RESUMEN
Rubisco, the key enzyme of CO2 fixation in photosynthesis, is prone to inactivation by inhibitory sugar phosphates. Inhibited Rubisco undergoes conformational repair by the hexameric AAA+ chaperone Rubisco activase (Rca) in a process that is not well understood. Here, we performed a structural and mechanistic analysis of cyanobacterial Rca, a close homolog of plant Rca. In the Rca:Rubisco complex, Rca is positioned over the Rubisco catalytic site under repair and pulls the N-terminal tail of the large Rubisco subunit (RbcL) into the hexamer pore. Simultaneous displacement of the C terminus of the adjacent RbcL opens the catalytic site for inhibitor release. An alternative interaction of Rca with Rubisco is mediated by C-terminal domains that resemble the small Rubisco subunit. These domains, together with the N-terminal AAA+ hexamer, ensure that Rca is packaged with Rubisco into carboxysomes. The cyanobacterial Rca is a dual-purpose protein with functions in Rubisco repair and carboxysome organization.
Asunto(s)
Cianobacterias/metabolismo , Ribulosa-Bifosfato Carboxilasa/metabolismo , Adenosina Trifosfato/metabolismo , Proteínas Bacterianas/metabolismo , Dominio Catalítico , Cristalografía por Rayos X , Modelos Moleculares , Chaperonas Moleculares/metabolismo , Orgánulos/metabolismo , Fotosíntesis/fisiología , Ribulosa-Bifosfato Carboxilasa/fisiología , Activador de Tejido Plasminógeno/química , Activador de Tejido Plasminógeno/metabolismoRESUMEN
To explore the effect of Hei Xiaoyaosan on autophagy levels in Alzheimer's disease(AD). A total of 100 4-month-old Wistar male rats were randomly selected as a blank group, and 10 rats were taken as a sham operation group and injected with 1 µL of normal saline on both sides of the hippocampus. The other rats were injected with Aß_(1-42) solution in the hippocampus to replicate the AD model. Fifty successfully modeled rats were selected and randomly divided into the model group, Aricatio group(0.5 mg·kg~(-1)), and high, medium, and low dose groups of Hei Xiaoyaosan(15.30, 7.65, and 3.82 g·kg~(-1)), with 10 rats in each group. The rats were administered by continuous gavage for 42 days. Morris water maze was used to detect the learning and memory ability of rats, and Hoechst staining was used to observe the pathological changes of nerve cells in the hippocampal CA1 region. The mRNA expression of p38MAPK, Beclin-1, and Bcl-2 was detected by RT-qPCR.Western blot was used to detect the expressions of p38MAPK, Beclin-1, Bcl-2, APP, and related proteins. The level of Aß_(1-42) in the hippocampus was detected by ELISA, and the expression level of LC3â ¡ in the hippocampus was detected by immunohistochemistry. The experimental results showed that compared with the blank group, the learning and memory ability of rats in the model group decreased(P<0.01). The nuclei in the CA1 region of the hippocampus showed blue bright spots and were closely arranged. The mRNA expression of p38MAPK was up-regulated, and the mRNA expressions of Beclin-1 and Bcl-2 were down-regulated(P<0.01). The expressions of p38MAPK, p-p38MAPK, and APP were increased, while those of Beclin-1, Bcl-2, and p-Bcl-2 were decreased(P<0.01). The expression of Aß_(1-42) was increased(P<0.01). The relative expression of LC3â ¡ decreased(P<0.01). Compared with the model group, the learning and memory ability of rats in each administration group was improved(P<0.05 or P<0.01). The nuclei in the CA1 region of the hippocampus gradually became clear, showing light blue. The mRNA expression of p38MAPK was down-regulated(P<0.01), and that of Beclin-1 and Bcl-2 was increased(P<0.05 or P<0.01). The expressions of p38MAPK, p-p38MAPK, and APP were down-regulated, while those of Beclin-1, Bcl-2, and p-Bcl-2 were up-regulated(P<0.05 or P<0.01). The expression of Aß_(1-42) was decreased(P<0.01). The relative expression of LC3â ¡ was increased(P<0.01). It can be concluded that Hei Xiaoyaosan can improve the cognitive ability of AD model rats, and its potential mechanism may be related to regulating the p38MAPK/Beclin-1/Bcl-2 signaling pathway, increasing the level of autophagy, and reducing the accumulation of Aß_(1-42).
