Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 85
Filtrar
Mais filtros

Base de dados
País/Região como assunto
Tipo de documento
País de afiliação
Intervalo de ano de publicação
1.
Brain ; 147(4): 1294-1311, 2024 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-38289861

RESUMO

Ischaemic stroke causes neuron loss and long-term functional deficits. Unfortunately, effective approaches to preserving neurons and promoting functional recovery remain unavailable. Oligodendrocytes, the myelinating cells in the CNS, are susceptible to oxygen and nutrition deprivation and undergo degeneration after ischaemic stroke. Technically, new oligodendrocytes and myelin can be generated by the differentiation of oligodendrocyte precursor cells (OPCs). However, myelin dynamics and their functional significance after ischaemic stroke remain poorly understood. Here, we report numerous denuded axons accompanied by decreased neuron density in sections from ischaemic stroke lesions in human brain, suggesting that neuron loss correlates with myelin deficits in these lesions. To investigate the longitudinal changes in myelin dynamics after stroke, we labelled and traced pre-existing and newly-formed myelin, respectively, using cell-specific genetic approaches. Our results indicated massive oligodendrocyte death and myelin loss 2 weeks after stroke in the transient middle cerebral artery occlusion (tMCAO) mouse model. In contrast, myelin regeneration remained insufficient 4 and 8 weeks post-stroke. Notably, neuronal loss and functional impairments worsened in aged brains, and new myelin generation was diminished. To analyse the causal relationship between remyelination and neuron survival, we manipulated myelinogenesis by conditional deletion of Olig2 (a positive regulator) or muscarinic receptor 1 (M1R, a negative regulator) in OPCs. Deleting Olig2 inhibited remyelination, reducing neuron survival and functional recovery after tMCAO. Conversely, enhancing remyelination by M1R conditional knockout or treatment with the pro-myelination drug clemastine after tMCAO preserved white matter integrity and neuronal survival, accelerating functional recovery. Together, our findings demonstrate that enhancing myelinogenesis is a promising strategy to preserve neurons and promote functional recovery after ischaemic stroke.


Assuntos
Isquemia Encefálica , AVC Isquêmico , Acidente Vascular Cerebral , Camundongos , Animais , Humanos , Idoso , Bainha de Mielina/patologia , Isquemia Encefálica/complicações , Isquemia Encefálica/patologia , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/patologia , Oligodendroglia/patologia , Neurônios , Diferenciação Celular/fisiologia
2.
J Neurosci ; 43(11): 1859-1870, 2023 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-36725322

RESUMO

Age-related decline in visual functions is a prevalent health problem among elderly people, and no effective therapies are available up-to-date. Axon degeneration and myelin loss in optic nerves (ONs) are age-dependent and become evident in middle-aged (13-18 months) and old (20-22 months) mice of either sex compared with adult mice (3-8 months), accompanied by functional deficits. Oligodendrocyte (OL) turnover is actively going on in adult ONs. However, the longitudinal change and functional significance of OL turnover in aging ONs remain largely unknown. Here, using cell-lineage labeling and tracing, we reported that oligodendrogenesis displayed an age-dependent decrease in aging ONs. To understand whether active OL turnover is required for maintaining axons and visual function, we conditionally deleted the transcription factor Olig2 in the oligodendrocyte precursor cells of young mice. Genetically dampening OL turnover by Olig2 ablation resulted in accelerated axon loss and retinal degeneration, and subsequently impaired ON signal transmission, suggesting that OL turnover is an important mechanism to sustain axon survival and visual function. To test whether enhancing oligodendrogenesis can prevent age-related visual deficits, 12-month-old mice were treated with clemastine, a pro-myelination drug, or induced deletion of the muscarinic receptor 1 in oligodendrocyte precursor cells. The clemastine treatment or muscarinic receptor 1 deletion significantly increased new OL generation in the aged ONs and consequently preserved visual function and retinal integrity. Together, our data indicate that dynamic OL turnover in ONs is required for axon survival and visual function, and enhancing new OL generation represents a potential approach to reversing age-related declines of visual function.SIGNIFICANCE STATEMENT Oligodendrocyte (OL) turnover has been reported in adult optic nerves (ONs), but the longitudinal change and functional significance of OL turnover during aging remain largely unknown. Using cell-lineage tracing and oligodendroglia-specific manipulation, this study reported that OL generation was active in adult ONs and the efficiency decreased in an age-dependent manner. Genetically dampening OL generation by Olig2 ablation resulted in significant axon loss and retinal degeneration, along with delayed visual signal transmission. Conversely, pro-myelination approaches significantly increased new myelin generation in aging ONs, and consequently preserved retinal integrity and visual function. Our findings indicate that promoting OL generation might be a promising strategy to preserve visual function from age-related decline.


