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1.
Cell ; 173(6): 1552-1552.e1, 2018 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-29856960

RESUMO

Post-translational modification of tubulin offers a mechanism for functional diversification of microtubules and regulation in a variety of physiological contexts. This SnapShot recaps the current state of understanding of tubulin posttranslational modifications and their functions in the regulation of biological processes. To view this SnapShot, open or download the PDF.


Assuntos
Processamento de Proteína Pós-Traducional , Tubulina (Proteína)/química , Animais , Humanos , Microtúbulos/química , Modelos Biológicos , Neurônios/metabolismo
2.
Cell ; 173(6): 1323-1327, 2018 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-29856952

RESUMO

Tubulin posttranslational modifications are currently emerging as important regulators of the microtubule cytoskeleton and thus have a strong potential to be implicated in a number of disorders. Here, we review the latest advances in understanding the physiological roles of tubulin modifications and their links to a variety of pathologies.


Assuntos
Processamento de Proteína Pós-Traducional , Tubulina (Proteína)/química , Animais , Plaquetas/metabolismo , Cílios/metabolismo , Citoesqueleto/metabolismo , Flagelos/metabolismo , Cardiopatias/metabolismo , Humanos , Camundongos , Microtúbulos/metabolismo , Mutação , Doenças Neurodegenerativas/terapia , Fenótipo , Fatores de Risco , Tubulina (Proteína)/fisiologia
3.
J Contemp Dent Pract ; 23(1): 83-88, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-35656663

RESUMO

AIM: The goal of this study was to compare the effects of magnetized water and 0.2% chlorhexidine mouthwash on gingivitis and plaque prevention in children aged 12-15 years for a period of 21 days. MATERIALS AND METHODS: A total of 24 youngsters between the ages of 12 and 15 years were chosen. A computer-generated random number sequence was used to split the research participants into two groups. Magnetized water was utilized as a mouthrinse in Category 1, while 0.2% chlorhexidine was employed in Category 2. Water purified with reverse osmosis was stored in glass bottles, which were then put near the magnets to create magnetic water. The magnets had 1000 Gauss power. The bottles were put for a period of 24 hours. The youngsters were given 140 mL of mouthrinse. These mouthrinses were to be used at home, they were told. The Gilmore Turesky adaptation of Quigley Hein's plaque index was used to assess the plaque whereas the gingival index recommended by Loe and Sillness was utilized to assess the gingiva. The plaque index and gingival index were analyzed at baseline, 14 days, and 21 days, as well as history and examination for adverse effects such as bitter taste, brownish discoloration, and so on, were recorded. The trial lasted 21 days with a follow-up period of another 21 days. RESULTS: Both magnetic water and chlorhexidine were similarly successful in managing periodontal and gingival infections; however, magnetized water had less side effects, such as a bitter metallic taste and brown stains. CONCLUSION: Because of its well-accepted flavor, softer nature, and lower frequency of brown stains, magnetized water can be a safer and more acceptable alternative to chlorhexidine mouthwashes, especially in youngsters. CLINICAL SIGNIFICANCE: The use of chlorhexidine as a mouthrinse in the oral cavity has been linked to side effects. These side effects are mostly localized, such as brownish discoloration of teeth, alterations in taste perception, and erosion of the oral mucosa. As chlorhexidine has such negative side effects, it was necessary to do research, particularly in children, to identify a replacement that is similarly efficient against germs but does not have these side effects. Water treated with a magnetic field (magnetized water) was compared with chlorhexidine in the current study.


Assuntos
Anti-Infecciosos , Placa Dentária , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Adolescente , Criança , Clorexidina/farmacologia , Clorexidina/uso terapêutico , Placa Dentária/prevenção & controle , Humanos , Antissépticos Bucais/farmacologia , Antissépticos Bucais/uso terapêutico , Água
4.
Plant Cell Rep ; 40(9): 1617-1630, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34159416

RESUMO

One of the most interesting signaling molecules that regulates a wide array of adaptive stress responses in plants are the micro RNAs (miRNAs) that are a unique class of non-coding RNAs constituting novel mechanisms of post-transcriptional gene regulation. Recent studies revealed the role of miRNAs in several biotic and abiotic stresses by regulating various phytohormone signaling pathways as well as by targeting a number of transcription factors (TFs) and defense related genes. Phytohormones are signal molecules modulating the plant growth and developmental processes by regulating gene expression. Studies concerning miRNAs in abiotic stress response also show their vital roles in abiotic stress signaling. Current research indicates that miRNAs may act as possible candidates to create abiotic stress tolerant crop plants by genetic engineering. Yet, the detailed mechanism governing the dynamic expression networks of miRNAs in response to stress tolerance remains unclear. In this review, we provide recent updates on miRNA-mediated regulation of phytohormones combating various stress and its role in adaptive stress response in crop plants.


