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Isoform Composition (isoform + composition)
Selected AbstractsCodon 129 polymorphism and the E200K mutation do not affect the cellular prion protein isoform composition in the cerebrospinal fluid from patients with Creutzfeldt,Jakob diseaseEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2010Matthias Schmitz Abstract The cellular prion protein (PrPc) is a multifunctional, highly conserved and ubiquitously expressed protein. It undergoes a number of modifications during its post-translational processing, resulting in different PrPc glycoforms and truncated PrPc fragments. Limited data are available in humans on the expression and cleavage of PrPc. In this study we investigated the PrPc isoform composition in the cerebrospinal fluid from patients with different human prion diseases. The first group of patients was affected by sporadic Creutzfeldt,Jakob disease exhibiting different PrP codon 129 genotypes. The second group contained patients with a genetic form of Creutzfeldt,Jakob disease (E200K). The third group consisted of patients with fatal familial insomnia and the last group comprised cases with the Gerstmann,Sträussler,Scheinker syndrome. We examined whether the PrP codon 129 polymorphism in sporadic Creutzfeldt,Jakob disease as well as the type of prion disease in human patients has an impact on the glycosylation and processing of PrPc. Immunoblotting analyses using different monoclonal PrPc antibodies directed against various epitopes of PrPc revealed, for all examined groups of patients, a consistent predominance of the glycosylated PrPc isoforms as compared with the unglycosylated form. In addition, the antibody SAF70 recognized a variety of PrPc fragments with sizes of 21, 18, 13 and 12 kDa. Our findings indicate that the polymorphisms at PrP codon 129, the E200K mutation at codon 200 or the examined types of human transmissible spongiform encephalopathies do not exert a measurable effect on the glycosylation and processing of PrPc in human prion diseases. [source] Expression of embryonic tau protein isoforms persist during adult neurogenesis in the hippocampusHIPPOCAMPUS, Issue 2 2007Torsten Bullmann Abstract Tau is a microtubule-associated protein with a developmentally regulated expression of multiple isoforms. The neonatal isoform is devoid of two amino terminal inserts and contains only three instead of four microtubule-binding repeats (0N/3R-,). We investigated the temporal expression pattern of 0N-, and 3R-, in the rat hippocampus. After the decline of 0N- and 3R-, immunoreactivity during the postnatal development both isoforms remain highly expressed in a few cells residing beneath the granule cell layer. Coexpression of the polysialylated neuronal cell adhesion molecule, doublecortin, and incorporated bromodeoxyuridine showed that these cells are proliferating progenitor cells. In contrast mature granule cells express the adult tau protein isoform containing one aminoterminal insert domain (1N-,). Therefore a shift in tau isoform expression takes place during adult neurogenesis, which might be related to migration, differentiation, and integration in the granule cell layer. A model for studying shifts in tau isoform expression in a defined subset of neurons might help to understand the etiology of tauopathies, when isoform composition is crucial for neurodegeneration, as in Pick's disease or FTDP-17. © 2006 Wiley-Liss, Inc. [source] Relationship of the extended tau haplotype to tau biochemistry and neuropathology in progressive supranuclear palsyANNALS OF NEUROLOGY, Issue 4 2001Wan-Kyng Liu PhD Two extended haplotypes of the tau gene (H1 and H2) have been described. The frequency of H1 haplotype is increased in progressive supranuclear palsy (PSP). PSP is associated with filamentous tau lesions in neurons and glia, which are reportedly composed exclusively of tau isoforms with four repeats in the microtubule-binding domain (4R tau). To determine the influence of the tau haplotype on tau isoform composition and neuropathology, we studied 25 PSP cases and 6 Alzheimer's disease patients matched for age, sex, and postmortem delay. In the basal ganglia, tau and amyloid burdens were determined to see if there was an effect of concurrent Alzheimer-type pathology, and the ratio of 4R to 3R tau was measured in detergent-insoluble tau fractions. Insoluble tau from PSP was not composed exclusively of 4R tau. All brains had a mixture of 4R and 3R tau, but the ratio was different in Alzheimer's disease and PSP. In Alzheimer's disease there was less 4R than 3R tau, whereas the ratio was reversed in PSP. In PSP cases with concurrent Alzheimer-type pathology, the ratio of 4R to 3R was intermediate between Alzheimer's disease and PSP. The H1 haplotype had no effect on the 4R to 3R ratio or on tau and amyloid burdens. In summary, the H1 haplotype does not have a major influence on the pathological or biochemical phenotype of PSP. [source] Characterization of four esterase genes and esterase activity from the gut of the termite Reticulitermes flavipesARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 1 2010Marsha M. Wheeler Abstract Four esterase genes and general esterase activity were investigated in the gut of the termite Reticulitermes flavipes. Two genes (RfEst1 and RfEst2) share significant translated identity with a number of insect JH esterases. The two remaining genes (RfEst3 and RfEst4) apparently code for much shorter proteins with similarity to fungal phenolic acid esterases involved in hemicellulose solubilization. All four genes showed consistently high midgut expression. This result was further supported by colorimetric activity assays and Native polyacrylamide gel electrophoresis, which showed significant esterase activity and a number of isoforms in the midgut. The greatest esterase activity and isoform composition were detected when ,-naphthyl propionate was used as a substrate. Moreover, esterase activity and diverse isoforms were present in gut mitochondrial, microsomal, and cytosolic sub-cellular protein fractions, as well as in the hindgut lumen. These findings reveal an agreement between gut esterase gene expression and activity distributions, and support the idea that R. flavipes gut esterase activity is host (not symbiont)-derived. In addition, these findings support the hypotheses that termite gut esterases may play important roles in lignocellulose digestion and caste differentiation. This study provides important baseline data that will assist ongoing functional-genomic efforts to identify novel genes with roles in semiochemical, hormone, and lignocellulose processing in the termite gut. © 2009 Wiley Periodicals, Inc. [source] | ||||||||||