Assuntos
Clemastina , Degeneração Retiniana , Camundongos , Animais , Clemastina/farmacologia , Oligodendroglia/fisiologia , Bainha de Mielina/fisiologia , Nervo Óptico , Axônios , Diferenciação Celular/fisiologia
3.
J Cell Mol Med ; 28(3): e18062, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38018906

RESUMO

Physical activity (PA) has the potential to bring about favourable changes in plasma lipid profile. However, the relationship between PA and remnant cholesterol (RC) remains unclear. We aimed to study the link between PA and RC using the database of the 2007-2020 National Health and Nutrition Examination Survey (NHANES). PA was categorized based on Physical Activity Guidelines for Americans. A multivariate linear regression model was used to determine the correlations between PA and RC. The study involved a total of 18,396 participants and revealed that individuals whose PA met the guidelines by engaging in moderate-intensity PA at least 150 min per week had lower body mass index and showed decreased levels of triglyceride, TC, and haemoglobin A1c compared to those who were physically inactive, exercising <150 min per week. Participants whose intensity of PA meets PA guidelines had a lower level of RC than those who did not met PA guidelines (ß = -1.3, 95% confidence interval [CI]: -1.9 to -0.7, p < 0.001), even after adjusting for confounders. During subgroup analysis, we observed that race (pinteraction = 0.0089) emerged as a significant factor of interaction.


Assuntos
Colesterol , Exercício Físico , Humanos , Estados Unidos , Inquéritos Nutricionais , Índice de Massa Corporal , Redução de Peso
4.
Anal Chem ; 96(36): 14354-14362, 2024 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-39177663

RESUMO

π-Stacking, a type of noncovalent interactions involving aromatic residues, plays an important role in protein folding and function. In this work, an attempt has been made to measure CH/π and NH/π stacking interactions in a protein in Escherichia coli cells using a combined double-mutant cycle and nuclear magnetic resonance spectroscopy method. The results show that the CH/π and NH/π stacking interactions are generally weaker in cells than those in the buffer. The transient intermolecular noncovalent interactions between the protein and the complex cellular environment may compete with and thus weaken the stacking interactions in the protein. The weakening of stacking interactions can enhance the local conformational opening of proteins in E. coli cells. This is evident from the faster rates of amide hydrogen/deuterium exchange observed in cells than in the buffer, for residues that undergo local conformational opening. This study highlights the influence of the cellular environment on π-stacking and the conformational dynamics of proteins.


Assuntos
Escherichia coli , Escherichia coli/química , Escherichia coli/metabolismo , Ressonância Magnética Nuclear Biomolecular , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/metabolismo , Conformação Proteica , Espectroscopia de Ressonância Magnética/métodos
5.
Anal Chem ; 96(18): 7065-7072, 2024 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-38652079

RESUMO

Protein allostery is commonly observed in vitro. But how protein allostery behaves in cells is unknown. In this work, a protein monomer-dimer equilibrium system was built with the allosteric effect on the binding characterized using NMR spectroscopy through mutations away from the dimer interface. A chemical shift linear fitting method was developed that enabled us to accurately determine the dissociation constant. A total of 28 allosteric mutations were prepared and grouped to negative allosteric, nonallosteric, and positive allosteric modulators. ∼ 50% of mutations displayed the allosteric-state changes when moving from a buffered solution into cells. For example, there were no positive allosteric modulators in the buffered solution but eight in cells. The change in protein allostery is correlated with the interactions between the protein and the cellular environment. These interactions presumably drive the surrounding macromolecules in cells to transiently bind to the monomer and dimer mutational sites and change the free energies of the two species differently which generate new allosteric effects. These surrounding macromolecules create a new protein allostery pathway that is only present in cells.