Assuntos
MicroRNAs/fisiologia , Reguladores de Crescimento de Plantas/metabolismo , Fenômenos Fisiológicos Vegetais/genética , Estresse Fisiológico/genética , Secas , Regulação da Expressão Gênica de Plantas , Metais Pesados/toxicidade , MicroRNAs/genética , Reguladores de Crescimento de Plantas/genética , RNA de Plantas/genética , RNA de Plantas/metabolismo , Estresse Salino/genética , Transdução de Sinais , Raios Ultravioleta
5.
J Contemp Dent Pract ; 22(4): 373-377, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-34267006

RESUMO

AIM AND OBJECTIVE: To evaluate the effect of nonsurgical periodontal therapy on periodontal parameters, serum C-reactive protein (CRP) level, total leukocyte count (TLC), and differential leukocyte count (DLC) in normolipidemic patients with generalized chronic periodontitis. MATERIALS AND METHODS: A total of 60 subjects (38 males and 22 females) between 20 and 55 years of age were included in this study. Twenty subjects with generalized chronic gingivitis were assigned group I. Forty subjects with generalized chronic periodontitis were randomly divided into test groups, i.e., group II (n = 20) and control group, i.e., group III (n = 20). At baseline, clinical parameters (plaque and gingival indices, clinical attachment loss) were recorded and blood collected for lipid profile test, TLC, DLC, and CRP estimation. Patients with lipid values in the normal range continued the study. Groups I and II were provided nonsurgical periodontal therapy. Follow-up clinical examination and blood examination were done for CRP level, TLC, and DLC after 1 and 2 months. RESULTS: A significant improvement in the clinical parameters was evident following scaling and root planning in group II as compared to group III. A decrease in serum CRP and TLC count was also observed, but the difference was not significant. Moreover, a reduction was observed in neutrophils, monocytes, eosinophils post therapeutically in group II but the decrease was significant only for monocyte count. CONCLUSION: Based on the findings of the study, it can be concluded that nonsurgical periodontal therapy can reduce the inflammatory component. CLINICAL SIGNIFICANCE: Periodontal diseases comprise a wide range of inflammatory conditions affecting the supporting structures of teeth. Effect of nonsurgical periodontal therapy on chronic periodontitis can be evaluated by measuring the CRP and leukocyte concentration.


Assuntos
Periodontite Crônica , Proteínas de Fase Aguda , Periodontite Crônica/terapia , Raspagem Dentária , Feminino , Humanos , Contagem de Leucócitos , Masculino , Perda da Inserção Periodontal , Índice Periodontal
6.
J Biol Chem ; 294(38): 13983-13994, 2019 09 20.
Artigo em Inglês | MEDLINE | ID: mdl-31362984

RESUMO

HNF4α (hepatocyte nuclear factor 4α) is one of the master regulators of pancreatic ß-cell development and function, and mutations in the HNF4α gene are well-known monogenic causes of diabetes. As a member of the nuclear receptor family, HNF4α exerts its gene regulatory function through various molecular interactions; however, there is a paucity of knowledge of the different functional complexes in which HNF4α participates. Here, to find HNF4α-binding proteins in pancreatic ß-cells, we used yeast two-hybrid screening, a mammalian two-hybrid assay, and glutathione S-transferase pulldown approaches, which identified EBP1 (ErbB3-binding protein 1) as a factor that binds HNF4α in a LXXLL motif-mediated manner. In the ß-cells, EBP1 suppressed the expression of HNF4α target genes that are implicated in insulin secretion, which is impaired in HNF4α mutation-driven diabetes. The crystal structure of the HNF4α ligand-binding domain in complex with a peptide harboring the EBP1 LXXLL motif at 3.15Å resolution hinted at the molecular basis of the repression. The details of the structure suggested that EBP1's LXXLL motif competes with HNF4α coactivators for the same binding pocket and thereby prevents recruitment of additional transcriptional coactivators. These findings provide further evidence that EBP1 plays multiple cellular roles and is involved in nuclear receptor-mediated gene regulation. Selective disruption of the HNF4α-EBP1 interaction or tissue-specific EBP1 inactivation can enhance HNF4α activities and thereby improve insulin secretion in ß-cells, potentially representing a new strategy for managing diabetes and related metabolic disorders.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Fator 4 Nuclear de Hepatócito/metabolismo , Células Secretoras de Insulina/metabolismo , Proteínas de Ligação a RNA/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/fisiologia , Proteínas de Transporte/metabolismo , Proteínas de Ligação a DNA/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Regulação da Expressão Gênica/genética , Células HeLa , Fator 4 Nuclear de Hepatócito/fisiologia , Humanos , Insulina/metabolismo , Secreção de Insulina/genética , Células Secretoras de Insulina/fisiologia , Regiões Promotoras Genéticas/genética , Ligação Proteica/fisiologia , Proteínas de Ligação a RNA/fisiologia , Fatores de Transcrição
7.
J Surg Res ; 255: 13-22, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32540576

