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1.
Mar Environ Res ; 197: 106476, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38609789

RESUMO

Blue carbon ecosystems, such as mangrove, seagrass bed and salt marsh, have attracted increasing attention due to their remarkable capacity for efficient carbon sequestration. However, the current threat posed by human activities to these ecosystems necessitates the characterization of their changes and identification of the primary driving factors in order to facilitate the gradual restoration of blue carbon ecosystems. In this study, we present an analysis of the spatio-temporal characteristics and primary influencing factors governing carbon sequestration in mangrove and seagrass beds located in Hainan Island. The findings revealed a 40% decline in carbon sequestration by mangroves from 1976 to 2017, while seagrass beds exhibited a 13% decrease in carbon sequestering between 2009 and 2016. The decline in carbon sequestration was primarily concentrated in Wenchang city, with aquaculture and population growth identified as the primary driving factors. Despite the implementation of measures aimed at reducing aquaculture in Hainan Island to promote blue carbon sequestration over the past two decades, the resulting recovery remains insufficient in achieving macro-level goals for carbon sequestration. This study emphasizes the necessity of safeguarding blue carbon ecosystems in Hainan Island by effectively mitigating anthropogenic disturbances.


Assuntos
Sequestro de Carbono , Ecossistema , Humanos , Áreas Alagadas , China , Carbono/análise
2.
Nat Commun ; 14(1): 2057, 2023 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-37045813

RESUMO

Mutations in glucocerebrosidase cause the lysosomal storage disorder Gaucher's disease and are the most common risk factor for Parkinson's disease. Therapies to restore the enzyme's function in the brain hold great promise for treating the neurological implications. Thus, we developed blood-brain barrier penetrant therapeutic molecules by fusing transferrin receptor-binding moieties to ß-glucocerebrosidase (referred to as GCase-BS). We demonstrate that these fusion proteins show significantly increased uptake and lysosomal efficiency compared to the enzyme alone. In a cellular disease model, GCase-BS rapidly rescues the lysosomal proteome and lipid accumulations beyond known substrates. In a mouse disease model, intravenous injection of GCase-BS leads to a sustained reduction of glucosylsphingosine and can lower neurofilament-light chain plasma levels. Collectively, these findings demonstrate the potential of GCase-BS for treating GBA1-associated lysosomal dysfunction, provide insight into candidate biomarkers, and may ultimately open a promising treatment paradigm for lysosomal storage diseases extending beyond the central nervous system.


Assuntos
Doença de Gaucher , Doença de Parkinson , Animais , Camundongos , Doença de Gaucher/genética , Glucosilceramidase/genética , Glucosilceramidase/metabolismo , Encéfalo/metabolismo , Neurônios/metabolismo , Doença de Parkinson/metabolismo , Lisossomos/metabolismo , Mutação , alfa-Sinucleína/metabolismo
3.
Mar Environ Res ; 186: 105928, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36889172

RESUMO

Water quality modeling facilitates management of nutrient flows from land to rivers and seas, in addition to environmental pollution management in watersheds. In the present paper, we review advances made in the development of seven water quality models and highlight their respective strengths and weaknesses. Afterward, we propose their future development directions, with distinct characteristics for different scenarios. We also discuss the practical problems that such models address in the same region, China, and summarize their different characteristics based on their performance. We focus on the temporal and geographical scales of the models, sources of pollution considered, and the main problems that can be addressed. Summary of such characteristics could facilitate the selection of appropriate models for resolving practical challenges on nutrient pollution in the corresponding scenarios globally by stakeholders. We also make recommendations for model enhancement to expand their capabilities.


Assuntos
Rios , Poluentes Químicos da Água , Poluentes Químicos da Água/análise , Monitoramento Ambiental , Nitrogênio/análise , Fósforo/análise , Qualidade da Água , Oceanos e Mares , China , Nutrientes
4.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-969303