Assuntos
Ressonância Magnética Nuclear Biomolecular , Regulação Alostérica , Mutação , Multimerização Proteica , Modelos Moleculares
6.
Reprod Biol Endocrinol ; 22(1): 91, 2024 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-39085874

RESUMO

OBJECTIVES: To explore the association between tea, coffee, and caffeine consumption and the risk of female infertility. METHODS: We analyzed data from 2099 females aged 18 to 44 years, participating in the National Health and Nutrition Examination Survey (NHANES) 2013-2018. We used generalized linear models (GLM) and generalized additive model (GAM) to investigate the dose-response relationship between the tea, coffee, and caffeine consumption and infertility, adjusting for potential confounders. RESULTS: A non-linear relationship was detected between tea consumption and infertility and the inflection point was 2 cups/day. On the right side of the inflection point, we did not detect a significant association. However, on the left side, we found a negative relationship between tea consumption and infertility (OR: 0.73; 95% CI: 0.57 to 0.93; P = 0.0122). Meanwhile, our study found no significant association between coffee (0.96, 0.81 to 1.13, P = 0.6189) or caffeine consumption (1.15, 0.93 to 1.42, P = 0.2148) and female infertility. CONCLUSIONS: Tea consumption was non-linearly associated with infertility, whereas no significant associations were found between coffee, caffeine consumption and infertility.


Assuntos
Cafeína , Café , Infertilidade Feminina , Chá , Humanos , Feminino , Chá/efeitos adversos , Café/efeitos adversos , Cafeína/efeitos adversos , Cafeína/administração & dosagem , Adulto , Estudos Transversais , Infertilidade Feminina/epidemiologia , Adulto Jovem , Adolescente , Inquéritos Nutricionais , Fatores de Risco
7.
Reprod Biol Endocrinol ; 22(1): 62, 2024 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-38811989

RESUMO

OBJECTIVES: To explore the relationship between different types of physical activity and female infertility. METHODS: This study analyzed data from 2,796 female participants aged 18-44 years in the United States, obtained from the National Health and Nutrition Examination Survey (NHANES) database spanning the years 2013 to 2020. Multiple logistic regression analyses and generalized linear models were used to explore the relationship between different types of physical activity and infertility after adjusting for potential confounding factors. RESULTS: We found a non-linear relationship between recreational activities and infertility with an inflection point of 5.83 h/week (moderate intensity), while work activities and traffic-related activities did not. On the left side of the inflection point, there was no significant association between recreational activity time and infertility (OR = 0.93, 95% CI: 0.86 to 1.02, P = 0.1146), but on the right side of the inflection point, there was a positive association between recreational activity time and the risk of infertility (OR = 1.04, 95% CI: 1.02 to 1.06, P = 0.0008). CONCLUSIONS: The relationship between different types of physical activity and female infertility varies. We acknowledge the potential influence of confounding variables on this relationship. However, we have already adjusted for these potential variables in our analysis. Therefore, our findings suggest that appropriate recreational activity programs are essential for promoting reproductive health in women of reproductive age. Nevertheless, it is important to note that the observed association does not imply causality. Given the limitations of cross-sectional studies, further prospective cohort studies are needed to explore the causal relationship while accounting for additional confounding factors.


Assuntos
Exercício Físico , Infertilidade Feminina , Inquéritos Nutricionais , Humanos , Feminino , Adulto , Infertilidade Feminina/epidemiologia , Infertilidade Feminina/etiologia , Exercício Físico/fisiologia , Adulto Jovem , Adolescente , Estados Unidos/epidemiologia , Estudos Transversais
8.
Lipids Health Dis ; 23(1): 356, 2024 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-39487451