RESUMO

BACKGROUND: Anal SCC is a rare disease mainly treated with chemoradiation. Abdominoperineal resection (APR), once the mainstay of treatment for anal cancer, now serves a role as salvage therapy for persistent or recurrent disease after chemoradiation. In addition, clinically positive nodes are currently treated by extending the radiation field to the groin. The role of inguinal lymph node dissection in recurrent or persistent anal SCC is unclear. The aim of the study is to determine the role of inguinal lymph node dissection in the management of inguinal lymph node metastasis for anal squamous cell carcinoma (SCC). METHODS: Retrospective analysis of patients with anal SCC in the National Cancer Database with positive inguinal nodes undergoing salvage APR between 2004 and 2014 was performed. A comparison of overall survival between patients who underwent APR with lymph node dissection versus APR only was analyzed using Kaplan-Meier plot. RESULTS: A total of 3424 patients underwent salvage APR, with 274 (8%) having clinically positive nodes. Within the subgroup that had clinically positive nodes, 195 (71%) underwent APR, whereas 79 (29%) underwent both APR and node dissection. Kaplan-Meier analysis demonstrates no difference in overall survival in the two groups (P = 0.99). Five-year survival for both groups was similar (36% versus 42%; P = 0.987). No significant difference was found when adjusted for age, gender, and Tumor Node Metastasis staging. CONCLUSIONS: Inguinal lymph node dissection does not appear to improve overall survival in patients with advanced-stage anal cancer requiring salvage APR. Proper patient selection for node dissection is essential to spare patients from additional morbid procedures.


Assuntos
Neoplasias do Ânus/terapia , Carcinoma de Células Escamosas/terapia , Excisão de Linfonodo/estatística & dados numéricos , Metástase Linfática/terapia , Protectomia/métodos , Terapia de Salvação/estatística & dados numéricos , Idoso , Neoplasias do Ânus/mortalidade , Neoplasias do Ânus/patologia , Carcinoma de Células Escamosas/mortalidade , Carcinoma de Células Escamosas/secundário , Quimiorradioterapia Adjuvante , Feminino , Humanos , Canal Inguinal , Estimativa de Kaplan-Meier , Linfonodos/patologia , Linfonodos/cirurgia , Masculino , Pessoa de Meia-Idade , Terapia Neoadjuvante/métodos , Estadiamento de Neoplasias , Seleção de Pacientes , Protectomia/estatística & dados numéricos , Estudos Retrospectivos , Terapia de Salvação/métodos
8.
J Contemp Dent Pract ; 21(6): 632-635, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33025931

RESUMO

AIM: To compare the effect of three different intracanal medicaments, namely, modified triple antibiotic paste (MTAP), calcium hydroxide (Ca(OH)2), and aloe vera, on the root dentine microhardness. MATERIALS AND METHODS: A total of 50 extracted mandibular bicuspids were prepared using ProTaper Next rotary files. The roots of the bicuspids were alienated to three groups (n = 10 each) and one control group (untreated; n = 20). In three groups, the root canals were filled with MTAP, Ca(OH)2, and aloe vera medicaments. After 21 days, medicaments were removed by Endo activator. Mean Knoop hardness numbers were calculated after treatment and compared with the untreated control group. Data were evaluated using the Student's t test (paired), ANOVA (one-way) followed, and the post hoc test. RESULTS: All treated groups except the aloe vera group had shown significant reduction (p < 0.05) in microhardness of the root dentin as compared with the untreated control group. The aloe vera group showed least reduction of microhardness and was statistically insignificant (p > 0.05). CONCLUSION: Aloe vera shows promising results in terms of fewer effects on microhardness of the root dentin compared to MTAP and Ca(OH)2. CLINICAL SIGNIFICANCE: Elimination of most of the bacterial infection from the root canal and very minimum to no effect on the microhardness of the dentin in the root part are the basics of success in any endodontic treatment. Further in vivo studies are required to compare the efficacy of these intracanal medicaments.


