Search results for "Glycosyl"
showing 10 items of 317 documents
UVA irradiation induces relocalisation of the DNA repair protein hOGG1 to nuclear speckles
2006
The DNA glycosylase hOGG1 initiates base excision repair (BER) of oxidised purines in cellular DNA. Using confocal microscopy and biochemical cell fractionation experiments we show that, upon UVA irradiation of human cells, hOGG1 is recruited from a soluble nucleoplasmic localisation to the nuclear matrix. More specifically, after irradiation, hOGG1 forms foci colocalising with the nuclear speckles, organelles that are interspersed between chromatin domains and that have been associated with transcription and RNA-splicing processes. The use of mutant forms of hOGG1 unable to bind the substrate showed that relocalisation of hOGG1 does not depend on the recognition of the DNA lesion by the en…
Photogenotoxicity of folic acid.
2013
Folic acid (FA), also named vitamin B9, is an essential cofactor for the synthesis of DNA bases and other biomolecules after bioactivation by dihydrofolate reductase (DHFR). FA is photoreactive and has been shown to generate DNA modifications when irradiated with UVA (360 nm) in the presence of DNA under cell-free conditions. To investigate the relevance of this reaction for cells and tissues, we irradiated three different cell lines (KB nasopharyngeal carcinoma cells, HaCaT keratinocytes, and a melanoma cell line) in the presence of FA and quantified cytotoxicity and DNA damage generation. The results indicate that FA is phototoxic and photogenotoxic by two different mechanisms. First, ext…
The glycosyltransferase activities of lysyl hydroxylase 3 (LH3) in the extracellular space are important for cell growth and viability.
2008
Abstract Lysyl hydroxylase (LH) isoform 3 is a post-translational enzyme possessing LH, collagen galactosyltransferase (GT) and glucosyltransferase (GGT) activities. We have demonstrated that LH3 is found not only intracellularly, but also on the cell surface and in the extracellular space, suggesting additional functions for LH3. Here we show that the targeted disruption of LH3 by siRNA causes a marked reduction of both glycosyltransferase activities, and the overexpression of LH3 in HT-1080 cells increases hydroxylation of lysyl residues and the subsequent galactosylation and glucosylation of hydroxylysyl residues. These data confirm the multi-functionality of LH3 in cells. Furthermore, t…
The Chaperone Activity of Clusterin is Dependent on Glycosylation and Redox Environment
2014
Background/Aims: Clusterin (CLU), also known as Apolipoprotein J (ApoJ) is a highly glycosylated extracellular chaperone. In humans it is expressed from a broad spectrum of tissues and related to a plethora of physiological and pathophysiological processes, such as Alzheimer's disease, atherosclerosis and cancer. In its dominant form it is expressed as a secretory protein (secreted CLU, sCLU). During its maturation, the sCLU-precursor is N-glycosylated and cleaved into an α- and a β-chain, which are connected by five symmetrical disulfide bonds. Recently, it has been demonstrated that besides the predominant sCLU, rare intracellular CLU forms are expressed in stressed cells. Since these for…
Arbutin synthase, a novel member of the NRD1β glycosyltransferase family, is a unique multifunctional enzyme converting various natural products and …
2002
Plant glucosyltransferases (GTs) play a crucial role in natural product biosynthesis and metabolization of xenobiotics. We expressed the arbutin synthase (AS) cDNA from Rauvolfia serpentina cell suspension cultures in Escherichia coli with a 6 x His tag and purified the active enzyme to homogeneity. The recombinant enzyme had a temperature optimum of 50 degrees C and showed two different pH optima (4.5 and 6.8 or 7.5, depending on the buffer). Out of 74 natural and synthetic phenols and two cinnamyl alcohols tested as substrates for the AS, 45 were accepted, covering a broad range of structural features. Converting rates comparable to hydroquinone were not achieved. In contrast to this broa…
The Implication of Xyloglucan Endotransglucosylase/Hydrolase (XTHs) in Tomato Fruit Infection by Penicillium expansum Link. A
2007
In general, cell wall-degrading enzymes produced by plant pathogenic fungi are considered important pathogenicity factors. In this work, we evaluate the implication of xyloglucan endotransglucosylase/ hydrolase (XTHs), a potential hemicellulosic repairing enzyme, in the infection mechanism process by the fungus. This study investigated the SIXTHS expresion and xyloglucan endotransglucosylase (XET) activity during infection of two tomato fruit cultivars by Penicillium expansum Link. A. In infected fruits, XET specific activity decreased drastically after long infection periods, 24 and 48 h for Canario and Money Maker tomato fruits, respectively. Real Time RT-PCR of eleven SIXTHS also showed …
Expression and purification of polyhistidine-tagged rotavirus NSP4 proteins in insect cells
2003
The rotavirus nonstructural NSP4 protein, a transmembrane endoplasmic reticulum-specific glycoprotein, has been described as the first viral enterotoxin. Purified NSP4 or a peptide corresponding to NSP4 residues 114-135 induces diarrhea in young mice. NSP4 has a membrane-destabilizing activity and causes an increase in intracellular calcium levels and chloride secretion by a calcium-dependent signalling pathway in eucaryotic cells. In this study, four recombinant baculoviruses were generated expressing the rotavirus NSP4 glycoprotein from the human strains Wa and Ito, the porcine strain OSU, and the simian strain SA11, which belong to two different NSP4 genotypes, A and B. The recombinant g…
Are the new genetic tools for diagnosis of Wilson disease helpful in clinical practice?
2020
Summary The diagnosis of Wilson disease is not always easy. For many patients, a combination of tests reflecting disturbed copper metabolism may be needed. Testing for ATP7B variants has become part of the routine diagnostic approach. The methods of genetic testing include analysis of the 21 coding exons and intronic flanking sequences, in which exons with recurrent variants would be prioritised depending on the mutation frequency in the local population. If sequencing the entire ATP7B gene cannot identify 2 variants and the suspicion for Wilson disease is high, after reviewing the clinical data, WES (whole-exome sequencing) or WGS (whole-genome sequencing) could be applied. A workflow base…
Drug-metabolizing enzymes in the skin of man, rat, and pig.
2007
The mammalian skin has long been considered to be poor in drug metabolism. However, many reports clearly show that most drug metabolizing enzymes also occur in the mammalian skin albeit at relatively low specific activities. This review summarizes the current state of knowledge on drug metabolizing enzymes in the skin of human, rat, and pig, the latter, because it is often taken as a model for human skin on grounds of anatomical similarities. However only little is known about drug metabolizing enzymes in pig skin. Interestingly, some cytochromes P450 (CYP) have been observed in the rat skin which are not expressed in the rat liver, such as CYP 2B12 and CYP2D4. As far as investigated most d…
N-Glycosylation modification of proteins is an early marker of the enterocytic differentiation process of HT-29 cells
1990
International audience; The human colon cancer cell line HT-29 remains totally undifferentiated when glucose is present in the culture medium (HT-29 Glc+), while the same cells may undergo typical enterocytic differentiation after reaching confluence when grown in glucose-deprived medium (HT-29 Glc-). Recently, we demonstrated a deficiency in the overall N-glycan processing in confluent undifferentiated cells, whereas differentiated cells follow a classical pattern of N-glycosylation. The main changes in N-glycosylation observed in confluent undifferentiated cells may be summarised as follows: 1) the conversion of high mannose into complex glycopeptides is greatly decreased; 2) this decreas…