RESUMO

Type 2 diabetes mellitus (T2DM) is a globally prevalent metabolic disorder, and cardiovascular disease (CVD) is a significant cause of mortality and morbidity in diabetic individuals. In addition to hyperglycemia, lipid abnormalities associated with T2DM play a crucial role in the development of CVD complications. Diabetic dyslipidemia is characterized by elevated levels of triglyceride (TG)-rich lipoproteins and small dense low-density lipoprotein (LDL) particles, reduced high-density lipoprotein (HDL) cholesterol, and impaired HDL function. Angiopoietin protein-like 3 (ANGPTL3) is a liver-derived protein that plays a crucial role in regulating plasma lipoprotein metabolism by inhibiting lipoprotein lipase and influencing lipid levels. Inhibiting ANGPTL3 has shown promising effects in promoting HDL-mediated cholesterol reverse transport and reducing the levels of TG-rich lipoproteins and LDL cholesterol. Here, we explore the potential of ANGPTL3 as a therapeutic target for lipid management in T2DM patients.


Assuntos
Proteína 3 Semelhante a Angiopoietina , Proteínas Semelhantes a Angiopoietina , Diabetes Mellitus Tipo 2 , Triglicerídeos , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/sangue , Humanos , Proteínas Semelhantes a Angiopoietina/antagonistas & inibidores , Triglicerídeos/sangue , Metabolismo dos Lipídeos/efeitos dos fármacos , Dislipidemias/tratamento farmacológico , Dislipidemias/sangue , LDL-Colesterol/sangue , HDL-Colesterol/sangue , Lipase Lipoproteica/metabolismo , Lipoproteínas/sangue , Lipoproteínas/metabolismo , Doenças Cardiovasculares
9.
Lipids Health Dis ; 23(1): 14, 2024 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-38216994

RESUMO

Reducing circulating lipid levels is the centerpiece of strategies for preventing and treating atherosclerotic cardiovascular disease (ASCVD). Despite many available lipid-lowering medications, a substantial residual cardiovascular risk remains. Current clinical guidelines focus on plasma levels of low-density lipoprotein (LDL). Recent attention has been given to very low-density lipoprotein (VLDL), the precursor to LDL, and its role in the development of coronary atherosclerosis. Preclinical investigations have revealed that interventions targeting VLDL production or promoting VLDL metabolism, independent of the LDL receptor, can potentially decrease cholesterol levels and provide therapeutic benefits. Currently, methods, such as mipomersen, lomitapide, and ANGPTL3 inhibitors, are used to reduce plasma cholesterol and triglyceride levels by regulating the lipidation, secretion, and metabolism of VLDL. Targeting VLDL represents an avenue for new lipid-lowering strategies. Interventions aimed at reducing VLDL production or enhancing VLDL metabolism, independent of the LDL receptor, hold promise for lowering cholesterol levels and providing therapeutic benefits beyond LDL in the management of ASCVD.


Assuntos
Aterosclerose , Lipoproteínas VLDL , Humanos , Lipoproteínas LDL , Receptores de LDL/genética , Colesterol , Proteína 3 Semelhante a Angiopoietina
10.
Lipids Health Dis ; 23(1): 89, 2024 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-38539180

RESUMO

BACKGROUND AND AIMS: Current research has suggested that asialoglycoprotein receptor 1 (ASGR1) is involved in cholesterol metabolism and is also related to systemic inflammation. This study aimed to assess the correlation between the serum soluble ASGR1 (sASGR1) concentration and inflammatory marker levels. Moreover, the second objective of the study was to assess the association between sASGR1 levels and the presence of coronary artery disease (CAD). METHODS: The study subjects included 160 patients who underwent coronary angiography. Ninety patients were diagnosed with CAD, while seventy age- and sex-matched non-CAD patients served as controls. We measured the serum sASGR1 levels using an ELISA kit after collecting clinical baseline characteristics. RESULTS: Patients with CAD had higher serum sASGR1 levels than non-CAD patients did (P < 0.0001). sASGR1 was independently correlated with the risk of CAD after adjusting for confounding variables (OR = 1.522, P = 0.012). The receiver operating characteristic (ROC) curve showed that sASGR1 had a larger area under the curve (AUC) than did the conventional biomarkers apolipoprotein B (APO-B) and low-density lipoprotein cholesterol (LDL-C). In addition, multivariate linear regression models revealed that sASGR1 is independently and positively correlated with high-sensitivity C-reactive protein (CRP) (ß = 0.86, P < 0.001) and WBC (ß = 0.13, P = 0.004) counts even after adjusting for lipid parameters. According to our subgroup analysis, this relationship existed only for CAD patients. CONCLUSION: Our research demonstrated the link between CAD and sASGR1 levels, suggesting that sASGR1 may be an independent risk factor for CAD. In addition, this study provides a reference for revealing the potential role of sASGR1 in the inflammation of atherosclerosis.


