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1.
Aggress Behav ; 50(3): e22158, 2024 05.
Artigo em Inglês | MEDLINE | ID: mdl-38785112

RESUMO

Green spaces, integral to natural environments, have been extensively studied for their positive impact on mental health, yet their influence on social behavior, particularly aggression, is less explored. While prior research has predominantly emphasized the effects of actively engaging with nature, the significant role of passive nature exposure-a more common daily occurrence-has often been overlooked. We conducted two studies to explore the influence of passive green space exposure on aggression and the mediating effect of the sense of control. Study 1 (N = 240) utilized a cross-sectional survey to assess the relationship between passive green space exposure, sense of control, and aggression. Study 2 (N = 260) employed a single-factor between-subjects experimental design to further explore these relationships in a controlled environment. The results from both studies indicated that passive green space exposure is negatively related to aggression, and that this relationship is partially mediated by an increased sense of control. Specifically, passive green space exposure was found to negatively predict aggression by bolstering individuals' sense of control. These findings underscore the potential of enhancing the sense of control through environmental factors like green spaces as an effective strategy to reduce aggression. This study enriches our understanding of the broader impacts of green spaces, extending beyond mental health to include social behaviors. We discussed both the theoretical and practical implications of our findings, highlighting how urban planning and environmental design can incorporate green spaces to foster community well-being and mitigate aggressive behaviors.


Assuntos
Agressão , Humanos , Agressão/psicologia , Masculino , Feminino , Adulto , Adulto Jovem , Estudos Transversais , Parques Recreativos , Adolescente , Pessoa de Meia-Idade , Controle Interno-Externo
2.
J Drug Target ; 31(8): 858-866, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37607069

RESUMO

Renal fibrosis, characterised by glomerulosclerosis and tubulointerstitial fibrosis, is a typical pathological alteration in the progression of chronic kidney disease (CKD) to end-stage renal disease (ESRD). However, the limited and expensive options for treating renal fibrosis place a heavy financial burden on patients and healthcare systems. Therefore, it is significant to find an effective treatment for renal fibrosis. Ferroptosis, a non-traditional form of cell death, has been found to play an important role in acute kidney injury (AKI), tumours, neurodegenerative diseases, and so on. Moreover, a growing body of research suggests that ferroptosis might be a potential target of renal fibrosis. Meanwhile, mitophagy is a type of selective autophagy that can selectively degrade damaged or dysfunctional mitochondria as a form of mitochondrial quality control, reducing the production of reactive oxygen species (ROS), the accumulation of which is the main cause of renal fibrosis. Additionally, as a receptor of mitophagy, NIX can release beclin1 to induce mitophagy, which can also bind to solute carrier family 7 member 11 (SLC7A11) to block the activity of cystine/glutamate antitransporter (system Xc-) and inhibit ferroptosis, thereby suggesting a link between mitophagy and ferroptosis. However, there have been only limited studies on the relationship among mitophagy, ferroptosis and renal fibrosis. In this paper, we review the mechanisms of mitophagy, and describe how ferroptosis and mitophagy are related to renal fibrosis in an effort to identify potential novel targets for the treatment of renal fibrosis.


Assuntos
Injúria Renal Aguda , Ferroptose , Humanos , Mitofagia , Cistina , Mitocôndrias
3.
Naunyn Schmiedebergs Arch Pharmacol ; 396(12): 3347-3361, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-37389601

RESUMO

Glucagon-like peptide 1 receptor agonist (GLP-1RA) is a new class of glucose-lowing agents with the kidney benefit effect. This paper aims at finding the current state and hotspots of the research on GLP-1RA in kidney disease by using bibliometric methodologies and visualization maps to analyze publications and provide the direction for future studies on that topic. Literature information was obtained by retrieving the WoSCC database. Then, software like Microsoft Excel, VOSviewer, and CiteSpace was used to analyze and process obtained data. Bibliometric analysis and visualization of nations, authors, organizations, journals, keywords, and references were also done by VOSviewer and CiteSpace. A total of 991 publications written by 4747 authors from 1637 organizations in 75 countries on GLP-1RA in renal disease in Web of Science Core Collection were retrieved. The number of publications and citations kept growing from 2015 to 2022. The USA, Univ Copenhagen, and Rossing Peter are the leading country, organization, and author on this topic, respectively. All literature was published in 346 journals, and DIABETES OBESITY & METABOLISM is the journal with the most contributions. Meanwhile, most references are from DIABETES CARE. "Cardiovascular outcome" is the most frequent keyword in the total publications, and the reference cited most times is "Liraglutide and Cardiovascular Outcomes in Type 2 Diabetes" by Marso SP. The topic of GLP-1RA in renal disease has attracted more and more attention all over the world. Existing studies are mainly about clinical use in patients with diabetes, and studies on the mechanism are lacking.


