Deletion of Mfsd2b impairs thrombotic functions of platelets

Madhuvanthi Chandrakanthan,Amaury Cazenave-Gassiot,Toan Quoc Nguyen,Thiet Minh Vu,Long N Nguyen,Zafrul Hasan,Aaron Wei Liang Li,Sang-Ha Baik,Juat Chin Foo,Markus R Wenk,Sneha Muralidharan,Wei Yi Ong,Hoa Thi Thuy Ha,Sock Hwee Tan,Uyen Thanh Nha Le,Federico Torta,Mark Yan Yee Chan

doi:10.1038/s41467-021-22642-x

Madhuvanthi Chandrakanthan, Amaury Cazenave-Gassiot + Show 15 more

Open Access

https://doi.org/10.1038/s41467-021-22642-x

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Abstract

We recently discovered that Mfsd2b, which is the S1P exporter found in blood cells. Here, we report that Mfsd2b is critical for the release of all S1P species in both resting and activated platelets. We show that resting platelets store S1P in the cytoplasm. After activation, this S1P pool is delivered to the plasma membrane, where Mfsd2b is predominantly localized for export. Employing knockout mice of Mfsd2b, we reveal that platelets contribute a minor amount of plasma S1P. Nevertheless, Mfsd2b deletion in whole body or platelets impairs platelet morphology and functions. In particular, Mfsd2b knockout mice show significantly reduced thrombus formation. We show that loss of Mfsd2b affects intrinsic platelet functions as part of remarkable sphingolipid accumulation. These findings indicate that accumulation of sphingolipids including S1P by deletion of Mfsd2b strongly impairs platelet functions, which suggests that the transporter may be a target for the prevention of thrombotic disorders.

Highlights

We recently discovered that Mfsd2b, which is the S1P exporter found in blood cells
To gain more insights into the effects of Mfsd2b deletion in platelets, we examined the thrombotic capacity of KO platelets in a deep venous thrombosis (DVT) model, by performing a stenosis of the inferior vena cava
We showed that the basal expression of podoplanin is highly induced in inferior vena cava (IVC) isolated from thrombotic wild type (WT) mice, suggesting that this receptor is involved in thrombotic events (Fig. 8e)

Summary

Introduction

We recently discovered that Mfsd2b, which is the S1P exporter found in blood cells. Here, we report that Mfsd2b is critical for the release of all S1P species in both resting and activated platelets. S1P is synthesized by two sphingosine kinases, namely SphK1 and 22 These cellular sources of S1P provide the signal for lymphocyte trafficking, maintenance of blood vessel integrity, and many other biological functions[3]. S1P release from platelets was shown to be responsible for maintenance of high endothelial venules via induction of VEcadherin[8] It remains elusive whether platelet-derived S1P contributes to the S1P pool in blood, especially at thrombotic and blood-clotting conditions. Deletion of SphK2 in mice results in loss of S1P synthesis in platelets and reduced platelet biogenesis and functions. We demonstrate that Mfsd2b is required for S1P release in resting and activated platelets and that ablation of Mfsd2b strongly affects the intrinsic functions of platelets that result in reduced thrombosis in mice. Our data support a mechanism in which inhibition of Mfsd2b causes lipotoxicity in platelets and this pathway may represent a novel strategy to reduce the functions of platelets in thrombotic disorders

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