LRRC8 complexes are ATP release channels that regulate platelet activation and arterial thrombosis

Area of Science:

• Biochemistry
• Physiology
• Molecular Biology

Background:

• Platelet activation and thrombosis involve mechanical changes like shape and volume alterations.
• The volume-regulated anion channel (VRAC) is formed by LRRC8 protein subunits and plays a role in cellular volume regulation.

Purpose of the Study:

• To investigate the role of LRRC8 protein subunits in platelet function and thrombosis.
• To identify LRRC8 as a potential therapeutic target for antithrombotic strategies.

Main Methods:

• Identification of single-nucleotide polymorphisms in LRRC8 associated with mean platelet volume.
• Generation and analysis of megakaryocyte-specific LRRC8A conditional knockout mice.
• Assessment of platelet function (adhesion, activation, aggregation, ATP secretion, calcium mobilization) in vitro and in vivo.
• Evaluation of thrombus formation and bleeding times in mouse models of thrombosis.
• Testing of small-molecule LRRC8 channel inhibitors.

Main Results:

• LRRC8A is essential for functional VRAC in megakaryocytes and regulates platelet volume, adhesion, activation, aggregation, ATP secretion, and calcium mobilization.
• LRRC8A deficiency in megakaryocytes leads to reduced thrombus formation in vivo without affecting bleeding times.
• Platelet LRRC8A mediates ATP release upon swelling, amplifying agonist-stimulated signaling pathways.
• LRRC8 channel inhibitors replicate the functional defects observed in LRRC8A-deficient platelets.

Conclusions:

• The mechanoresponsive LRRC8 channel complex functions as an ATP release channel in platelets.
• LRRC8 positively regulates platelet function and thrombosis, presenting a novel target for antithrombotic therapies.