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1.
Clin Exp Immunol ; 215(2): 137-147, 2024 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-37708215

RESUMO

Primary biliary cholangitis (PBC) is a chronic autoimmune liver disease caused by intrahepatic bile duct injuries, resulting in fibrosis, cirrhosis, and eventually liver failure. T helper (Th) 17 cells are proposed to involve in the pathogenesis of PBC. However, how and which Th17 cell-derived cytokines affect PBC remains unclear. In this study, we investigated the effects of Th17 effector cytokines, including interleukin (IL)-17A, IL-17F, and IL-21 in PBC using a xenobiotic-induced mouse model of autoimmune cholangitis (inducible chemical xenobiotic models of PBC) treated with cytokine-expressing adeno-associated virus. Our results showed that administration of IL-17A, the well-known main cytokine produced by Th17 cells, did not augment liver inflammation or fibrosis. In contrast, we noted IL-17A-treated mice had lower hepatic Th1 cell numbers and higher hepatic CD11b+Ly6G+ polymorphonuclear myeloid-derived suppressor cell numbers. IL-17F did not alter liver inflammation or fibrosis. However, the administration of IL-21 exacerbated liver inflammatory responses and portal cell infiltration. IL-21 markedly increased the numbers of activated CD8+ T cells and liver tissue-resident memory CD8+ T cells. Moreover, IL-21 aggravates liver fibrosis in mice with autoimmune cholangitis. These results emphasized that not IL-17A but IL-21 in Th17 cell-derived cytokines affected the pathogenesis of PBC. IL-21 enhanced liver inflammation and progression to fibrosis by enhancing the numbers and effector activities of CD8+ T cells. Delineation of the effects of different Th17 effector cytokines in PBC offers clues for developing new therapeutic approaches.


Assuntos
Doenças Autoimunes , Colangite , Cirrose Hepática Biliar , Animais , Camundongos , Interleucina-17 , Xenobióticos , Interleucinas , Citocinas , Colangite/patologia , Fibrose , Cirrose Hepática , Doenças Autoimunes/patologia , Inflamação
2.
Clin Exp Immunol ; 215(3): 225-239, 2024 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-37916967

RESUMO

Primary biliary cholangitis (PBC) is a chronic autoimmune disease characterized by immune-mediated destruction of intrahepatic small bile ducts. CD8 T cells play a critical role in biliary destruction. However, regulatory T cells (Tregs) have also been identified in the portal tracts of PBC patients. This study tested the hypothesis that hepatic Tregs in PBC were dysfunctional in suppressing immune responses in disease by using our human PBC-like autoimmune cholangitis (AIC) mouse model induced by 2-octynoic acid-conjugated ovalbumin (2-OA-OVA). Our results showed that female and male mice immunized with 2-OA-OVA developed AIC; however, female AIC mice had more severe liver inflammation and fibrosis than male AIC mice. Levels of functional effector CD8 T cells and their chemoattractants, CXCL9 and CXCL10, in the liver were markedly elevated in female AIC mice than in male AIC mice. These results reinforce that CD8 T cells are the primary effector cells in PBC. The number of hepatic Tregs in AIC mice was also higher than in saline-treated mice, but there was no difference between male and female AIC mice. The suppressive function of AIC Tregs was evident despite a discrepancy in the changes in their co-inhibitory receptors and inhibitory cytokines. However, the expansion of hepatic Tregs by low-dose IL-2 treatment did not reduce immune responses to AIC, which may be due to the dysfunction of Tregs in inhibiting T cells. In conclusion, the function of Tregs in the inflamed liver of PBC was insufficient, and low-dose IL-2 treatment could not restore their function to suppress pathological immune responses. Transferring normal Tregs or directly targeting effector CD8 T cells may be beneficial for treating PBC.


Assuntos
Doenças Autoimunes , Colangite , Cirrose Hepática Biliar , Humanos , Masculino , Feminino , Camundongos , Animais , Linfócitos T Reguladores , Interleucina-2 , Fígado , Colangite/patologia
3.
World J Urol ; 42(1): 128, 2024 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-38460023