Assuntos
Diabetes Mellitus Tipo 2 , Nefropatias , Humanos , Diabetes Mellitus Tipo 2/tratamento farmacológico , Rim , Bibliometria , Bases de Dados Factuais
4.
Proc Natl Acad Sci U S A ; 119(44): e2206649119, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36279472

RESUMO

Conformational changes in voltage-sensing domains (VSDs) are driven by the transmembrane electric field acting on the protein charges. Yet, the overall energetics and detailed mechanism of this process are not fully understood. Here, we determined free energy and displacement charge landscapes as well as the major conformations visited during a complete functional gating cycle in the isolated VSD of the phosphatase Ci-VSP (Ci-VSD) comprising four transmembrane helices (segments S1 to S4). Molecular dynamics simulations highlight the extent of S4 movements. In addition to the crystallographically determined activated "Up" and resting "Down" states, the simulations predict two Ci-VSD conformations: a deeper resting state ("down-minus") and an extended activated ("up-plus") state. These additional conformations were experimentally probed via systematic cysteine mutagenesis with metal-ion bridges and the engineering of proton conducting mutants at hyperpolarizing voltages. The present results show that these four states are visited sequentially in a stepwise manner during voltage activation, each step translocating one arginine or the equivalent of ∼1 e0 across the membrane electric field, yielding a transfer of ∼3 e0 charges in total for the complete process.


Assuntos
Ativação do Canal Iônico , Prótons , Monoéster Fosfórico Hidrolases , Cisteína , Estrutura Secundária de Proteína , Arginina
5.
Appl Opt ; 61(31): 9163-9167, 2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-36607049

RESUMO

Polarimeters, which measure the polarization states of light directly, are essentially desired in many areas of science and technology. In our previous work, we have constructed a polarimeter based on a rotating-metasurface, and the polarization Stokes parameters of the light were measured with the known Mueller elements of the metasurface. Here, we further perform the error analysis of the metasurface polarimeter. The errors in the measured Stokes parameters have been formulated for the errors in Mueller elements of the metasurface. This analysis can be used to evaluate and minimize the errors of the metasurface polarimeter.

6.
Neural Regen Res ; 17(6): 1293-1298, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34782574

RESUMO

Studies in animals indicate that sevoflurane exposure in the second trimester of pregnancy has harmful effects on the learning and memory of offspring. Whether an enriched environment can reverse the damage of sevoflurane exposure in the second trimester of pregnancy on the learning and memory of rat offspring remains unclear. In this study, rats at 14 days of pregnancy were exposed to 3.5% sevoflurane for 2 hours and their offspring were treated with an enriched environment for 20 successive days. We found that the enriched environment for offspring increased nestin and Ki67 levels in hippocampal tissue, increased hippocampal neurogenesis, inhibited glycogen synthase kinase 3ß activity, and increased the expression of cell proliferation-related ß-catenin and apoptosis-related Bcl-2, indicating that an enriched environment reduces sevoflurane-induced damage by increasing the proliferation of stem cells in the hippocampus. These findings suggest that an enriched environment can reverse the effects of sevoflurane inhaled by rats during the second trimester of pregnancy on learning and memory of offspring. This study was approved by the Animal Ethics Committee of Shengjing Hospital of China Medical University (approval No. 2018PS07K) on January 2, 2018.

