A case of a novel mutation in the F7 gene that results in factor VII coagulant activity (VII:c) of less than 1% and VII antigen (VII:Ag) levels of 10% is presented. DNA analysis revealed a homozygous 15-base pair (bp) in-frame insertion-type mutation at nucleotide 10554, This insertion consisted of a duplication of residues leucine (L)213 to aspartic acid (D)217 (leucine, serine, glutamic acid, histidine, and aspartic acid), probably arising by slipped mispairing between 2 copies of a direct repeat (GCGAGCACGAC) separated by 4 bp, Molecular graphic analyses showed that the insertion is located at the surface of the catalytic domain in an exposed loop stabilized by extensive salt-bridge and hydrogen bond formation at which the calcium binding site is located. The mutation probably interferes with protein folding during VII biosynthesis and/or diminishes functional activity through the loss of calcium binding, In vitro expression studies demonstrated that the levels of VII:Ag in lysates of cells transfected with wild type VII (VIIWT) were equivalent to those with mutant type VII (VIIMT), but the level of secreted VIIMT was 5% to 10% that of VIIWT. Pulse chase studies demonstrated that VIIMT did not accumulate intracellularly, and studies with inhibitors of protein degradation showed that recombinant VIIMT was partially degraded in the pre-Golgi compartment, Accordingly, only small amounts of VIIMT with undetectable procoagulant activity were secreted into conditioned media. These results demonstrate that a combination of secretion and functional defects is the mechanism whereby this insertion causes VII deficiency. (C) 2001 by The American Society of Hematology.
Abnormal secretion and function of recombinant human factor VII as the result of modification to a calcium binding site caused by a 15 base pair insertion in the factor VII gene / F. Peyvandi, J.A. Carew, D.J. Perry, M. Hanault, U. Khanduri, S.J. Perkins, P.M. Mannucci, K.A. Bauer. - In: BLOOD. - ISSN 0006-4971. - 97:4(2001), pp. 960-965.
|Titolo:||Abnormal secretion and function of recombinant human factor VII as the result of modification to a calcium binding site caused by a 15 base pair insertion in the factor VII gene|
PAYVANDI, FLORA (Primo)
MANNUCCI, PIER MANNUCCIO (Penultimo)
|Settore Scientifico Disciplinare:||Settore MED/09 - Medicina Interna|
|Data di pubblicazione:||2001|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1182/blood.V97.4.960|
|Appare nelle tipologie:||01 - Articolo su periodico|