Huntington's disease (HD) is a familial neurodegenerative disorder caused by an abnormal expansion of CAG repeats in the coding region of huntingtin gene. A major hallmark of HD is the proteolytic production of N-terminal fragments of huntingtin containing polyglutamine repeats that form ubiquitinated aggregates in the nucleus and cytoplasm of the affected neurons. However, the mechanism by which the mutant huntingtin causes neurodegeneration is not well understood.
View Article and Find Full Text PDFCurcumin, a natural polyphenolic compound, has long been known as an anti-tumour and anti-inflammatory compound; although, the common mechanism through which it exhibits such properties are remains unclear. Recently, we reported that the curcumin-induced apoptosis is mediated through the impairment of ubiquitin proteasome system (UPS). Here, we show that curcumin disrupts UPS function by directly inhibiting the enzyme activity of the proteasome's 20S core catalytic component.
View Article and Find Full Text PDFThe innate immune response is a key barrier against pathogenic microorganisms such as human immunodeficiency virus type 1 (HIV-1). Because HIV-1 is rarely transmitted orally, we hypothesized that oral epithelial cells participate in the innate immune defense against this virus. We further hypothesized that secretory leukocyte protease inhibitor (SLPI), a 12-kDa mucosal antiviral protein, is a component of the host immune response to this virus.
View Article and Find Full Text PDFHuntington disease is caused by polyglutamine (polyQ) expansion in huntingtin. Selective and progressive neuronal loss is observed in the striatum and cerebral cortex in Huntington disease. We have addressed whether expanded polyQ aggregates appear in regions of the brain apart from the striatum and cortex and whether there is a correlation between expanded polyQ aggregate formation and dysregulated transcription.
View Article and Find Full Text PDFHuntington's disease (HD) is characterised by the proteolytic production of N-terminal fragments of huntingtin containing polyglutamine repeats that forms intracellular ubiquitinated aggregates in the affected neurons. Using cellular and transgenic mice model of HD, we report here that BAG-1 co-immunoprecipitates with the polyglutamine-expanded truncated N-terminal huntingtin (tNhtt) and associates with their aggregates through its interaction with the chaperones Hsc70/Hsp70. We further demonstrate that the over expression of BAG-1 protects polyglutamine-expanded tNhtt induced cell death.
View Article and Find Full Text PDFA major hallmark of the polyglutamine diseases is the formation of neuronal intranuclear inclusions of the disease proteins that are ubiquitinated and often associated with various chaperones and proteasome components. But, how the polyglutamine proteins are ubiquitinated and degraded by the proteasomes are not known. Here, we demonstrate that CHIP (C terminus of Hsp70-interacting protein) co-immunoprecipitates with the polyglutamine-expanded huntingtin or ataxin-3 and associates with their aggregates.
View Article and Find Full Text PDFA major hallmark of the polyglutamine diseases is the formation of neuronal intranuclear inclusions (NIIs) of the disease proteins that are ubiquitinated and often associated with various chaperones and proteasome components. Recently, misfolding has come to be considered one of the primary factors for polyglutamine protein aggregation, although, the nature of misfolding and the relationship between misfolding and ubiquitination of the expanded polyglutamine protein is not yet known. By using ataxin-3, the defective gene product of SCA3/MJD, we demonstrate here that the misfolding propensity and the cellular toxicity of a polyglutamine protein is directly proportional to the length of the glutamine repeats and inversely dependent on the size of the corresponding protein.
View Article and Find Full Text PDFHuntington's disease is a progressive neurodegenerative disorder that is associated with a CAG repeat expansion in the gene encoding huntingtin. We found that a 60-kDa protein was increased in Neuro2a cells expressing the N-terminal portion of huntingtin with expanded polyglutamine. We purified this protein, and, using mass spectrometry, identified it as p62, an ubiquitin-associated domain-containing protein.
View Article and Find Full Text PDFMethods Mol Biol
September 2004
A protein marked for degradation by the ubiquitin-proteasome pathway (UPP) is attached to multiple molecules of ubiquitin, a 76-amino-acid protein that targets the protein for rapid hydrolysis by 26S proteasome. Impaired function of UPP results in accumulation of misfolded and ubiquitinated proteins and has been implicated in the pathogenesis of various neurodegenerative diseases, including polyglutamine diseases. Impaired function of UPP can be evaluated either by assaying the proteasome's protease activity or the accumulation of ubiquitinated proteins.
View Article and Find Full Text PDFInhibition of polyglutamine-induced protein aggregation could provide treatment options for polyglutamine diseases such as Huntington disease. Here we showed through in vitro screening studies that various disaccharides can inhibit polyglutamine-mediated protein aggregation. We also found that various disaccharides reduced polyglutamine aggregates and increased survival in a cellular model of Huntington disease.
View Article and Find Full Text PDFCurcumin is a natural polyphenolic compound having an antiproliferative property, which recent evidence suggests is due to its ability to induce apoptosis. However, the molecular mechanisms through which curcumin induces apoptosis are not fully understood. Here, we report that the curcumin-induced apoptosis is mediated through the impairment of the ubiquitin-proteasome system.
View Article and Find Full Text PDFSingle-phase approaches are introduced for the synthesis of nearly monodisperse Au and other noble metal nanocrystals. The new approaches possess all the advantages of the popular Brust method. With weak ligands or surfactants for the metal ions, the control of the size and size distribution of the nanocrystals in synthesis in the size range between 1 and 15 nm was achieved via maintaining balanced nucleation and growth by tuning the activities of the metal precursors and reducing reagents.