RESUMO

PURPOSES: Our aim is to build and evaluate models to screen for clinically significant nephrolithiasis in overweight and obesity populations using machine learning (ML) methodologies and simple health checkup clinical and urine parameters easily obtained in clinics. METHODS: We developed ML models to screen for clinically significant nephrolithiasis (kidney stone > 2 mm) in overweight and obese populations (body mass index, BMI ≥ 25 kg/m2) using gender, age, BMI, gout, diabetes mellitus, estimated glomerular filtration rate, bacteriuria, urine pH, urine red blood cell counts, and urine specific gravity. The data were collected from hospitals in Kaohsiung, Taiwan between 2012 and 2021. RESULTS: Of the 2928 subjects we enrolled, 1148 (39.21%) had clinically significant nephrolithiasis and 1780 (60.79%) did not. The testing dataset consisted of data collected from 574 subjects, 235 (40.94%) with clinically significant nephrolithiasis and 339 (59.06%) without. One model had a testing area under curve of 0.965 (95% CI, 0.9506-0.9794), a sensitivity of 0.860 (95% CI, 0.8152-0.9040), a specificity of 0.947 (95% CI, 0.9230-0.9708), a positive predictive value of 0.918 (95% CI, 0.8820-0.9544), and negative predictive value of 0.907 (95% CI, 0.8756-0.9371). CONCLUSION: This ML-based model was found able to effectively distinguish the overweight and obese subjects with clinically significant nephrolithiasis from those without. We believe that such a model can serve as an easily accessible and reliable screening tool for nephrolithiasis in overweight and obesity populations and make possible early intervention such as lifestyle modifications and medication for prevention stone complications.


Assuntos
Diabetes Mellitus , Cálculos Renais , Nefrolitíase , Humanos , Sobrepeso/complicações , Sobrepeso/epidemiologia , Nefrolitíase/diagnóstico , Nefrolitíase/epidemiologia , Nefrolitíase/etiologia , Obesidade/complicações , Obesidade/epidemiologia , Cálculos Renais/complicações , Índice de Massa Corporal
4.
Angew Chem Int Ed Engl ; 63(1): e202315844, 2024 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-37963815

RESUMO

Valanimycin is an azoxy-containing natural product isolated from the fermentation broth of Streptomyces viridifaciens MG456-hF10. While the biosynthesis of valanimycin has been partially characterized, how the azoxy group is constructed remains obscure. Herein, the membrane protein VlmO and the putative hydrazine synthetase ForJ from the formycin biosynthetic pathway are demonstrated to catalyze N-N bond formation converting O-(l-seryl)-isobutyl hydroxylamine into N-(isobutylamino)-l-serine. Subsequent installation of the azoxy group is shown to be catalyzed by the non-heme diiron enzyme VlmB in a reaction in which the N-N single bond in the VlmO/ForJ product is oxidized by four electrons to yield the azoxy group. The catalytic cycle of VlmB appears to begin with a resting µ-oxo diferric complex in VlmB, as supported by Mössbauer spectroscopy. This study also identifies N-(isobutylamino)-d-serine as an alternative substrate for VlmB leading to two azoxy regioisomers. The reactions catalyzed by the kinase VlmJ and the lyase VlmK during the final steps of valanimycin biosynthesis are established as well. The biosynthesis of valanimycin was thus fully reconstituted in vitro using the enzymes VlmO/ForJ, VlmB, VlmJ and VlmK. Importantly, the VlmB-catalyzed reaction represents the first example of enzyme-catalyzed azoxy formation and is expected to proceed by an atypical mechanism.


Assuntos
Compostos Azo , Compostos Azo/química
5.
Nutr Metab Cardiovasc Dis ; 33(12): 2479-2487, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37788955

RESUMO

BACKGROUND AND AIMS: It is currently unclear whether the nonalcoholic fatty liver disease (NAFLD) fibrosis score, when compared to major anthropometric indices, is useful in estimating the risk of atherosclerotic cardiovascular disease (ASCVD). METHODS AND RESULTS: This study included 3886 adults undergoing a health checkup. An elevated risk of ASCVD was determined as a 10-year ASCVD risk ≥7.5% using Pooled Cohort Equations. NAFLD was diagnosed with abdominal ultrasonography. Receiver operating characteristic curves were used to evaluate the performance of estimating an elevated ASCVD risk. Among study participants, 521 (13.4%) had an elevated ASCVD risk and 1473 (37.9%) had NAFLD. Subjects with NAFLD had a significantly higher rate of ASCVD risk ≥7.5% (p < 0.001) compared to those without NAFLD. After adjusting for cardiometabolic risk factors, NAFLD (OR = 1.49, 95% CI: 1.10-2.00, p = 0.009) in all participants and NAFLD fibrosis score >0.676 (OR = 1.95, 95% CI: 1.30-2.92, p = 0.001) in individuals with NAFLD were significantly associated with an elevated risk of ASCVD. When compared to different anthropometric indices, NAFLD fibrosis score exhibited the largest area under the curve (AUC) in individuals with NAFLD (AUC = 0.750) in estimating an elevated ASCVD risk. Furthermore, NAFLD fibrosis score displayed the best predictive performance for identifying an elevated ASCVD risk in male participants with NAFLD (AUC = 0.737). CONCLUSION: NAFLD was a significant risk factor for elevated ASCVD risk. NAFLD fibrosis score >0.676 was associated with increased ASCVD risk in individuals with NAFLD. Compared with anthropometric indices, NAFLD fibrosis score demonstrated the best performance in estimating elevated ASCVD risk among those with NAFLD.