Assuntos
Aloe , Óxido de Zinco , Antibacterianos , Hidróxido de Cálcio , Dentina , Humanos
9.
J Struct Biol ; 198(1): 54-64, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-28223045

RESUMO

Human glucose-6-phosphatase plays a vital role in blood glucose homeostasis and holds promise as a therapeutic target for diabetes. Expression of its catalytic subunit gene 1 (G6PC1) is tightly regulated by metabolic-response transcription factors such as FoxO1 and CREB. Although at least three potential FoxO1 binding sites (insulin response elements, IREs) and one CREB binding site (cAMP response element, CRE) within the proximal region of the G6PC1 promoter have been identified, the interplay between FoxO1 and CREB and between FoxO1 bound at multiple IREs has not been well characterized. Here we present the crystal structures of the FoxO1 DNA binding domain in complex with the G6PC1 promoter. These complexes reveal the presence of a new non-consensus FoxO1 binding site that overlaps the CRE, suggesting a mutual exclusion mechanism for FoxO1 and CREB binding at the G6PC1 promoter. Additional findings include (i) non-canonical FoxO1 recognition sites, (ii) incomplete FoxO1 occupancies at the available IRE sites, and (iii) FoxO1 dimeric interactions that may play a role in stabilizing DNA looping. These findings provide insight into the regulation of G6PC1 gene transcription by FoxO1, and demonstrate a high versatility of target gene recognition by FoxO1 that correlates with its diverse roles in biology.


Assuntos
Proteína Forkhead Box O1/metabolismo , Glucose-6-Fosfatase/genética , Regiões Promotoras Genéticas , Sítios de Ligação , Domínio Catalítico/genética , Cristalografia por Raios X , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Regulação da Expressão Gênica , Humanos , Fatores de Transcrição/metabolismo
10.
J Biol Chem ; 289(46): 31719-31735, 2014 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-25246530

RESUMO

Centrosome-mediated microtubule nucleation is essential for spindle assembly during mitosis. Although γ-tubulin complexes have primarily been implicated in the nucleation process, details of the underlying mechanisms remain poorly understood. Here, we demonstrated that a member of the human transforming acidic coiled-coil (TACC) protein family, TACC3, plays a critical role in microtubule nucleation at the centrosome. In mitotic cells, TACC3 knockdown substantially affected the assembly of microtubules in the astral region and impaired microtubule nucleation at the centrosomes. The TACC3 depletion-induced mitotic phenotype was rescued by expression of the TACC3 C terminus predominantly consisting of the TACC domain, suggesting that the TACC domain plays an important role in microtubule assembly. Consistently, experiments with the recombinant TACC domain of TACC3 demonstrated that this domain possesses intrinsic microtubule nucleating activity. Co-immunoprecipitation and sedimentation experiments revealed that TACC3 mediates interactions with proteins of both the γ-tubulin ring complex (γ-TuRC) and the γ-tubulin small complex (γ-TuSC). Interestingly, TACC3 depletion resulted in reduced levels of γ-TuRC and increased levels of γ-TuSC, indicating that the assembly of γ-TuRC from γ-TuSC requires TACC3. Detailed analyses suggested that TACC3 facilitates the association of γ-TuSC-specific proteins with the proteins known to be involved in the assembly of γ-TuRC. Consistent with such a role for TACC3, the suppression of TACC3 disrupted localization of γ-TuRC proteins to the centrosome. Our findings reveal that TACC3 is involved in the regulation of microtubule nucleation at the centrosome and functions in the stabilization of the γ-tubulin ring complex assembly.