View Article and Find Full Text PDFPolyglutamine diseases consist of a group of familial neurodegenerative disorders caused by expression of proteins containing expanded polyglutamine stretch. Over the past several years, tremendous progress has been made in identifying the molecular mechanisms by which the expanded polyglutamine tract leads to neuronal dysfunction and neurodegeneration. A common feature of most polyglutamine disorders is the occurrence of ubiquitin-positive neuronal intranuclear inclusions.
View Article and Find Full Text PDF[reaction: see text] In cases where both reactants in a phase-vanishing reaction are less dense than the fluorous phase, an alternative to the U-tube method is to employ a solvent with greater density than the fluorous phase, such as 1,2-dibromoethane. This modification has been successfully applied to the methylation of a phenol derivative with dimethyl sulfate and to the m-CPBA-induced epoxidation of alkenes, N-oxide formation from nitrogen-containing compounds, and S-oxide or sulfone formation from organic sulfides.
View Article and Find Full Text PDFIn order to investigate any effect of truncated mutant huntingtin (tNhtt) aggregation on protein kinase C (PKC) signaling in Huntington's disease (HD), we studied a possible association of PKC isoforms with the aggregates using cellular and transgenic models of HD. In this report we describe an association of mutant tNhtt with at least three PKC isoforms (alpha, delta, zeta), as revealed by co-immunoprecipitation assays and immunocytochemistry in a cellular model of HD (Neuro2a cells expressing tNhtt-150Q-EGFP), as well as a specific association of PKC delta with intranuclear aggregates in a transgenic model (R6/2 mice). Immunoblot analysis of isolated nuclear fractions shows an elevation of nuclear PKC delta in transgenic brain tissue.
View Article and Find Full Text PDFHigh quality single size nanorods can be separated from polydisperse samples using surfactant-assisted nanorod self-assembly.
View Article and Find Full Text PDFExpansion of CAG repeats within the coding region of target genes is the cause of several autosomal dominant neurodegenerative diseases including Huntington's disease (HD). A hallmark of HD is the proteolytic production of N-terminal fragments of huntingtin containing polyglutamine repeats that form ubiquitinated aggregates in the nucleus and cytoplasm of the affected neurons. In this study, we used an ecdysone-inducible stable mouse neuro2a cell line that expresses truncated N-terminal huntingtin (tNhtt) with different polyglutamine length, along with mice transgenic for HD exon 1, to demonstrate that the ubiquitin-proteasome pathway is involved in the pathogenesis of HD.
View Article and Find Full Text PDFA study was conducted to investigate whether target hormones affect 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-inducible gene expression, using as an experimental model system three human cancer cell lines, breast (MCF-7), uterine (RL95-2), and prostate (LNCaP). Exposure to TCDD induced the CYP1A1 gene in all three cell lines. MCF-7 and RL95-2 cells showed more than 15- and 10-fold induction of EROD (7-ethoxyresorufin O-deethylase) activity, respectively, compared with the less responsive LNCaP cells.
View Article and Find Full Text PDFProtein Eng
September 2000
A lambda-repressor mutant, S228N, which is defective in tetramer formation in the free state but retains full cooperativity, was studied in detail. Isolated single operator-bound S228N repressor shows association properties similar to those of the wild-type repressor. Fluorescence anisotropy studies with dansyl chloride-labeled repressor show a dimer-monomer dissociation constant of around 10(-5) M.
View Article and Find Full Text PDFHuntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by polyglutamine expansion in the disease protein, huntingtin. In HD patients and transgenic mice, the affected neurons form characteristic ubiquitin-positive nuclear inclusions (NIs). We have established ecdysone-inducible stable mouse Neuro2a cell lines that express truncated N-terminal huntingtin (tNhtt) with different polyglutamine lengths which form both cytoplasmic and nuclear aggregates in a polyglutamine length- and inducer dose-dependent manner.
View Article and Find Full Text PDFHormonal regulation of a major 20 kDa protein of hamster exorbital lacrimal gland (LG) was studied by SDS-PAGE profile analysis and the purified protein's antisera was used to screen tissues of hamster and other species for crossreacting proteins. This protein was seen in female LG but not in males and late-pregnant or hCG-treated females. Low estrogen state in females after gonadectomy, prolonged light-deprivation, prolonged starvation or lactation increased its level several folds to approximately 20% of LG soluble proteins and similar levels were induced in males after gonadectomy (low androgen state).
View Article and Find Full Text PDFA human carcinogen, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induces liver tumors in female rats. In this study, we examined the effects of estrogen on an arylhydrocarbon receptor (AhR)-responsible protein, CYP1A1 expression induced by TCDD in female rat livers. The induction of CYP1A1 by a dose of 300 ng TCDD/kg and its resultant enzymatic activity were significantly enhanced by 5 microg 17beta-estradiol/kg body weight treatment to both intact and ovariectomized rats.
View Article and Find Full Text PDFWe have previously identified massively expressed 24- and 20.5-kDa male-specific proteins in submandibular salivary glands (SMG) of adult hamsters. Here we report the cloning of the cDNA encoding the 24-kDa protein which we have now found to be a heterogenously N-glycosylated form of the 20.
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