Defective Association of the Platelet Glycoprotein Ib–IX Complex with the Glycosphingolipid-Enriched Membrane Domain Inhibits Murine Thrombus and Atheroma Formation

Abstract

Localization of the platelet glycoprotein Ib-IX complex to the membrane lipid domain is essential for platelet adhesion to von Willebrand factor (vWf) and subsequent platelet activation in vitro. Yet, the in vivo importance of this localization has never been addressed. We recently found that the disulfide linkage between Ibα and Ibβ is critical for the association of Ibα with the glycosphingolipid-enriched membrane (GEM) domain, in this study, we established a transgenic mouse model expressing this mutant human Ibα that is also devoid of endogenous Ibα (HαSSMα−/−). Characterization of this model demonstrated a similar dissociation of Ibα from murine platelet GEMs to that expressed in CHO cells, which correlates well with the impaired adhesion of the transgenic platelets to vWf ex vivo and in vivo. Furthermore, we bred our transgenic mice into an atherosclerosis-prone background (HαSSMα−/−ApoE−/− and HαWTMα−/−ApoE−/−). We observed that atheroma formation was significantly inhibited in mutant mice where fewer platelet-bound CD11c+ leukocytes were circulating (CD45+/CD11c+/CD41+) and residing in atherosclerotic lesions (CD45+/CD11c+), suggesting that platelet-mediated adhesion and infiltration of CD11c+ leukocytes may be one of the mechanisms. These observations provide the first in vivo evidence showing that the membrane GEMs is physiologically and pathophysiologically critical in the function of the GP Ib-IX complex.

Eosinophil-platelet interactions promote atherosclerosis and stabilize thrombosis with eosinophil extracellular traps

“…[54][55][56] Interference with these platelet adhesion molecules as well as deletion of VWF results in attenuated atherosclerotic plaque formation. [57][58][59][60] At the endothelium, platelets exert proinflammatory effects that trigger the recruitment of leukocytes through mediators such as RANTES. 61 In summary, eosinophils promote atherosclerotic lesion formation, which is associated with increased platelet adhesion and leukocyte recruitment.…”

Proteolysis of Von Willebrand Factor Influences Inflammatory Endothelial Activation and Vascular Compliance in Atherosclerosis

“…Immobilized platelets also can provide an additional surface for the adhesion of leukocytes through a variety of adhesive interactions and are known to direct leukocytes to sites for extravasation in the microcirculation ( 32 , 33 ). In murine models of atherosclerosis, functional inhibition of platelet GPIbα or genetic deletion of either GPIbα or vWF reduce plaque size and macrophage content ( 5 , 14 , 15 , 34 , 35 ). Likewise, crossing atherosclerosis-prone mice deficient for apolipoprotein-E (Apo-E −/− ) with AD13 −/− mice increases atherosclerotic plaque size and macrophage content ( 13 ).…”

MicroRNAs 10a and 10b Regulate the Expression of Human Platelet Glycoprotein Ibα for Normal Megakaryopoiesis

“…Furthermore, in order to investigate the physiological relevance of our finding, we isolated the murine lineage negative cells from a well-established transgenic mouse line which only expresses human GP Ibα. This mouse was generated by an integration of an entire cassette of the human GP1BA gene into the mouse genome with removal of the endogenous murine GP1BA gene by genetic manipulation [20,21]. Prior to in vitro megakaryocytic differentiation by megakaryocyte differentiation-inducing cytokines (e.g., thrombopoietin and Interleukin-3), we transfected these progenitors with the various miRNA mimics of interest.…”

“…Total bone marrow cells were collected from the femurs of mice whose genome is integrated with a ~6-kb EcoRI fragment possessing an entire cassette of the human GP1BA gene (including native human GP1BA 3′-UTR) to induce a high level of human GP Ibα expression in murine platelets and megakaryocytes [20,21]. After lysis of red blood cells with a red blood cell (RBC) lysis buffer, the lineage negative cells (Lin −/− ) were enriched with a BD IMag™ Mouse Hematopoietic Progenitor Cell Enrichment Set Kit according to the manufacturer′s instructions (BD Bioscience, San Jose, CA, USA).…”