RESUMO

Objective@# To compare the efficiency of four methods that remove calcium hydroxide in root canals and to guide clinical practice. @* Methods @# Sixty-five isolated mandibular single root canal premolars were collected. After crown cutting and root canal preparation, a tooth was randomly selected as the blank control group, and the remaining 64 teeth were equally divided into Groups A and B (n = 32). Group A was injected with water-soluble calcium hydroxide, and Group B was injected with oil-soluble calcium hydroxide. After 2 weeks of drug sealing, Groups A and B were randomly divided into 4 groups (n = 8), including the lateral opening syringe group, sonic vibration group, ultrasonic group, and Er: YAG laser group. Before and after calcium hydroxide removal, the samples were scanned by cone-beam CT, and the data were imported into Mimics for 3D reconstruction. The root canal was divided into the following segments: superior root segment, middle and apical, and the calcium hydroxide volume of each segment of the root canal was calculated. The volumes of calcium hydroxide before and after removal were V1 and V2, respectively, with a clearance rate = (V1-V2)/V1×100%. Three-factor ANOVA was used for statistical analysis. After Groups A and B were reconstructed, the apical region with residual calcium hydroxide was selected, and the blank control was observed by scanning electron microscopy (SEM). @*Results @# Two types of calcium hydroxide could not be completely removed by the four flushing methods. The clearance rate of water-soluble calcium hydroxide was higher than that of oil-soluble calcium hydroxide (P<0.001). Among the three segments of the root canal, the clearance rate of the apical segment was lower (P<0.05). The Er: YAG laser treatment group showed the highest removal efficiency of two kinds of calcium hydroxide, which was higher than that of the other groups, especially in apical of the root. Compared with the sonic wave washing group and the syringe washing group, the ultrasonic wave washing group exhibited significant advantages (P<0.05). The clearance rate of the sonic wave washing group was higher in the oily calcium hydroxide root middle group than in the syringe washing group (P<0.05). SEM showed that the two kinds of calcium hydroxide could not be completely removed, but the residual rate of oil-soluble calcium hydroxide was large.@*Conclusion @# Both types of calcium hydroxide could not be completely removed, and compared to water-soluble calcium hydroxide, oil-soluble calcium hydroxide was more difficult to remove. Among the four cleaning methods, Er:YAG laser swing washing showed the higher cleaning efficiency.

5.
Proc Natl Acad Sci U S A ; 119(29): e2200553119, 2022 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-35858317

RESUMO

Loss of activity of the lysosomal glycosidase ß-glucocerebrosidase (GCase) causes the lysosomal storage disease Gaucher disease (GD) and has emerged as the greatest genetic risk factor for the development of both Parkinson disease (PD) and dementia with Lewy bodies. There is significant interest into how GCase dysfunction contributes to these diseases, however, progress toward a full understanding is complicated by presence of endogenous cellular factors that influence lysosomal GCase activity. Indeed, such factors are thought to contribute to the high degree of variable penetrance of GBA mutations among patients. Robust methods to quantitatively measure GCase activity within lysosomes are therefore needed to advance research in this area, as well as to develop clinical assays to monitor disease progression and assess GCase-directed therapeutics. Here, we report a selective fluorescence-quenched substrate, LysoFQ-GBA, which enables measuring endogenous levels of lysosomal GCase activity within living cells. LysoFQ-GBA is a sensitive tool for studying chemical or genetic perturbations of GCase activity using either fluorescence microscopy or flow cytometry. We validate the quantitative nature of measurements made with LysoFQ-GBA using various cell types and demonstrate that it accurately reports on both target engagement by GCase inhibitors and the GBA allele status of cells. Furthermore, through comparisons of GD, PD, and control patient-derived tissues, we show there is a close correlation in the lysosomal GCase activity within monocytes, neuronal progenitor cells, and neurons. Accordingly, analysis of clinical blood samples using LysoFQ-GBA may provide a surrogate marker of lysosomal GCase activity in neuronal tissue.


Assuntos
Doença de Gaucher , Glucosilceramidase , Doença de Parkinson , Doença de Gaucher/enzimologia , Doença de Gaucher/genética , Glucosilceramidase/análise , Glucosilceramidase/genética , Humanos , Corpos de Lewy/enzimologia , Doença por Corpos de Lewy/enzimologia , Lisossomos/enzimologia , Mutação , Doença de Parkinson/enzimologia , Doença de Parkinson/genética , Especificidade por Substrato , alfa-Sinucleína/metabolismo
6.
Lasers Med Sci ; 37(8): 3249-3258, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35854018