Assuntos
Regulação da Expressão Gênica , Proteínas Associadas aos Microtúbulos/metabolismo , Microtúbulos/metabolismo , Tubulina (Proteína)/química , Centrossomo/química , Proteínas de Fluorescência Verde/metabolismo , Células HeLa , Humanos , Células MCF-7 , Microscopia de Fluorescência , Centro Organizador dos Microtúbulos/metabolismo , Ligação Proteica , Estrutura Terciária de Proteína , RNA Interferente Pequeno/metabolismo , Fuso Acromático/metabolismo
11.
J Biol Chem ; 289(52): 35839-48, 2014 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-25368326

RESUMO

Non-small-cell lung cancer (NSCLC) is associated with diverse genetic alterations including mutation of epidermal growth factor receptor (EGFR). Isoliquiritigenin (ILQ), a chalcone derivative, possesses anticancer activities. In the present study, we investigated the effects of ILQ on the growth of tyrosine kinase inhibitor (TKI)-sensitive and -resistant NSCLC cells and elucidated its underlying mechanisms. Treatment with ILQ inhibited growth and induced apoptosis in both TKI-sensitive and -resistant NSCLC cells. ILQ-induced apoptosis was associated with the cleavage of caspase-3 and poly-(ADP-ribose)-polymerase, increased expression of Bim, and reduced expression of Bcl-2. In vitro kinase assay results revealed that ILQ inhibited the catalytic activity of both wild type and double mutant (L858R/T790M) EGFR. Treatment with ILQ inhibited the anchorage-independent growth of NIH3T3 cells stably transfected with either wild type or double-mutant EGFR with or without EGF stimulation. ILQ also reduced the phosphorylation of Akt and ERK1/2 in both TKI-sensitive and -resistant NSCLC cells, and attenuated the kinase activity of Akt1 and ERK2 in vitro. ILQ directly interacted with both wild type and double-mutant EGFR in an ATP-competitive manner. A docking model study showed that ILQ formed two hydrogen bonds (Glu-762 and Met-793) with wild type EGFR and three hydrogen bonds (Lys-745, Met-793, and Asp-855) with mutant EGFR. ILQ attenuated the xenograft tumor growth of H1975 cells, which was associated with decreased expression of Ki-67 and diminished phosphorylation of Akt and ERK1/2. Taken together, ILQ suppresses NSCLC cell growth by directly targeting wild type or mutant EGFR.


Assuntos
Antineoplásicos Fitogênicos/farmacologia , Apoptose/efeitos dos fármacos , Chalconas/farmacologia , Receptores ErbB/genética , Neoplasias Pulmonares/tratamento farmacológico , Animais , Linhagem Celular Tumoral , Proliferação de Células , Receptores ErbB/antagonistas & inibidores , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Células HEK293 , Humanos , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patologia , Camundongos , Camundongos Nus , Mutação de Sentido Incorreto , Células NIH 3T3 , Ligação Proteica , Processamento de Proteína Pós-Traducional , Proteínas Proto-Oncogênicas c-akt/metabolismo , Carga Tumoral/efeitos dos fármacos , Ensaios Antitumorais Modelo de Xenoenxerto
12.
BMC Immunol ; 16: 28, 2015 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-25962726

RESUMO

BACKGROUND: Multiple sclerosis (MS) is an autoimmune disease in which dysregulated immune cells attack myelin in the central nervous system (CNS), leading to irreversible neuronal degeneration. Our previous studies have demonstrated that epidermal fatty acid binding protein (E-FABP), widely expressed in immune cells, in particular in dendritic cells (DCs) and T lymphocytes, fuels the overactive immune responses in the mouse model of experimental autoimmune encephalomyelitis (EAE). METHODS: In the present study, we conducted an intensive computational docking analysis to identify novel E-FABP inhibitors for regulation of immune cell functions and for treatment of EAE. RESULTS: We demonstrate that compound [2-(4-acetylphenoxy)-9,10-dimethoxy-6,7-dihydropyrimido[6,1-a]isoquinolin-4-one; designated as EI-03] bound to the lipid binding pocket of E-FABP and enhanced the expression of peroxisome proliferator-activating receptor (PPAR) γ. Further in vitro experiments showed that EI-03 regulated DC functions by inhibition of TNFα production while promoting IL-10 secretion. Moreover, EI-03 treatment counterregulated T cell balance by decreasing effector T cell differentiation (e.g. Th17, Th1) while increasing regulatory T cell development. Most importantly, mice treated with this newly identified compound exhibited reduced clinical symptoms of EAE in mouse models. CONCLUSIONS: Taken together, we have identified a new compound which displays a potential therapeutic benefit for treatment of MS by targeting E-FABP.