Assuntos
Doença da Artéria Coronariana , Humanos , Angiografia Coronária/efeitos adversos , Fatores de Risco , Biomarcadores , Inflamação/complicações , Colesterol , Receptor de Asialoglicoproteína
11.
Opt Lett ; 48(9): 2457-2460, 2023 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-37126297

RESUMO

A Ga hybridization strategy is proposed for simultaneously enhancing the near-infrared activity and extending the bandwidth of Bi-activated photonic glass. Systematic studies on the near-infrared optical responses of Ga/Bi and Al/Bi co-doped silica glasses are performed. It is interesting to note that Ga/Bi co-doped glasses have a similar near-infrared emission center to Al/Bi co-doped glass, while the former is more effective in improving near-infrared activity. The different luminescence mechanisms of Ga/Bi and Al/Bi co-doped silica glasses are elucidated, and the corresponding microstructure-optical response relationship is discussed. In addition, the Ga/Bi co-doped silica optical fiber is successfully prepared, and the principal fiber amplifier device is fabricated. Furthermore, amplified spontaneous emission and broadband on-off gain are realized. The results suggest that Ga-hybridized Bi-activated photonic glass is a promising gain material for broadband fiber amplifiers.

12.
Lipids Health Dis ; 22(1): 142, 2023 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-37667265

RESUMO

BACKGROUND: Recent studies have shown that loss-of-function mutations in hepatic asialoglycoprotein receptor 1 (ASGR1) are associated with low levels of circulating cholesterol and a reduced risk of coronary artery disease (CAD). In contrast to ASGR1 on the hepatocyte membrane, serum soluble ASGR1 (sASGR1) is a secreted form that has been detected in circulation. However, the functions of serum sASGR1 are unclear. This study aims to investigate the relationship between human serum sASGR1 concentration and low-density lipoprotein cholesterol (LDL-C) levels. METHODS: In a cohort of 134 participants who underwent coronary angiography examination, basic information was recorded, and blood samples were collected for biochemical testing. The serum sASGR1 concentration was determined by ELISA kits. The relationship between sASGR1 concentration and LDL-C levels was examined using linear regression models and interaction tests. Univariate and multivariate analyses were used to identify clinical variables that affect sASGR1 levels. RESULTS: After adjusting for potential confounders such as age, sex, BMI, and statin use, the serum sASGR1 concentration was positively correlated with LDL-C levels (ß = 0.093, 95% CI: 0.04 to 0.14, P < 0.001). Subgroup analysis and interaction tests showed that the effect of serum sASGR1 concentration on LDL-C levels was significantly influenced by hypertension status (P for interaction = 0.0067). The results of a multivariate linear regression analysis incorporating age, serum TG, LDL-C, nonesterified fatty acid (NEFA), white blood cell counts (WBCC), and fibrinogen revealed that LDL-C (ß = 1.005, 95% CI: 0.35 to 1.66, P = 0.003) and WBCC (ß = 0.787, 95% CI: 0.41 to 1.16, P < 0.0001) were independent influencing factors for serum sASGR1 levels. CONCLUSIONS: The serum sASGR1 concentration was positively correlated with LDL-C levels. In addition, hypertension status significantly affected the effect of serum sASGR1 on LDL-C levels. This study provides some research ideas for clinical doctors and researchers, as well as some references for additional research on serum sASGR1.


