Natural and engineered carboxy-terminal variants: decreased secretion and gain-of-function result in asymptomatic coagulation factor VII deficiency.

6533b856fe1ef96bd12b1da9

RESEARCH PRODUCT

Natural and engineered carboxy-terminal variants: decreased secretion and gain-of-function result in asymptomatic coagulation factor VII deficiency.

Mirko Pinotti Mario Lapecorella Alessio Branchini Guglielmo Mariani Rosella Mari Alessandro Canella Francesco Bernardi Mariasanta Napolitano Lara Rizzotto Muriel Giansily-blaizot

subject

Male Proteases Heterozygote Factor VII Deficiency Enzyme-Linked Immunosorbent Assay FVII Biology medicine.disease_cause Thromboplastin Tissue factor chemistry.chemical_compound Carboxy-terminal hemic and lymphatic diseases medicine FACTOR VII DEFICIENCY MOLECULAR VARIANTS Thromboplastin Missense mutation Animals Humans cardiovascular diseases Child Blood Coagulation Prothrombin time Mutation medicine.diagnostic_test Factor VII Homozygote Hematology Factor VII Middle Aged Molecular biology Asymptomatic; Carboxy-terminal; FVII; Mutation;Asymptomatic chemistry Coagulation Codon Nonsense Mutation Mutagenesis Site-Directed Prothrombin Time Cattle Female Rabbits Original Articles and Brief Reports

description

We report 2 asymptomatic homozygotes for the nonsense p.R462X mutation affecting the carboxy-terminus of coagulation factor VII (FVII, 466 aminoacids). FVII levels of 3-5% and 2.7 ± 0.4% were found in prothrombin time-based and activated factor X (FXa) generation assays with human thromboplastins. Noticeably, FVII antigen levels were barely detectable (0.7 ± 0.2%) which suggested a gain-of-function effect. This effect was more pronounced with bovine thromboplastin (4.8 ± 0.9%) and disappeared with rabbit thromboplastin (0.7 ± 0.2%). This suggests that the mutation influences tissue factor/FVII interactions. Whereas the recombinant rFVII-462X variant confirmed an increase in specific activity (~400%), a panel of nonsense (p.P466X, p.F465X, p.P464X, p.A463X) and missense (p.R462A, p.R462Q, p.R462W) mutations of the FVII carboxy-terminus resulted in reduced secretion but normal specific activity. These data provide evidence for counteracting pleiotropic effects of the p.R462X mutation, which explains the asymptomatic FVII deficiency, and contributes to our understanding of the role of the highly variable carboxy-terminus of coagulation serine proteases.

year	journal	country	edition	language
2012-01-01

10.3324/haematol.2011.049403 http://hdl.handle.net/10447/71163