator achieves a continuous output voltage of â¼0.55 V for at least 5 h in ambient environments in contrast to that using pure CNF-C and carbon-based generators with transient voltage response. Intriguingly, the wearable generator with an aerogel in a mask is more sensitive to human respiration and achieves repeatable and reliable self-charge for persistent electricity along with an increased output voltage of up to 1.0 V and much faster self-charge (only 3 min), both of which surpass most reported moisture-enabled generators.
Assuntos
Eletricidade , Prótons , Humanos , Condutividade Elétrica , Celulose , RespiraçãoRESUMO
Aryl hydrocarbon receptor (AhR) is a key transcription factor that modulates the differentiation of T helper 17 (Th17) cells. How AhR is regulated at the post-translational level in Th17 cells remains largely unclear. Here we identify USP21 as a newly defined deubiquitinase of AhR. We demonstrate that USP21 interacts with and stabilizes AhR by removing the K48-linked polyubiquitin chains from AhR. Interestingly, USP21 inhibits the transcriptional activity of AhR in a deubiquitinating-dependent manner. USP21 deubiquitinates AhR at the K432 residue, and the maintenance of ubiquitination on this site is required for the intact transcriptional activity of AhR. Moreover, the deficiency of USP21 promotes the differentiation of Th17 cells both in vitro and in vivo. Consistently, adoptive transfer of USP21 deficient naïve CD4+ T cells elicits more severe colitis in Rag1-/- recipients. Therefore, our study reveals a novel mechanism in which USP21 deubiquitinates AhR and negatively regulates the differentiation of Th17 cells.
RESUMO
Targeting tumor-infiltrating regulatory T cells (Tregs) is an efficient way to evoke an anti-tumor immune response. However, how Tregs maintain their fragility and stability remains largely unknown. IFITM3 and STAT1 are interferon-induced genes that play a positive role in the progression of tumors. Here, we showed that IFITM3-deficient Tregs blunted tumor growth by strengthening the tumor-killing response and displayed the Th1-like Treg phenotype with higher secretion of IFNγ. Mechanistically, depletion of IFITM3 enhances the translation and phosphorylation of STAT1. On the contrary, the decreased IFITM3 expression in STAT1-deficient Tregs indicates that STAT1 conversely regulates the expression of IFITM3 to form a feedback loop. Blocking the inflammatory cytokine IFNγ or directly depleting STAT1-IFITM3 axis phenocopies the restored suppressive function of tumor-infiltrating Tregs in the tumor model. Overall, our study demonstrates that the perturbation of tumor-infiltrating Tregs through the IFNγ-IFITM3-STAT1 feedback loop is essential for anti-tumor immunity and constitutes a targetable vulnerability of cancer immunotherapy.
Assuntos
Neoplasias , Linfócitos T Reguladores , Humanos , Retroalimentação , Neoplasias/genética , Neoplasias/terapia , Citocinas/metabolismo , Fatores de Transcrição Forkhead/metabolismo , Proteínas de Membrana/metabolismo , Proteínas de Ligação a RNA/metabolismo , Fator de Transcrição STAT1/genética , Fator de Transcrição STAT1/metabolismoRESUMO
Follicular helper T (Tfh) cells are essential for germinal center (GC) B cell responses. However, it is not clear which PD-1+CXCR5+Bcl6+CD4+ T cells will differentiate into PD-1hiCXCR5hiBcl6hi GC-Tfh cells and how GC-Tfh cell differentiation is regulated. Here, we report that the sustained Tigit expression in PD-1+CXCR5+CD4+ T cells marks the precursor Tfh (pre-Tfh) to GC-Tfh transition, whereas Tigit-PD-1+CXCR5+CD4+ T cells upregulate IL-7Rα to become CXCR5+CD4+ T memory cells with or without CCR7. We demonstrate that pre-Tfh cells undergo substantial further differentiation at the transcriptome and chromatin accessibility levels to become GC-Tfh cells. The transcription factor c-Maf appears critical in governing the pre-Tfh to GC-Tfh transition, and we identify Plekho1 as a stage-specific downstream factor regulating the GC-Tfh competitive fitness. In summary, our work identifies an important marker and regulatory mechanism of PD-1+CXCR5+CD4+ T cells during their developmental choice between memory T cell fate and GC-Tfh cell differentiation.