Assuntos
Aterosclerose , Doenças Cardiovasculares , Hepatopatia Gordurosa não Alcoólica , Adulto , Humanos , Masculino , Hepatopatia Gordurosa não Alcoólica/diagnóstico por imagem , Hepatopatia Gordurosa não Alcoólica/epidemiologia , Doenças Cardiovasculares/etiologia , Fatores de Risco , Aterosclerose/diagnóstico por imagem , Aterosclerose/epidemiologia , Fibrose
6.
Proc Natl Acad Sci U S A ; 117(40): 24794-24801, 2020 10 06.
Artigo em Inglês | MEDLINE | ID: mdl-32958639

RESUMO

The structure of lincomycin A consists of the unusual eight-carbon thiosugar core methyllincosamide (MTL) decorated with a pendent N-methylprolinyl moiety. Previous studies on MTL biosynthesis have suggested GDP-ᴅ-erythro-α-ᴅ-gluco-octose and GDP-ᴅ-α-ᴅ-lincosamide as key intermediates in the pathway. However, the enzyme-catalyzed reactions resulting in the conversion of GDP-ᴅ-erythro-α-ᴅ-gluco-octose to GDP-ᴅ-α-ᴅ-lincosamide have not yet been elucidated. Herein, a biosynthetic subpathway involving the activities of four enzymes-LmbM, LmbL, CcbZ, and CcbS (the LmbZ and LmbS equivalents in the closely related celesticetin pathway)-is reported. These enzymes catalyze the previously unknown biosynthetic steps including 6-epimerization, 6,8-dehydration, 4-epimerization, and 6-transamination that convert GDP-ᴅ-erythro-α-ᴅ-gluco-octose to GDP-ᴅ-α-ᴅ-lincosamide. Identification of these reactions completes the description of the entire lincomycin biosynthetic pathway. This work is significant since it not only resolves the missing link in octose core assembly of a thiosugar-containing natural product but also showcases the sophistication in catalytic logic of enzymes involved in carbohydrate transformations.


Assuntos
Lincomicina/biossíntese , Streptomyces/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Vias Biossintéticas , Lincomicina/química , Lincosamidas/química , Lincosamidas/metabolismo , Streptomyces/química , Streptomyces/enzimologia , Streptomyces/genética
7.
Environ Health ; 21(1): 58, 2022 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-35710478

RESUMO

BACKGROUND: Association between smoking and sleep apnea is well-known from previous studies. However, the influence of secondhand smoke (SHS), which is a potential risk factor of obstructive sleep apnea (OSA), remains unclear. Our aim was to investigate the relationship between SHS and OSA using a meta-analysis. MATERIALS AND METHODS: For the meta-analysis, searches were performed in MEDLINE, EMBASE, and Web of Science databases on January 10, 2022, by combining various keywords including "SHS exposure" and "OSA". Data were extracted using defined inclusion and exclusion criteria. Fixed-effects model meta-analyses were used to pool risk ratio (RR) estimates with their 95% confidence intervals (CI). I2 was used to assess heterogeneity. Moreover, we performed subgroup meta-analyses of children-adults, and smoker fathers and mothers. RESULTS: In total, 267 articles were obtained through an electronic search. Twenty-six articles were included in our analysis according to the inclusion and exclusion criteria. We found evidence of an association between SHS exposure and possible OSA (RR 1.64, 95% CI 1.44-1.88). The results of the subgroup analyses showed that children passive smokers (RR 1.84, 95% CI 1.60-2.13) were at greater risks of possible OSA than adult passive smokers (RR 1.35, 95% CI 1.21-1.50). Also, significant differences were observed in mothers with smoking exposure (RR 2.61, 95% CI 1.62-4.21, p < 0.0001), as well as in fathers with smoking exposure (RR 2.15, 95% CI 0.98-4.72, p = 0.06). SHORT CONCLUSION: Our meta-analysis confirmed that SHS exposure is significantly associated with OSA. In the subgroup analyses, the association of SHS and possible OSA was significant in both children and adults, as well as in smoker mothers and fathers.