Assuntos
Encefalomielite Autoimune Experimental/terapia , Proteínas de Ligação a Ácido Graxo/antagonistas & inibidores , Terapia de Alvo Molecular , Proteínas de Neoplasias/antagonistas & inibidores , Animais , Diferenciação Celular , Citocinas/biossíntese , Células Dendríticas/metabolismo , Avaliação Pré-Clínica de Medicamentos , Proteínas de Ligação a Ácido Graxo/química , Proteínas de Ligação a Ácido Graxo/metabolismo , Camundongos Endogâmicos C57BL , Simulação de Acoplamento Molecular , Proteínas de Neoplasias/química , Proteínas de Neoplasias/metabolismo
13.
Biochem Biophys Res Commun ; 468(1-2): 14-20, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26549228

RESUMO

HNF1α (Hepatocyte Nuclear Factor 1α) is one of the master regulators in pancreatic beta-cell development and function, and the mutations in Hnf1α are the most common monogenic causes of diabetes mellitus. As a member of the POU transcription factor family, HNF1α exerts its gene regulatory function through various molecular interactions; however, there is a paucity of knowledge in their functional complex formation. In this study, we identified the Groucho protein AES (Amino-terminal Enhancer of Split) as a HNF1α-specific physical binding partner and functional repressor of HNF1α-mediated transcription, which has a direct link to glucose-stimulated insulin secretion in beta-cells that is impaired in the HNF1α mutation-driven diabetes.


Assuntos
Fator 1-alfa Nuclear de Hepatócito/metabolismo , Células Secretoras de Insulina/metabolismo , Proteínas Repressoras/metabolismo , Animais , Linhagem Celular , Proteínas Correpressoras , Glucose/metabolismo , Células HeLa , Fator 1-alfa Nuclear de Hepatócito/química , Fator 1-alfa Nuclear de Hepatócito/genética , Humanos , Insulina/metabolismo , Camundongos , Mutação , Domínios e Motivos de Interação entre Proteínas , Mapas de Interação de Proteínas , Transcrição Gênica , Ativação Transcricional
14.
J Neurosci ; 33(23): 9840-5, 2013 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-23739980

RESUMO

Most fast excitatory synaptic transmission in the nervous system is mediated by glutamate acting through ionotropic glutamate receptors (iGluRs). iGluRs (AMPA, kainate, and NMDA receptor subtypes) are tetrameric assemblies, formed as a dimer of dimers. Still, the mechanism underlying tetramerization--the necessary step for the formation of functional receptors that can be inserted into the plasma membrane--is unknown. All eukaryotic compared to prokaryotic iGluR subunits have an additional transmembrane segment, the M4 segment, which positions the physiologically critical C-terminal domain on the cytoplasmic side of the membrane. AMPA receptor (AMPAR) subunits lacking M4 do not express on the plasma membrane. Here, we show that these constructs are retained in the endoplasmic reticulum, the major cellular compartment mediating protein oligomerization. Using approaches to assay the native oligomeric state of AMPAR subunits, we find that subunits lacking M4 or containing single amino acid substitutions along an "interacting" face of the M4 helix that block surface expression no longer tetramerize in either homomeric or heteromeric assemblies. In contrast, subunit dimerization appears to be largely intact. These experiments define the M4 segment as a unique functional unit in AMPARs that is required for the critical dimer-to-tetramer transition.


Assuntos
Células Eucarióticas/química , Multimerização Proteica/fisiologia , Receptores de AMPA/química , Animais , Membrana Celular/química , Membrana Celular/fisiologia , Células Eucarióticas/fisiologia , Células HEK293 , Humanos , Estrutura Secundária de Proteína , Subunidades Proteicas/química , Subunidades Proteicas/fisiologia , Ratos , Receptores de AMPA/fisiologia
15.
Biochemistry ; 53(34): 5551-7, 2014 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-25111064