7.
Neurochem Res ; 46(8): 2046-2055, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34003417

RESUMO

Mild intrauterine hypoperfusion (MIUH) can induce placental dysfunction and lead to long-term changes during the process of brain development. A better understanding of the mechanism of MIUH will help in the development of new neuroprotective strategies for the placental chamber. To better understand the mechanism of the effect of MIUH on the neural development of offspring, we constructed a model of MIUH in pregnant rats. The proliferation, apoptosis, and autophagy of hippocampal neurons in fetal rats were studied via flow cytometry, immunofluorescence staining, JC-1 staining, western blotting, and real-time polymerase chain reaction at different time points (6, 24, 48, and 72 h). The results showed that MIUH significantly inhibited the proliferation of hippocampal neurons and promoted their apoptosis and autophagy. Simultaneously, MIUH could promote PTEN expression and affect the PTEN signaling pathway. bpV, an inhibitor of PTEN, could restore the inhibition of hippocampal nerve cell growth caused by MIUH. MIUH may inhibit neuronal proliferation and promote neuronal apoptosis and autophagy by regulating the PTEN signaling pathway.


Assuntos
Proliferação de Células/fisiologia , Hipóxia Fetal/fisiopatologia , Transtornos do Neurodesenvolvimento/fisiopatologia , Neurônios/metabolismo , Circulação Placentária/fisiologia , Transdução de Sinais/fisiologia , Animais , Apoptose/fisiologia , Autofagia/fisiologia , Constrição Patológica , Feminino , Retardo do Crescimento Fetal/fisiopatologia , Feto , Pontos de Checagem da Fase G1 do Ciclo Celular/fisiologia , Hipocampo/patologia , Neurônios/patologia , Ovário/irrigação sanguínea , Ovário/patologia , PTEN Fosfo-Hidrolase/metabolismo , Gravidez , Ratos Sprague-Dawley , Artéria Uterina/patologia
8.
Bioengineered ; 12(1): 540-554, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-33535891

RESUMO

Preeclampsia (PE) is an important topic in obstetrics. In this study, we used weighted gene co-expression network analysis (WGCNA) to screen the key modules related to immune cell infiltration and to identify the hub genes for the molecular subtyping of PE. We first downloaded a set of PE transcriptional data (GSE75010; 157 samples: 80 PE and 77 non-PE) from the GEO database. We then analyzed the PE samples and non-PE samples for immune cell infiltration and screened cells with differences in such infiltration. Next, we downloaded the immune-related genes from an immune-related database to screen the expression profile of the immune-related genes. Then, we obtained a candidate gene set by screening the immune-related genes differentially expressed between the two groups. We used WGCNA to construct a weighted co-expression network for these candidate genes, mined co-expression modules, and then calculated the correlation between each module and immune cells with differential infiltration. We screened the modules related to infiltrating immune cells, identified the key modules' hub genes, and determined the key module genes that interacted with each other. Finally, we obtained the hub genes related to the infiltrating immune cells. We classified the preeclampsia patients by unsupervised cluster molecular typing, determined the difference of immune cell infiltration among the different PE subtypes, and calculated the expression of hub genes in these different subtypes. In conclusion, we found 41 hub genes that may be closely related to the molecular typing of PE.


Assuntos
Redes Reguladoras de Genes , Pré-Eclâmpsia , Transcriptoma , Biologia Computacional , Feminino , Perfilação da Expressão Gênica , Redes Reguladoras de Genes/genética , Redes Reguladoras de Genes/imunologia , Marcadores Genéticos/genética , Marcadores Genéticos/imunologia , Humanos , Fenômenos do Sistema Imunitário/genética , Leucócitos/imunologia , Macrófagos/imunologia , Tipagem Molecular , Pré-Eclâmpsia/genética , Pré-Eclâmpsia/imunologia , Gravidez , Transcriptoma/genética , Transcriptoma/imunologia
9.
Nat Chem Biol ; 17(2): 152-160, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33199914

RESUMO

Heterobifunctional chimeric degraders are a class of ligands that recruit target proteins to E3 ubiquitin ligases to drive compound-dependent protein degradation. Advancing from initial chemical tools, protein degraders represent a mechanism of growing interest in drug discovery. Critical to the mechanism of action is the formation of a ternary complex between the target, degrader and E3 ligase to promote ubiquitination and subsequent degradation. However, limited insights into ternary complex structures exist, including a near absence of studies on one of the most widely co-opted E3s, cellular inhibitor of apoptosis 1 (cIAP1). In this work, we use a combination of biochemical, biophysical and structural studies to characterize degrader-mediated ternary complexes of Bruton's tyrosine kinase and cIAP1. Our results reveal new insights from unique ternary complex structures and show that increased ternary complex stability or rigidity need not always correlate with increased degradation efficiency.


