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Expression of the SERPING1 gene is not regulated by promoter hypermethylation in peripheral blood mononuclear cells from patients with hereditary angioedema due to C1-inhibitor deficiency.

ABSTRACT: SERPING1 mutations causing Hereditary Angioedema type I (HAE-I) due to C1-Inhibitor (C1-INH) deficiency display a dominant-negative effect usually resulting in protein levels far below the expected 50%. To further investigate mechanisms for its reduced expression, we analyzed the promoter DNA methylation status of SERPING1 and its influence on C1-INH expression. Global epigenetic reactivation correlated with C1-INH mRNA synthesis and protein secretion in Huh7 hepatoma cells. However, PBMCs extracted from controls, HAE-I and HAE-II patients presented identical methylation status of the SERPING1 promoter when analyzed by bisulphite sequencing; the proximal CpG island (exon 2) is constitutively unmethylated, while the most distant one (5.7Kb upstream the transcriptional start site) is fully methylated. These results correlate with the methylation profile observed in Huh7 cells and indicate that there is not a direct epigenetic regulation of C1-INH expression in PBMCs specific for each HAE type. Other indirect modes of epigenetic regulation cannot be excluded.

SUBMITTER: Lopez-Lera A

PROVIDER: S-EPMC4115163 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Expression of the SERPING1 gene is not regulated by promoter hypermethylation in peripheral blood mononuclear cells from patients with hereditary angioedema due to C1-inhibitor deficiency.

López-Lera Alberto A Pernia Olga O López-Trascasa Margarita M Ibanez de Caceres Inmaculada I

Orphanet journal of rare diseases 20140722

SERPING1 mutations causing Hereditary Angioedema type I (HAE-I) due to C1-Inhibitor (C1-INH) deficiency display a dominant-negative effect usually resulting in protein levels far below the expected 50%. To further investigate mechanisms for its reduced expression, we analyzed the promoter DNA methylation status of SERPING1 and its influence on C1-INH expression. Global epigenetic reactivation correlated with C1-INH mRNA synthesis and protein secretion in Huh7 hepatoma cells. However, PBMCs extra ...[more]

PMID: 25053016

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Project description:BackgroundIn hereditary angioedema (HAE) due to C1-inhibitor deficiency (C1-INH-HAE), bradykinin-mediated submucosal and/or subcutaneous angioedema dominates the clinical picture. The deficiency of C1-inhibitor can lead to the over-activation of the complement system. Complement plays an important role in all types of hypersensitivity reactions. On the other hand, during the degranulation of mast cells, heparin is also released amongst other substances. Heparin can activate the plasma kinin-kallikrein system, leading to bradykinin generation. These observations suggest a possible connection between C1-INH-HAE and mast cell-mediated hypersensitivity reactions.ObjectiveTo assess the occurrence of hypersensitivity reactions in the Hungarian C1-INH-HAE population.MethodsPatients filled out a questionnaire of 112 questions, either online or on paper. The questions were about hypersensitivity and C1-INH-HAE symptoms, the relation between these 2, general health, and demographic data. The study protocol was approved by the institutional review board of Semmelweis University, Budapest, and informed consent was obtained from the participants.ResultsOne hundred and six patients (64 female, 42 male, median age 46 years) responded, with 63.2% having hypersensitivity. Hypersensitivity was provoked by pollen in 25.5% of patients, by contact sensitivity in 22.6%, by food in 21.7%, by insect sting in 19.8%, by pet in 15.1%, by drug in 14.2%, by dust mite in 5.7%, and by mold in 1.9%. In 11 patients, hypersensitivity symptoms appeared after the diagnosis of C1-INH-HAE. Six hypersensitive patients experienced improvement in their symptoms; 42 remained the same, but none experienced worsening after the diagnosis of C1-INH-HAE. In 7.8% of the hypersensitive patients, a C1-INH-HAE attack worsened the hypersensitivity symptoms, while 15.7% of the hypersensitive patients experienced a C1-INH-HAE attack provoked by contact with the provoking factor.ConclusionWhile 63.2% of our C1-INH-HAE patients have reported hypersensitivity symptoms, Eurostat's latest data puts the prevalence of self-reported allergies in Hungary at 19.3%. Since in our experience most Hungarian patients report hypersensitivity reactions as allergies, this may support a possible connection between the 2 diseases, but further molecular studies are needed.

Project description:Hereditary angioedema (HAE) is a rare autosomal dominant disease characterized by swelling of the face, lips, tongue, larynx, genitalia, or extremities, with abdominal pain caused by intra-abdominal edema. HAE is caused by mutations affecting the C1 inhibitor gene, SERPING1, resulting in low levels of C1 inhibitor (Type I HAE) or normal levels of ineffective C1 inhibitor (Type II HAE). A nationwide survey identified nine unrelated families with HAE in Slovenia, among whom 17 individuals from eight families were recruited for genetic analyses. A diagnosis of HAE was established in the presence of clinical and laboratory criteria (low C1 inhibitor antigenic levels and/or function), followed up by a positive family history. Genetic studies were carried out using PCR and sequencing to detect SERPING1 mutations in promoter, noncoding exon 1, the 7 coding exons, and exon-intron boundaries. Multiplex ligation-dependent probe amplification was performed in order to search for large deletions/duplications in SERPING1 gene. A mutation responsible for HAE was identified in patients from seven families with the disease. In HAE type I families, one previously reported substitution (Gln67Stop, c.265C>T) and four novel mutations were identified. The new mutations included two missense substitutions, Ser128Phe (c.449C>T), and Glu429Lys (c.1351G>A), together with two frameshift mutations, indel (c.49delGinsTT) and deletion (c.593_594delCT). Both families with HAE type II harbored the two well-known substitutions affecting the arginyl residue at the reactive center in exon 8, Arg444Cys (c.1396C>T) and Arg444His (c.1397G>A), respectively. In one patient only the homozygous variant g.566T>C (c.-21T>C) was identified. Our study identified four novel mutations in the Slovenian HAE population, highlighting the heterogeneity of mutations in the SERPING1 gene causing C1 inhibitor deficiency and HAE. In a single patient with HAE a homozygous variant g.566T>C (c.-21T>C) might be responsible for the disease.

Dataset Information

Expression of the SERPING1 gene is not regulated by promoter hypermethylation in peripheral blood mononuclear cells from patients with hereditary angioedema due to C1-inhibitor deficiency.

Publications

Expression of the SERPING1 gene is not regulated by promoter hypermethylation in peripheral blood mononuclear cells from patients with hereditary angioedema due to C1-inhibitor deficiency.

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