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Increased Expression Level (increased + expression_level)
Selected AbstractsEntamoeba histolytica sirtuin EhSir2a deacetylates tubulin and regulates the number of microtubular assemblies during the cell cycleCELLULAR MICROBIOLOGY, Issue 7 2010Somasri Dam Summary We have discovered four sirtuin genes in Entamoeba histolytica, two of which are similar to eukaryotic sirtuins and two to bacterial and archaeal sirtuins. The eukaryotic sirtuin homologue, EhSir2a, showed NAD+ -dependent deacetylase activity and was sensitive to class III HDAC inhibitors. Localization of EhSir2a at different cellular sites suggested that this deacetylase could have multiple targets. Using an E. histolytica cDNA library in the yeast two-hybrid genetic screen, we identified several proteins that bound to EhSir2a. These proteins included Eh ,-tubulin, whose interaction with EhSir2a was validated in E. histolytica. We have shown that EhSir2a deacetylated tubulin and localized with microtubules in E. histolytica. Increased expression levels of EhSir2a in stable transformants led to reduced number of microtubular assemblies in serum synchronized cells. This effect was abrogated by mutations in the deacetylase domain of EhSir2a, showing that EhSir2a deacetylase activity affected the stability and number of microtubular assemblies during the cell cycle of E. histolytica. Our results suggest that epigenetic modification of tubulin by EhSir2a is one of the mechanisms that regulates microtubular assembly in E. histolytica. [source] Altered signalling from germline to intestine pushes daf-2;pept-1 Caenorhabditis elegans into extreme longevityAGING CELL, Issue 4 2010Britta Spanier Summary The insulin-like signalling pathway is a central regulator of development, metabolism, stress resistance and lifespan in eukaryotes. Caenorhabditis elegans daf-2(e1370) animals with a loss-of-function mutation in the insulin-like receptor live twice as long as wild-type animals, and the additional knockout of the intestinal di- and tripeptide transporter pept-1 further increases lifespan by 60%. In assessing the underlying molecular mechanisms for this phenomenon, microarray-based transcriptome data sets of daf-2(e1370) and daf-2(e1370);pept-1(lg601) animals were compared with a focus on genes that showed significantly higher changes in expression levels in daf-2;pept-1 than in daf-2. We identified 187 genes with at least fourfold decreased transcript levels and 170 with more than a fourfold increase. A large fraction of the down-regulated genes encode proteins involved in germline proliferation and reproduction. The DAF-9/DAF-12 signalling cascade was identified as a prime pathway that mediates the longevity of daf-2;pept-1 with a strict dependance on DAF-16. Loss of DAF-9/DAF-12 or KRI-1 reduces the lifespan of daf-2;pept-1 to that of the daf-2 mutant. Amongst the DAF-16 target genes, numerous enzymes involved in the defence of reactive oxygen species were with increased expression level in daf-2;pept-1. On a functional level, it was demonstrated that amongst those, a high de novo synthesis rate of glutathione is most important for the longevity phenotype of this strain. Taken together, a close interdependence of endocrine hormone signalling from germline to intestine was identified as an essential element in the control of the extreme longevity of C. elegans lacking a proper function of the insulin receptor and lacking the intestinal peptide transporter. [source] Effect of Doxycycline-Regulated ERp57 Expression on Specific Thrombopoietin Productivity of Recombinant CHO CellsBIOTECHNOLOGY PROGRESS, Issue 1 2003Sun Ok Hwang In an attempt to increase the specific thrombopoietin (TPO) productivity ( qTPO) of recombinant Chinese hamster ovary (rCHO) cells (TPO-33), the effect of expression level of ERp57, an isoform of protein disulfide isomerase, on qTPO was investigated. To regulate ERp57 expression level, the Tet-Off system was first introduced in TPO-33 cells and stable Tet-Off cells (TPO-33-Tet-Off) were screened by the luciferase assay. The rCHO cells with a doxycycline-regulated ERp57 expression system (TPO-33-ERp57) were obtained by cotransfection of pTRE-ERp57 and pTK-Hyg expression vectors into TPO-33-Tet-Off cells and subsequent screening by Western blot analysis of