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91.
92.
Williams A Sarkar S Cuddon P Ttofi EK Saiki S Siddiqi FH Jahreiss L Fleming A Pask D Goldsmith P O'Kane CJ Floto RA Rubinsztein DC 《Nature chemical biology》2008,4(5):295-305
Autophagy is a major clearance route for intracellular aggregate-prone proteins causing diseases such as Huntington's disease. Autophagy induction with the mTOR inhibitor rapamycin accelerates clearance of these toxic substrates. As rapamycin has nontrivial side effects, we screened FDA-approved drugs to identify new autophagy-inducing pathways. We found that L-type Ca2+ channel antagonists, the K+ATP channel opener minoxidil, and the G(i) signaling activator clonidine induce autophagy. These drugs revealed a cyclical mTOR-independent pathway regulating autophagy, in which cAMP regulates IP3 levels, influencing calpain activity, which completes the cycle by cleaving and activating G(s)alpha, which regulates cAMP levels. This pathway has numerous potential points where autophagy can be induced, and we provide proof of principle for therapeutic relevance in Huntington's disease using mammalian cell, fly and zebrafish models. Our data also suggest that insults that elevate intracytosolic Ca2+ (like excitotoxicity) inhibit autophagy, thus retarding clearance of aggregate-prone proteins. 相似文献
93.
Sfar S Abid A Mahfoudh W Ouragini H Ouechtati F Abdelhak S Chouchane L 《Molecular biology reports》2009,36(4):661-667
Hereditary multiple exostoses (HME) is an autosomal dominant orthopaedic disorder most frequently caused by mutations in the
EXT1 gene. The aim of the present study is to determine the underlying molecular defect of HME in two multigenerational Tunisian
families with 21 affected members and to examine the degree of intrafamilial variability. Linkage analysis was performed using
three microsatellite markers encompassing the EXT1 locus and mutation screening was carried out by direct sequencing. In family 1, evidence for linkage to EXT1 was obtained on the basis of a maximum LOD score of 4.26 at θ = 0.00 with D8S1694 marker. Sequencing of the EXT1 revealed a heterozygous G > T transversion (c.1019G>T) in exon 2, leading to a missense mutation at the codon 340 (p.Arg340Leu).
In family 2 we identified a novel heterozygous 1 bp deletion in the exon 1 (c.529_531delA) leading to a premature codon stop
and truncated EXT1 protein expression (p.Lys177LysfsX15). This mutation was associated with the evidence of an intrafamilial
clinical variability and considered to be a novel disease-causing mutation in the EXT1 gene. These findings provide additional support for the involvement of EXT1 gene in the HME disease. 相似文献
94.
95.
Nadiawati Alias Nor Muhammad Mahadi Abdul Munir Abdul Murad Farah Diba Abu Bakar Nik Azmi Nik Mahmood Rosli Md Illias 《World journal of microbiology & biotechnology》2009,25(4):561-572
A gene encoding endochitinase from Trichoderma virens UKM-1 was cloned and expressed in E. coli BL21 (DE3). Both the endochitinase gene and its cDNA sequences were obtained. The endochitinase gene encodes 430 amino acids
from an open reading frame comprising of 1,690 bp nucleotide sequence with three introns. The endochitinase was expressed
as soluble and active enzyme at 20°C when induced with 1 mM IPTG. Maximum activity was observed at 4 h of post-induction time.
SDS-PAGE showed that the purified endochitinase exhibited a single band with molecular weight of 42 kDa. Biochemical characterization
of the enzyme displayed a near neutral pH characteristic with an optimum pH at 6.0 and optimum temperature at 50°C. The enzyme
is stable between pH 3.0–7.0 and is able to retain its activity from 30 to 60°C. The presence of Mg2+ and Ca2+ ions increased the enzyme activity up to 20%. The purified enzyme has a strong affinity towards colloidal chitin and low
effect on ethyl cellulose and D-cellubiose which are non-chitin related substrates. HPLC analysis from the chitin hydrolysis
showed the release of (GlcNAc)3, (GlcNAc)2 and GlcNAc, in which (GlcNAc)2 was the main product. 相似文献
96.
Nyon MP Rice DW Berrisford JM Hounslow AM Moir AJ Huang H Nathan S Mahadi NM Bakar FD Craven CJ 《Journal of molecular biology》2009,385(1):226-15716
Cutinase belongs to a group of enzymes that catalyze the hydrolysis of esters and triglycerides. Structural studies on the enzyme from Fusarium solani have revealed the presence of a classic catalytic triad that has been implicated in the enzyme's mechanism. We have solved the crystal structure of Glomerella cingulata cutinase in the absence and in the presence of the inhibitors E600 (diethyl p-nitrophenyl phosphate) and PETFP (3-phenethylthio-1,1,1-trifluoropropan-2-one) to resolutions between 2.6 and 1.9 Å. Analysis of these structures reveals that the catalytic triad (Ser136, Asp191, and His204) adopts an unusual configuration with the putative essential histidine His204 swung out of the active site into a position where it is unable to participate in catalysis, with the imidazole ring 11 Å away from its expected position. Solution-state NMR experiments are consistent with the disrupted configuration of the triad observed crystallographically. H204N, a site-directed mutant, was shown to be catalytically inactive, confirming the importance of this residue in the enzyme mechanism. These findings suggest that, during its catalytic cycle, cutinase undergoes a significant conformational rearrangement converting the loop bearing the histidine from an inactive conformation, in which the histidine of the triad is solvent exposed, to an active conformation, in which the triad assumes a classic configuration. 相似文献
97.