RESUMO

The disinfection of root canal through minimally invasive access cavity remains questionable. This in vitro study compared the effectiveness of three disinfection measures including conventional irrigation, ultrasonic assisted irrigation, and erbium:yttrium-aluminum-garnet (Er:YAG) laser assisted irrigation through conventionally or minimally invasive access. Sixty-six extracted maxillary first molars were randomly divided into group 1 conventionally invasive access group (CIA) and group 2 computer-guided minimally invasive access group (MIA). Each group was further randomly divided into three subgroups, (A) conventional irrigation (CI), (B) passive ultrasonic agitation (PUI), and (C) Er:YAG laser activated irrigation (LAI). Enterococcus faecalis (E. faecalis) infection model was established inside all root canals after instrumentation was performed up to ProTaper Universal F2. After various disinfection methods, microbial samples were collected from root canals by paper tip method and cultured, and colony forming units (CFU) values of each sample were calculated. Then the root canals were enlarged to the size of F3, after which dentin debris was collected from the F3 file. After dilution and culturing, the CFU value was calculated for each group. Two-way analysis of variance (ANOVA) was performed to test the interaction. The results revealed a significant antagonism (F = 3.394, P = 0.043). The bacterial CFU counts of group B and group C were significantly less than that of group A (P < 0.05), and there was no significant difference between group B and C (P > 0.05). Additionally, group 2A was better than group 1A (P < 0.05); there was no significant difference between group 1B and group 2B, group 1C and group 2C (P > 0.05). Comparison of the bacterial CFU counts in dentin debris after disinfection, the results revealed a significant antagonism (F = 7.224, P = 0.002), and group C had the least. The disinfection effect of Er:YAG laser or ultrasonic assisted computer-guided minimally invasive access is similar to conventionally invasive access, and Er:YAG laser is better than ultrasonic in removing bacteria from dentinal tubules and is easy to operate, which is more suitable for minimally invasive root canal treatment.


Assuntos
Lasers de Estado Sólido , Cavidade Pulpar , Desinfecção/métodos , Enterococcus faecalis , Érbio , Lasers de Estado Sólido/uso terapêutico , Irrigantes do Canal Radicular/farmacologia , Preparo de Canal Radicular/métodos , Hipoclorito de Sódio/farmacologia , Ultrassom
7.
Ear Nose Throat J ; : 1455613221098786, 2022 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-35581165

RESUMO

After removal of a large frontal sinus osteoma in this case, the contralateral nasofrontal canal was opened to drain the intraoperative fluid and prevent infection, and the defect in the orbitofrontal area was restored using a titanium mesh designed with 3D printing technology.

8.
Shanghai Kou Qiang Yi Xue ; 31(1): 17-23, 2022 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-35587662

RESUMO

PURPOSE: To obtain an efficient and simple root canal disinfection method based on minimally invasive root canal treatment by comparing different root canal disinfection methods between minimally invasive root canal treatment and conventional root canal treatment. METHODS: Sixty-six extracted maxillary first molars were randomly divided into experimental group (computer-guided precision minimally invasive root canal treatment) and control group (conventional root canal treatment). All teeth were prepared to ProTaper universal F2, and Enterococcus faecalis infection models were established.Each group was randomly divided into three subgroups, sodium hypochlorite+EDTA root canal irrigation, sodium hypochlorite+EDTA+ultrasonic and sodium hypochlorite +EDTA +Er: YAG laser. After root canal disinfection,the samples were collected by paper tip method and cultured, and colony forming units (CFU) values of each sample were calculated. Then dentin debris was prepared and collected with F3 file. After being diluted and cultured, the CFU value was calculated. Statistical analysis was performed by SPSS 26.0 software package. RESULTS: Comparison of the amount of bacterial inner wall of root canal between the experimental group and the control group showed that the germicidal efficacy of group C and group B were significantly better than that of group A (P<0.05), but there was no significant difference between group B and group C(P>0.05). In the experimental group, there was significant difference between group B1, C1 and A1 (P<0.05). The results of group B1 and C1 were lower than that of group A1, but there was no significant difference between group B1 and group C1(P>0.05). In the control group, there were significant differences between group B2, C2 and A2 (P<0.05). The results of group B2 and C2 were lower than that of group A2, but there was no significant difference between group B2 and C2(P>0.05). Comparison of the amount of bacteria in dentin debris between the experimental group and the control group showed that the effect of group C was the best, followed by group B, and group A, and there were significant differences between three groups(P<0.05). CONCLUSIONS: The disinfection effect of Er:YAG laser or ultrasound assisted computer-guided precision minimally invasive root canal treatment is similar to conventional root canal treatment, and Er:YAG laser is better than ultrasound in removing bacteria from dentinal tubules, which is more suitable for minimally invasive root canal treatment.