Assuntos
Apneia Obstrutiva do Sono , Poluição por Fumaça de Tabaco , Adulto , Criança , Feminino , Humanos , Mães , Fatores de Risco , Apneia Obstrutiva do Sono/epidemiologia , Poluição por Fumaça de Tabaco/efeitos adversos
8.
Int J Mol Sci ; 23(15)2022 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-35955808

RESUMO

The Kaposi's sarcoma-associated herpesvirus (KSHV)-encoded ORF50 protein is a potent transcriptional activator essential for triggering KSHV lytic reactivation. Despite extensive studies, little is known about whether ORF50 possesses the ability to repress gene expression or has an antagonistic action to cellular transcription factors. Previously, we demonstrated that human oncoprotein MDM2 can promote the degradation of ORF50 protein. Herein, we show that abundant ORF50 expression in cells can conversely downregulate MDM2 expression via repressing both the upstream (P1) and internal (P2) promoters of the MDM2 gene. Deletion analysis of the MDM2 P1 promoter revealed that there were two ORF50-dependent negative response elements located from -102 to -63 and from -39 to +1, which contain Sp1-binding sites. For the MDM2 P2 promoter, the ORF50-dependent negative response element was identified in the region from -110 to -25, which is coincident with the location of two known p53-binding sites. Importantly, we further demonstrated that overexpression of Sp1 or p53 in cells indeed upregulated MDM2 expression; however, coexpression with ORF50 protein remarkably reduced the Sp1- or p53-mediated MDM2 upregulation. Collectively, our findings propose a reciprocal negative regulation between ORF50 and MDM2 and uncover that ORF50 decreases MDM2 expression through repressing Sp1- and p53-mediated transactivation.


Assuntos
Herpesvirus Humano 8 , Regulação Viral da Expressão Gênica , Herpesvirus Humano 8/genética , Humanos , Regiões Promotoras Genéticas , Proteínas Proto-Oncogênicas c-mdm2/genética , Proteínas Proto-Oncogênicas c-mdm2/metabolismo , Elementos de Resposta , Fator de Transcrição Sp1/genética , Fator de Transcrição Sp1/metabolismo , Fatores de Transcrição/metabolismo , Ativação Transcricional , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Proteínas Virais
9.
Int J Mol Sci ; 23(3)2022 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-35163779

RESUMO

We used gastric cancer cell line AGS and clinical samples to investigate the roles of mitochondrial DNA (mtDNA) alterations and mitochondrial respiratory dysfunction in gastric adenocarcinoma (GAC). A total of 131 clinical samples, including 17 normal gastric mucosa (N-GM) from overweight patients who had received sleeve gastrectomy and 57 paired non-cancerous gastric mucosae (NC-GM) and GAC from GAC patients who had undergone partial/subtotal/total gastrectomy, were recruited to examine the copy number and D310 sequences of mtDNA. The gastric cancer cell line AGS was used with knockdown (KD) mitochondrial transcription factor A (TFAM) to achieve mitochondrial dysfunction through a decrease of mtDNA copy number. Parental (PT), null-target (NT), and TFAM-KD-(A/B/C) represented the parental, control, and TFAM knocked-down AGS cells, respectively. These cells were used to compare the parameters reflecting mitochondrial biogenesis, glycolysis, and cell migration activity. The median mtDNA copy numbers of 17 N-GM, 57 NC-GM, and 57 GAC were 0.058, 0.055, and 0.045, respectively. The trend of decrease was significant (p = 0.030). In addition, GAC had a lower mean mtDNA copy number of 0.055 as compared with the paired NC-GM of 0.078 (p < 0.001). The mean mtDNA copy number ratio (mtDNA copy number of GAC/mtDNA copy number of paired NC-GM) was 0.891. A total of 35 (61.4%) GAC samples had an mtDNA copy number ratio ≤0.804 (p = 0.017) and 27 (47.4%) harbored a D310 mutation (p = 0.047), and these patients had shorter survival time and poorer prognosis. After effective knockdown of TFAM, TFAM-KD-B/C cells expressed higher levels of hexokinase II (HK-II) and v-akt murine thymoma viral oncogene homolog 1 gene (AKT)-encoded AKT, but lower levels of phosphorylated pyruvate dehydrogenase (p-PDH) than did the NT/PT AGS cells. Except for a higher level of p-PDH, the expression levels of these proteins remained unchanged in TFAM-KD-A, which had a mild knockdown of TFAM. Compared to those of NT, TFAM-KD-C had not only a lower mtDNA copy number (p = 0.050), but also lower oxygen consumption rates (OCR), including basal respiration (OCRBR), ATP-coupled respiration (OCRATP), reserve capacity (OCRRC), and proton leak (OCRPL)(all with p = 0.050). In contrast, TFAM-KD-C expressed a higher extracellular acidification rate (ECAR)/OCRBR ratio (p = 0.050) and a faster wound healing migration at 6, 12, and 18 h, respectively (all with p = 0.050). Beyond a threshold, the decrease in mtDNA copy number, the mtDNA D310 mutation, and mitochondrial dysfunction were involved in the carcinogenesis and progression of GACs. Activation of PDH might be considered as compensation for the mitochondrial dysfunction in response to glucose metabolic reprogramming or to adjust mitochondrial plasticity in GAC.


