TMEM16E regulates endothelial cell procoagulant activity and thrombosis

• Authors: Alec A Schmaier, Beth Israel Deaconess Medical Center and Harvard Medical School; Papa F Anderson, Beth Israel Deaconess Medical Center; Siyu M Chen, Beth Israel Deaconess Medical Center; Emale El-Darzi, Beth Israel Deaconess Medical Center; Ivan Aivasovsky, Beth Israel Deaconess Medical Center; Milan P Kaushik, Beth Israel Deaconess Medical Center; Kelsey D Sack, Beth Israel Deaconess Medical Center, Boston; Criss H Hartzell, Emory University; Samir M Parikh, Harvard Medical School; Robert Flaumenhaft, Beth Israel Deaconess Medical Center and Harvard Medical School; Sol Schulman, Beth Israel Deaconess Medical Center and Harvard Medical School
• Journal Title: JOURNAL OF CLINICAL INVESTIGATION
• Volume: Volume 133, Number 11
• Publisher: AMER SOC CLINICAL INVESTIGATION INC | 2023-06-01
• Type of Work: Article | Final Publisher PDF
• Publisher DOI: http://doi.org/10.1172/JCI163808
• Subjects: Biology, Cell; Health Sciences, Medicine and Surgery
• Keywords: Science & Technology; Life Sciences & Biomedicine; Medicine, Research & Experimental; Research & Experimental Medicine; PROTEIN DISULFIDE-ISOMERASE; TISSUE FACTOR EXPRESSION; PHOSPHATIDYLSERINE EXPOSURE; PROTHROMBINASE COMPLEX; PLASMA-MEMBRANE; BLOOD-CELLS; SURFACE; COAGULATION; HEMOSTASIS; BENZBROMARONE

Abstract

Endothelial cells (ECs) normally form an anticoagulant surface under physiological conditions, but switch to support coagulation following pathogenic stimuli. This switch promotes thrombotic cardiovascular disease. To generate thrombin at physiologic rates, coagulation proteins assemble on a membrane containing anionic phospholipid, most notably phosphatidylserine (PS). PS can be rapidly externalized to the outer cell membrane leaflet by phospholipid “scramblases,” such as TMEM16F. TMEM16F-dependent PS externalization is well characterized in platelets. In contrast, how ECs externalize phospholipids to support coagulation is not understood. We employed a focused genetic screen to evaluate the contribution of transmembrane phospholipid transport on EC procoagulant activity. We identified 2 TMEM16 family members, TMEM16F and its closest paralog, TMEM16E, which were both required to support coagulation on ECs via PS externalization. Applying an intravital laser-injury model of thrombosis, we observed, unexpectedly, that PS externalization was concentrated at the vessel wall, not on platelets. TMEM16E-null mice demonstrated reduced vessel-wall-dependent fibrin formation. The TMEM16 inhibitor benzbromarone prevented PS externalization and EC procoagulant activity and protected mice from thrombosis without increasing bleeding following tail transection. These findings indicate the activated endothelial surface is a source of procoagulant phospholipid contributing to thrombus formation. TMEM16 phospholipid scramblases may be a therapeutic target for thrombotic cardiovascular disease.