Molecular dynamics simulation of force-regulated interaction between glycoprotein Ib α and filamin / 生物医学工程学杂志

In resting platelets, the 17 th domain of filamin a (FLNa17) constitutively binds to the platelet membrane glycoprotein Ibα (GPIbα) at its cytoplasmic tail (GPIbα-CT) and inhibits the downstream signal activation, while the binding of ligand and blood shear force can activate platelets. To imitate the pull force transmitted from the extracellular ligand of GPIbα and the lateral tension from platelet cytoskeleton deformation, two pulling modes were applied on the GPIbα-CT/FLNa17 complex, and the molecular dynamics simulation method was used to explore the mechanical regulation on the affinity and mechanical stability of the complex. In this study, at first, nine pairs of key hydrogen bonds on the interface between GPIbα-CT and FLNa17 were identified, which was the basis for maintaining the complex structural stability. Secondly, it was found that these hydrogen bonding networks would be broken down and lead to the dissociation of FLNa17 from GPIbα-CT only under the axial pull force; but, under the lateral tension, the secondary structures at both terminals of FLNa17 would unfold to protect the interface of the GPIbα-CT/FLNa17 complex from mechanical damage. In the range of 0~40 pN, the increase of pull force promoted outward-rotation of the nitrogen atom of the 563 rd phenylalanine (PHE 563-N) at GPIbα-CT and the dissociation of the complex. This study for the first time revealed that the extracellular ligand-transmitted axial force could more effectively relieve the inhibition of FLNa17 on the downstream signal of GPIbα than pure mechanical tension at the atomic level, and would be useful for further understanding the platelet intracellular force-regulated signal pathway.

Investigation of platelet membrane glycoprotein Ibα gene polymorphisms in children with Kawasaki disease / 中华实用儿科临床杂志

Objective To investigate the association between platelet glycoprotein Ibα (GPIbα) gene HPA-2a/b polymorphisms and the risk of Kawasaki disease (KD) and that complicated with coronary artery lesion (CAL).Methods A total of 30 patients with KD and 60 healthy controls were genotyped by polymerase chain reaction-restriction fragment length polymorphism and agarose gel electrophoresis for the HPA-2a/b polymorphism in GPIbα gene.Results For HPA-2a/b polymorphism in GPIbα gene,there was only genotype TC and CC of HPA-2a/b polymorphism in GPIbα gene in children with KD and healthy controls,and genotype TF was not found in both groups.There were no significant differences between KD patients and the controls in genotype frequencies of CC,TC and TT and allele frequencies of C and T (x2 =0.052,0.048,all P ＞ 0.05) ; also there was no significant difference between KD patients with CAL and that without CAL in genotype and allele frequencies (x2 =2.672,2.481,all P ＞ 0.05).Conclusion No association is found between HPA-2a/b polymorphism in GPIbα gene and the risk of KD or its complication of CAL in this study.