Assuntos
Tirosina Quinase da Agamaglobulinemia/genética , Proteínas Inibidoras de Apoptose/genética , Cromatografia em Gel , Reagentes de Ligações Cruzadas , Humanos , Cinética , Modelos Moleculares , Ressonância Magnética Nuclear Biomolecular , Conformação Proteica , Proteólise , Espectrometria de Massas por Ionização por Electrospray , Ubiquitina-Proteína Ligases , Ubiquitinação , Difração de Raios X
10.
Mol Biol Rep ; 48(1): 969-974, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33289909

RESUMO

Haemophilic arthropathy (HA), caused by intra-articular haemorrhage, is one of the most common complications in patients with haemophilia. Factor replacement therapy provides missing coagulation factors to prevent children with haemophilia from joint bleeding and decreases their risk for HA. However, haemophilia patients in developing countries are still suffering from HA due to insufficient replacement therapy. Symptoms such as pain and activity limitations caused by HA seriously affect the functional abilities and quality of life of patients with HA, causing a high disability rate in the haemophilia cohort. The pathological mechanism of HA is complicated because the whole pathological mainly involves hypertrophic synovitis, osteopenia, cartilage and bone destruction, and these pathological changes occur in parallel and interact with each other. Inflammation plays an important role in the whole complex pathological process, and iron, cytokines, growth factors and other factors are involved. This review summarizes the pathological mechanism of HA to provide background for clinical and basic research.


Assuntos
Artrite/patologia , Doenças Ósseas Metabólicas/patologia , Hemartrose/patologia , Hemofilia A/patologia , Osteonecrose/patologia , Sinovite/patologia , Adulto , Artrite/genética , Artrite/imunologia , Artrite/metabolismo , Doenças Ósseas Metabólicas/genética , Doenças Ósseas Metabólicas/imunologia , Doenças Ósseas Metabólicas/metabolismo , Criança , Citocinas/genética , Citocinas/imunologia , Fator VIII/uso terapêutico , Regulação da Expressão Gênica , Hemartrose/genética , Hemartrose/imunologia , Hemartrose/metabolismo , Hemofilia A/genética , Hemofilia A/imunologia , Hemofilia A/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/genética , Peptídeos e Proteínas de Sinalização Intercelular/imunologia , Ferro/imunologia , Ferro/metabolismo , Articulações/imunologia , Articulações/metabolismo , Articulações/patologia , Osteonecrose/genética , Osteonecrose/imunologia , Osteonecrose/metabolismo , Qualidade de Vida , Sinovite/genética , Sinovite/imunologia , Sinovite/metabolismo
11.
Front Genet ; 11: 594078, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33193741

RESUMO

Multiple congenital anomalies-hypotonia-seizures syndrome 1 (MCAHS1) caused by phosphatidylinositol-glycan biosynthesis class N (PIGN) mutations is an autosomal recessive disease involving many systems of the body, such as the urogenital, cardiovascular, gastrointestinal, and central nervous systems. Here, compound heterozygous variants NM_012327.6:c.2427-2A > G and c.963G > A in PIGN were identified in a Chinese proband with MCAHS1. The features of the MCAHS1 family proband were evaluated to understand the mechanism of the PIGN mutation leading to the occurrence of MCAHS1. Ultrasound was conducted to examine the fetus, and his clinical manifestations were evaluated. Genetic testing was performed by whole-exome sequencing and the results were verified by Sanger sequencing of the proband and his parents. Reverse transcription-polymerase chain reaction was performed, and the products were subjected to Sanger sequencing. Quantitative PCR (Q-PCR) was conducted to compare gene expression between the patient and wild-type subjects. The compound heterozygous mutation NM_012327.6:c.2427-2A > G and c.963G > A was identified by whole-exome sequencing and was confirmed by Sanger sequencing. The NM_012327.6:c.2427-2A > G mutation led to skipping of exon 26, which resulted in a low expression level of the gene, as measured by Q-PCR. These findings provided a basis for genetic counseling and reproduction guidance in this family. Phenotype-genotype correlations may be defined by an expanded array of mutations.

