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161.
Michael R. Heaven Anthony W. Herren Daniel L. Flint Natasha L. Pacheco Jiangtao Li Alice Tang Fatima Khan James E. Goldman Brett S. Phinney Michelle L. Olsen 《Molecular & cellular proteomics : MCP》2022,21(1):100180
Alexander disease (AxD) is a rare and fatal neurodegenerative disorder caused by mutations in the gene encoding glial fibrillary acidic protein (GFAP). In this report, a mouse model of AxD (GFAPTg;Gfap+/R236H) was analyzed that contains a heterozygous R236H point mutation in murine Gfap as well as a transgene with a GFAP promoter to overexpress human GFAP. Using label-free quantitative proteomic comparisons of brain tissue from GFAPTg;Gfap+/R236H versus wild-type mice confirmed upregulation of the glutathione metabolism pathway and indicated proteins were elevated in the peroxisome proliferator-activated receptor (PPAR) signaling pathway, which had not been reported previously in AxD. Relative protein-level differences were confirmed by a targeted proteomics assay, including proteins related to astrocytes and oligodendrocytes. Of particular interest was the decreased level of the oligodendrocyte protein, 2-hydroxyacylsphingosine 1-beta-galactosyltransferase (Ugt8), since Ugt8-deficient mice exhibit a phenotype similar to GFAPTg;Gfap+/R236H mice (e.g., tremors, ataxia, hind-limb paralysis). In addition, decreased levels of myelin-associated proteins were found in the GFAPTg;Gfap+/R236H mice, consistent with the role of Ugt8 in myelin synthesis. Fabp7 upregulation in GFAPTg;Gfap+/R236H mice was also selected for further investigation due to its uncharacterized association to AxD, critical function in astrocyte proliferation, and functional ability to inhibit the anti-inflammatory PPAR signaling pathway in models of amyotrophic lateral sclerosis (ALS). Within Gfap+ astrocytes, Fabp7 was markedly increased in the hippocampus, a brain region subjected to extensive pathology and chronic reactive gliosis in GFAPTg;Gfap+/R236H mice. Last, to determine whether the findings in GFAPTg;Gfap+/R236H mice are present in the human condition, AxD patient and control samples were analyzed by Western blot, which indicated that Type I AxD patients have a significant fourfold upregulation of FABP7. However, immunohistochemistry analysis showed that UGT8 accumulates in AxD patient subpial brain regions where abundant amounts of Rosenthal fibers are located, which was not observed in the GFAPTg;Gfap+/R236H mice. 相似文献
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The chemical synthesis of the title compounds as maltose analogs, in which the non-reducing end is modified by acetylation of the 4'-OH group or by reversing its configuration, is reported. For synthesis of the 4'-O-acetylated analog, beta-maltose was converted into its per-O-benzylated-4',6'-O-benzylidene derivative followed by removal of the benzylidene acetal function and selective silylation at C-6'. Acetylation at C-4' of the obtained silylated compound followed by removal of the benzyl ether protecting groups and subsequent desilylation afforded the desired analog. The other maltose analog was synthesized via the glycosidation reaction between the glycosyl donor, O-(2,3,4,6-tetra-O-benzyl-alpha/beta-D-galactopyranosyl)trichloroacetimidate and the glycosyl acceptor, phenyl 2,3,6-tri-O-benzyl-1-thio-beta-D-glucopyranoside followed by removal of the phenylthio group and debenzylation to provide the desired analog. 相似文献
164.
The crystal structure of mature dipeptidyl peptidase I reveals insight into the unique tetrameric structure, substrate binding and activation of this atypical papain family peptidase. Each subunit is composed of three peptides. The heavy and light chains form the catalytic domain, which adopts the papain fold. The residual pro-part forms a beta-barrel with the carboxylate group of Asp1 pointing towards the substrate amino-terminus. The tetrameric structure appears to stabilize the association of the two domains and encloses a 12700 A3 spherical cavity. The tetramer contains six chloride ions, one buried in each S2 pocket and two at subunit interfaces. 相似文献
165.
Bak S Olsen CE Petersen BL Møller BL Halkier BA 《The Plant journal : for cell and molecular biology》1999,20(6):663-671
Glucosinolates are natural products in cruciferous plants, including Arabidopsis thaliana. CYP79A1 is the cytochrome P450 catalysing the conversion of tyrosine to p-hydroxyphenylacetaldoxime in the biosynthesis of the cyanogenic glucoside dhurrin in sorghum. Both glucosinolates and cyanogenic glucosides have oximes as intermediates. Expression of CYP79A1 in A. thaliana results in the production of high levels of the tyrosine-derived glucosinolate p-hydroxybenzylglucosinolate, which is not a natural constituent of A. thaliana. This provides further evidence that the enzymes have low substrate specificity with respect to the side chain. The ability of the cyanogenic CYP79A1 to integrate itself into the glucosinolate pathway has important implications for an evolutionary relationship between cyanogenic glucosides and glucosinolates, and for the possibility of genetic engineering of novel glucosinolates. 相似文献
166.
Olsen JG Kadziola A von Wettstein-Knowles P Siggaard-Andersen M Lindquist Y Larsen S 《FEBS letters》1999,460(1):46-52
The crystal structure of the fatty acid elongating enzyme beta-ketoacyl [acyl carrier protein] synthase I (KAS I) from Escherichia coli has been determined to 2.3 A resolution by molecular replacement using the recently solved crystal structure of KAS II as a search model. The crystal contains two independent dimers in the asymmetric unit. KAS I assumes the thiolase alpha(beta)alpha(beta)alpha fold. Electrostatic potential distribution reveals an acyl carrier protein docking site and a presumed substrate binding pocket was detected extending the active site. Both subunits contribute to each substrate binding site in the dimer. 相似文献
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168.
At Bird Island, South Georgia, we studied the effects of the tick Ixodes uriae on survival of chicks at two colonies of the black-browed albatross Diomedea melanophrys, one where most chicks were infested with ticks, the other where most chicks were tick-free. When the two colonies were compared, it was found that the colony heavily-infested with ticks had significantly greater chick mortality than the colony lightly-infested with ticks. However, within each of the two colonies, there was no significant difference in survival between chicks with ticks and those without ticks. 相似文献
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170.
N(6)-Furfuryladenine, kinetin, protects against Fenton reaction-mediated oxidative damage to DNA 总被引:7,自引:0,他引:7
Olsen A Siboska GE Clark BF Rattan SI 《Biochemical and biophysical research communications》1999,265(2):499-502
N(6)-Furfuryladenine (kinetin) has been shown to have anti-ageing effects on several different systems including plants, human cells in culture, and fruitflies. Since most of the experimental data point toward kinetin acting as an antioxidant both in vitro and in vivo, and since much evidence supporting a causal role of oxidative damage in ageing is accumulating, we tested the antioxidant properties of kinetin directly. Using 8-oxo-2'deoxyguanosine (8-oxo-dG) in calf thymus DNA as a marker for oxidative damage, we demonstrate that kinetin significantly (P < 0.005) protects the DNA against oxidative damage mediated by the Fenton reaction. Kinetin inhibited 8-oxo-dG formation in a dose-dependent manner with a maximum of 50% protection observed at 100 microM kinetin. 相似文献