Asunto(s)
Enfermedad de Alzheimer , Autofagia , Beclina-1 , Modelos Animales de Enfermedad , Medicamentos Herbarios Chinos , Proteínas Proto-Oncogénicas c-bcl-2 , Ratas Wistar , Proteínas Quinasas p38 Activadas por Mitógenos , Animales , Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/tratamiento farmacológico , Enfermedad de Alzheimer/genética , Masculino , Ratas , Medicamentos Herbarios Chinos/administración & dosificación , Medicamentos Herbarios Chinos/farmacología , Autofagia/efectos de los fármacos , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismo , Proteínas Quinasas p38 Activadas por Mitógenos/genética , Beclina-1/metabolismo , Beclina-1/genética , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Proteínas Proto-Oncogénicas c-bcl-2/genética , Humanos , Hipocampo/efectos de los fármacos , Hipocampo/metabolismo , Transducción de Señal/efectos de los fármacosRESUMEN
The effect and mechanism of Heixiaoyao Powder on the polarization of microglia(MG) in APP/PS1 double transgenic mice were explored based on NADPH oxidase 2(NOX2)/reactive oxygen species(ROS)/nuclear factor kappaB(NF-κB) signaling pathway. Fifty 4-month-old male APP/PS1 mice were randomly divided into a model group, an MCC950 group(10 mg·kg~(-1)), and low-, medium-, and high-dose Heixiaoyao Powder groups(6.45, 12.89, and 25.78 g·kg~(-1)). Thirty male C57BL/6J mice of the same age and strain were randomly divided into a blank group, a blank + intragastric intervention group, and a blank + intraperitoneal injection group. Drug intervention lasted 90 days. Morris water maze test was used to detect learning and cognitive ability. Nissl staining and transmission electron microscopy were used to observe the pathological morphology and ultrastructure of hippocampal neurons. Immunofluorescence was used to detect the positive expression of M1-type marker CD16/32~+/Iba-1~+, M2-type marker CD206~+/Iba-1~+ of MG and the expression of hippocampal ROS. The colorimetric method was used to detect the content of malondialdehyde(MDA) and superoxide dismutase(SOD) in the hippocampus. Enzyme linked immunosorbent assay(ELISA) was used to detect the levels of inflammatory factors, including interleukin-6(IL-6), interleukin-8(IL-8), and tumor necrosis factor-α(TNF-α), in the hippocampus. Western blot was used to detect the protein expression of ß-amyloid protein(Aß), Iba-1, CD16/32, CD206, NOX2, NF-κB, p-NF-κB, NF-κB inhibitor alpha(IκBα), and p-IKBα in the hippocampus. The results showed that as compared with the blank group, the model group showed prolonged target quadrant movement distance and escape latency(P<0.01), shortened target quadrant retention time and percentage(P<0.01), disorganized neuronal cells with swelling, nuclear disappearance or bias, reduced number of cells, dissolved or absent Nissl bodies, and a clear area in the cytoplasm, damaged and shrunk cell membrane with abnormal cell morphology, few organelles in the cytoplasm, reduced and swollen mitochondria, increased MG M1-type marker CD16/32~+/Iba-1~+(P<0.01), decreased M2-type marker CD206~+/Iba-1~+(P<0.01), increased ROS activity and MDA content(P<0.01), decreased SOD level(P<0.01), elevated inflammatory factors IL-6, IL-8, and TNF-α(P<0.01), up-regulated protein expression and phosphorylation of Aß, CD16/32, Iba-1, NOX2, NF-κB, and IKBα(P<0.01), and down-regulated CD206(P<0.01). There was no statistically significant difference between the blank group, the blank + intragastric intervention group, and the blank + intraperitoneal injection group. After the intervention of Heixiaoyao Powder, the Heixiaoyao Powder groups showed shortened target quadrant movement distance and escape latency(P<0.01), prolonged target quadrant retention time and percentage(P<0.01), increased and neatly arranged cells with relieved swelling, increased Nissl bodies, regular cell morphology, and intact cell membrane, relieved swelling of mitochondria, slightly expanded endoplasmic reticulum, decreased CD16/32~+/Iba-1~+(P<0.05 or P<0.01), increased CD206~+/Iba-1~+(P<0.01), decreased ROS activity and MDA content(P<0.01), increased SOD level(P<0.01), decreased content of inflammatory factors IL-6, IL-8, and TNF-α(P<0.01), down-regulated protein expression and phosphorylation of Aß, CD16/32, Iba-1, NOX2, NF-κB, and IKBα(P<0.01), and up-regulated CD206(P<0.01). In conclusion, Heixiaoyao Powder can alleviate neuronal damage and improve the learning and memory abilities of APP/PS1 mice. The mechanism of action may be related to the inhibition of NOX2/ROS/NF-κB signaling pathway, regulating the polarization of MG, increasing the expression of M2 type, inhibiting the expression of M1 type, and reducing the release of inflammatory factor.
