Dataset Information

Identification of Regulatory Mutations in SERPINC1 Affecting Vitamin D Response Elements Associated with Antithrombin Deficiency.

ABSTRACT: Antithrombin is a crucial anticoagulant serpin whose even moderate deficiency significantly increases the risk of thrombosis. Most cases with antithrombin deficiency carried genetic defects affecting exons or flanking regions of SERPINC1.We aimed to identify regulatory mutations inSERPINC1 through sequencing the promoter, intron 1 and 2 of this gene in 23 patients with antithrombin deficiency but without known genetic defects. Three cases with moderate antithrombin deficiency (63-78%) carried potential regulatory mutations. One located 200 bp before the initiation ATG and two in intron 1. These mutations disrupted two out of five potential vitamin D receptor elements (VDRE) identified in SERPINC1 with different software. One genetic defect, c.42-1060_-1057dupTTGA, was a new low prevalent polymorphism (MAF: 0.01) with functional consequences on plasma antithrombin levels. The relevance of the vitamin D pathway on the regulation of SERPINC1 was confirmed in a cell model. Incubation of HepG2 with paricalcitol, a vitamin D analog, increased dose-dependently the levels of SERPINC1transcripts and antithrombin released to the conditioned medium. This study shows further evidence of the transcriptional regulation of SERPINC1 by vitamin D and first describes the functional and pathological relevance of mutations affecting VDRE of this gene. Our study opens new perspectives in the search of new genetic defects involved in antithrombin deficiency and the risk of thrombosis as well as in the design of new antithrombotic treatments.

SUBMITTER: Toderici M

PROVIDER: S-EPMC4803246 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Identification of Regulatory Mutations in SERPINC1 Affecting Vitamin D Response Elements Associated with Antithrombin Deficiency.

Toderici Mara M de la Morena-Barrio María Eugenia ME Padilla José J Miñano Antonia A Antón Ana Isabel AI Iniesta Juan Antonio JA Herranz María Teresa MT Fernández Nuria N Vicente Vicente V Corral Javier J

PloS one 20160322 3

Antithrombin is a crucial anticoagulant serpin whose even moderate deficiency significantly increases the risk of thrombosis. Most cases with antithrombin deficiency carried genetic defects affecting exons or flanking regions of SERPINC1.We aimed to identify regulatory mutations inSERPINC1 through sequencing the promoter, intron 1 and 2 of this gene in 23 patients with antithrombin deficiency but without known genetic defects. Three cases with moderate antithrombin deficiency (63-78%) carried po ...[more]

PMID: 27003919

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Project description:BackgroundAntithrombin (AT) is the main physiological anticoagulant involved in hemostasis. Hereditary AT deficiency is a rare autosomal dominant thrombotic disease mainly caused by mutations in SERPINC1, which was usually manifested as venous thrombosis and pulmonary embolism. In this study, we analyzed the clinical characteristics and screened for mutant genes in two pedigrees with hereditary AT deficiency, and the functional effects of the pathogenic mutations were evaluated.MethodsCandidate gene variants were analyzed by next-generation sequencing to screen pathogenic mutations in probands, followed by segregation analysis in families by Sanger sequencing. Mutant and wild-type plasmids were constructed and transfected into HEK293T cells to observe protein expression and cellular localization of SERPINC1. The structure and function of the mutations were analyzed by bioinformatic analyses.ResultsThe proband of pedigree A with AT deficiency carried a heterozygous frameshift mutation c.1377delC (p.Asn460Thrfs*20) in SERPINC1 (NM000488.3), a 1377C base deletion in exon 7 resulting in a backward shift of the open reading frame, with termination after translation of 20 residues, and a different residue sequence translated after the frameshift. Bioinformatics analysis suggests that the missing amino acid sequence caused by the frameshift mutation might disrupt the disulfide bond between Cys279 and Cys462 and affect the structural function of the protein. This newly discovered variant is not currently included in the ClinVar and HGMD databases. p.Arg229* resulted in a premature stop codon in exon 4, and bioinformatics analysis suggests that the truncated protein structure lost its domain of interaction with factor IX (Ala414 site) after the deletion of nonsense mutations. However, considering the AT truncation protein resulting from the p.Arg229* variant loss a great proportion of the molecule, we speculate the variant may affect two functional domains HBS and RCL and lack of the corresponding function. The thrombophilia and decreased-AT-activity phenotypes of the two pedigrees were separated from their genetic variants. After lentiviral plasmid transfection into HEK293T cells, the expression level of AT protein decreased in the constructed c.1377delC mutant cells compared to that in the wild-type, which was not only reduced in c.685C > T mutant cells but also showed a significant band at 35 kDa, suggesting a truncated protein. Immunofluorescence localization showed no significant differences in protein localization before and after the mutation.ConclusionsThe p.Asn460Thrfs*20 and p.Arg229* variants of SERPINC1 were responsible for the two hereditary AT deficiency pedigrees, which led to AT deficiency by different mechanisms. The p.Asn460Thrfs*20 variant is reported for the first time.

Dataset Information

Identification of Regulatory Mutations in SERPINC1 Affecting Vitamin D Response Elements Associated with Antithrombin Deficiency.

Publications

Identification of Regulatory Mutations in SERPINC1 Affecting Vitamin D Response Elements Associated with Antithrombin Deficiency.

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