Assuntos
Células T Auxiliares Foliculares , Linfócitos T Auxiliares-Indutores , Linfócitos T Auxiliares-Indutores/metabolismo , Células T Auxiliares Foliculares/metabolismo , Receptor de Morte Celular Programada 1/genética , Receptor de Morte Celular Programada 1/metabolismo , Centro Germinativo , Diferenciação Celular , Receptores CXCR5/genética , Receptores CXCR5/metabolismoRESUMO
A novel polymerization methodology for efficient synthesis of hyperbranched polyethylene amphiphiles by chain walking polymerization (CWP) followed by RAFT polymerization has been developed. Hyperbranched polyethylene with hydroxyl ends (HBPE-OHs) is first synthesized via chain walking copolymerization of ethylene with 2-hydroxyethyl acrylate with Pd-α-diimine catalyst. The hydroxyl groups of hyperbranched polyethylene are then converted into thiocarbonyl thio moieties by an esterification reaction with trithiocarbonate 3-benzylsulfanylthiocarbonyl sulfanylpropionic acid (BSPA). The hyperbranched polyethylene with thiocarbonyl thio moiety ends (HBPE-BSPAs) is used as a macro-RAFT agent for the synthesis of hyperbranched polyethylene amphiphiles, HBPE-PDMAEMAs, by RAFT polymerization of N,N-dimethylaminoethyl methacrylate (DMAEMA). The resultant HBPE-PDMAEMAs can self-assemble to form supramolecular polymer vesicles in aqueous solution. A preliminary investigation on thermo- and pH-responsive behaviors of the polymer is also reported.
Assuntos
Técnicas de Química Sintética/métodos , Polietileno/química , Polímeros/síntese química , Técnicas de Química Sintética/instrumentação , Estrutura Molecular , Polimerização , Polímeros/químicaRESUMO
Trehalose, one of the most chemically stable sugars, can effectively improve the tolerance of various plants against abiotic stress by protecting and stabilizing protein and cell membranes. However, the signaling pathway in trehalose biosynthesis triggered by abiotic stresses is still unclear. In the study, it can be shown that exogenous trehalose can alleviate the inhibitory effect of osmotic stress on cell growth, suppress extracellular alkalization, ROS burst, and maintain the integrity of the microtubular cytoskeleton. Trehalose-6-phosphate synthase (TPS) is the key limiting enzyme for trehalose synthesis and is encoded by 7 ClTPS genes, located in 7 different chromosomes of the watermelon genome. Expression analysis by qRT-PCR indicated that osmotic stress could upregulate the expression of all the family members of ClTPS and promote the accumulation of trehalose in watermelon cells accordingly. Exogenous methyl jasmonate (MeJA), ethephon (ETH), abscisic acid (ABA), or salicylic acid (SA) induced trehalose accumulation, with MeJA being the most effective treatment. When fluridone (FL), an ABA biosynthesis inhibitor, was pre-perfused into the cells before osmotic stress, trehalose accumulation and packed cell volume were suppressed significantly, whereas inhibition of ethylene biosynthesis could even restore cell growth. Moreover, inhibition of trehalose hydrolysis could also increase the tolerance against osmotic stress. This study shows that trehalose biosynthesis is phytohormone-dependent and the hydrolysis of trehalose is involved in osmotic tolerance regulation.