Assuntos
Adenocarcinoma/cirurgia , DNA Mitocondrial/genética , Proteínas de Ligação a DNA/genética , Mitocôndrias/metabolismo , Proteínas Mitocondriais/genética , Obesidade/cirurgia , Neoplasias Gástricas/cirurgia , Fatores de Transcrição/genética , Adenocarcinoma/genética , Adenocarcinoma/metabolismo , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Linhagem Celular Tumoral , Movimento Celular , Variações do Número de Cópias de DNA , Feminino , Gastrectomia , Regulação Neoplásica da Expressão Gênica , Técnicas de Silenciamento de Genes , Glicólise , Humanos , Masculino , Pessoa de Meia-Idade , Mitocôndrias/genética , Obesidade/genética , Obesidade/metabolismo , Biogênese de Organelas , Prognóstico , Neoplasias Gástricas/genética , Neoplasias Gástricas/metabolismo , Análise de Sobrevida
10.
J Autoimmun ; 95: 159-170, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30274824

RESUMO

The immunomodulatory effect of IL-10 as an immunosuppressive and anti-inflammatory cytokine is well known. Taking advantage of our established mouse model of autoimmune cholangitis using 2-octynoic acid conjugated ovalbumin (2-OA-OVA) induction, we compared liver pathology, immune cell populations and antimitochondrial antibodies between IL-10 knockout and wild type mice immunized with 2-OA-OVA. At 10 weeks post immunization, portal inflammation and fibrosis were more severe in 2-OA-OVA immunized IL-10 knockout mice than in wild type mice. This was accompanied by significant higher levels of collagen I and III expression, T, NK and NKT subsets in liver and IgG anti-mitochondrial autoantibodies (AMAs) compared to 2-OA-OVA immunized wild type mice, suggesting that endogenous IL-10 is necessary for the maintenance of immune tolerance in primary biliary cholangitis (PBC). Further, we investigated whether administration of exogenous IL-10 could prevent PBC by administration of IL-10 expressing recombinant adeno-associated virus (AAV-IL-10) either 3 days before or 3 weeks after the establishment of liver pathology. Interestingly, administration of AAV-IL-10 resulted in increased liver inflammation and fibrosis, accompanied by increases in IFN-γ in liver CD4+ T cell, granzyme B, FasL, and CD107a in liver CD8+ T and NKT cells, and granzyme B and FasL in liver NK cells of AAV-IL-10 administered mice compared with control mice. Furthermore, administration of AAV-IL-10 significantly increased levels of proinflammatory cytokines and chemokines (IFN-γ, TNF-α, CXCL9 and CXCL10) and collagen I and III production in naïve mice, together with increase in immune cell infiltration and collagen deposition in the liver, suggesting a role of IL-10 in fibrosis. In conclusion, our data demonstrate that endogenous IL-10 is critical in the maintenance of immune tolerance but exogenous administration of IL-10 exacerbates liver inflammation and fibrosis. Furthermore, the distinctive presence of inflammatory immune cell populations and collagen expression in AAV-IL-10 treated naïve mice cautions against the clinical use of exogenous IL-10 in patients with autoimmune cholangitis.


Assuntos
Autoanticorpos/sangue , Doenças Autoimunes/genética , Tolerância Imunológica , Interleucina-10/imunologia , Cirrose Hepática Biliar/imunologia , Animais , Doenças Autoimunes/sangue , Doenças Autoimunes/patologia , Quimiocina CXCL10/genética , Quimiocina CXCL10/imunologia , Colágeno Tipo I/genética , Colágeno Tipo I/imunologia , Colágeno Tipo III/genética , Colágeno Tipo III/imunologia , Dependovirus/genética , Dependovirus/imunologia , Modelos Animais de Doenças , Proteína Ligante Fas/genética , Proteína Ligante Fas/imunologia , Feminino , Regulação da Expressão Gênica , Vetores Genéticos/administração & dosagem , Vetores Genéticos/química , Vetores Genéticos/imunologia , Granzimas/genética , Granzimas/imunologia , Imunoglobulina G/sangue , Imunoglobulina M/sangue , Interferon gama/genética , Interferon gama/imunologia , Interleucina-10/administração & dosagem , Interleucina-10/deficiência , Interleucina-10/genética , Células Matadoras Naturais/imunologia , Células Matadoras Naturais/patologia , Fígado/imunologia , Fígado/patologia , Cirrose Hepática Biliar/sangue , Cirrose Hepática Biliar/genética , Cirrose Hepática Biliar/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Transdução de Sinais , Linfócitos T/imunologia , Linfócitos T/patologia , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/imunologia
11.
Angew Chem Int Ed Engl ; 56(13): 3446-3489, 2017 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-27505692

RESUMO

Chemical reactions that are named in honor of their true, or at least perceived, discoverers are known as "name reactions". This Review is a collection of biological representatives of named chemical reactions. Emphasis is placed on reaction types and catalytic mechanisms that showcase both the chemical diversity in natural product biosynthesis as well as the parallels with synthetic organic chemistry. An attempt has been made, whenever possible, to describe the enzymatic mechanisms of catalysis within the context of their synthetic counterparts and to discuss the mechanistic hypotheses for those reactions that are currently active areas of investigation. This Review has been categorized by reaction type, for example condensation, nucleophilic addition, reduction and oxidation, substitution, carboxylation, radical-mediated, and rearrangements, which are subdivided by name reactions.