12.
Zhonghua Yi Xue Yi Chuan Xue Za Zhi ; 37(7): 767-770, 2020 Jul 10.
Artigo em Chinês | MEDLINE | ID: mdl-32619261

RESUMO

OBJECTIVE: To explore the genetic basis for fetus with short limbs detected by prenatal ultrasonography. METHODS: Results of clinical imaging of the fetus was collected. Amniotic fluid sample was collected through amniocentesis for the extraction of fetal DNA. Whole exome sequencing was carried out to detect variants related to the clinical phenotypes. Candidate variant was verified by Sanger sequencing. RESULTS: Prenatal ultrasound showed that the fetus had short limbs but no other abnormality. Whole exome sequencing has identified that the fetus carried two heterozygous pathogenic variants c.484G>T and c.1436dupA of the SLC26A2 gene, for which its mother and father were heterozygous carriers, respectively. CONCLUSION: The fetus was diagnosed with atelosteogenesis type 2 by combined prenatal ultrasonography and whole exome sequencing, which may be attributed to the compound heterozygous variants of the SLC26A2 gene. Above findings provided evidence for the diagnosis of the fetus and genetic counseling.


Assuntos
Osteocondrodisplasias , Feminino , Feto/diagnóstico por imagem , Humanos , Osteocondrodisplasias/diagnóstico , Osteocondrodisplasias/genética , Gravidez , Diagnóstico Pré-Natal , Ultrassonografia Pré-Natal , Sequenciamento do Exoma
13.
Neural Regen Res ; 15(11): 2082-2088, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32394966

RESUMO

Mild intrauterine hypoperfusion (MIUH) is a serious pathological event that affects the growth and development of fetuses and offspring. MIUH can lead to growth restriction, low birth weight, neurodevelopmental disorders, and other adverse clinical outcomes. To study the effects of MIUH on learning and memory function in offspring, a model of MIUH was established by placing a coil (length 2.5 mm, diameter 0.24 mm) on the uterine artery and ovarian uterine artery of Sprague-Dawley rats in the second trimester of pregnancy (day 17). Next, 120 mg/kg lithium chloride (the MIUH + Li group) or normal saline (the MIUH group) was injected intraperitoneally into these rats. In addition, 120 mg/kg lithium chloride (the Li group) or normal saline (the SHAM group) was injected intraperitoneally into pregnant rats without coil placement. The Morris water maze was used to detect changes in learning and memory ability in the offspring at 4 weeks after birth. In the MIUH group, the escape latency and journey length before reaching the platform were both increased, and the number of times that the platform was crossed and the activity time in the target quadrant within 90 seconds were both decreased compared with the SHAM group. Immunofluorescence double staining and western blot assays demonstrated that hippocampal nestin and Ki67 (both cell-proliferation-related proteins) expression was significantly downregulated in the MIUH group compared with the SHAM group. Furthermore, western blot assays were conducted to investigate changes in related signaling pathway proteins in the brains of offspring rats, and revealed that glycogen synthase kinase 3ß (GSK3ß) expression was upregulated and ß-catenin expression was downregulated in the MIUH group compared with the SHAM group. In addition, compared with the MIUH group, the expression levels of p-GSK3ß and ß-catenin were upregulated in the MIUH + Li group. These results suggest that MIUH may affect learning and memory function in rat offspring by regulating the GSK3ß signaling pathway. The experimental procedures were approved by Animal Ethics Committee of Shengjing Hospital of China Medical University (approval No. 2018PS07K) in June 2018.

14.
J Chem Theory Comput ; 16(3): 1896-1912, 2020 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-31999924

RESUMO

Kinases are important targets for drug development. However, accounting for the impact of possible structural rearrangements on the binding of kinase inhibitors is complicated by the extensive flexibility of their catalytic domain. The dynamic N-lobe contains four particular mobile structural elements: the Asp-Phe-Gly (DFG) motif, the phosphate (P) positioning loop, the activation (A) loop, and the αC helix. In our previous study [Meng et al. J. Chem. Theory Comput. 2018 14, 2721-2732], we combined various simulation techniques with Markov state modeling (MSM) to explore the free energy landscape of Abl kinase beyond conformations that are known from X-ray crystallography. Here we examine the resulting Markov model in greater detail by analyzing its metastable states. A characterization of the states in terms of their DFG state, P-loop, and αC conformations is presented and compared to existing classification schemes. Several metastable states are found to be structurally close to known crystal structures of different kinases in complex with a variety of inhibitors. These results suggest that the set of conformations accessible to tyrosine kinases may be shared within the entire family and that the conformational dynamics of one kinase in the absence of any ligand can provide meaningful information about possible target conformations for inhibitors of any member of the kinase family.