Assuntos
Citrullus , Reguladores de Crescimento de Plantas , Ácido Abscísico/metabolismo , Citrullus/genética , Citrullus/metabolismo , Regulação da Expressão Gênica de Plantas , Pressão Osmótica , Reguladores de Crescimento de Plantas/metabolismo , Proteínas de Plantas/metabolismo , Estresse Fisiológico/genética , Trealose/metabolismoRESUMO
Two salalen titanium(iv) complexes ((H-salalen)TiCl2 and (F-salalen)TiCl2) containing hydrogen and fluorine respectively on the phenolate ring close to the imine were synthesized for the copolymerization of ethylene with 1-octene to prepare poly(ethylene-co-1-octene) in the presence of methylaluminoxane (MAO). The (F-salalen)TiCl2/MAO showed higher catalytic activity and better copolymer characteristics such as a higher molecular weight, narrower molecular weight distribution, and higher 1-octene incorporation than (H-salalen)TiCl2/MAO, which revealed that the electron-withdrawing conjugated effect introduced by fluorine substituents led to improvements on catalytic performance and thermal stability. The influences of copolymerization conditions including temperature, Al/Ti molar ratios and comonomer feed ratios on the copolymerization behavior of (F-salalen)TiCl2/MAO and the copolymer microstructure were investigated in detail. Under the activation of MAO, the (F-salalen)TiCl2 could produce ultrahigh molecular weight poly(ethylene-co-1-octene) with 1-octene incorporation ratios in the range of 0.9-3.1 mol% and exhibit relatively high activity. It could be inferred that long ethylene sequences in the copolymer were segregated by the isolated 1-octene units based on the 13C NMR characterization of the copolymer. Moreover, the thermal properties and crystallization of copolymers were determined by DSC and XRD and correlated to the ethylene sequence length distribution. The reactivity ratios calculated by the triad distribution in 13C NMR revealed the random comonomer distribution in the copolymer chain.
RESUMO
Regulatory T (Treg) cells are critical for maintaining immune homeostasis and preventing autoimmunity. Here, we show that the non-oxidative pentose phosphate pathway (PPP) regulates Treg function to prevent autoimmunity. Deletion of transketolase (TKT), an indispensable enzyme of non-oxidative PPP, in Treg cells causes a fatal autoimmune disease in mice, with impaired Treg suppressive capability despite regular Treg numbers and normal Foxp3 expression levels. Mechanistically, reduced glycolysis and enhanced oxidative stress induced by TKT deficiency triggers excessive fatty acid and amino acid catabolism, resulting in uncontrolled oxidative phosphorylation and impaired mitochondrial fitness. Reduced α-KG levels as a result of reductive TCA cycle activity leads to DNA hypermethylation, thereby limiting functional gene expression and suppressive activity of TKT-deficient Treg cells. We also find that TKT levels are frequently downregulated in Treg cells of people with autoimmune disorders. Our study identifies the non-oxidative PPP as an integrator of metabolic and epigenetic processes that control Treg function.
Assuntos
Autoimunidade , Via de Pentose Fosfato , Linfócitos T Reguladores , Transcetolase , Animais , Autoimunidade/genética , Autoimunidade/imunologia , Epigênese Genética/genética , Epigênese Genética/imunologia , Glicólise , Humanos , Camundongos , Via de Pentose Fosfato/genética , Via de Pentose Fosfato/imunologia , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismo , Transcetolase/genética , Transcetolase/imunologiaRESUMO
T follicular helper (Tfh) cells play an essential role in germinal center formation and the generation of high-affinity antibodies. Studies have proposed that Tfh cell differentiation is a multi-step process. However, it is still not fully understood how a subset of activated CD4+ T cells begin to express CXCR5 during the early stage of the response and, shortly after, how some CXCR5+ precursor Tfh (pre-Tfh) cells enter B cell follicles and differentiate further into germinal center Tfh (GC-Tfh) cells while others have a different fate. In this mini-review, we summarize the recent advances surrounding these two aspects of Tfh cell differentiation and discuss related long-standing questions, including Tfh memory.