Farah Idali Jan Wahlstr?m Benita Dahlberg Mohsen Khademi Tomas Olsson Anders Eklund Johan Grunewald 《Respiratory research》2009,10(1):42
Background
Activated T helper (Th)-1 pulmonary CD4+ cells and their mediators are essential for the inflammation and granulomatous process in sarcoidosis. Recently, T-cell immunoglobulin and mucin domain (TIM) molecules were suggested to be important regulators of immune function. In this study, we wanted to investigate whether TIM molecules could play a role in sarcoidosis.Methods
We used real-time polymerase chain reaction to investigate the differential gene expression of TIM-1 and TIM-3 as well as a few Th1 and Th2 cytokines (IL-2, IFN-γ, IL-4, IL-5 and IL-13) in CD4+ T cells isolated from bronchoalveolar lavage fluid (BALF) of patients (n = 28) and healthy controls (n = 8). Using flow cytometry, we were also able to analyse TIM-3 protein expression in 10 patients and 6 healthy controls.Results
A decreased TIM-3 mRNA (p < 0.05) and protein (p < 0.05) expression was observed in patients, and the level of TIM-3 mRNA correlated negatively with the CD4/CD8 T cell ratio in BALF cells of patients. Compared to a distinct subgroup of patients i.e. those with Löfgren''s syndrome, BALF CD4+ T cells from non- Löfgren''s patients expressed decreased mRNA levels of TIM-1 (p < 0.05). mRNA expression of IL-2 was increased in patients (p < 0.01) and non-Löfgren''s patients expressed significantly higher levels of IFN-γ mRNA (p < 0.05) versus patients with Löfgren''s syndrome.Conclusion
These findings are the first data on the expression of TIM-1 and TIM-3 molecules in sarcoidosis. The reduced TIM-3 expression in the lungs of patients may result in a defective T cell ability to control the Th1 immune response and could thus contribute to the pathogenesis of sarcoidosis. The down-regulated TIM-1 expression in non-Löfgren''spatients is in agreement with an exaggerated Th1 response in these patients. 相似文献98.
Beadell JS Ishtiaq F Covas R Melo M Warren BH Atkinson CT Bensch S Graves GR Jhala YV Peirce MA Rahmani AR Fonseca DM Fleischer RC 《Proceedings. Biological sciences / The Royal Society》2006,273(1604):2935-2944
The introduction of avian malaria (Plasmodium relictum) to Hawaii has provided a model system for studying the influence of exotic disease on naive host populations. Little is known, however, about the origin or the genetic variation of Hawaii's malaria and traditional classification methods have confounded attempts to place the parasite within a global ecological and evolutionary context. Using fragments of the parasite mitochondrial gene cytochrome b and the nuclear gene dihydrofolate reductase-thymidylate synthase obtained from a global survey of greater than 13000 avian samples, we show that Hawaii's avian malaria, which can cause high mortality and is a major limiting factor for many species of native passerines, represents just one of the numerous lineages composing the morphological parasite species. The single parasite lineage detected in Hawaii exhibits a broad host distribution worldwide and is dominant on several other remote oceanic islands, including Bermuda and Moorea, French Polynesia. The rarity of this lineage in the continental New World and the restriction of closely related lineages to the Old World suggest limitations to the transmission of reproductively isolated parasite groups within the morphological species. 相似文献
99.
Evidence that DNA (cytosine-5) methyltransferase regulates synaptic plasticity in the hippocampus 总被引:7,自引:0,他引:7
Levenson JM Roth TL Lubin FD Miller CA Huang IC Desai P Malone LM Sweatt JD 《The Journal of biological chemistry》2006,281(23):15763-15773
DNA (cytosine-5) methylation represents one of the most widely used mechanisms of enduring cellular memory. Stable patterns of DNA methylation are established during development, resulting in creation of persisting cellular phenotypes. There is growing evidence that the nervous system has co-opted a number of cellular mechanisms used during development to subserve the formation of long term memory. In this study, we examined the role DNA (cytosine-5) methyltransferase (DNMT) activity might play in regulating the induction of synaptic plasticity. We found that the DNA within promoters for reelin and brain-derived neurotrophic factor, genes implicated in the induction of synaptic plasticity in the adult hippocampus, exhibited rapid and dramatic changes in cytosine methylation when DNMT activity was inhibited. Moreover, zebularine and 5-aza-2-deoxycytidine, inhibitors of DNMT activity, blocked the induction of long term potentiation at Schaffer collateral synapses. Activation of protein kinase C in the hippocampus decreased reelin promoter methylation and increased DNMT3A gene expression. Interestingly, DNMT activity is required for protein kinase C-induced increases in histone H3 acetylation. Considered together, these results suggest that DNMT activity is dynamically regulated in the adult nervous system and that DNMT may play a role in regulating the induction of synaptic plasticity in the mature CNS. 相似文献
100.
Walter Jaoko Etienne Karita Kayitesi Kayitenkore Gloria Omosa-Manyonyi Susan Allen Soe Than Elizabeth M. Adams Barney S. Graham Richard A. Koup Robert T. Bailer Carol Smith Len Dally Bashir Farah Omu Anzala Claude M. Muvunyi Jean Bizimana Tony Tarragona-Fiol Philip J. Bergin Peter Hayes Martin Ho Kelley Loughran Wendy Komaroff Gwynneth Stevens Helen Thomson Mark J. Boaz Josephine H. Cox Claudia Schmidt Jill Gilmour Gary J. Nabel Patricia Fast Job Bwayo 《PloS one》2010,5(9)