Shiho Satomi1, Atsushi Morio2, Hirotsugu Miyoshi2, Ryuji Nakamura2, Rie Tsutsumi3, Hiroshi Sakaue3, Toshimichi Yasuda2, Noboru Saeki2, Yasuo M Tsutsumi4. 1. Department of Anesthesiology, University of California, San Diego, CA, United States of America. 2. Department of Anesthesiology and Critical Care, Hiroshima University, Hiroshima, Japan. 3. Department of Nutrition, Tokushima University, Tokushima, Japan. 4. Department of Anesthesiology and Critical Care, Hiroshima University, Hiroshima, Japan. Electronic address: yasuo223@hiroshima-u.ac.jp.
Abstract
AIMS: Amino acids, especially branched chain amino acids (BCAAs), have important regulatory roles in protein synthesis. Recently studies revealed that BCAAs protect against ischemia/reperfusion (I/R) injury. We studied the signaling pathway and mitochondrial function affecting a cardiac preconditioning of BCAAs. MAIN METHODS: An in vivo model of I/R injury was tested in control, mTOR+/+, and mTOR+/-. Mice were randomly assigned to receive BCAAs, rapamycin, or BCAAs + rapamycin. Furthermore, isolated cardiomyocytes were subjected to simulated ischemia and cell death was quantified. Biochemical and mitochondrial swelling assays were also performed. KEY FINDINGS: Mice treated with BCAAs had a significant reduction in infarct size as a percentage of the area at risk compared to controls (34.1 ± 3.9% vs. 44.7 ± 2.6%, P = 0.001), whereas mice treated with the mTOR inhibitor rapamycin were not protected by BCAA administration (42.2 ± 6.5%, vs. control, P = 0.015). This protection was not detected in our hetero knockout mice of mTOR. Western blot analysis revealed no change in AKT signaling whereas activation of mTOR was identified. Furthermore, BCAAs prevented swelling which was reversed by the addition of rapamycin. In myocytes undergoing simulated I/R, BCAA treatment significantly preserved cell viability (71.7 ± 2.7% vs. 34.5 ± 1.6%, respectively, p < 0.0001), whereas rapamycin prevented this BCAA-induced cardioprotective effect (43.5 ± 3.4% vs. BCAA, p < 0.0001). SIGNIFICANCE: BCAA treatment exhibits a protective effect in myocardial I/R injury and that mTOR plays an important role in this preconditioning effect.
AIMS: Amino acids, especially branched chain amino acids (BCAAs), have important regulatory roles in protein synthesis. Recently studies revealed that BCAAs protect against ischemia/reperfusion (I/R) injury. We studied the signaling pathway and mitochondrial function affecting a cardiac preconditioning of BCAAs. MAIN METHODS: An in vivo model of I/R injury was tested in control, mTOR+/+, and mTOR+/-. Mice were randomly assigned to receive BCAAs, rapamycin, or BCAAs + rapamycin. Furthermore, isolated cardiomyocytes were subjected to simulated ischemia and cell death was quantified. Biochemical and mitochondrial swelling assays were also performed. KEY FINDINGS:Mice treated with BCAAs had a significant reduction in infarct size as a percentage of the area at risk compared to controls (34.1 ± 3.9% vs. 44.7 ± 2.6%, P = 0.001), whereas mice treated with the mTOR inhibitor rapamycin were not protected by BCAA administration (42.2 ± 6.5%, vs. control, P = 0.015). This protection was not detected in our hetero knockout mice of mTOR. Western blot analysis revealed no change in AKT signaling whereas activation of mTOR was identified. Furthermore, BCAAs prevented swelling which was reversed by the addition of rapamycin. In myocytes undergoing simulated I/R, BCAA treatment significantly preserved cell viability (71.7 ± 2.7% vs. 34.5 ± 1.6%, respectively, p < 0.0001), whereas rapamycin prevented this BCAA-induced cardioprotective effect (43.5 ± 3.4% vs. BCAA, p < 0.0001). SIGNIFICANCE: BCAA treatment exhibits a protective effect in myocardial I/R injury and that mTOR plays an important role in this preconditioning effect.
Authors: Vincent Portero; Thomas Nicol; Svitlana Podliesna; Gerard A Marchal; Antonius Baartscheer; Simona Casini; Rafik Tadros; Jorien L Treur; Michael W T Tanck; I Jane Cox; Fay Probert; Tertius A Hough; Sara Falcone; Leander Beekman; Martina Müller-Nurasyid; Gabi Kastenmüller; Christian Gieger; Annette Peters; Stefan Kääb; Moritz F Sinner; Andrew Blease; Arie O Verkerk; Connie R Bezzina; Paul K Potter; Carol Ann Remme Journal: Cardiovasc Res Date: 2022-06-22 Impact factor: 13.081