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Microglía , FN-kappa B , Ratones , Masculino , Animales , FN-kappa B/genética , Especies Reactivas de Oxígeno , Interleucina-8 , Polvos , Factor de Necrosis Tumoral alfa , Interleucina-6 , Ratones Endogámicos C57BL , Transducción de Señal , Ratones Transgénicos , Superóxido DismutasaRESUMEN
OBJECTIVE: To evaluate the effects of baicalin in human gastric cancer cells, including apoptosis-inducing effects, and to investigate its underlying mechanisms of action. METHODS: Cell proliferation and apoptosis assays were performed to investigate the anti-proliferation effects of baicalin in human gastric cancer BGC-823 and MGC-803 cells. Real time-quantitative polymerase chain reaction and Western blotting analysis were performed to elucidate the molecular mechanisms underlying the anti-tumor properties of baicalin. RESULTS: In BGC-823 and MGC-803 gastric cancer cells treated with 80, 120, and 160 µmol/L baicalin for 48 h, a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay showed that baicalin significantly inhibited cell proliferation in a dose-dependent manner, while flow cytometric analysis demonstrated that baicalin could induce apoptosis, also in a dose-dependent manner. Moreover, baicalin up-regulated the expression of caspase-3, caspase-9, and B cell lymphoma (Bcl-2)-associated X protein and down-regulated the expression of Bcl-2 at both the mRNA and protein level. CONCLUSION: Baicalin has potential as a therapeutic agent for gastric cancer by inducing apoptosis in cancer cells.
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Apoptosis/efectos de los fármacos , Caspasa 3/metabolismo , Caspasa 9/metabolismo , Flavonoides/farmacología , Extractos Vegetales/farmacología , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Scutellaria baicalensis/química , Neoplasias Gástricas/fisiopatología , Caspasa 3/genética , Caspasa 9/genética , Línea Celular Tumoral , Humanos , Proteínas Proto-Oncogénicas c-bcl-2/genética , Transducción de Señal/efectos de los fármacos , Neoplasias Gástricas/tratamiento farmacológico , Neoplasias Gástricas/genética , Neoplasias Gástricas/metabolismoRESUMEN
Objective To observe the effect of Heixiaoyao Powder (HP) on gene microarray profile of hippocampus in Aß23â35 fragments induced Alzheimer's disease rat model. Methods Female SD rats were chosen to establish AD model by injecting Aß25â35 amyloid into hippocampus ,and then they were divid- ed into 6 groups, i.e., the sham-operation group, the model group,the Western medicine (WM) group, high, middle, and low dose HP groups, 14 in each group. After 7 days of modeling, all rats were administered with respective solution at the daily dose of 3 mL/kg by gastrogavage for 28 successive days. Normal saline was administered to rats in the sham-operation group and the model group. Huperzine A Tablets wa- ter solution was administered to rats in the WM group at the daily dose of 0. 02 mL/kg. HP at the daily dose of 4. 25, 8. 50, 17. 00 g/kg was administered to rats in the low, middle, high HP groups. All rats were sacri- ficed after ending gastrogavage, and their hippocampal tissues were collected to extract tissue RNA. Rat gene microarray was used to screen differentially expressed genes, and then differentially expressed genes with partial dose-dependently changing obtained by microarry were verified by qRT-PCR. Results Compared with the sham-operation group, 538 genes were up-regulated, and 579 genes were down-regulated in the model group. mRNA expressions of wisp1 , crebbp, igfbp-1 , znf483, zfp37, and zic4 increased, while mRNA expressions of casq2 and bcl-2 decreased in the model group (P <0. 05). Compared with the model group, 276 genes were up-regulated, and 170 genes were down-regulated in the 3 HP groups. Of them, 71 up-regulated genes dose-dependently and 70 down-regulated genes dose-dependently. mRNA expressions of igfbp-1 , znf483, zfp37, and zic4 decreased, while mRNA expressions of casq2 and bcl-2 in- creased in the WM group (P <0. 01). mRNA expressions of wisp1 , crebbp, igfbp-1 , znf483, zfp37, and zic4 decreased, while mRNA expressions of casq2 and bcl-2 increased in the high dose HP group (P <0. 01). mRNA expressions of crebbp, igfbp-1, znf483, zfp37, and zic4 decreased (P <0. 01, P <0. 05), while mR- NA expressions of casq2 and bcl-2 increased in the middle dose HP group (P <0. 01, P <0. 05). mRNA ex- pressions of igfbp-1 , znf483, zfp37, and zic4 decreased in the low dose HP group (P <0. 01). Compared with the middle dose HP group, mRNA expressions of crebbp, zfp37, and zic4 increased (P <0.01) , mR- NA expressions of igfbp-1 and bcl-2 decreased in the middle dose HP group (P <0. 01, P <0. 05); mRNA expressions of crebbp, znf483, and zfp37 increased (P <0. 01, P <0. 05), mRNA expressions of igfbp-1, zic4, and bcl-2 decreased in the low dose HP group (P <0. 01). Compared with the middle HP group, mRNA expressions of casq2, zic4, and bcl-2 decreased in the low dose HP group (P <0. 01, P <0. 05). Conclusion HP could affect the occurrence of AD by regulating mRNA expressions of zfp37, znf483, and zic4, and af- fect the metabolism of Aß and abnormal phosphorylation of Tau protein by inhibiting wnt signal pathway re- lated genes such as wisp-1 , crebbp, igfbp-1 , and casq2.