ERp57 and an enzyme-linked immunosorbent assay of secreted TPO. Western blot analysis showed that ERp57 expression level in TPO-33-ERp57 cells could be regulated tightly by the addition of different concentrations of doxycycline to a culture medium. A doxycycline concentration of 1 ,g/mL, which did not influence cell growth and TPO production of TPO-33-Tet-Off cells, was high enough to suppress the ERp57 expression to a basal level. Compared with the basal level, a 1.7-fold increase in ERp57 expression level was obtained in the absence of doxycycline. This increased expression level of ERp57 resulted in a 2.1-fold increase in qTPO without growth inhibition, probably as a result of the chaperone-like activity of ERp57 in CHO cells. Taken together, the results obtained here demonstrate that qTPO of rCHO cells can be increased by elevating the expression level of ERp57. [source] Regulation of keratinocyte growth factor and scatter factor in cyclosporin-induced gingival overgrowthJOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 7 2004P. L. Hyland Background:, Epithelial proliferation is a histological characteristic of drug-induced gingival overgrowth. Keratinocyte growth factor (KGF) and scatter factor (SF) are fibroblast-derived growth factors with potent mitogenic and motogenic effects on epithelial cells, and, therefore, could be involved in the pathogenesis of gingival overgrowth. The aims of this study were to investigate: (i) the effects of cyclosporin on KGF and SF expression by gingival fibroblasts; and (ii) the expression levels of KGF and SF mRNA in normal and overgrown gingival tissue. Methods:, The KGF and SF protein production was determined by enzyme-linked immunosorbent assay. Relative levels of KGF and SF mRNA expression were determined using semi-quantitative reverse transcriptase polymerase chain reaction. Expression levels in biopsies of normal and overgrown gum were also determined. Results:, In overgrown fibroblasts, 500 ng/ml cyclosporin significantly inhibited KGF and SF mRNA and protein while 2000 ng/ml cyclosporin induced a stimulatory effect. In normal cells cyclosporin significantly increased both KGF and SF. KGF and SF mRNA was detected in both normal and overgrown tissues with a tendency towards increased expression levels in overgrown tissue. Conclusion:, These results suggest that KGF and SF may have an important role in cyclosporin-induced gingival overgrowth. [source] Over-Expression of Neuropeptide Urocortin and Its Receptors in Human Allergic Nasal Mucosa,THE LARYNGOSCOPE, Issue 9 2007Tae Hoon Kim MD Abstract Objectives: Urocortin (UCN) is a member of the corticotropin releasing factor (CRF) neuropeptide family. UCN act as locally expressed proinflammatory factor and induce mast cell degranulation, cytokine secretion, and trigger vascular permeability, which are mediated by CRF receptors in peripheral tissues. Considering its functional roles, UCN and its receptors may play a role in the pathogenesis of allergic nasal mucosa. Therefore, we investigated the expression profile and distribution of UCN and CRF receptors in normal and allergic nasal mucosa. Methods: Reverse transcriptase-polymerase chain reaction, immunohistochemistry, and Western blotting were applied to the normal and allergic nasal mucosa. Results: The expression levels of UCN and CRF receptors were increased in allergic nasal mucosa in comparison with normal nasal mucosa. In normal nasal mucosa, UCN and CRF receptors were restricted to the vascular endothelium of submucosal cavernous sinusoids where faint staining was found. However, in allergic nasal mucosa, UCN was expressed in small vessels distributed in lamina propria and the vascular endothelium of cavernous sinusoid located in submucosa. Many scattered positive cells were also found in allergic nasal mucosa, probably UCN-positive leukocytes. CRF receptors were also localized in the vascular endothelium of small vessels and cavernous sinusoid. Conclusions: These results indicate that UCN may play a role in the regulation of vascular swelling in normal nasal mucosa. Moreover, in allergic nasal mucosa, increased expression levels of UCN and its receptors may contribute to increased mucosal swelling and vascular permeability, playing an important role in the pathogenesis of allergic rhinitis. [source] | |||||||||||||