Marina Bayeva1, Arineh Khechaduri1, Rongxue Wu1, Michael A Burke1, J Andrew Wasserstrom1, Neha Singh1, Marc Liesa2, Orian S Shirihai2, Nathaniel B Langer3, Barry H Paw3, Hossein Ardehali1. 1. Feinberg Cardiovascular Research Institute, Northwestern University School of Medicine, Chicago, IL. 2. Department of Medicine, Obesity and Nutrition Section, Mitochondria ARC, Evans Biomedical Research Center, Boston University School of Medicine, 650 Albany St., Boston, MA 02118, USA. 3. Hematology Division, Brigham & Women's Hospital; Hematology-Oncology Division, Children's Hospital Boston; Harvard Medical School, Boston, MA.
Abstract
RATIONALE: Heme plays a critical role in gas exchange, mitochondrial energy production, and antioxidant defense in cardiovascular system. The mitochondrial transporter ATP-binding cassette (ABC) B10 has been suggested to export heme out of the mitochondria and is required for normal hemoglobinization of erythropoietic cells and protection against ischemia-reperfusion injury in the heart; however, its primary function has not been established. OBJECTIVE: The aim of this study was to identify the function of ABCB10 in heme synthesis in cardiac cells. METHODS AND RESULTS: Knockdown of ABCB10 in cardiac myoblasts significantly reduced heme levels and the activities of heme-containing proteins, whereas supplementation with δ-aminolevulinic acid reversed these defects. Overexpression of mitochondrial δ-aminolevulinic acid synthase 2, the rate-limiting enzyme upstream of δ-aminolevulinic acid export, failed to restore heme levels in cells with ABCB10 downregulation. ABCB10 and heme levels were increased by hypoxia, and reversal of ABCB10 upregulation caused oxidative stress and cell death. Furthermore, ABCB10 knockdown in neonatal rat cardiomyocytes resulted in a significant delay of calcium removal from the cytoplasm, suggesting a relaxation defect. Finally, ABCB10 expression and heme levels were altered in failing human hearts and mice with ischemic cardiomyopathy. CONCLUSIONS: ABCB10 plays a critical role in heme synthesis pathway by facilitating δ-aminolevulinic acid production or export from the mitochondria. In contrast to previous reports, we show that ABCB10 is not a heme exporter and instead is required for the early mitochondrial steps of heme biosynthesis.
RATIONALE: Heme plays a critical role in gas exchange, mitochondrial energy production, and antioxidant defense in cardiovascular system. The mitochondrial transporter ATP-binding cassette (ABC) B10 has been suggested to export heme out of the mitochondria and is required for normal hemoglobinization of erythropoietic cells and protection against ischemia-reperfusion injury in the heart; however, its primary function has not been established. OBJECTIVE: The aim of this study was to identify the function of ABCB10 in heme synthesis in cardiac cells. METHODS AND RESULTS: Knockdown of ABCB10 in cardiac myoblasts significantly reduced heme levels and the activities of heme-containing proteins, whereas supplementation with δ-aminolevulinic acid reversed these defects. Overexpression of mitochondrial δ-aminolevulinic acid synthase 2, the rate-limiting enzyme upstream of δ-aminolevulinic acid export, failed to restore heme levels in cells with ABCB10 downregulation. ABCB10 and heme levels were increased by hypoxia, and reversal of ABCB10 upregulation caused oxidative stress and cell death. Furthermore, ABCB10 knockdown in neonatal rat cardiomyocytes resulted in a significant delay of calcium removal from the cytoplasm, suggesting a relaxation defect. Finally, ABCB10 expression and heme levels were altered in failing human hearts and mice with ischemic cardiomyopathy. CONCLUSIONS:ABCB10 plays a critical role in heme synthesis pathway by facilitating δ-aminolevulinic acid production or export from the mitochondria. In contrast to previous reports, we show that ABCB10 is not a heme exporter and instead is required for the early mitochondrial steps of heme biosynthesis.
Authors: George C Shaw; John J Cope; Liangtao Li; Kenneth Corson; Candace Hersey; Gabriele E Ackermann; Babette Gwynn; Amy J Lambert; Rebecca A Wingert; David Traver; Nikolaus S Trede; Bruce A Barut; Yi Zhou; Emmanuel Minet; Adriana Donovan; Alison Brownlie; Rena Balzan; Mitchell J Weiss; Luanne L Peters; Jerry Kaplan; Leonard I Zon; Barry H Paw Journal: Nature Date: 2006-03-02 Impact factor: 49.962
Authors: Alexandra Seguin; Naoko Takahashi-Makise; Yvette Y Yien; Nicholas C Huston; Jared C Whitman; Gabriel Musso; Jared A Wallace; Thomas Bradley; Hector A Bergonia; Martin D Kafina; Mitsuyo Matsumoto; Kazuhiko Igarashi; John D Phillips; Barry H Paw; Jerry Kaplan; Diane M Ward Journal: J Biol Chem Date: 2017-08-14 Impact factor: 5.157
Authors: Mark J Burton; Sofia M Kapetanaki; Tatyana Chernova; Andrew G Jamieson; Pierre Dorlet; Jérôme Santolini; Peter C E Moody; John S Mitcheson; Noel W Davies; Ralf Schmid; Emma L Raven; Nina M Storey Journal: Proc Natl Acad Sci U S A Date: 2016-03-22 Impact factor: 11.205
Authors: Amy E Medlock; Mesafint T Shiferaw; Jason R Marcero; Ajay A Vashisht; James A Wohlschlegel; John D Phillips; Harry A Dailey Journal: PLoS One Date: 2015-08-19 Impact factor: 3.240