Assuntos
Enterococcus faecalis , Hipoclorito de Sódio , Cavidade Pulpar/microbiologia , Desinfecção/métodos , Ácido Edético , Irrigantes do Canal Radicular , Preparo de Canal Radicular/métodos , Hipoclorito de Sódio/farmacologia
9.
Nat Chem Biol ; 18(3): 332-341, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35210619

RESUMO

Understanding the function and regulation of enzymes within their physiologically relevant milieu requires quality tools that report on their cellular activities. Here we describe a strategy for glycoside hydrolases that overcomes several limitations in the field, enabling quantitative monitoring of their activities within live cells. We detail the design and synthesis of bright and modularly assembled bis-acetal-based (BAB) fluorescence-quenched substrates, illustrating this strategy for sensitive quantitation of disease-relevant human α-galactosidase and α-N-acetylgalactosaminidase activities. We show that these substrates can be used within live patient cells to precisely measure the engagement of target enzymes by inhibitors and the efficiency of pharmacological chaperones, and highlight the importance of quantifying activity within cells using chemical perturbogens of cellular trafficking and lysosomal homeostasis. These BAB substrates should prove widely useful for interrogating the regulation of glycosidases within cells as well as in facilitating the development of therapeutics and diagnostics for this important class of enzymes.


Assuntos
Acetais , Lisossomos , Fluorescência , Glicosídeo Hidrolases , Humanos , alfa-Galactosidase
10.
ACS Chem Biol ; 15(4): 824-829, 2020 04 17.
Artigo em Inglês | MEDLINE | ID: mdl-32109051

RESUMO

Within mammals, there are often several functionally related glycoside hydrolases, which makes monitoring their activities problematic. This problem is particularly acute for the enzyme ß-glucocerebrosidase (GCase), the malfunction of which is a key driver of Gaucher's disease (GD) and a major risk factor for Parkinson's disease (PD). Humans harbor two other functionally related ß-glucosidases known as GBA2 and GBA3, and the currently used fluorogenic substrates are not selective, which has driven the use of complicated subtractive assays involving the use of detergents and inhibitors. Here we describe the preparation of fluorogenic substrates based on the widely used nonselective substrate resorufin ß-d-glucopyranoside. Using recombinant enzymes, we show that these substrates are highly selective for GCase. We also demonstrate their value through the analysis of GCase activity in brain tissue homogenates from transgenic mice expressing mutant human GCase and patient fibroblasts expressing mutant GCase. This approach simplifies the analysis of cell and tissue homogenates and should facilitate the analysis of clinical and laboratory tissues and samples.


Assuntos
Benzoxazinas/metabolismo , Corantes Fluorescentes/metabolismo , Glucosídeos/metabolismo , Glucosilceramidase/análise , Animais , Benzoxazinas/síntese química , Encéfalo/enzimologia , Ensaios Enzimáticos/métodos , Fibroblastos/enzimologia , Corantes Fluorescentes/síntese química , Glucosídeos/síntese química , Glucosilceramidase/genética , Glucosilceramidase/metabolismo , Humanos , Cinética , Camundongos Transgênicos , Mutação
11.
Angew Chem Int Ed Engl ; 57(26): 7644-7648, 2018 06 25.
Artigo em Inglês | MEDLINE | ID: mdl-29756380