Assuntos
Inibidores de Proteínas Quinases/química , Humanos , Cadeias de Markov , Modelos Moleculares
16.
J Chem Theory Comput ; 14(5): 2721-2732, 2018 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-29474075

RESUMO

Understanding protein conformational variability remains a challenge in drug discovery. The issue arises in protein kinases, whose multiple conformational states can affect the binding of small-molecule inhibitors. To overcome this challenge, we propose a comprehensive computational framework based on Markov state models (MSMs). Our framework integrates the information from explicit-solvent molecular dynamics simulations to accurately rank-order the accessible conformational variants of a target protein. We tested the methodology using Abl kinase with a reference and blind-test set. Only half of the Abl conformational variants discovered by our approach are present in the disclosed X-ray structures. The approach successfully identified a protein conformational state not previously observed in public structures but evident in a retrospective analysis of Lilly in-house structures: the X-ray structure of Abl with WHI-P154. Using a MSM-derived model, the free energy landscape and kinetic profile of Abl was analyzed in detail highlighting opportunities for targeting the unique metastable states.


Assuntos
Simulação de Dinâmica Molecular , Proteínas Proto-Oncogênicas c-abl/química , Trifosfato de Adenosina/química , Sítio Alostérico , Cinética , Cadeias de Markov , Ácido Mirístico/química , Conformação Proteica , Termodinâmica
17.
J Mol Biol ; 430(6): 881-889, 2018 03 16.
Artigo em Inglês | MEDLINE | ID: mdl-29410316

RESUMO

Tyrosine kinases are enzymes playing a critical role in cellular signaling. Molecular dynamics umbrella sampling potential of mean force computations are used to quantify the impact of activating and inactivating mutations of c-Src kinase. The potential of mean force computations predict that a specific double mutant can stabilize c-Src kinase into an active-like conformation while disabling the binding of ATP in the catalytic active site. The active-like conformational equilibrium of this catalytically dead kinase is affected by a hydrophobic unit that connects to the hydrophobic spine network via the C-helix. The αC-helix plays a crucial role in integrating the hydrophobic residues, making it a hub for allosteric regulation of kinase activity and the active conformation. The computational free-energy landscapes reported here illustrate novel design principles focusing on the important role of the hydrophobic spines. The relative stability of the spines could be exploited in future efforts to artificially engineer active-like but catalytically dead forms of protein kinases.


Assuntos
Mutação , Conformação Proteica , Quinases da Família src/química , Quinases da Família src/genética , Trifosfato de Adenosina/metabolismo , Regulação Alostérica , Catálise , Ativação Enzimática , Interações Hidrofóbicas e Hidrofílicas , Simulação de Dinâmica Molecular , Proteínas Mutantes/química , Proteínas Mutantes/genética
18.
Acc Chem Res ; 50(5): 1193-1201, 2017 05 16.
Artigo em Inglês | MEDLINE | ID: mdl-28426203

RESUMO

Protein kinases are enzymes that catalyze the covalent transfer of the γ-phosphate of an adenosine triphosphate (ATP) molecule onto a tyrosine, serine, threonine, or histidine residue in the substrate and thus send a chemical signal to networks of downstream proteins. They are important cellular signaling enzymes that regulate cell growth, proliferation, metabolism, differentiation, and migration. Unregulated protein kinase activity is often associated with a wide range of diseases, therefore making protein kinases major therapeutic targets. A prototypical system of central interest to understand the regulation of kinase activity is provided by tyrosine kinase c-Src, which belongs to the family of Src-related non-receptor tyrosine kinases (SFKs). Although the broad picture of autoinhibition via the regulatory domains and via the phosphorylation of the C-terminal tail is well characterized from a structural point of view, a detailed mechanistic understanding at the atomic-level is lacking. Advanced computational methods based on all-atom molecular dynamics (MD) simulations are employed to advance our understanding of tyrosine kinase activation. The computational studies suggest that the isolated kinase domain (KD) is energetically most favorable in the inactive conformation when the activation loop (A-loop) of the KD is not phosphorylated. The KD makes transient visits to a catalytically competent active-like conformation. The process of bimolecular trans-autophosphorylation of the A-loop eventually locks the KD in the active state. Activating point mutations may act by slightly increasing the population of the active-like conformation, enhancing the availability of the A-loop to be phosphorylated. The Src-homology 2 (SH2) and Src-homology 3 (SH3) regulatory domains, depending upon their configuration, either promote the inactive or the active state of the kinase domain. In addition to the roles played by the SH3, SH2, and KD, the Src-homology 4-Unique domain (SH4-U) region also serves as a key moderator of substrate specificity and kinase function. Thus, a fundamental understanding of the conformational propensity of the SH4-U region and how this affects the association to the membrane surface are likely to lead to the discovery of new intermediate states and alternate strategies for inhibition of kinase activity for drug discovery. The existence of a multitude of KD conformations poses a great challenge aimed at the design of specific inhibitors. One promising computational strategy to explore the conformational flexibility of the KD is to construct Markov state models from aggregated MD data.