Assuntos
Hipertensão , Humanos , Estudos Transversais , LDL-Colesterol , Transporte Biológico , Angiografia Coronária , Hipertensão/genética , Receptor de Asialoglicoproteína
13.
Sensors (Basel) ; 23(13)2023 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-37447669

RESUMO

BACKGROUND: Protective antigen (PA) is an important biomarker for the early diagnosis of anthrax, and the accurate detection of protective antigen under extremely low concentration conditions has always been a hot topic in the biomedical field. To complete the diagnosis of anthrax in a timely manner, it is necessary to detect PA at extremely low concentrations, as the amount of PA produced in the early stage of anthrax invasion is relatively small. Graphene field-effect transistor (Gr-FET) biosensors are a new type of material for preparing biosensors, with the advantages of a short detection time and ultra-low detection limit. METHODS: The effect of different concentrations of diluents on the affinity of PA monoclonal antibodies was determined via an ELISA experiment. Combined with the Debye equation, 0.01 × PBS solution was finally selected as the diluent for the experiment. Then, a PA monoclonal antibody was selected as the bio-recognition element to construct a Gr-FET device based on CVD-grown graphene, which was used to detect the concentration of PA while recording the response time, linear range, detection limit, and other parameters. RESULTS: The experimental results showed that the biosensor could quickly detect PA, with a linear range of 10 fg/mL to 100 pg/mL and a detection limit of 10 fg/mL. In addition, the biosensor showed excellent specificity and repeatability. CONCLUSIONS: By constructing a Gr-FET device based on CVD-grown graphene and selecting a PA monoclonal antibody as the bio-recognition element, a highly sensitive, specific, and repeatable Gr-FET biosensor was successfully prepared for detecting extremely low concentrations of anthrax protective antigen (PA). This biosensor is expected to have a wide range of applications in clinical medicine and biological safety monitoring.


Assuntos
Antraz , Técnicas Biossensoriais , Doenças Cardiovasculares , Grafite , Humanos , Antraz/diagnóstico , Técnicas Biossensoriais/métodos , Anticorpos Monoclonais
14.
Int J Mol Sci ; 23(23)2022 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-36499147

RESUMO

The hydrogen bond (H-bond) cooperativity in the ß-sheet of GB3 is investigated by a NMR hydrogen/deuterium (H/D) exchange method. It is shown that the weakening of one backbone N-H…O=C H-bond between two ß-strands, ß1 and ß2, due to the exchange of NH to ND of the H-bond donor in ß1, perturbs the chemical shift of 13Cα, 13Cß, 1Hα, 1HN, and 15N of the H-bond acceptor and its following residue in ß2. Quantum mechanical calculations suggest that the -H-bond chemical shift isotope effect is caused by the structural reorganization in response to the H-bond weakening. This structural reorganization perturbs four neighboring H-bonds, with three being weaker and one being stronger, indicating that three H-bonds are cooperative and one is anticooperative with the perturbed H-bond. The sign of the cooperativity depends on the relative position of the H-bonds. This H-bond cooperativity, which contributes to ß-sheet stability overall, can be important for conformational coupling across the ß-sheet.


Assuntos
Hidrogênio , Isótopos , Ligação de Hidrogênio , Conformação Proteica em Folha beta , Conformação Molecular
15.
Appl Environ Microbiol ; 87(11)2021 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-33712426