RESUMO

O-Linked glycosylation of serine and threonine residues of nucleocytoplasmic proteins with N-acetylglucosamine (O-GlcNAc) residues is catalyzed by O-GlcNAc transferase (OGT). O-GlcNAc is conserved within mammals and is implicated in a wide range of physiological processes. Herein, we describe metabolic precursor inhibitors of OGT suitable for use both in cells and in vivo in mice. These 5-thiosugar analogues of N-acetylglucosamine are assimilated through a convergent metabolic pathway, most likely involving N-acetylglucosamine-6-phosphate de-N-acetylase (NAGA), to generate a common OGT inhibitor within cells. We show that of these inhibitors, 2-deoxy-2-N-hexanamide-5-thio-d-glucopyranoside (5SGlcNHex) acts in vivo to induce dose- and time-dependent decreases in O-GlcNAc levels in various tissues. Decreased O-GlcNAc correlates, both in vitro within adipocytes and in vivo within mice, with lower levels of the transcription factor Sp1 and the satiety-inducing hormone leptin, thus revealing a link between decreased O-GlcNAc levels and nutrient sensing in peripheral tissues of mammals.


Assuntos
Acetilglucosamina/metabolismo , Inibidores Enzimáticos/farmacologia , Leptina/metabolismo , N-Acetilglucosaminiltransferases/antagonistas & inibidores , Adipócitos/metabolismo , Animais , Relação Dose-Resposta a Droga , Eletroforese Capilar , Ensaio de Imunoadsorção Enzimática , Glicosilação , Camundongos , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/enzimologia , N-Acetilglucosaminiltransferases/metabolismo , Fosforilação , Especificidade por Substrato
12.
ACS Chem Neurosci ; 9(6): 1366-1379, 2018 06 20.
Artigo em Inglês | MEDLINE | ID: mdl-29460617

RESUMO

The glycosylation of nucleocytoplasmic proteins with O-linked N-acetylglucosamine residues (O-GlcNAc) is conserved among metazoans and is particularly abundant within brain. O-GlcNAc is involved in diverse cellular processes ranging from the regulation of gene expression to stress response. Moreover, O-GlcNAc is implicated in various diseases including cancers, diabetes, cardiac dysfunction, and neurodegenerative diseases. Pharmacological inhibition of O-GlcNAcase (OGA), the sole enzyme that removes O-GlcNAc, reproducibly slows neurodegeneration in various Alzheimer's disease (AD) mouse models manifesting either tau or amyloid pathology. These data have stimulated interest in the possibility of using OGA-selective inhibitors as pharmaceuticals to alter the progression of AD. The mechanisms mediating the neuroprotective effects of OGA inhibitors, however, remain poorly understood. Here we show, using a range of methods in neuroblastoma N2a cells, in primary rat neurons, and in mouse brain, that selective OGA inhibitors stimulate autophagy through an mTOR-independent pathway without obvious toxicity. Additionally, OGA inhibition significantly decreased the levels of toxic protein species associated with AD pathogenesis in the JNPL3 tauopathy mouse model as well as the 3×Tg-AD mouse model. These results strongly suggest that OGA inhibitors act within brain through a mechanism involving enhancement of autophagy, which aids the brain in combatting the accumulation of toxic protein species. Our study supports OGA inhibition being a feasible therapeutic strategy for hindering the progression of AD and other neurodegenerative diseases. Moreover, these data suggest more targeted strategies to stimulate autophagy in an mTOR-independent manner may be found within the O-GlcNAc pathway. These findings should aid the advancement of OGA inhibitors within the clinic.


Assuntos
Autofagia/efeitos dos fármacos , Serina-Treonina Quinases TOR/farmacologia , Doença de Alzheimer/metabolismo , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Modelos Animais de Doenças , Humanos , Neurônios/efeitos dos fármacos , Processamento de Proteína Pós-Traducional/efeitos dos fármacos , Serina-Treonina Quinases TOR/metabolismo , Tauopatias/tratamento farmacológico , Tauopatias/metabolismo , Proteínas tau/efeitos dos fármacos , Proteínas tau/metabolismo
13.
Angew Chem Int Ed Engl ; 54(51): 15429-33, 2015 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-26545827

RESUMO

Pyrrolidine-based iminocyclitols are a promising class of glycosidase inhibitors. Reported herein is a convenient epimerization strategy that provides direct access to a range of stereoisomeric iminocyclitol inhibitors of O-GlcNAcase (OGA), the enzyme responsible for catalyzing removal of O-GlcNAc from nucleocytoplasmic proteins. Structural details regarding the binding of these inhibitors to a bacterial homologue of OGA reveal the basis for potency. These compounds are orally available and permeate into rodent brain to increase O-GlcNAc, and should prove useful tools for studying the role of OGA in health and disease.


