Characterization of VWF gene conversions causing von Willebrand disease

TY - JOUR

T1 - Characterization of VWF gene conversions causing von Willebrand disease

AU - Ahmad, Firdos

AU - Kannan, Meganathan

AU - Obser, Tobias

AU - Budde, Ulrich

AU - Schneppenheim, Sonja

AU - Saxena, Renu

AU - Schneppenheim, Reinhard

N1 - © 2018 British Society for Haematology and John Wiley & Sons Ltd.

PY - 2019/3

Y1 - 2019/3

N2 - We previously reported that von Willebrand Factor gene (VWF) conversions are a relatively frequent cause of von Willebrand disease (VWD), however, their molecular pathomechanisms resulting in variant phenotypes is largely unknown. Here, we characterized VWF conversions harbouring missense and synonymous mutations, through generating a series of mutant constructs followed by transient expression in 293 cells, and qualitative and quantitative analysis of recombinant VWF (rVWF). The characterization of mutant rVWF showed the critical roles of synonymous variants in the pathogenicity of VWF conversions. The gene conversion variants p.Val1229Gly, p.Asn1231Thr, p.Asn1231Ser and p.Ala1464Pro in the absence of synonymous p.Ser1263= and p.Gln1449= showed minimal effect on rVWF synthesis and activity. Interestingly, a construct including the synonymous variants displayed significantly low rVWF expression and activity. The variant p.Pro1266Leu showed gain of rVWF function toward glycoprotein Ibα; surprisingly, this function was significantly abolished in the presence of gene conversion variants p.Val1229Gly-p.Asn1231Thr. Taken together, our expression studies suggest that synonymous variants in the combination of other gene conversion variants suppress the protein expression, possibly due to defective primary mRNA structure or processing. The variants p.Val1229Gly-p.Asn1231Thr affected the VWF gain of function caused by variant p.Pro1266Leu, probably due to conformational changes in VWF.

AB - We previously reported that von Willebrand Factor gene (VWF) conversions are a relatively frequent cause of von Willebrand disease (VWD), however, their molecular pathomechanisms resulting in variant phenotypes is largely unknown. Here, we characterized VWF conversions harbouring missense and synonymous mutations, through generating a series of mutant constructs followed by transient expression in 293 cells, and qualitative and quantitative analysis of recombinant VWF (rVWF). The characterization of mutant rVWF showed the critical roles of synonymous variants in the pathogenicity of VWF conversions. The gene conversion variants p.Val1229Gly, p.Asn1231Thr, p.Asn1231Ser and p.Ala1464Pro in the absence of synonymous p.Ser1263= and p.Gln1449= showed minimal effect on rVWF synthesis and activity. Interestingly, a construct including the synonymous variants displayed significantly low rVWF expression and activity. The variant p.Pro1266Leu showed gain of rVWF function toward glycoprotein Ibα; surprisingly, this function was significantly abolished in the presence of gene conversion variants p.Val1229Gly-p.Asn1231Thr. Taken together, our expression studies suggest that synonymous variants in the combination of other gene conversion variants suppress the protein expression, possibly due to defective primary mRNA structure or processing. The variants p.Val1229Gly-p.Asn1231Thr affected the VWF gain of function caused by variant p.Pro1266Leu, probably due to conformational changes in VWF.

KW - Amino Acid Substitution

KW - Cell Line

KW - Humans

KW - Mutation, Missense

KW - von Willebrand Diseases/genetics

KW - von Willebrand Factor/genetics

U2 - 10.1111/bjh.15709

DO - 10.1111/bjh.15709

M3 - SCORING: Journal article

C2 - 30488424

VL - 184

SP - 817

EP - 825

JO - BRIT J HAEMATOL

JF - BRIT J HAEMATOL

SN - 0007-1048

IS - 5

ER -