13 research outputs found

    Dissection of Structure and Function of the N-Terminal Domain of Mouse DNMT1 Using Regional Frame-Shift Mutagenesis

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    Deletion analysis of mouse DNMT1, the primary maintenance methyltransferase in mammals, showed that most of the N-terminal regulatory domain (amino acid residues 412–1112) is required for its enzymatic activity. Although analysis of deletion mutants helps to identify regions of a protein sequence required for a particular activity, amino acid deletions can have drastic effects on protein structure and/or stability. Alternative approaches represented by rational design and directed evolution are resource demanding, and require high-throughput selection or screening systems. We developed Regional Frame-shift Mutagenesis (RFM) as a new approach to identify portions required for the methyltransferase activity of DNMT1 within the N-terminal 89–905 amino acids. In this method, a short stretch of amino acids in the wild-type protein is converted to a different amino acid sequence. The resultant mutant protein retains the same amino acid length as the wild type, thereby reducing physical constrains on normal folding of the mutant protein. Using RFM, we identified three small regions in the amino-terminal one-third of the protein that are essential for DNMT1 function. Two of these regions (amino acids 124–160 and 341–368) border a large disordered region that regulates maintenance methylation activity. This organization of DNMT1's amino terminus suggests that the borders define the position of the disordered region within the DNMT1 protein, which in turn allows for its proper function

    Melanocortin-1 Receptor Positively Regulates Human Artery Endothelial Cell Migration.

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    Background/aims Melanocortin receptors (MCRs) belong to a hormonal signalling pathway with multiple homeostatic and protective actions. Microvascular and umbilical vein endothelial cells (ECs) express components of the melanocortin system, including the type 1 receptor (MC1R), playing a role in modulating inflammation and vascular tone. Since ECs exhibit a remarkable heterogeneity, we investigated whether human artery ECs express any functional MCR and whether its activation affects cell migration. Methods We used reverse transcription real-time PCR to examine the expression of melanocortin system components in primary human artery ECs. We assessed MC1R protein expression and activity by western blot, immunohistochemistry, cAMP production, and intracellular Ca²⁺ mobilization assays. We performed gap closure and scratch tests to examine cell migration after stimulation with alpha-melanocyte-stimulating hormone (α-MSH), the receptor highest-affinity natural ligand. We assessed differential time-dependent transcriptional changes in migrating cells by microarray analysis. Results We showed that human aortic ECs (HAoECs) express a functionally active MC1R. Unlike microvascular ECs, arterial cells did not express the α-MSH precursor proopiomelanocortin, nor produced the hormone. MC1R engagement with a single pulse of α-MSH accelerated HAoEC migration both in the directional migration assay and in the scratch wound healing test. This was associated with an enhancement in Ca²⁺ signalling and inhibition of cAMP elevation. Time-course genome-wide expression analysis in HAoECs undergoing directional migration allowed identifying dynamic co-regulation of genes involved in extracellular matrix-receptor interaction, vesicle-mediated trafficking, and metal sensing - which have all well-established influences on EC motility -, without affecting the balance between pro- and anticoagulant genes. Conclusion Our work broadens the knowledge on peripherally expressed MC1R. These results indicate that the receptor is constitutively expressed by arterial ECs and provide evidence of a novel homeostatic function for MC1R, whose activation may participate in preventing/healing endothelial dysfunction or denudation in macrovascular arteries

    Time-course gene expression data on the transcriptional effects of Aminaphtone on ECV304 endothelial cells

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    We previously showed that Aminaphtone, a drug used in the treatment of chronic venous insufficiency, modulates several vasoactive factors, such as endothelin-1 and adhesion molecules. Here, we provide data of time-course experiments about the effects of Aminaphtone on gene expression at the genome-wide level in human endothelial cells undergoing cytokine stimulation in vitro. ECV-304 endothelial cells were incubated with interleukin-1β (IL-1β) in the presence or absence of Aminaphtone for 1, 3, and 6 h. Gene expression profiles were analyzed by microarray. This article contains complete data on the genes significantly modulated by the drug over time. The data are supplemental to our original research article reporting detailed analysis of the actions of Aminaphtone on IL-1β stimulated endothelial cells at the molecular level, ''Gene expression profiling reveals novel protective effects of Aminaphtone on ECV304 endothelial cells'' (Salazar et al., 2016) [1]. Chemical compound studied in this article: Aminaphtone (PubChem CID: 84621), Keywords: Endothelial cells, Transcriptome, Inflammation, Vasoactive dru

    Systemic allergic reactions induced by labile plant‐food allergens: Seeking potential cofactors. A multicenter study

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    Background: Heat-and-pepsin-sensitive plant food allergens (PR-10 and profilin) sometimes cause systemic reaction.Objective: To detect the risk factors for systemic reactions induced by labile food allergens.Methods: A retrospective multicenter study was performed on patients with a documented history of systemic allergic reaction to labile plant food allergens and on age-matched controls with a history of oral allergy syndrome (OAS) induced by the same foods. Offending foods, their amount, and state (solid or liquid), and potential cofactors (nonsteroidal anti-inflammatory drugs, protonic pump inhibitors, exercise, alcohol, and fasting) were considered.Results: We studied 89 patients and 81 controls. Sensitization to PR-10 or profilin, IgE to Bet v 1 and/or Bet v 2, and foods causing OAS were similar in the two groups. Twenty patients experienced >1 systemic allergic reaction. Tree nuts, Rosaceae, Apiaceae, and soymilk were the main offending foods. Seventeen (19%) patients were taking a PPI when the systemic reaction occurred (vs 5% in controls; P < .025). The ingestion of the offending food in liquid form (soymilk) was frequent among patients (15%) but unusual among controls (2%; P < .025). Soy milk-induced systemic reactions were independent of PPI treatment. Fasting and excess of allergen, but not NSAID and exercise, were other relevant cofactors for systemic reactions. Systemic reactions occurred without any identifiable cofactor in 39 (44%) cases.Conclusion: PR-10- and profilin-induced systemic reactions are facilitated by PPI, ingestion of large amounts of unprocessed foods, and fasting. Soybean beverages represent a risk for PR-10 hypersensitive patients and should be avoided
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