RESUMO

The +TIP protein EB1 autonomously tracks the growing plus end of microtubules and regulates plus-end dynamics. Previous studies have indicated that EB1 can recognize GTP-bound tubulin structures at the plus end, and it localizes on the microtubule surface at a site close to the exchangeable GTP-binding site of tubulin. Although the GTP-dependent structural change in tubulin has been demonstrated to be a critical determinant for recognition of plus ends by EB1, the effect of GTP on the structure of EB1 has remained unclear. Here, we have used spectroscopic, calorimetric, and biochemical methods to analyze the effect of GTP on EB1 in vitro. Isothermal titration calorimetry and tryptophan fluorescence quenching experiments demonstrated that EB1 binds to GTP with a dissociation constant ~30 µM. Circular dichroism measurements showed that EB1 undergoes changes in its secondary structure on binding GTP. Size-exclusion chromatography and urea-induced unfolding analyses revealed that GTP binding induces dissociation of the EB1 dimer to monomers. Size-exclusion chromatography followed by biochemical analysis further determined that EB1-GTP binding involves association of approximately one molecule of GTP per EB1 monomer. The results reveal a hitherto unknown GTP-dependent mechanism of dimer-to-monomer transition in EB1 and further implicate its possible role in regulating the stability of the EB1 dimer vs monomer as well as plus-end regulation in cells.


Assuntos
Guanosina Trifosfato/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , Calorimetria , Cromatografia em Gel , Dicroísmo Circular , Dimerização , Ligação Proteica
16.
Mol Pharmacol ; 85(2): 237-48, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24220010

RESUMO

Recently we identified the serotonin reuptake inhibitor paroxetine as an inhibitor of G protein-coupled receptor kinase 2 (GRK2) that improves cardiac performance in live animals. Paroxetine exhibits up to 50-fold selectivity for GRK2 versus other GRKs. A better understanding of the molecular basis of this selectivity is important for the development of even more selective and potent small molecule therapeutics and chemical genetic probes. We first sought to understand the molecular mechanisms underlying paroxetine selectivity among GRKs. We directly measured the K(D) for paroxetine and assessed its mechanism of inhibition for each of the GRK subfamilies and then determined the atomic structure of its complex with GRK1, the most weakly inhibited GRK tested. Our results suggest that the selectivity of paroxetine for GRK2 largely reflects its lower affinity for adenine nucleotides. Thus, stabilization of off-pathway conformational states unique to GRK2 will likely be key for the development of even more selective inhibitors. Next, we designed a benzolactam derivative of paroxetine that has optimized interactions with the hinge of the GRK2 kinase domain. The crystal structure of this compound in complex with GRK2 confirmed the predicted interactions. Although the benzolactam derivative did not significantly alter potency of inhibition among GRKs, it exhibited 20-fold lower inhibition of serotonin reuptake. However, there was an associated increase in the potency for inhibition of other AGC kinases, suggesting that the unconventional hydrogen bond formed by the benzodioxole ring of paroxetine is better accommodated by GRKs.


Assuntos
Quinases de Receptores Acoplados a Proteína G/antagonistas & inibidores , Paroxetina/análogos & derivados , Paroxetina/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Inibidores Seletivos de Recaptação de Serotonina/farmacologia , Trifosfato de Adenosina/metabolismo , Cristalografia , Quinase 2 de Receptor Acoplado a Proteína G/antagonistas & inibidores , Quinase 2 de Receptor Acoplado a Proteína G/química , Quinases de Receptores Acoplados a Proteína G/química , Ligação de Hidrogênio , Paroxetina/química , Fosforilação , Conformação Proteica
17.
EMBO J ; 29(19): 3249-59, 2010 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-20729810

RESUMO

G protein-coupled receptor (GPCR) kinases (GRKs) selectively recognize and are allosterically regulated by activated GPCRs, but the molecular basis for this interaction is not understood. Herein, we report crystal structures of GRK6 in which regions known to be critical for receptor phosphorylation have coalesced to stabilize the kinase domain in a closed state and to form a likely receptor docking site. The crux of this docking site is an extended N-terminal helix that bridges the large and small lobes of the kinase domain and lies adjacent to a basic surface of the protein proposed to bind anionic phospholipids. Mutation of exposed, hydrophobic residues in the N-terminal helix selectively inhibits receptor, but not peptide phosphorylation, suggesting that these residues interact directly with GPCRs. Our structural and biochemical results thus provide an explanation for how receptor recognition, phospholipid binding, and kinase activation are intimately coupled in GRKs.