Assuntos
Encéfalo/metabolismo , Ciclitóis/farmacocinética , Inibidores Enzimáticos/farmacocinética , beta-N-Acetil-Hexosaminidases/antagonistas & inibidores , Animais , Ciclitóis/química , Inibidores Enzimáticos/química , Camundongos , Camundongos Endogâmicos C57BL , Estrutura Molecular , Estereoisomerismo
14.
J Am Chem Soc ; 137(3): 1181-9, 2015 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-25562638

RESUMO

Deficiency of the lysosomal glycoside hydrolase glucocerebrosidase (GCase) leads to abnormal accumulation of glucosyl ceramide in lysosomes and the development of the lysosomal storage disease known as Gaucher's disease. More recently, mutations in the GBA1 gene that encodes GCase have been uncovered as a major genetic risk factor for Parkinson's disease (PD). Current therapeutic strategies to increase GCase activity in lysosomes involve enzyme replacement therapy (ERT) and molecular chaperone therapy. One challenge associated with developing and optimizing these therapies is the difficulty in determining levels of GCase activity present within the lysosomes of live cells. Indeed, visualizing the activity of endogenous levels of any glycoside hydrolases, including GCase, has proven problematic within live mammalian cells. Here we describe the successful modular design and synthesis of fluorescence-quenched substrates for GCase. The selection of a suitable fluorophore and quencher pair permits the generation of substrates that allow convenient time-dependent monitoring of endogenous GCase activity within cells as well as localization of activity within lysosomes. These efficiently quenched (∼99.9%) fluorescent substrates also permit assessment of GCase inhibition in live cells by either confocal microscopy or high content imaging. Such substrates should enable improved understanding of GCase in situ as well the optimization of small-molecule chaperones for this enzyme. These findings also suggest routes to generate fluorescence-quenched substrates for other mammalian glycoside hydrolases for use in live cell imaging.


Assuntos
Fibroblastos/enzimologia , Corantes Fluorescentes/química , Glucosilceramidase/metabolismo , Células Cultivadas , Ativação Enzimática , Corantes Fluorescentes/síntese química , Humanos , Lisossomos/metabolismo , Microscopia Confocal , Microscopia de Fluorescência , Estrutura Molecular
15.
J Biol Chem ; 289(50): 34472-81, 2014 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-25336656

RESUMO

Regional glucose hypometabolism is a defining feature of Alzheimer disease (AD). One emerging link between glucose hypometabolism and progression of AD is the nutrient-responsive post-translational O-GlcNAcylation of nucleocytoplasmic proteins. O-GlcNAc is abundant in neurons and occurs on both tau and amyloid precursor protein. Increased brain O-GlcNAcylation protects against tau and amyloid-ß peptide toxicity. Decreased O-GlcNAcylation occurs in AD, suggesting that glucose hypometabolism may impair the protective roles of O-GlcNAc within neurons and enable neurodegeneration. Here, we review how O-GlcNAc may link cerebral glucose hypometabolism to progression of AD and summarize data regarding the protective role of O-GlcNAc in AD models.


Assuntos
Acetilglucosamina/metabolismo , Doença de Alzheimer/metabolismo , Doença de Alzheimer/etiologia , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/metabolismo , Animais , Glucose/metabolismo , Humanos , Neurônios/metabolismo , Proteínas tau/metabolismo
16.
Mol Neurodegener ; 9: 42, 2014 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-25344697

RESUMO

BACKGROUND: Amyloid plaques and neurofibrillary tangles (NFTs) are the defining pathological hallmarks of Alzheimer's disease (AD). Increasing the quantity of the O-linked N-acetylglucosamine (O-GlcNAc) post-translational modification of nuclear and cytoplasmic proteins slows neurodegeneration and blocks the formation of NFTs in a tauopathy mouse model. It remains unknown, however, if O-GlcNAc can influence the formation of amyloid plaques in the presence of tau pathology. RESULTS: We treated double transgenic TAPP mice, which express both mutant human tau and amyloid precursor protein (APP), with a highly selective orally bioavailable inhibitor of the enzyme responsible for removing O-GlcNAc (OGA) to increase O-GlcNAc in the brain. We find that increased O-GlcNAc levels block cognitive decline in the TAPP mice and this effect parallels decreased ß-amyloid peptide levels and decreased levels of amyloid plaques. CONCLUSIONS: This study indicates that increased O-GlcNAc can influence ß-amyloid pathology in the presence of tau pathology. The findings provide good support for OGA as a promising therapeutic target to alter disease progression in Alzheimer disease.