RESUMO

Selective oxidation of C-H bonds in alkylphenols holds great significance for not only structural derivatization in pharma- and biomanufacturing but also biological degradation of these toxic chemicals in environmental protection. A unique chemomimetic biocatalytic system using enzymes from a p-cresol biodegradation pathway has recently been developed. As the central biocatalyst, the cytochrome P450 monooxygenase CreJ oxidizes diverse p- and m-alkylphenol phosphates with perfect stereoselectivity at different efficiencies. However, the mechanism of regio- and stereoselectivity of this chemomimetic biocatalytic system remained unclear. Here, using p- and m-ethylphenol substrates, we elucidate the CreJ-catalyzed key steps for selective oxidations. The crystal structure of CreJ in complex with m-ethylphenol phosphate was solved and compared with its complex structure with p-ethylphenol phosphate isomer. The results indicate that the conformational changes of substrate-binding residues are slight, while the substrate promiscuity is achieved mainly by the available space in the catalytic cavity. Moreover, the catalytic preferences of regio- and stereoselective hydroxylation for the two ethylphenol substrates is explored by molecular dynamics simulations. The ethyl groups in the complexes display different flexibilities, and the distances of the active oxygen to H pro-S and H pro-R of methylene agree with the experimental stereoselectivity. The regioselectivity can be explained by the distances and bond dissociation energy. These results provide not only the mechanistic insights into CreJ regio- and stereoselectivity but also the structural basis for further P450 enzyme design and engineering.IMPORTANCE The key cytochrome P450 monooxygenase CreJ showed excellent regio- and stereoselectivity in the oxidation of various alkylphenol substrates. C-H bond functionalization of these toxic alkylphenols holds great significance for both biological degradation of these environmental chemicals and production of value-added structural derivatives in pharmaceutical and biochemical industries. Our results, combined with in vitro enzymatic assays, crystal structure determination of enzyme-substrate complex, and molecular dynamics simulations, provide not only significant mechanism elucidation of the regio- and stereoselective catalyzation mediated by CreJ but also the promising directions for future engineering efforts of this enzyme toward more useful products. It also has great extendable potential to couple this multifunctional P450 enzyme with other biocatalysts (e.g., hydroxyl-based glycosylase) to access more alkylphenol-derived high-value chemicals through environment-friendly biocatalysis and biotransformation.


Assuntos
Proteínas de Bactérias/metabolismo , Corynebacterium glutamicum/metabolismo , Fenóis/metabolismo , Oxirredução , Fosforilação
16.
FASEB J ; 34(12): 16243-16261, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33070362

RESUMO

Our previous research revealed that steroid receptor coactivators (Src)-1 and -2 serve a critical cooperative role in production of parturition signals, surfactant protein A and platelet-activating factor, by the developing mouse fetal lung (MFL). To identify the global landscape of genes in MFL affected by Src-1/-2 double-deficiency, we conducted RNA-seq analysis of lungs from 18.5 days post-coitum (dpc) Src-1-/- /-2-/- (dKO) vs. WT fetuses. One of the genes most highly downregulated (~4.8 fold) in Src-1/-2 dKO fetal lungs encodes 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1), which catalyzes conversion of inactive 11-dehydrocorticosterone to the glucocorticoid receptor (GR) ligand, corticosterone. Glucocorticoids were reported to upregulate 11ß-HSD1 expression in various cell types via induction of C/EBP transcription factors. We observed that C/ebpα and C/ebpß mRNA and protein were markedly reduced in Src-1/-2 double-deficient (Src-1/-2d/d ) fetal lungs, compared to WT. Moreover, glucocorticoid induction of 11ß-hsd1, C/ebpα and C/ebpß in cultured MFL epithelial cells was prevented by the SRC family inhibitor, SI-2. Cytokines also contribute to the induction of 11ß-HSD1. Expression of IL-1ß and TNFα, which dramatically increased toward term in lungs of WT fetuses, was markedly reduced in Src-1/-2d/d fetal lungs. Our collective findings suggest that impaired lung development and surfactant synthesis in Src-1/-2d/d fetuses are likely caused, in part, by decreased GR and cytokine induction of C/EBP and NF-κB transcription factors. This results in reduced 11ß-HSD1 expression and glucocorticoid signaling within the fetal lung, causing a break in the glucocorticoid-induced positive feedforward loop.


Assuntos
11-beta-Hidroxiesteroide Desidrogenase Tipo 1/metabolismo , Citocinas/metabolismo , Feto/metabolismo , Glucocorticoides/metabolismo , Pulmão/metabolismo , Receptores de Glucocorticoides/metabolismo , Transdução de Sinais/fisiologia , Animais , Proteína alfa Estimuladora de Ligação a CCAAT/metabolismo , Proteína beta Intensificadora de Ligação a CCAAT/metabolismo , Proteínas Estimuladoras de Ligação a CCAAT/metabolismo , Células Epiteliais/metabolismo , Feminino , Masculino , Camundongos , Camundongos Knockout , Ligação Proteica/fisiologia , RNA Mensageiro/metabolismo , Fatores de Transcrição/metabolismo , Fator de Necrose Tumoral alfa/metabolismo
17.
Proc Natl Acad Sci U S A ; 114(26): E5129-E5137, 2017 06 27.
Artigo em Inglês | MEDLINE | ID: mdl-28607077