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Enfermedad de Alzheimer , Medicamentos Herbarios Chinos , Transcriptoma , Enfermedad de Alzheimer/tratamiento farmacológico , Enfermedad de Alzheimer/metabolismo , Animales , Medicamentos Herbarios Chinos/farmacología , Femenino , Hipocampo/efectos de los fármacos , Hipocampo/metabolismo , Ratas , Ratas Sprague-DawleyRESUMEN
OBJECTIVE: To study the effect of Guiqicongzhi Decoction on expression of HSP27 and HSP70 in brain tissue of VD model rats. METHODS: The method of "repeatedly clip carotid artery join with injection of sodium nitroprusside and with permanent unilateral carotid artery ligation" was used to prepare the vascular dementia model. And then the effect of Guiqicongzhi Decoction on the model rats from rats praxiology, histopathological and the molecules expression of heat shock protein (HSP) were observed. RESULTS: Compared with control group, the navigation incubation period extended and space search ability became worse in model group; cell number was less, contour fuzzy shrivel, cytoplasm deep stain and nuclear was not clear in hippocampus pathological section; as well as an increase in the expression of HSP27 and HSP70. The above indexes changed significantly in middle dose group and high dose group. The curative effect of middle dose group was better than piracetam. CONCLUSION: Guiqicongzhi Decoction can protect brain tissue and improve the pathological damage and memory functions of VD rats, the mechanism maybe related to the regulation of HSP27 and HSP70 expression.
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Encéfalo/efectos de los fármacos , Demencia Vascular/tratamiento farmacológico , Medicamentos Herbarios Chinos/farmacología , Proteínas de Choque Térmico HSP27/metabolismo , Proteínas HSP70 de Choque Térmico/metabolismo , Animales , Encéfalo/metabolismo , Encéfalo/patología , Modelos Animales de Enfermedad , RatasRESUMEN
OBJECTIVE: To investigate the effect of Xiaoyao Powder (XP) and its compatible prescriptions on the ethology, morphology, and activities of neurotransmitters, thus exploring their effects and mechanism in preventing and treating D-galactose induced Alzheimer's disease (AD) model mice, and clarifying the compatibility mechanism for soothing Gan, nourishing blood, and invigorating Pi. METHODS: Sixty SPF mice were randomly divided into the blank control group, the model group, and the XP group, Shugan Jianpi group (SJ), Shugan Yangxue group (SY), and Jianpi Yangxue group (JY), 10 in each group.The AD mouse model was prepared by peritoneal injecting D-galactose. Meanwhile, mice in the blank control group and the model group were administered with physiological saline (at the daily dose of 24 mL/kg) by gastrogavage. Mice in the XP group (2.485 g/kg), the SY group (1.136 g/kg), the SJ group (1.775 g/kg), and the JY group (2.059 g/kg) were administered with corresponding medicated decoction by gastrogavage, with the gastric volume of 24 mL/kg. On the 41st day the training of capability for learning and memory was started. On the 42nd day capability for learning and memory was tested. The brain tissue was cut. One half was used to determine the contents of homogenate acetyl cholinesterase (AchE), choline acetyltransferase (ChAT), and monoamine oxidase (MAO).Another half was used to carry out morphological observations. RESULTS: The capability for learning and memory could be improved and the latency time could be lowered in all the treatment groups. Besides, the homogenate AchE and MAO could also be elevated, ChAT could be lowered; the morphology, number, and distribution of neurons could be improved. But the improvement of ethology, morphology, and activities of neurotransmitters were most obviously seen in the XP group. CONCLUSIONS: XP could improve the ethology, morphology, and activities of neurotransmitters, and showed better effects on prevention and treatment of AD. The rationality of compatibility methods and combination thinking ways of soothing Gan, nourishing blood, and invigorating Pi were clarified.
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Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/psicología , Conducta Animal , Medicamentos Herbarios Chinos/farmacología , Animales , Modelos Animales de Enfermedad , Femenino , Masculino , Ratones , Ratones Endogámicos , Neurotransmisores/metabolismoRESUMEN
Carboxysomes are large, cytosolic bodies present in all cyanobacteria and many proteobacteria that function as the sites of photosynthetic CO2 fixation by the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). The carboxysome lumen is enriched with Rubisco and carbonic anhydrase (CA). The polyhedral proteinaceous shell allows the passage of HCO3- ions into the carboxysome, where they are converted to CO2 by CA. Thus, the carboxysome functions as a CO2-concentrating mechanism (CCM), enhancing the efficiency of Rubisco in CO2 fixation. In ß-cyanobacteria, carboxysome biogenesis first involves the aggregation of Rubisco by CcmM, a scaffolding protein that exists in two isoforms. Both isoforms contain a minimum of three Rubisco small subunit-like (SSUL) domains, connected by flexible linkers. Multivalent interaction between these linked SSUL domains with Rubisco results in phase separation and condensate formation. Here, we use Rubisco and the short isoform of CcmM (M35) of the ß-cyanobacterium Synechococcus elongatus PCC7942 to describe the methods used for in vitro analysis of the mechanism of condensate formation driven by the SSUL domains. The methods include turbidity assays, bright-field and fluorescence microscopy, as well as transmission electron microscopy (TEM) in both negative staining and cryo-conditions.
