Tetraspanin Tspan9 regulates platelet collagen receptor GPVI lateral diffusion and activation

Abstract

The tetraspanins are a superfamily of four-transmembrane proteins, which regulate the trafficking, lateral diffusion and clustering of the transmembrane proteins with which they interact. We have previously shown that tetraspanin Tspan9 is expressed on platelets. Here we have characterised gene-trap mice lacking Tspan9. The mice were viable with normal platelet numbers and size. Tspan9-deficient platelets were specifically defective in aggregation and secretion induced by the platelet collagen receptor GPVI, despite normal surface GPVI expression levels. A GPVI activation defect was suggested by partially impaired GPVI-induced protein tyrosine phosphorylation. In mechanistic experiments, Tspan9 and GPVI co-immunoprecipitated and co-localised, but super-resolution imaging revealed no defects in collagen-induced GPVI clustering on Tspan9-deficient platelets. However, single particle tracking using total internal reflection fluorescence microscopy showed that GPVI lateral diffusion was reduced by approximately 50% in the absence of Tspan9. Therefore, Tspan9 plays a fine-tuning role in platelet activation by regulating GPVI membrane dynamics.

Role of platelets and platelet receptors in cancer metastasis

“…In areas of vascular injury and subendothelial matrix exposure, GPVI in conjunction with integrin α 2 β 1 , is the key receptor for collagen type I and responsible for stable platelet adhesion after a transient interaction of GPIb-IX-V with vWf at high shear rates [ 65 , 66 , 177 ]. A density of approximately 4000 copies of GPVI per platelet was reported, partially organized in a mono- or dimeric form in tetraspanin microdomains regulating GPVI lateral diffusion [ 178 – 180 ]. Upon binding of GPVI dimers to collagen, a clustering of GPVI was described accompanied by increased avidity towards collagen and enhanced proximity of GPVI associated signaling molecules [ 181 , 182 ].…”

C-type lectin-like receptor 2 (CLEC-2)-dependent DC migration is controlled by tetraspanin CD37

“…RAW cells were mycoplasma-free. The HEK-293T (HEK-293 cells expressing the large T-antigen of simian virus 40) cell line (Brummer et al, 2018;Haining et al, 2012Haining et al, , 2017Noy et al, 2016;Reyat et al, 2017) was cultured in complete Dulbecco's modified Eagle medium (DMEM) (Sigma-Aldrich) containing 10% FCS (Gibco, via Thermo Fisher Scientific), 4 mM L-glutamine, 100 U/ml penicillin and 100 μg/ml streptomycin (Thermo Fisher Scientific). HEK-293T cells were mycoplasma-free, genomic sequencing has recently confirmed their origin as human and resistance to neomycin is consistent with their continued expression of the large T antigen.…”

Association between Platelet-Specific Collagen Receptor Glycoprotein 6 Gene Variants, Selected Biomarkers, and Recurrent Pregnancy Loss in Korean Women

“…Moreover, a previous study identified several SNPs (rs1671153, rs1654419, and rs1613662) in patients with sticky platelet syndrome (SPS) [ 21 ] and a history of miscarriage (rs1671152, rs1654433, rs1613662, rs1654416, and rs2304167) [ 22 ]. In addition to their normal role in hemostasis, platelets can cause arterial thrombosis by blocking the collateral arteries after a collagen-rich atherosclerotic plaque has ruptured, resulting in heart attack and stroke [ 23 ]. After an atherosclerotic plaque rupture, the relationship between GP6 and thrombus GP6 -specific signaling plays a major role in platelet adhesion to activated endothelium [ 24 , 25 ] and thrombus formation [ 26 ], whereas platelet GP6 mediates adherence to the endothelial matrix [ 27 ].…”