A number of disorders due to abnormalities in heme biosynthesis influence erythropoiesis. During normal erythroid maturation, heme precursors are generated in the mitochondria, modified in the cytosol and then returned to the mitochondria for final assembly with iron. Remarkably, accumulation of toxic heme intermediates or substrates, and secondary mitochondrial damage, are key elements in the pathophysiology of all heme biosynthesis disorders. However, the mechanisms of export or import of heme products, by-products and intermediates to or from the mitochondrial matrix are as yet poorly understood. This proposal will focus on such mechanisms taking advantage of our discovery of ABC-me, a novel mitochondrial erythroid transporter. ABC-me expression is controlled by the erythroid transcription factor GATA-1 and is down regulated by heme. In differentiating erythroleukemic cells, ABC-me is rate limiting for heme biosynthesis. As such, ABC-me is the only mitochondrial inner membrane transporter implicated in heme biosynthesis. To explore its function in heme biosynthesis, we have developed ABC-me deficient cell culture models and functional assays of reconstituted transporter in proteoliposomes. We have established that differentiating erythroid cells with reduced ABC-me activity produce less heme and exhibit signs of mitochondrial stress. We postulate that transporters involved in the heme pathway serve as gatekeepers for reactive substrates, intermediates and byproducts and thus couple production of essential end products to protection from toxic intermediates. We propose a combined biochemical and biophysical approach to the study of the function of ABC-me in heme biosynthesis and the consequences of its malfunction. We will address the following questions: 1) Which steps in the heme biosynthetic pathway are facilitated by ABC-me? 2) Does ABC-me deficiency result in the accumulation of heme precursors in the cytosol and mitochondria? 3) What is the source of mitochondrial stress associated with ABC-me deficiency and what are the morphological and functional consequences? 4) Does ABC-me transport a heme biosynthesis intermediate, product or co-factor, and in which direction? 5) Does ABC-me facilitate heme biosynthesis indirectly by opposing mitochondrial stress.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL071629-03
Application #
6850115
Study Section
Hematology Subcommittee 2 (HEM)
Program Officer
Qasba, Pankaj
Project Start
2002-12-03
Project End
2007-11-30
Budget Start
2004-12-01
Budget End
2005-11-30
Support Year
3
Fiscal Year
2005
Total Cost
$277,375
Indirect Cost
Name
Tufts University
Department
Pharmacology
Type
Schools of Medicine
DUNS #
039318308
City
Boston
State
MA
Country
United States
Zip Code
02111
Qiu, Wei; Liesa, Marc; Carpenter, Elizabeth P et al. (2015) ATP Binding and Hydrolysis Properties of ABCB10 and Their Regulation by Glutathione. PLoS One 10:e0129772
Liesa, Marc; Qiu, Wei; Shirihai, Orian S (2012) Mitochondrial ABC transporters function: the role of ABCB10 (ABC-me) as a novel player in cellular handling of reactive oxygen species. Biochim Biophys Acta 1823:1945-57
Hyde, B B; Liesa, M; Elorza, A A et al. (2012) The mitochondrial transporter ABC-me (ABCB10), a downstream target of GATA-1, is essential for erythropoiesis in vivo. Cell Death Differ 19:1117-26
Las, Guy; Serada, Sam B; Wikstrom, Jakob D et al. (2011) Fatty acids suppress autophagic turnover in ?-cells. J Biol Chem 286:42534-44
Liesa, Marc; Luptak, Ivan; Qin, Fuzhong et al. (2011) Mitochondrial transporter ATP binding cassette mitochondrial erythroid is a novel gene required for cardiac recovery after ischemia/reperfusion. Circulation 124:806-13
Hyde, Brigham B; Twig, Gilad; Shirihai, Orian S (2010) Organellar vs cellular control of mitochondrial dynamics. Semin Cell Dev Biol 21:575-81
Twig, Gilad; Liu, Xingguo; Liesa, Marc et al. (2010) Biophysical properties of mitochondrial fusion events in pancreatic beta-cells and cardiac cells unravel potential control mechanisms of its selectivity. Am J Physiol Cell Physiol 299:C477-87
Molina, Anthony J A; Shirihai, Orian S (2009) Monitoring mitochondrial dynamics with photoactivatable [corrected] green fluorescent protein. Methods Enzymol 457:289-304
Mouli, Pradeep K; Twig, Gilad; Shirihai, Orian S (2009) Frequency and selectivity of mitochondrial fusion are key to its quality maintenance function. Biophys J 96:3509-18
Molina, Anthony J A; Wikstrom, Jakob D; Stiles, Linsey et al. (2009) Mitochondrial networking protects beta-cells from nutrient-induced apoptosis. Diabetes 58:2303-15

Showing the most recent 10 out of 17 publications