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Anhidrasas Carbónicas , Ribulosa-Bifosfato Carboxilasa , Proteínas Bacterianas/metabolismo , Dióxido de Carbono/metabolismo , Anhidrasas Carbónicas/metabolismo , Orgánulos/metabolismo , Oxigenasas/metabolismo , Isoformas de Proteínas/metabolismo , Ribulosa-Bifosfato Carboxilasa/metabolismoRESUMEN
OBJECTIVE: Angelica (A.) sinensis is used as a traditional medical herb for the treatment of neurodegeneration, aging, and inflammation in Asia. A. sinensis optimal formula (AOF) is the best combination in A. sinensis that has been screened to rescue the cognitive ability in ß-amyloid peptide (Aß25-35)-treated Alzheimer's disease (AD) rats. The objective of this study was to investigate the effect of AOF on the learning and memory of AD rats as well as to explore the underlying mechanisms. METHODS: Male Wistar rats were infused with Aß25-35 for AD model induction or saline (negative control). Five groups of AD rats were fed on AOF at 20, 40, or 80 mL/kg every day, donepezil at 0.9 mg/kg every day (positive control), or an equal volume of water (AD model) intragastrically once a day for 4 weeks, while the negative control rats were fed on water. The Morris water maze test was used to evaluate the cognitive function of the rats. The Aß accumulation, cholinergic levels, and antioxidative ability were detected by ELISA. Additionally, the candidate mechanism was determined by gene sequencing and quantitative real-time polymerase chain reaction. RESULTS: The results showed that AOF administration significantly ameliorated Aß25-35-induced memory impairment. AOF decreased the levels of amyloid-ß precursor protein and Aß in the hippocampus, rescued the cholinergic levels, increased the activity of superoxide dismutase, and decreased the malondialdehyde level. In addition, AOF inhibited the expression of IL1b, Mpo, and Prkcg in the hippocampus. CONCLUSION: These experimental findings illustrate that AOF prevents the decrease in cognitive function and Aß deposits in Aß25-35-treated rats via modulating neuroinflammation and oxidative stress, thus highlighting a potential therapeutic avenue to promote the co-administration of formulas that act on different nodes to maximize beneficial effects and minimize negative side effects.
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Enfermedad de Alzheimer/tratamiento farmacológico , Péptidos beta-Amiloides/farmacología , Angelica sinensis , Trastornos de la Memoria/tratamiento farmacológico , Enfermedades Neuroinflamatorias/tratamiento farmacológico , Nootrópicos/farmacología , Estrés Oxidativo/efectos de los fármacos , Preparaciones de Plantas/farmacología , Enfermedad de Alzheimer/inducido químicamente , Enfermedad de Alzheimer/inmunología , Enfermedad de Alzheimer/metabolismo , Animales , Modelos Animales de Enfermedad , Masculino , Trastornos de la Memoria/inducido químicamente , Trastornos de la Memoria/inmunología , Trastornos de la Memoria/metabolismo , Enfermedades Neuroinflamatorias/inducido químicamente , Enfermedades Neuroinflamatorias/inmunología , Enfermedades Neuroinflamatorias/metabolismo , Nootrópicos/administración & dosificación , Preparaciones de Plantas/administración & dosificación , Ratas , Ratas WistarRESUMEN
Carboxysomes in cyanobacteria enclose the enzymes Rubisco and carbonic anhydrase to optimize photosynthetic carbon fixation. Understanding carboxysome assembly has implications in agricultural biotechnology. Here we analyzed the role of the scaffolding protein CcmM of the ß-cyanobacterium Synechococcus elongatus PCC 7942 in sequestrating the hexadecameric Rubisco and the tetrameric carbonic anhydrase, CcaA. We find that the trimeric CcmM, consisting of γCAL oligomerization domains and linked small subunit-like (SSUL) modules, plays a central role in mediation of pre-carboxysome condensate formation through multivalent, cooperative interactions. The γCAL domains interact with the C-terminal tails of the CcaA subunits and additionally mediate a head-to-head association of CcmM trimers. Interestingly, SSUL modules, besides their known function in recruiting Rubisco, also participate in intermolecular interactions with the γCAL domains, providing further valency for network formation. Our findings reveal the mechanism by which CcmM functions as a central organizer of the pre-carboxysome multiprotein matrix, concentrating the core components Rubisco and CcaA before ß-carboxysome shell formation.