Assuntos
Produtos Biológicos/química , Produtos Biológicos/metabolismo , Vias Biossintéticas , Animais , Bactérias/química , Bactérias/enzimologia , Bactérias/metabolismo , Biocatálise , Ciclização , Fungos/química , Fungos/enzimologia , Fungos/metabolismo , Humanos , Oxirredução , Plantas/química , Plantas/enzimologia , Plantas/metabolismo , Especificidade por Substrato
12.
Chembiochem ; 17(17): 1606-11, 2016 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-27431934

RESUMO

Lincosamides such as lincomycin A, celesticetin, and Bu-2545, constitute an important group of antibiotics. These natural products are characterized by a thiooctose linked to a l-proline residue, but they differ with regards to modifications of the thioacetal moiety, the pyrrolidine ring, and the octose core. Here we report that the pyridoxal 5'-phosphate-dependent enzyme CcbF (celesticetin biosynthetic pathway) is a decarboxylating deaminase that converts a cysteine S-conjugated intermediate into an aldehyde. In contrast, the homologous enzyme LmbF (lincomycin biosynthetic pathway) catalyzes C-S bond cleavage of the same intermediate to afford a thioglycoside. We show that Ccb4 and LmbG (downstream methyltransferases) convert the aldehyde and thiol intermediates into a variety of methylated lincosamide compounds including Bu-2545. The substrates used in these studies are the ß-anomers of the natural substrates. The findings not only provide insight into how the biosynthetic pathway of lincosamide antibiotics can bifurcate to generate different lincosamides, but also reveal the promiscuity of the enzymes involved.


Assuntos
Biocatálise , Cisteína/metabolismo , Lincosamidas/biossíntese , Metiltransferases/metabolismo , Vias Biossintéticas , Cisteína/química , Lincosamidas/química , Estrutura Molecular , Streptomyces/enzimologia
13.
J Am Chem Soc ; 136(3): 906-9, 2014 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-24380627

RESUMO

Lincomycin A is a clinically useful antibiotic isolated from Streptomyces lincolnensis. It contains an unusual methylmercapto-substituted octose, methylthiolincosamide (MTL). While it has been demonstrated that the C8 backbone of MTL moiety is derived from D-fructose 6-phosphate and D-ribose 5-phosphate via a transaldol reaction catalyzed by LmbR, the subsequent enzymatic transformations leading to the MTL moiety remain elusive. Here, we report the identification of GDP-D-erythro-α-D-gluco-octose (GDP-D-α-D-octose) as a key intermediate in the MTL biosynthetic pathway. Our data show that the octose 1,8-bisphosphate intermediate is first converted to octose 1-phosphate by a phosphatase, LmbK. The subsequent conversion of the octose 1-phosphate to GDP-D-α-D-octose is catalyzed by the octose 1-phosphate guanylyltransferase, LmbO. These results provide significant insight into the lincomycin biosynthetic pathway, because the activated octose likely serves as the acceptor for the installation of the C1 sulfur appendage of MTL.


Assuntos
Açúcares de Guanosina Difosfato/metabolismo , Lincomicina/biossíntese , Monossacarídeos/metabolismo , Nucleotidiltransferases/metabolismo , Monoéster Fosfórico Hidrolases/metabolismo , Streptomyces/enzimologia
14.
Chem Soc Rev ; 42(10): 4377-407, 2013 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-23348524

RESUMO

Carbohydrates serve many structural and functional roles in biology. While the majority of monosaccharides are characterized by the chemical composition (CH2O)n, modifications including deoxygenation, C-alkylation, amination, O- and N-methylation, which are characteristic of many sugar appendages of secondary metabolites, are not uncommon. Interestingly, some sugar molecules are formed via modifications including amine oxidation, sulfur incorporation, and "high-carbon" chain attachment. Most of these unusual sugars have been identified over the past several decades as components of microbially produced natural products, although a few high-carbon sugars are also found in the lipooligosaccharides of the outer cell walls of Gram-negative bacteria. Despite their broad distribution in nature, these sugars are considered "rare" due to their relative scarcity. The biosynthetic steps that underlie their formation continue to perplex researchers to this day and many questions regarding key transformations remain unanswered. This review will focus on our current understanding of the biosynthesis of unusual sugars bearing oxidized amine substituents, thio-functional groups, and high-carbon chains.