Assuntos
Quinases da Família src/química , Regulação Alostérica , Sequência de Aminoácidos , Ativação Enzimática , Cadeias de Markov , Simulação de Dinâmica Molecular , Mutação , Fosforilação , Domínios Proteicos , Termodinâmica , Quinases da Família src/genética
19.
J Phys Chem B ; 121(15): 3352-3363, 2017 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-27715044

RESUMO

Tyrosine kinases are important cellular signaling allosteric enzymes that regulate cell growth, proliferation, metabolism, differentiation, and migration. Their activity must be tightly controlled, and malfunction can lead to a variety of diseases, particularly cancer. The nonreceptor tyrosine kinase c-Src, a prototypical model system and a representative member of the Src-family, functions as complex multidomain allosteric molecular switches comprising SH2 and SH3 domains modulating the activity of the catalytic domain. The broad picture of self-inhibition of c-Src via the SH2 and SH3 regulatory domains is well characterized from a structural point of view, but a detailed molecular mechanism understanding is nonetheless still lacking. Here, we use advanced computational methods based on all-atom molecular dynamics simulations with explicit solvent to advance our understanding of kinase activation. To elucidate the mechanism of regulation and self-inhibition, we have computed the pathway and the free energy landscapes for the "inactive-to-active" conformational transition of c-Src for different configurations of the SH2 and SH3 domains. Using the isolated c-Src catalytic domain as a baseline for comparison, it is observed that the SH2 and SH3 domains, depending upon their bound orientation, promote either the inactive or active state of the catalytic domain. The regulatory structural information from the SH2-SH3 tandem is allosterically transmitted via the N-terminal linker of the catalytic domain. Analysis of the conformational transition pathways also illustrates the importance of the conserved tryptophan 260 in activating c-Src, and reveals a series of concerted events during the activation process.


Assuntos
Simulação de Dinâmica Molecular , Quinases da Família src/metabolismo , Conformação Proteica , Quinases da Família src/química
20.
Proc Natl Acad Sci U S A ; 113(33): 9193-8, 2016 08 16.
Artigo em Inglês | MEDLINE | ID: mdl-27482115

RESUMO

Nonreceptor tyrosine kinases of the Src family are large multidomain allosteric proteins that are crucial to cellular signaling pathways. In a previous study, we generated a Markov state model (MSM) to simulate the activation of c-Src catalytic domain, used as a prototypical tyrosine kinase. The long-time kinetics of transition predicted by the MSM was in agreement with experimental observations. In the present study, we apply the framework of transition path theory (TPT) to the previously constructed MSM to characterize the main features of the activation pathway. The analysis indicates that the activating transition, in which the activation loop first opens up followed by an inward rotation of the αC-helix, takes place via a dense set of intermediate microstates distributed within a fairly broad "transition tube" in a multidimensional conformational subspace connecting the two end-point conformations. Multiple microstates with negligible equilibrium probabilities carry a large transition flux associated with the activating transition, which explains why extensive conformational sampling is necessary to accurately determine the kinetics of activation. Our results suggest that the combination of MSM with TPT provides an effective framework to represent conformational transitions in complex biomolecular systems.


Assuntos
Quinases da Família src/química , Proteína Tirosina Quinase CSK , Domínio Catalítico , Ativação Enzimática , Cadeias de Markov , Simulação de Dinâmica Molecular , Conformação Proteica , Termodinâmica , Quinases da Família src/metabolismo
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