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Proteínas Bacterianas/metabolismo , Anhidrasas Carbónicas/metabolismo , Dominios y Motivos de Interacción de Proteínas/fisiología , Ribulosa-Bifosfato Carboxilasa/metabolismo , Synechococcus/metabolismo , Condensados Biomoleculares/fisiología , Microscopía por Crioelectrón , Fotosíntesis/fisiología , Conformación Proteica , Synechococcus/genéticaRESUMEN
Spreading of aggregate pathology across brain regions acts as a driver of disease progression in Tau-related neurodegeneration, including Alzheimer's disease (AD) and frontotemporal dementia. Aggregate seeds released from affected cells are internalized by naïve cells and induce the prion-like templating of soluble Tau into neurotoxic aggregates. Here we show in a cellular model system and in neurons that Clusterin, an abundant extracellular chaperone, strongly enhances Tau aggregate seeding. Upon interaction with Tau aggregates, Clusterin stabilizes highly potent, soluble seed species. Tau/Clusterin complexes enter recipient cells via endocytosis and compromise the endolysosomal compartment, allowing transfer to the cytosol where they propagate aggregation of endogenous Tau. Thus, upregulation of Clusterin, as observed in AD patients, may enhance Tau seeding and possibly accelerate the spreading of Tau pathology.
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Clusterina/metabolismo , Agregación Patológica de Proteínas/metabolismo , Proteínas tau/metabolismo , Animales , Clusterina/genética , Progresión de la Enfermedad , Endocitosis , Humanos , Ratones , Enfermedades Neurodegenerativas/metabolismo , Enfermedades Neurodegenerativas/patología , Neuronas/metabolismo , Neuronas/patología , Agregación Patológica de Proteínas/patología , Unión Proteica , alfa-Sinucleína/metabolismo , Proteínas tau/genéticaRESUMEN
Chaperonins are ubiquitous molecular chaperones found in all domains of life. They form ring-shaped complexes that assist in the folding of substrate proteins in an ATP-dependent reaction cycle. Key to the folding cycle is the transient encapsulation of substrate proteins by the chaperonin. Here we present a structural and functional characterization of the chaperonin gp146 (ɸEL) from the phage EL of Pseudomonas aeruginosa. ɸEL, an evolutionarily distant homolog of bacterial GroEL, is active in ATP hydrolysis and prevents the aggregation of denatured protein in a nucleotide-dependent manner. However, ɸEL failed to refold the encapsulation-dependent model substrate rhodanese and did not interact with E. coli GroES, the lid-shaped co-chaperone of GroEL. ɸEL forms tetradecameric double-ring complexes, which dissociate into single rings in the presence of ATP. Crystal structures of ɸEL (at 3.54 and 4.03 Å) in presence of ATPâ¢BeFx revealed two distinct single-ring conformational states, both with open access to the ring cavity. One state showed uniform ATP-bound subunit conformations (symmetric state), whereas the second combined distinct ATP- and ADP-bound subunit conformations (asymmetric state). Cryo-electron microscopy of apo-ɸEL revealed a double-ring structure composed of rings in the asymmetric state (3.45 Å resolution). We propose that the phage chaperonin undergoes nucleotide-dependent conformational switching between double- and single rings and functions in aggregation prevention without substrate protein encapsulation. Thus, ɸEL may represent an evolutionarily more ancient chaperonin prior to acquisition of the encapsulation mechanism.
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Chaperoninas/química , Pliegue de Proteína , Fagos Pseudomonas/química , Pseudomonas aeruginosa/virología , Proteínas Virales/química , Chaperonina 10/química , Chaperonina 60/química , Microscopía por Crioelectrón , Escherichia coli/química , Proteínas de Escherichia coli/química , Dominios Proteicos , Fagos Pseudomonas/metabolismoRESUMEN
Cryo-electron microscopy (cryo-EM) has been established as one of the central tools in the structural study of macromolecular complexes. Although intermediate- or low-resolution structural information through negative staining or cryo-EM analysis remains highly valuable, we lack general and efficient ways to achieve unambiguous subunit identification in these applications. Here, we took advantage of the extremely high affinity between a dodecapeptide "PA" tag and the NZ-1 antibody Fab fragment to develop an efficient "yeast inner-subunit PA-NZ-1 labeling" strategy that when combined with cryo-EM could precisely identify subunits in macromolecular complexes. Using this strategy combined with cryo-EM 3D reconstruction, we were able to visualize the characteristic NZ-1 Fab density attached to the PA tag inserted into a surface-exposed loop in the middle of the sequence of CCT6 subunit present in the Saccharomyces cerevisiae group II chaperonin TRiC/CCT. This procedure facilitated the unambiguous localization of CCT6 in the TRiC complex. The PA tag was designed to contain only 12 amino acids and a tight turn configuration; when inserted into a loop, it usually has a high chance of maintaining the epitope structure and low likelihood of perturbing the native structure and function of the target protein compared to other tagging systems. We also found that the association between PA and NZ-1 can sustain the cryo freezing conditions, resulting in very high occupancy of the Fab in the final cryo-EM images. Our study demonstrated the robustness of this strategy combined with cryo-EM in efficient and accurate subunit identification in challenging multi-component complexes.