Assuntos
Carboidratos/biossíntese , Carbono/química , Nitrogênio/química , Enxofre/química , Aminas/química , Antibacterianos/biossíntese , Antibacterianos/química , Produtos Biológicos/química , Produtos Biológicos/metabolismo , Carboidratos/química
15.
J Transl Autoimmun ; 6: 100182, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36619656

RESUMO

Primary biliary cholangitis (PBC) is a female-predominant liver autoimmune disease characterized by the specific immune-mediated destruction of the intrahepatic small bile duct. Although apoptosis of biliary epithelial cells (BECs) and alterations in gut microbiota are observed in patients with PBC, it is still unclear whether these events happen in the early stage and cause the breakdown of tolerance in PBC. In this study, we examined the early events in the loss of tolerance in our well-defined 2-OA-OVA-induced murine autoimmune cholangitis (AIC) model. We report herein that apoptosis of BECs was notable in the early stage of murine AIC. An altered gut microbiota, in particular, an increased percentage of gram-positive Firmicutes in AIC mice was also observed. BECs in AIC mice expressed adhesion molecule ICAM-1, cytokines/chemokines TNF-α, CCL2, CXCL9, CXCL10, and toll-like receptor (TLR) 2. Moreover, BECs treated with TLR2 ligand had elevated apoptosis and CXCL10 production. These data collectively suggest a new mechanism of tolerance breakdown in AIC. Altered gut microbiota induces apoptosis of BECs through TLR2 signaling. BECs secrete chemokines to recruit CD8 T cells to damage BECs further.

16.
J Am Chem Soc ; 134(42): 17432-5, 2012 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-22989310

RESUMO

Lincomycin A is a potent antimicrobial agent noted for its unusual C1 methylmercapto-substituted 8-carbon sugar. Despite its long clinical history for the treatment of Gram-positive infections, the biosynthesis of the C(8)-sugar, methylthiolincosamide (MTL), is poorly understood. Here, we report our studies of the two initial enzymatic steps in the MTL biosynthetic pathway leading to the identification of D-erythro-D-gluco-octose 8-phosphate as a key intermediate. Our experiments demonstrate that this intermediate is formed via a transaldol reaction catalyzed by LmbR using D-fructose 6-phosphate or D-sedoheptulose 7-phosphate as the C(3) donor and D-ribose 5-phosphate as the C(5) acceptor. Subsequent 1,2-isomerization catalyzed by LmbN converts the resulting 2-keto C(8)-sugar (octulose 8-phosphate) to octose 8-phosphate. These results provide, for the first time, in vitro evidence for the biosynthetic origin of the C(8) backbone of MTL.


Assuntos
Aldose-Cetose Isomerases/metabolismo , Carbono-Carbono Liases/metabolismo , Lincomicina/biossíntese , Fosfatos Açúcares/metabolismo , Aldose-Cetose Isomerases/química , Biocatálise , Carbono-Carbono Liases/química , Lincomicina/química , Estrutura Molecular , Fosfatos Açúcares/química
17.
J Biomed Biotechnol ; 2012: 521267, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22969273

RESUMO

Digitizing medical information is an emerging trend that employs information and communication technology (ICT) to manage health records, diagnostic reports, and other medical data more effectively, in order to improve the overall quality of medical services. However, medical information is highly confidential and involves private information, even legitimate access to data raises privacy concerns. Medical records provide health information on an as-needed basis for diagnosis and treatment, and the information is also important for medical research and other health management applications. Traditional privacy risk management systems have focused on reducing reidentification risk, and they do not consider information loss. In addition, such systems cannot identify and isolate data that carries high risk of privacy violations. This paper proposes the Hiatus Tailor (HT) system, which ensures low re-identification risk for medical records, while providing more authenticated information to database users and identifying high-risk data in the database for better system management. The experimental results demonstrate that the HT system achieves much lower information loss than traditional risk management methods, with the same risk of re-identification.


Assuntos
Segurança Computacional , Confidencialidade , Bases de Dados Factuais , Registros Eletrônicos de Saúde , Armazenamento e Recuperação da Informação/métodos , Interface Usuário-Computador , Taiwan
18.
Biomedicines ; 9(8)2021 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-34440235

