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J Biol Chem. 2017 Sep 29;292(39):16284-16299. doi: 10.1074/jbc.M117.797415. Epub 2017 Aug 14.

Reductions in the mitochondrial ABC transporter Abcb10 affect the transcriptional profile of heme biosynthesis genes.

Author information

1
From the Division of Microbiology and Immunology, Department of Pathology, and.
2
the Division of Hematology and.
3
the Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115.
4
the Division of Hematology-Oncology, Department of Medicine, University of Utah School of Medicine, Salt Lake City, Utah 84132.
5
the Department of Biochemistry, Tohoku University Graduate School of Medicine, Sendai 980-8576, Japan.
6
the Division of Hematology-Oncology, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, and.
7
the Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115.
8
From the Division of Microbiology and Immunology, Department of Pathology, and diane.mcveyward@path.utah.edu.

Abstract

ATP-binding cassette subfamily B member 10 (Abcb10) is a mitochondrial ATP-binding cassette (ABC) transporter that complexes with mitoferrin1 and ferrochelatase to enhance heme biosynthesis in developing red blood cells. Reductions in Abcb10 levels have been shown to reduce mitoferrin1 protein levels and iron import into mitochondria, resulting in reduced heme biosynthesis. As an ABC transporter, Abcb10 binds and hydrolyzes ATP, but its transported substrate is unknown. Here, we determined that decreases in Abcb10 did not result in protoporphyrin IX accumulation in morphant-treated zebrafish embryos or in differentiated Abcb10-specific shRNA murine Friend erythroleukemia (MEL) cells in which Abcb10 was specifically silenced with shRNA. We also found that the ATPase activity of Abcb10 is necessary for hemoglobinization in MEL cells, suggesting that the substrate transported by Abcb10 is important in mediating increased heme biosynthesis during erythroid development. Inhibition of 5-aminolevulinic acid dehydratase (EC 4.2.1.24) with succinylacetone resulted in both 5-aminolevulinic acid (ALA) accumulation in control and Abcb10-specific shRNA MEL cells, demonstrating that reductions in Abcb10 do not affect ALA export from mitochondria and indicating that Abcb10 does not transport ALA. Abcb10 silencing resulted in an alteration in the heme biosynthesis transcriptional profile due to repression by the transcriptional regulator Bach1, which could be partially rescued by overexpression of Alas2 or Gata1, providing a mechanistic explanation for why Abcb10 shRNA MEL cells exhibit reduced hemoglobinization. In conclusion, our findings rule out that Abcb10 transports ALA and indicate that Abcb10's ATP-hydrolysis activity is critical for hemoglobinization and that the substrate transported by Abcb10 provides a signal that optimizes hemoglobinization.

KEYWORDS:

ABC transporter; ALA; abcb10; hemoglobin; mitochondria; porphyrin; red cell; transcription

PMID:
28808058
PMCID:
PMC5625058
DOI:
10.1074/jbc.M117.797415
[Indexed for MEDLINE]
Free PMC Article

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