Yanyan Xu1, Haojie Jiang1, Li Li2, Fengwu Chen3, Yunxia Liu4, Meiyi Zhou4, Ji Wang4, Jingjing Jiang5, Xiaoying Li5, Xuemei Fan1, Lin Zhang1, Junfeng Zhang6, Junqiang Qiu7, Yi Wu3, Chao Fang2, Haipeng Sun4, Junling Liu1,3. 1. Department of Biochemistry and Molecular Cell Biology (Y.X., H.J., X.F., L.Z., J.L.), Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, China. 2. Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China (L.L., C.F.). 3. The Cyrus Tang Hematology Center, Collaborative Innovation Center of Hematology, Soochow University, Suzhou, China (F.C., Y.W., J.L.). 4. Department of Pathophysiology (Y.L., M.Z., J.W., H.S.), Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, China. 5. Department of Endocrinology and Catabolism, Zhongshan Hospital, Fudan University, Shanghai, China (J.J., X.L.). 6. Department of Cardiology, Shanghai Jiao Tong University School of Medicine Affiliated Ninth People's Hospital, China (J.Z.). 7. Sport Science School, Beijing Sport University, China (J.Q.).
Abstract
BACKGROUND: Branched-chain amino acids (BCAAs), essential nutrients including leucine, isoleucine, and valine, serve as a resource for energy production and the regulator of important nutrient and metabolic signals. Recent studies have suggested that dysfunction of BCAA catabolism is associated with the risk of cardiovascular disease. Platelets play an important role in cardiovascular disease, but the functions of BCAA catabolism in platelets remain unknown. METHODS: The activity of human platelets from healthy subjects before and after ingestion of BCAAs was measured. Protein phosphatase 2Cm specifically dephosphorylates branched-chain α-keto acid dehydrogenase and thereby activates BCAA catabolism. Protein phosphatase 2Cm-deficient mice were used to elucidate the impacts of BCAA catabolism on platelet activation and thrombus formation. RESULTS: We found that ingestion of BCAAs significantly promoted human platelet activity (n=5; P<0.001) and arterial thrombosis formation in mice (n=9; P<0.05). We also found that the valine catabolite α-ketoisovaleric acid and the ultimate oxidation product propionyl-coenzyme A showed the strongest promotion effects on platelet activation, suggesting that the valine/α-ketoisovaleric acid catabolic pathway plays a major role in BCAA-facilitated platelet activation. Protein phosphatase 2Cm deficiency significantly suppresses the activity of platelets in response to agonists (n=5; P<0.05). Our results also suggested that BCAA metabolic pathways may be involved in the integrin αIIbβ3-mediated bidirectional signaling pathway that regulates platelet activation. Mass spectrometry identification and immunoblotting revealed that BCAAs enhanced propionylation of tropomodulin-3 at K255 in platelets or Chinese hamster ovary cells expressing integrin αIIbβ3. The tropomodulin-3 K255A mutation abolished propionylation and attenuated the promotion effects of BCAAs on integrin-mediated cell spreading, suggesting that K255 propionylation of tropomodulin-3 is an important mechanism underlying integrin αIIbβ3-mediated BCAA-facilitated platelet activation and thrombosis formation. In addition, the increased levels of BCAAs and the expression of positive regulators of BCAA catabolism in platelets from patients with type 2 diabetes mellitus are significantly correlated with platelet hyperreactivity. Lowering dietary BCAA intake significantly reduced platelet activity in ob/ob mice (n=4; P<0.05). CONCLUSIONS: BCAA catabolism is an important regulator of platelet activation and is associated with arterial thrombosis risk. Targeting the BCAA catabolism pathway or lowering dietary BCAA intake may serve as a novel therapeutic strategy for metabolic syndrome-associated thrombophilia.
BACKGROUND:Branched-chain amino acids (BCAAs), essential nutrients including leucine, isoleucine, and valine, serve as a resource for energy production and the regulator of important nutrient and metabolic signals. Recent studies have suggested that dysfunction of BCAA catabolism is associated with the risk of cardiovascular disease. Platelets play an important role in cardiovascular disease, but the functions of BCAA catabolism in platelets remain unknown. METHODS: The activity of human platelets from healthy subjects before and after ingestion of BCAAs was measured. Protein phosphatase 2Cm specifically dephosphorylates branched-chain α-keto acid dehydrogenase and thereby activates BCAA catabolism. Protein phosphatase 2Cm-deficient mice were used to elucidate the impacts of BCAA catabolism on platelet activation and thrombus formation. RESULTS: We found that ingestion of BCAAs significantly promoted human platelet activity (n=5; P<0.001) and arterial thrombosis formation in mice (n=9; P<0.05). We also found that the valine catabolite α-ketoisovaleric acid and the ultimate oxidation product propionyl-coenzyme A showed the strongest promotion effects on platelet activation, suggesting that the valine/α-ketoisovaleric acid catabolic pathway plays a major role in BCAA-facilitated platelet activation. Protein phosphatase 2Cm deficiency significantly suppresses the activity of platelets in response to agonists (n=5; P<0.05). Our results also suggested that BCAA metabolic pathways may be involved in the integrin αIIbβ3-mediated bidirectional signaling pathway that regulates platelet activation. Mass spectrometry identification and immunoblotting revealed that BCAAs enhanced propionylation of tropomodulin-3 at K255 in platelets or Chinese hamster ovary cells expressing integrin αIIbβ3. The tropomodulin-3K255A mutation abolished propionylation and attenuated the promotion effects of BCAAs on integrin-mediated cell spreading, suggesting that K255 propionylation of tropomodulin-3 is an important mechanism underlying integrin αIIbβ3-mediated BCAA-facilitated platelet activation and thrombosis formation. In addition, the increased levels of BCAAs and the expression of positive regulators of BCAA catabolism in platelets from patients with type 2 diabetes mellitus are significantly correlated with platelet hyperreactivity. Lowering dietary BCAA intake significantly reduced platelet activity in ob/ob mice (n=4; P<0.05). CONCLUSIONS:BCAA catabolism is an important regulator of platelet activation and is associated with arterial thrombosis risk. Targeting the BCAA catabolism pathway or lowering dietary BCAA intake may serve as a novel therapeutic strategy for metabolic syndrome-associated thrombophilia.
Authors: Roberto Martínez-Beamonte; Javier Sánchez-Marco; Gonzalo Lázaro; María Barco; Tania Herrero-Continente; Marta Serrano-Megías; David Botaya; Carmen Arnal; Cristina Barranquero; Joaquín C Surra; Jesús Osada; María A Navarro Journal: Nutrients Date: 2021-05-27 Impact factor: 5.717