RESUMO

Primary biliary cholangitis (PBC) is a chronic liver autoimmune disease with augmented T helper (Th) 1 and corresponding cytokine IFN-γ immune responses. Using 2-octynoic acid (2-OA) coupled to OVA (2-OA-OVA)-induced mouse models of autoimmune cholangitis (inducible chemical xenobiotic models of PBC), our previous study demonstrated that overexpression of IFN-γ in the model mice enhanced liver inflammation upon disease initiation, but subsequently led to the suppression of chronic inflammation with an increase in interleukin-30 (IL-30) levels. In this study, we investigated whether IL-30 had an immunosuppressive function and whether it could be part of an immune therapeutic regimen for PBC, by treating model mice with murine IL-30-expressing recombinant adeno-associated virus (AAV-mIL-30). We first defined the effects of AAV-mIL-30 in vivo by administering it to a well-known concanavalin A (ConA)-induced hepatitis model of mice and found that AAV-mIL-30 reduced the numbers of activated CD25+CD4+ T cells and the levels of serum IFN-γ and IL-12. In autoimmune cholangitis, decreased numbers of activated CD4+ T cells and Foxp3+ regulatory T cells were noted in the mice treated with AAV-mIL-30 at 3 weeks after the 2-OA-OVA immunization. Treatment with IL-30 did not change the features of autoimmune cholangitis including autoantibodies, cell infiltration, and collagen deposition in the liver at 11 weeks of examination. However, increased levels of cytokines and chemokines were observed. These results suggest that IL-30 suppresses not only CD4+ T cells but also regulatory T cells. Additionally, the administration of IL-30 did not suppress liver inflammation in the murine model of PBC.

19.
Am J Surg Pathol ; 45(11): 1476-1486, 2021 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-33927156

RESUMO

Pulmonary lymphoepithelioma-like carcinoma (LELC) is a distinct type of Epstein-Barr virus (EBV)-associated non-small cell carcinoma characterized by a syncytial growth pattern with heavy lymphocytic infiltration. We recently identified a group of non-small cell carcinomas, which are also associated with EBV but lack significant lymphocytic infiltration. These EBV-associated pulmonary carcinomas with low lymphocytic infiltration morphologically resemble nonkeratinizing squamous cell carcinoma, but their patient characteristics are more similar to those of LELC, including female sex and nonsmoking status. To clarify the relationships between these disease entities, in this study, we explored the molecular characteristics of the EBV-associated carcinomas with low lymphocytic infiltration using whole-exome sequencing and compared their molecular profiles with those of classic LELC and pulmonary squamous cell carcinoma. We demonstrate that the molecular characteristics of EBV-associated carcinomas with low lymphocytic infiltration are highly similar to those of classic LELC. Both show low tumor mutational burden, lack of commonly mutated driver genes in other types of non-small cell lung cancer, similar mutational signature involving APOBEC-related mutations, and enrichment of CD274 (programmed death-ligand 1) amplification. These molecular characteristics are very different from those of pulmonary squamous cell carcinoma. The unique patient demographics and molecular characteristics shared by EBV-associated carcinomas with low lymphocytic infiltration and classic LELC suggest that these tumors represent one single disease entity defined by EBV association. This study supports the proposal for the usage of the term "EBV-associated pulmonary carcinoma" to encompass the entire morphologic spectrum of this distinct EBV-associated disease entity.


Assuntos
Biomarcadores Tumorais/genética , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma de Células Escamosas/genética , Infecções por Vírus Epstein-Barr/virologia , Sequenciamento do Exoma , Herpesvirus Humano 4/patogenicidade , Neoplasias Pulmonares/genética , Linfócitos do Interstício Tumoral/imunologia , Idoso , Carcinoma Pulmonar de Células não Pequenas/imunologia , Carcinoma Pulmonar de Células não Pequenas/patologia , Carcinoma Pulmonar de Células não Pequenas/virologia , Carcinoma de Células Escamosas/imunologia , Carcinoma de Células Escamosas/patologia , Carcinoma de Células Escamosas/virologia , Variações do Número de Cópias de DNA , Análise Mutacional de DNA , Feminino , Dosagem de Genes , Humanos , Neoplasias Pulmonares/imunologia , Neoplasias Pulmonares/patologia , Neoplasias Pulmonares/virologia , Pessoa de Meia-Idade , Mutação , Valor Preditivo dos Testes , Terminologia como Assunto
20.
Front Hum Neurosci ; 15: 650838, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34239426

RESUMO

The present study aimed to use event-related potentials with the stop-signal task to investigate the effects of trait anxiety on inhibitory control, error monitoring, and post-error adjustments. The stop-signal reaction time (SSRT) was used to evaluate the behavioral competence of inhibitory control. Electrophysiological signals of error-related negativity (ERN) and error positivity (Pe) were used to study error perception and error awareness, respectively. Post-error slowing (PES) was applied to examine the behavioral adjustments after making errors. The results showed that SSRT and PES did not differ significantly between individuals with high trait anxiety (HTA) and those with low trait anxiety (LTA). However, individuals with HTA demonstrated reduced ERN amplitudes and prolonged Pe latencies than those with LTA. Prolonged Pe latencies were also significantly associated with poorer post-error adjustments. In conclusion, HTA led to reduced cortical responses to error monitoring. Furthermore, inefficient conscious awareness of errors might lead to maladaptive post-error adjustments.

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