Assuntos
Doença de Alzheimer/enzimologia , N-Acetilglucosaminiltransferases/metabolismo , Placa Amiloide/patologia , Doença de Alzheimer/patologia , Precursor de Proteína beta-Amiloide/genética , Animais , Western Blotting , Modelos Animais de Doenças , Inibidores Enzimáticos/farmacologia , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Imuno-Histoquímica , Aprendizagem em Labirinto/efeitos dos fármacos , Camundongos , Camundongos Transgênicos , Proteínas tau/genética
17.
Neurosci Lett ; 516(2): 296-301, 2012 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-22521585

RESUMO

In the neurodegenerative disease amyotrophic lateral sclerosis (ALS), a number of proteins have been found to be hyperphosphorylated, including neurofilament proteins (NFs). In addition to protein phosphorylation, another important post-translational modification is O-glycosylation with ß-N-acetylglucosamine residues (O-GlcNAc) and it has been found that O-GlcNAc can modify proteins competitively with protein phosphorylation, so that increased O-GlcNAc can reduce phosphorylation at specific sites. We evaluated a transgenic mouse model of ALS that overexpresses mutant superoxide dismutase (mSOD) and found that O-GlcNAc immunoreactivity levels are decreased in spinal cord tissue from mSOD mice, compared to controls. This reduction in O-GlcNAc levels is prominent in the motor neurons of spinal cord. We find that inhibition of O-GlcNAcase (OGA), the enzyme catalyzing removal of O-GlcNAc, using the inhibitor NButGT for 3 days, resulted in increased O-GlcNAc levels in spinal cord, both in mSOD and control mice. Furthermore, NButGT increased levels of O-GlcNAc modified NF-medium in spinal cords of control mice, but not in mSOD mice. These observations suggest that the neurodegeneration found in mSOD mice is associated with a reduction of O-GlcNAc levels in neurons, including motor neurons.


Assuntos
Esclerose Lateral Amiotrófica/metabolismo , Proteínas/metabolismo , Medula Espinal/metabolismo , Superóxido Dismutase/metabolismo , Animais , Western Blotting , Modelos Animais de Doenças , Glicosilação , Humanos , Imuno-Histoquímica , Camundongos , Camundongos Transgênicos , Mutação , Neurônios/metabolismo , Processamento de Proteína Pós-Traducional , Superóxido Dismutase/genética , Superóxido Dismutase-1
18.
Nat Chem Biol ; 8(4): 393-9, 2012 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-22366723

RESUMO

Oligomerization of tau is a key process contributing to the progressive death of neurons in Alzheimer's disease. Tau is modified by O-linked N-acetylglucosamine (O-GlcNAc), and O-GlcNAc can influence tau phosphorylation in certain cases. We therefore speculated that increasing tau O-GlcNAc could be a strategy to hinder pathological tau-induced neurodegeneration. Here we found that treatment of hemizygous JNPL3 tau transgenic mice with an O-GlcNAcase inhibitor increased tau O-GlcNAc, hindered formation of tau aggregates and decreased neuronal cell loss. Notably, increases in tau O-GlcNAc did not alter tau phosphorylation in vivo. Using in vitro biochemical aggregation studies, we found that O-GlcNAc modification, on its own, hinders tau oligomerization. O-GlcNAc also inhibits thermally induced aggregation of an unrelated protein, TAK-1 binding protein, suggesting that a basic biochemical function of O-GlcNAc may be to prevent protein aggregation. These results also suggest O-GlcNAcase as a potential therapeutic target that could hinder progression of Alzheimer's disease.