RESUMO

Selective oxidation of aliphatic C-H bonds in alkylphenols serves significant roles not only in generation of functionalized intermediates that can be used to synthesize diverse downstream chemical products, but also in biological degradation of these environmentally hazardous compounds. Chemo-, regio-, and stereoselectivity; controllability; and environmental impact represent the major challenges for chemical oxidation of alkylphenols. Here, we report the development of a unique chemomimetic biocatalytic system originated from the Gram-positive bacterium Corynebacterium glutamicum The system consisting of CreHI (for installation of a phosphate directing/anchoring group), CreJEF/CreG/CreC (for oxidation of alkylphenols), and CreD (for directing/anchoring group offloading) is able to selectively oxidize the aliphatic C-H bonds of p- and m-alkylated phenols in a controllable manner. Moreover, the crystal structures of the central P450 biocatalyst CreJ in complex with two representative substrates provide significant structural insights into its substrate flexibility and reaction selectivity.


Assuntos
Proteínas de Bactérias/química , Corynebacterium glutamicum/enzimologia , Sistema Enzimático do Citocromo P-450/química , Fenóis/química , Catálise , Oxirredução
18.
J Am Chem Soc ; 141(29): 11363-11366, 2019 07 24.
Artigo em Inglês | MEDLINE | ID: mdl-31305080

RESUMO

In this work, we measured the millisecond residue specific protein folding and unfolding dynamics in E. coli cells for two protein GB3 mutants using NMR. The results show that the protein folding and unfolding dynamics in cells is different from that in buffer. Through a two-site exchange model, it is shown that both the population and the exchange rate are changed by the E. coli cellular environment. Further investigation suggests that the change is likely due to the quinary interaction with crowded molecules in the cell. Our work underlines the importance of cellular environment to protein folding kinetics and thermodynamics although this environmental effect may not be large enough to change the protein structure.


Assuntos
Proteínas de Escherichia coli/metabolismo , Dobramento de Proteína , Desdobramento de Proteína , DNA Glicosilases/genética , DNA Glicosilases/metabolismo , Escherichia coli/metabolismo , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/genética , Espectroscopia de Ressonância Magnética , Mutação , Conformação Proteica
20.
Cardiovasc Diabetol ; 18(1): 54, 2019 04 27.
Artigo em Inglês | MEDLINE | ID: mdl-31029144

RESUMO

With an increasing global burden of coronary artery disease (CAD), early detection and timely management of risk factors are crucial to reduce morbidity and mortality in such patients. Diabetes mellitus (DM) is considered an independent risk factor for the development of CAD. Metformin, an anti-diabetic drug, has been shown in pre-clinical and clinical studies, to lower the cardiovascular events in the DM patients. Growing evidence suggests that metformin has a protective effect on coronary artery beyond its hypoglycemic effects. Given its global availability, route of administration and cost, metformin provides an alternate/additional therapeutic option for primary and secondary prevention of CAD in DM and non-diabetics alike. Future prospective cohort-based studies and randomized clinical trials are needed to identify 'at-risk' population who may potentially benefit from metformin.


Assuntos
Glicemia/efeitos dos fármacos , Fármacos Cardiovasculares/uso terapêutico , Doenças Cardiovasculares/tratamento farmacológico , Diabetes Mellitus/tratamento farmacológico , Hipoglicemiantes/uso terapêutico , Metformina/uso terapêutico , Animais , Biomarcadores/sangue , Glicemia/metabolismo , Fármacos Cardiovasculares/efeitos adversos , Doenças Cardiovasculares/diagnóstico , Doenças Cardiovasculares/epidemiologia , Doenças Cardiovasculares/fisiopatologia , Tomada de Decisão Clínica , Diabetes Mellitus/sangue , Diabetes Mellitus/diagnóstico , Diabetes Mellitus/epidemiologia , Humanos , Hipoglicemiantes/efeitos adversos , Metformina/efeitos adversos , Fatores de Risco , Resultado do Tratamento
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA