This Article Full Text Full Text (PDF) Supplementary Data All Versions of this Article: 0008-5472.CAN-09-0078v1 69/13/5560    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Google Scholar Articles by Lynch, J. Articles by Schuetz, J. D. PubMed PubMed Citation Articles by Lynch, J. Articles by Schuetz, J. D.

Cell Survival under Stress Is Enhanced by a Mitochondrial ATP-Binding Cassette Transporter That Regulates Hemoproteins

Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee

Requests for reprints: John D. Schuetz, Department of Pharmaceutical Sciences, MS 313, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105-3678. Phone: 901-595-2174; Fax: 901-595-3125; E-mail: john.schuetz{at}stjude.org.

Key Words: ABCB6 • porphyrins • heme • protoporphyrin IX • superoxide dismutase • hemoproteins • peroxide • oxidative stress

The ATP-binding cassette (ABC) transporter ABCB6 localizes to the mitochondria, where it imports porphyrins and up-regulates de novo porphyrin synthesis. If ABCB6 also increases the intracellular heme concentration, it may broadly affect the regulation and physiology of cellular hemoproteins. We tested whether the ability of ABCB6 to accelerate de novo porphyrin biosynthesis alters mitochondrial and extramitochondrial heme levels. ABCB6 overexpression increased the quantity of cytosolic heme but did not affect mitochondrial heme levels. We then tested whether the increased extramitochondrial heme would increase the concentration and/or activity of cellular hemoproteins (hemoglobin, catalase, and cytochrome c oxidase). ABCB6 overexpression increased the activity and quantity of hemoproteins found in several subcellular compartments, and reduction of ABCB6 function (by small interfering RNA or knockout) reversed these findings. In complementary studies, suppression of ABCB6 expression sensitized cells to stress induced by peroxide and cyanide, whereas overexpression of ABCB6 protected against both stressors. Our findings show that the ability of ABCB6 to increase cytosolic heme levels produces phenotypic changes in hemoproteins that protect cells from certain stresses. Collectively, these findings have implications for the health and survival of both normal and abnormal cells, which rely on heme for multiple cellular processes. [Cancer Res 2009;69(13):5560–7]

This article has been cited by other articles:

				S. K. Park, T. L. Sheffler, M. E. Spurlock, A. L. Grant, and D. E. Gerrard Chronic activation of 5'-AMP-activated protein kinase changes myosin heavy chain expression in growing pigs J Anim Sci, October 1, 2009; 87(10): 3124 - 3133. [Abstract] [Full Text] [PDF]