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Antígenos de Superficie/química , Chaperonina con TCP-1/química , Chaperoninas del Grupo II/química , Proteínas de Saccharomyces cerevisiae/química , Saccharomyces cerevisiae/metabolismo , Sitios de Unión , Microscopía por Crioelectrón , Epítopos/química , Modelos Moleculares , Conformación Proteica , Saccharomyces cerevisiae/química , Coloración y EtiquetadoRESUMEN
Unambiguous subunit assignment in a multicomponent complex is critical for thorough understanding of the machinery and its functionality. The eukaryotic group II chaperonin TRiC/CCT folds approximately 10% of cytosolic proteins and is important for the maintenance of cellular homeostasis. TRiC consists of two rings and each ring has eight homologous but distinct subunits. Unambiguous subunit identification of a macromolecular machine such as TRiC through intermediate or low-resolution cryo-EM map remains challenging. Here we present a yeast internal-subunit eGFP labeling strategy termed YISEL, which can quickly introduce an eGFP tag in the internal position of a target subunit by homologous recombination, and the tag labeled protein can be expressed in endogenous level. Through this method, the labeling efficiency and tag-occupancy is ensured, and the inserted tag is usually less mobile compared to that fused to the terminus. It can also be used to bio-engineer other tag in the internal position of a protein in yeast. By applying our YISEL strategy and combined with cryo-EM 3D reconstruction, we unambiguously identified all the subunits in the cryo-EM map of TRiC, demonstrating the potential for broad application of this strategy in accurate and efficient subunit identification in other challenging complexes.
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Chaperoninas del Grupo II/análisis , Biología Molecular/métodos , Subunidades de Proteína/análisis , Saccharomyces cerevisiae/enzimología , Coloración y Etiquetado/métodos , Microscopía por Crioelectrón , Proteínas Fluorescentes Verdes/análisis , Proteínas Fluorescentes Verdes/genética , Chaperoninas del Grupo II/genética , Recombinación Homóloga , Imagenología Tridimensional , Subunidades de Proteína/genéticaRESUMEN
Background Individualized medication reviews may improve our understanding of the distribution of CYP2C19 polymorphisms in ethnic populations. Objective To evaluate differences in CYP2C19 gene polymorphisms between Mongolian and Han nationals and determine the effect of adjustments of antiplatelet treatments according to the genetic profile in patients undergoing percutaneous coronary intervention (PCI). Setting Prospective, observational, single-center study. Methods 397 patients diagnosed with acute coronary syndrome were enrolled. Additionally, 186 patients undergoing PCI were given different treatments according to their CYP2C19 genotypes. Patients with the genotype of an extensive metabolizers (EMs; *1/*1) were co-administered aspirin 100 mg/day and clopidogrel 75 mg/day, following a loading dose of 300 mg; intermediate metabolizers (IMs; e.g., *1/*2 and *1/*3) and poor metabolizers (PMs; e.g., *2/*2 and *2/*3) were administered a loading dose of 180 mg ticagrelor, followed by a maintenance dose of 90 mg twice a day. Results In Mongolians, 60.79% of patients were EMs, which was significantly higher than that in Han nationals (P = 0.002). In Han individuals, 62.14% of patients were IMs and PMs, which was significantly higher than that in Mongolians (P < 0.05). Three patients died, and the frequency of adverse events during follow-up was significantly higher in patients given conventional treatment than in patients given tailored treatment (P = 0.039). However, differences in metabolism subtypes did not affect the incidence of adverse reactions. Conclusions There were differences in CYP2C19 polymorphisms between Mongolians and Hans. Effective, safe therapy was achieved by tailoring antiplatelet drug therapy based on genotype.
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Pueblo Asiatico/genética , Citocromo P-450 CYP2C19/genética , Inhibidores de Agregación Plaquetaria/uso terapéutico , Polimorfismo de Nucleótido Simple/genética , Síndrome Coronario Agudo/tratamiento farmacológico , Síndrome Coronario Agudo/genética , Síndrome Coronario Agudo/cirugía , Adulto , Anciano , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Intervención Coronaria Percutánea/tendencias , Estudios ProspectivosRESUMEN
The eukaryotic chaperonin TRiC (or CCT) assists in the folding of 10% of cytosolic proteins. Here we present two cryo-EM structures of Saccharomyces cerevisiae TRiC in a newly identified nucleotide partially preloaded (NPP) state and in the ATP-bound state, at 4.7-Å and 4.6-Å resolution, respectively. Through inner-subunit eGFP tagging, we identified the subunit locations in open-state TRiC and found that the CCT2 subunit pair forms an unexpected Z shape. ATP binding induces a dramatic conformational change on the CCT2 side, thereby suggesting that CCT2 plays an essential role in TRiC allosteric cooperativity. Our structural and biochemical data reveal a staggered ATP binding mechanism of TRiC with preloaded nucleotide on the CCT6 side of NPP-TRiC and demonstrate that TRiC has evolved into a complex that is structurally divided into two sides. This work offers insight into how the TRiC nucleotide cycle coordinates with its mechanical cycle in preparing folding intermediates for further productive folding.