Assuntos
Ativação Enzimática/fisiologia , Quinases de Receptores Acoplados a Proteína G/química , Quinases de Receptores Acoplados a Proteína G/metabolismo , Modelos Moleculares , Conformação Proteica , Transdução de Sinais/fisiologia , Sequência de Aminoácidos , Sítios de Ligação/genética , Cristalização , Análise Mutacional de DNA , Ativação Enzimática/genética , Cinética , Dados de Sequência Molecular , Fosforilação , Nucleosídeos de Pirimidina/química , Nucleosídeos de Pirimidina/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Transdução de Sinais/genética
18.
Cureus ; 16(5): e59530, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38826974

RESUMO

Purpose The portfolio can be used as a crucial tool for self-reflection, which allows us not only to showcase achievements but also course correct on our personal and professional journey. However, there is a significant lack of awareness among medical professionals about portfolios. Arranging a workshop to impart this knowledge could be a potential mitigation approach. This study aims to assess the impact of workshops on portfolios on students' and faculty's knowledge. In addition, the study also analyzes the effect of using rubrics on reflective writing skills. Method A portfolio workshop was organized for the medical faculty and students in the Bundelkhand Government Medical College, Sagar, M.P. The Kirkpatrick model of training evaluation along with a rubric for the evaluation of reflective writing skills were used to measure the effectiveness of the workshop. Pre and post-tests for the workshop, pre and post-reflective writing skills, and workshop feedback were collected using questionnaires. The Shapiro-Wilk test and the Wilcoxon signed rank test were applied to the data collected. Results Out of 89 registrations for the workshop, only 81 people consented to the workshop and participated in the study. The total number of faculty was only 17 and the rest were students from all the phases. Both the Shapiro-Wilk test and the Wilcoxon signed rank test showed a significantly small p-value, stating that there was a significant positive impact on the knowledge, perception, and effectiveness of the workshop. Conclusion This study clearly outlines the positive impact of conducting a workshop on portfolios. A significant increase in participants' knowledge of portfolios is identified. Similarly, employing rubrics has a significant increase in the quality of reflective writing skills.

19.
Chem Commun (Camb) ; 60(35): 4633-4647, 2024 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-38606528

RESUMO

Organosilanes have secured a special place in the synthetic world for several decades. However, among them, allylsilanes are a choice reagent for organic chemists to develop novel organic transformations. In recent years researchers have proved that visible-light photoredox catalysis has emerged as one of the most mild, sustainable, straightforward, and efficient strategies to construct simple to complex molecules with or without enantioselectivity. This review provides an in-depth analysis of recent advances and strategies employed in visible-light photoredox catalysis for allylsilane and its analogues for the development of various organic transformations. The review is divided into sections, each focused on a specific reactivity of allylsilane under light irradiation with C(sp2) center arene or alkene, C(sp2) center carbonyl, and C(sp3) center carbon functionality. In this review, we present optimization data, reaction scope, and mechanistic aspects to bring forward specific reactivity and selectivity trends of allylsilane in photoredox conditions.

20.
J Hazard Mater ; 471: 134325, 2024 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-38643573

RESUMO

Arsenic (As) contamination in rice poses a significant threat to human health due to its toxicity and widespread consumption. Identifying and manipulating key genes governing As accumulation in rice is crucial for reducing this threat. The large NIP gene family of aquaporins in rice presents a promising target due to functional redundancy, potentially allowing for gene manipulation without compromising plant growth. This study aimed to utilize genome editing to generate knock-out (KO) lines of genes of NIP family (OsLsi1, OsNIP3;1) and an anion transporter family (OsLsi2), in order to assess their impact on As accumulation and stress tolerance in rice. KO lines were created using CRISPR/Cas9 technology, and the As accumulation patterns, physiological performance, and grain yield were compared against wild-type (WT) under As-treated conditions. KO lines exhibited significantly reduced As accumulation in grain compared to WT. Notably, Osnip3;1 KO line displayed reduced As in xylem sap (71-74%) and grain (32-46%) upon treatment. Additionally, these lines demonstrated improved silicon (23%) uptake, photosynthetic pigment concentrations (Chl a: 77%; Chl b: 79%, Total Chl: 79% & Carotenoid: 49%) overall physiological and agronomical performance under As stress compared to WT. This study successfully utilized genome editing for the first time to identify OsNIP3;1 as a potential target for manipulating As accumulation in rice without compromising grain yield or plant vigor.


Assuntos
Arsênio , Sistemas CRISPR-Cas , Edição de Genes , Oryza , Proteínas de Plantas , Oryza/genética , Oryza/metabolismo , Oryza/crescimento & desenvolvimento , Arsênio/metabolismo , Arsênio/toxicidade , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Aquaporinas/genética , Aquaporinas/metabolismo , Técnicas de Inativação de Genes , Silício/metabolismo , Plantas Geneticamente Modificadas/genética , Clorofila/metabolismo
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