The Factor VII Variant p.A354V-p.P464Hfs: Clinical versus Intracellular and Biochemical Phenotypes Induced by Chemical Chaperones

• Published in: Applied sciences Vol. 11; no. 13; p. 5762
• Main Authors: Andersen, Elisabeth, Chollet, Maria Eugenia, Bernardi, Francesco, Branchini, Alessio, Baroni, Marcello, Mariani, Guglielmo, Dolce, Alberto, Batorova, Angelika, Skarpen, Ellen, Myklebust, Christiane Filion, Skretting, Grethe, Sandset, Per Morten
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01-07-2021
• Subjects: Antigens; Biological activity; Biological effects; Chaperones; chemical chaperones; Coagulation factors; Comparative analysis; endoplasmic reticulum; factor VII deficiency; Gene expression; Genotype & phenotype; Intracellular; Mammalian cells; Molecular modelling; Mutation; mutations; Patients; Phenotypes; Phenotypic variations; Phenylbutyric acid; Plasma; Plasma levels; protein misfolding; Proteins; trafficking; United States > US; Switzerland
• ISSN: 2076-3417; 2076-3417
• DOI: 10.3390/app11135762

(1) Background: Congenital factor (F) VII deficiency is caused by mutations in the F7 gene. Patients with modest differences in FVII levels may display large differences in clinical severity. The variant p.A354V-p.P464Hfs is associated with reduced FVII antigen and activity. The aim of the study was to investigate the clinical manifestation of this variant and the underlying molecular mechanisms. (2) Methods: Analyses were conducted in 37 homozygous patients. The recombinant variant was produced in mammalian cells. (3) Results: We report a large variation in clinical phenotypes, which points out genetic and acquired components beyond F7 mutations as a source of variability. In contrast, patients displayed similarly reduced FVII plasma levels with antigen higher than its activity. Comparative analysis of the recombinant variant and of plasma samples from a subset of patients indicated the presence of an elongated variant with indistinguishable migration. Treatment of cells with the chemical chaperone 4-phenylbutyrate (4-PBA) improved the intracellular trafficking of the variant and increased its secretion to the conditioned medium up to 2-fold. However, the effect of 4-PBA on biological activity was marginal. (4) Conclusions: Chemical chaperones can be used as biochemical tools to study the intracellular fate of a trafficking-defective FVII variant.