Faculty Collaboration Database

A single F153Sβ3 mutation causes constitutive integrin αIIbβ3 activation in a variant form of Glanzmann thrombasthenia. Blood Adv 2023 Jul 11;7(13):3180-3191

Date

03/09/2023

Pubmed ID

36884296

Pubmed Central ID

PMC10338211

DOI

10.1182/bloodadvances.2022009495

Scopus ID

2-s2.0-85179497686 (requires institutional sign-in at Scopus site)   3 Citations

Abstract

This report identifies a novel variant form of the inherited bleeding disorder Glanzmann thrombasthenia, exhibiting only mild bleeding in a physically active individual. The platelets cannot aggregate ex vivo with physiologic agonists of activation, although microfluidic analysis with whole blood displays moderate ex vivo platelet adhesion and aggregation consistent with mild bleeding. Immunocytometry shows reduced expression of αIIbβ3 on quiescent platelets that spontaneously bind/store fibrinogen, and activation-dependent antibodies (ligand-induced binding site-319.4 and PAC-1) report β3 extension suggesting an intrinsic activation phenotype. Genetic analysis reveals a single F153Sβ3 substitution within the βI-domain from a heterozygous T556C nucleotide substitution of ITGB3 exon 4 in conjunction with a previously reported IVS5(+1)G>A splice site mutation with undetectable platelet messenger RNA accounting for hemizygous expression of S153β3. F153 is completely conserved among β3 of several species and all human β-integrin subunits suggesting that it may play a vital role in integrin structure/function. Mutagenesis of αIIb-F153Sβ3 also displays reduced levels of a constitutively activated αIIb-S153β3 on HEK293T cells. The overall structural analysis suggests that a bulky aromatic, nonpolar amino acid (F,W)153β3 is critical for maintaining the resting conformation of α2- and α1-helices of the βI-domain because small amino acid substitutions (S,A) facilitate an unhindered inward movement of the α2- and α1-helices of the βI-domain toward the constitutively active αIIbβ3 conformation, while a bulky aromatic, polar amino acid (Y) hinders such movements and restrains αIIbβ3 activation. The data collectively demonstrate that disruption of F153β3 can significantly alter normal integrin/platelet function, although reduced expression of αIIb-S153β3 may be compensated by a hyperactive conformation that promotes viable hemostasis.

Author List

Koukouritaki SB, Thinn AMM, Ashworth KJ, Fang J, Slater HS, Du LM, Nguyen HTT, Pillois X, Nurden AT, Ng CJ, Di Paola J, Zhu J, Wilcox DA

Authors

Sevasti Koukouritaki Research Scientist II in the Pediatrics department at Medical College of Wisconsin
David A. Wilcox PhD Professor in the Pediatrics department at Medical College of Wisconsin
Jieqing Zhu PhD Professor in the Biochemistry department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Amino Acids
HEK293 Cells
Humans
Integrin beta3
Mutation
Platelet Glycoprotein GPIIb-IIIa Complex
Thrombasthenia