Assuntos
Acetilglucosamina/metabolismo , Proteínas tau/metabolismo , Acetilglucosamina/química , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Animais , Configuração de Carboidratos , Modelos Animais de Doenças , Inibidores Enzimáticos/farmacologia , Feminino , Humanos , Camundongos , Camundongos Transgênicos , N-Acetilglucosaminiltransferases/antagonistas & inibidores , N-Acetilglucosaminiltransferases/metabolismo , Doenças Neurodegenerativas/tratamento farmacológico , Doenças Neurodegenerativas/metabolismo , Doenças Neurodegenerativas/patologia , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Neurônios/patologia , Fosforilação , Piranos/farmacologia , Tiazóis/farmacologia , Proteínas tau/genética
19.
Chem Biol ; 17(9): 949-58, 2010 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-20851344

RESUMO

The O-GlcNAc modification is proposed to be a nutrient sensor with studies suggesting that global increases in O-GlcNAc levels cause insulin resistance and impaired glucohomeostasis. We address this hypothesis by using a potent and selective inhibitor of O-GlcNAcase, known as NButGT, in a series of in vivo studies. Treatment of rats and mice with NButGT, for various time regimens and doses, dramatically increases O-GlcNAc levels throughout all tissues but does not perturb insulin sensitivity or alter glucohomeostasis. NButGT also does not affect the severity or onset of insulin resistance induced by a high-fat diet. These results suggest that pharmacological increases in global O-GlcNAc levels do not cause insulin resistance nor do they appear to disrupt glucohomeostasis. Therefore, the protective benefits of elevated O-GlcNAc levels may be achieved without deleteriously affecting glucohomeostasis.


Assuntos
Acetilglucosamina/metabolismo , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Inibidores Enzimáticos/farmacologia , Glucose/metabolismo , Resistência à Insulina , beta-N-Acetil-Hexosaminidases/antagonistas & inibidores , Animais , Compostos Bicíclicos Heterocíclicos com Pontes/química , Inibidores Enzimáticos/química , Gangliosídeo G(M2)/metabolismo , Camundongos , Ratos , Ratos Sprague-Dawley , Transdução de Sinais , beta-N-Acetil-Hexosaminidases/metabolismo
20.
Neurosci Lett ; 458(2): 70-4, 2009 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-19379791

RESUMO

Previous evidence demonstrates that TAR DNA binding protein (TDP-43) mislocalization is a key pathological feature of amyotrophic lateral sclerosis (ALS). TDP-43 normally shows nuclear localization, but in CNS tissue from patients who died with ALS this protein mislocalizes to the cytoplasm. Disease specific TDP-43 species have also been reported to include hyperphosphorylated TDP-43, as well as a C-terminal fragment. Whether these abnormal TDP-43 features are present in patients with SOD1-related familial ALS (fALS), or in mutant SOD1 over-expressing transgenic mouse models of ALS remains controversial. Here we investigate TDP-43 pathology in transgenic mice expressing the G93A mutant form of SOD1. In contrast to previous reports we observe redistribution of TDP-43 to the cytoplasm of motor neurons in mutant SOD1 transgenic mice, but this is seen only in mice having advanced disease. Furthermore, we also observe rounded TDP-43 immunoreactive inclusions associated with intense ubiquitin immunoreactivity in lumbar spinal cord at end stage disease in mSOD mice. These data indicate that TDP-43 mislocalization and ubiquitination are present in end stage mSOD mice. However, we do not observe C-terminal TDP-43 fragments nor TDP-43 hyperphosphorylated species in these end stage mSOD mice. Our findings indicate that G93A mutant SOD1 transgenic mice recapitulate some key pathological, but not all biochemical hallmarks, of TDP-43 pathology previously observed in human ALS. These studies suggest motor neuron degeneration in the mutant SOD1 transgenic mice is associated with TDP-43 histopathology.


Assuntos
Esclerose Lateral Amiotrófica , Proteínas de Ligação a DNA/metabolismo , Medula Espinal/metabolismo , Superóxido Dismutase/genética , Esclerose Lateral Amiotrófica/genética , Esclerose Lateral Amiotrófica/metabolismo , Esclerose Lateral Amiotrófica/patologia , Animais , Modelos Animais de Doenças , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Neurônios Motores/citologia , Neurônios Motores/metabolismo , Fosfopiruvato Hidratase/metabolismo , Transporte Proteico/genética , Medula Espinal/patologia
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