Search results for "regulation"
showing 10 items of 4463 documents
Sildenafil protects human mammary epithelial cells against ROS production induced by estradiol
2010
Several studies suggest that xanthine dehydrogenase (XDH) and its oxidase form (XO) play an important role in various types of ischemic and vascular injuries. Recently, we have demonstrated that estradiol (E2) induces a significant decrease of the expression and activity of XDH and of its conversion to XO in human mammary epithelial cells. E2 is known to induce upregulation of eNOS gene expression in aortic endothelial cells. Because the XO-derived O2·- combines with ·NO to yield ONOO-, and considering that ONOO- converts XDH to XO, the resulting increase of XO activity and reactive oxygen species production would eventually lead to a further increase of ONOO- production, thus creating a vi…
Validation strategies for antibodies targeting modified ribonucleotides
2020
Chemical modifications are found on almost all RNAs and affect their coding and noncoding functions. The identification of m6A on mRNA and its important role in gene regulation stimulated the field to investigate whether additional modifications are present on mRNAs. Indeed, modifications including m1A, m5C, m7G, 2′-OMe, and Ψ were detected. However, since their abundances are low and tools used for their corroboration are often not well characterized, their physiological relevance remains largely elusive. Antibodies targeting modified nucleotides are often used but have limitations such as low affinity or specificity. Moreover, they are not always well characterized and due to the low abun…
Antioxidants in skeletal muscle physiology, a radically different approach.
2015
Regular physical exercise has many health benefits (1). Paradoxically, it is also clear that contracting skeletal muscles generate reactive oxygen species (ROS) and that prolonged and intense exercise can result in oxidative damage to cellular constituents (2-4). Reactive oxygen species production is dependent on the intensity of the exercise with higher amount of ROS generated by strenuous exercise (5, 6). Antioxidants may reduce the adverse effects of exercise-induced ROS (2-4). However, ROS are not only toxic but rather play an important role in cell signalling and in the regulation of gene expression (7, 8) and force production in skeletal muscle (9). Thus, we have recently raised quest…
Chemical Synthesis of 2′-O-Alkylated siRNAs
2010
Chemical synthesis has been a major endeavor to create active siRNAs. The downregulation of mRNA by 21-mer double-stranded siRNAs can be improved by using modified nucleotides, especially 2'-O-alkylated ones. Besides the commercially available 2 cent-O-methyl ribosides, 2'-alkyl groups bearing positive charges are especially promising candidates. We have shown that in a proper formulation they are superior to unmodified siRNAs. This may be due to enhanced stability and most probably to a better uptake into the cells.
2004
β-oxidation of long and very long chain fatty acyl-CoA derivatives occurs in peroxisomes, which are ubiquitous subcellular organelles of eukaryotic cells. This pathway releases acetyl-CoA as precursor for several key molecules such as cholesterol. Numerous enzymes participating to cholesterol and fatty acids biosynthesis pathways are co-localized in peroxisomes and some of their encoding genes are known as targets of the NFY transcriptional regulator. However, until now no interaction between NFY transcription factor and genes encoding peroxisomal β-oxidation has been reported. This work studied the interactions between NFY factor with the rat gene promoters of two enzymes of the fatty acid…
Differential Expression of theS-Adenosyl-l-Methionine Synthase Genes during Pea Development1
1998
Abstract Two genes coding for S-adenosyl-l-methionine synthase (SAMS, EC 2.5.1.6) were previously isolated from pea (Pisum sativum) ovaries. Both SAMS genes were highly homologous throughout their coding regions but showed a certain degree of sequence divergence within the 5′ and the 3′ untranslated regions. These regions have been used as gene-specific probes to analyze the differential expression of SAMS1and SAMS2 genes in pea plants. The ribonuclease protection assay revealed different expression patterns for each individual gene. SAMS1 was strongly expressed in nearly all tissues, especially in roots. SAMS2 expression was weaker, reaching its highest level at the apex. Following pollina…
Revisiting delta-6 desaturase regulation by C18 unsaturated fatty acids, depending on the nutritional status.
2009
Dietary polyunsaturated fatty acids (PUFA) play a key role in regulating delta-6 desaturase (D6D), the key enzyme for long-chain PUFA biosynthesis. Nevertheless, the extent of their effects on this enzyme remains controversial and difficult to assess. It has been generally admitted that C18 unsaturated fatty acids (UFAs) regulate negatively delta-6 desaturase (D6D). This inhibition has been evidenced in regard to a high glucose/fat free (HG/FF) diet used in reference. However, several nutritional investigations did not evidence any inhibition of desaturases when feeding fatty acids. Because the choice of the basal diet appeared to be of primary importance in such experiments, our goal was t…
Influence of negative allosteric cooperativity in cation transport.
1992
Abstract The bis-macrocyclic ether5 seems to have a negative allosteric cooperativity and is able to transport double the amount of Na+ and K+ cations as monocyclic systems. This compound could be used as a simple model of the plasma membrane Na+−K+ ATPase which actively pumps Na+ out and K+ into the cell, respectively.
Kinetics of alkaline phosphatase from pig kidney. Influence of complexing agents on stability and activity
1976
Metal ion-complexing agents, like KCN, EDTA etc., inactivate alkaline phosphatase of pig kidney. This inactivation is reversible at low concentrations of the complexing agents and irreversible at high concentrations. The reversible inhibition is probably due to removal of Zn2+ ions from the active site, where they are necessary for catalytic action, whereas the irreversible inhibition results from the removal of Zn2+ ions necessary for preservation of the structure. The inactivation is pseudo-first order. It depends on the concentration, size and charge of the complexing agents. β-Glycerophosphate and Mg2+ ions protect the enzyme from inactivation by complexing agents. Quantitative examinat…