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Adenosina Trifosfato/metabolismo , Chaperonina con TCP-1/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Regulación Alostérica , Chaperonina con TCP-1/química , Microscopía por Crioelectrón , Cristalografía por Rayos X , Modelos Moleculares , Unión Proteica , Conformación Proteica , Subunidades de Proteína/química , Subunidades de Proteína/metabolismo , Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/químicaRESUMEN
BACKGROUND: Heparanase is believed to be involved in gastric carcinogenesis. However, the clinicopathologic features of gastric cancer with high heparanase expression remain unclear. AIM: The purpose of this study was to comprehensively and quantitatively summarize available evidence for the use of heparanase mRNA and protein expression to evaluate the clinicopathological associations in gastric cancer in Asian patients by meta-analysis. MATERIALS AND METHODS: Relevant articles listed in MEDLINE, CNKI and the Cochrane Library databases up to MARCH 2015 were searched by use of several keywords in electronic databases. A meta-analysis was performed to clarify the impact of heparanase mRNA and protein on clinicopathological parameters in gastric cancer. Combined ORs with 95%CIs were calculated by Revman 5.0, and publication bias testing was performed by stata12.0. RESULTS: A total of 27 studies which included 3,891 gastric cancer patients were combined in the final analysis. When stratifying the studies by the pathological variables of heparanase mRNA expression, the depth of invasion (633 patients) (OR=4.96; 95% CI=2.38-1.37; P<0.0001), lymph node metastasis (639 patients) (OR=6.22; 95%CI=2.70-14.34, P<0.0001), and lymph node metastasis (383 patients) (OR=6.85; 95% CI=2.04-23.04; P=0.002) were all significant. When stratifying the studies by the pathological variables of heparanase protein expression, this was the case for depth of invasion (1250 patients) (OR=2.76; 95% CI=1.52-5.03; P=0.0009), lymph node metastasis (1178 patients) (OR=4.79 ; 95% CI=3.37-6.80, P<0.00001), tumor size (727 patients) (OR=2.06 ; 95% CI=1.31-3.23; P=0.002) (OR=2.61; 95% CI=2.09-3.27; P=0.000), and TNM stage (1233 patients) (OR=6.85; 95% CI=2.04-23.04; P=0.002). Egger's tests suggested publication bias for depth of invasion, lymph node metastasis, lymph node metastasis and tumor size of heparanase mRNA and protein expression. CONCLUSIONS: This meta- analysis suggests that higher heparanase expression in gastric cancer is associated with clinicopathologic features of depth of invasion, lymph node metastasis and TNM stage at mRNA and protein levels, and of tumor size only at the protein level. Egger's tests suggested publication bias for these clinicopathologic features of heparanase mRNA and protein expression, and which may be caused by shortage of relevant studies. As a result, although abundant reports showed heparanase may be associated with clinicopathologic features in gastric cancer, this meta-analysis indicates that more strict studies were needed to evaluate its clinicopathologic significance.
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Biomarcadores de Tumor/metabolismo , Glucuronidasa/genética , Glucuronidasa/metabolismo , ARN Mensajero/genética , Neoplasias Gástricas/patología , Biomarcadores de Tumor/genética , Humanos , Metástasis Linfática , Invasividad Neoplásica , Estadificación de Neoplasias , Pronóstico , Neoplasias Gástricas/genética , Neoplasias Gástricas/metabolismoRESUMEN
Matrine, a major alkaloid extracted from Sophora flavescens, has been reported to possess antitumor properties in several types of cancers, including gastric cancer. However, its mechanisms of action on gastric cancer remain poorly understood. Dysregulation of microRNAs, a class of small, non-coding, regulatory RNA molecules involved in gene expression, is strongly correlated with cancer. The aim of the present study was to demonstrate that matrine treatment altered miRNA expression in SGC7901 cells. Using miRCURY™ microarray analysis, we identified 128 miRNAs substantially exhibiting >2-fold expression changes in matrine-treated cells relative to their expression levels in untreated cells. RT-qPCR was used to show that the levels of 8 miRNAs whose target genes were clustered in the cell cycle pathway increased, while levels of 14 miRNAs whose target genes were clustered in the MAPK signaling pathway decreased. These results were consistent with those from the miRNA microarray experiment. Bioinformatical analysis revealed that the majority of 57 identified enrichment pathways were highly involved in tumorigenesis. In conclusion, the results demonstrated that matrine induces considerable changes in the miRNA expression profiles of SGC7901 cells, suggesting miRNA microarray combined with RT-qPCR validation and bioinformatical analysis provide a novel and promising approach to identify anticancer targets and the mechanisms of matrine involved.