Regulation and Expression of the ATP-Binding Cassette Transporter ABCG2 in Human Embryonic Stem Cells§

Authors

  • Raji Padmanabhan,

    1. Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute,National Institutes of Health, Bethesda, Maryland, USA
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  • Kevin G. Chen,

    1. NIH Stem Cell Unit, National Institute of Neurological Disorders and Stroke,National Institutes of Health, Bethesda, Maryland, USA
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  • Jean-Pierre Gillet,

    1. Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute,National Institutes of Health, Bethesda, Maryland, USA
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  • Misty Handley,

    1. Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute,National Institutes of Health, Bethesda, Maryland, USA
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  • Barbara S. Mallon,

    1. NIH Stem Cell Unit, National Institute of Neurological Disorders and Stroke,National Institutes of Health, Bethesda, Maryland, USA
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  • Rebecca S. Hamilton,

    1. NIH Stem Cell Unit, National Institute of Neurological Disorders and Stroke,National Institutes of Health, Bethesda, Maryland, USA
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  • Kyeyoon Park,

    1. NIH Stem Cell Unit, National Institute of Neurological Disorders and Stroke,National Institutes of Health, Bethesda, Maryland, USA
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  • Sudhir Varma,

    1. Bioinformatics and Computational Biosciences Branch, National Institute of Allergy and Infectious Diseases,National Institutes of Health, Bethesda, Maryland, USA
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  • Michele G. Mehaffey,

    1. SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
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  • Pamela G. Robey,

    1. NIH Stem Cell Unit, National Institute of Neurological Disorders and Stroke,National Institutes of Health, Bethesda, Maryland, USA
    2. Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research,National Institutes of Health, Bethesda, Maryland, USA
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  • Ronald D. G. McKay,

    1. NIH Stem Cell Unit, National Institute of Neurological Disorders and Stroke,National Institutes of Health, Bethesda, Maryland, USA
    2. Laboratory of Molecular Biology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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  • Michael M. Gottesman

    Corresponding author
    1. Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute,National Institutes of Health, Bethesda, Maryland, USA
    • Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA

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    • Telephone: (301) 496-1530; Fax: (301) 402-0450


  • Author contributions: R.P.: conception and design, collection and/or assembly of data, and data analysis and interpretation; K.G.C.: conception and design, provision of study material, collection and/or assembly of data, data analysis and interpretation, and manuscript writing and editing; J.-P. G.: collection and/or assembly of data and data analysis and interpretation; M.H. and M.M.: collection and/or assembly of data; B.S.M.: provision of study material and collection and/or assembly of data; R.S.H. and K.P.: provision of study material; S.V.: data analysis; P.G.R.: provision of study material and data analysis and interpretation; R.D.M.: conception and design, provision of study material, and data analysis and interpretation; M.M.G.: conception and design, data analysis and interpretation, and writing and editing of manuscript. R.P. and K.G.C. contributed equally to this article.

  • Disclosure of potential conflicts of interest is found at the end of this article.

  • §

    First published online in STEM CELLSEXPRESS August 7, 2012.

Abstract

The expression and function of several multidrug transporters (including ABCB1 and ABCG2) have been studied in human cancer cells and in mouse and human adult stem cells. However, the expression of ABCG2 in human embryonic stem cells (hESCs) remains unclear. Limited and contradictory results in the literature from two research groups have raised questions regarding its expression and function. In this study, we used quantitative real-time PCR, Northern blots, whole genome RNA sequencing, Western blots, and immunofluorescence microscopy to study ABCG2 expression in hESCs. We found that full-length ABCG2 mRNA transcripts are expressed in undifferentiated hESC lines. However, ABCG2 protein was undetectable even under embryoid body differentiation or cytotoxic drug induction. Moreover, surface ABCG2 protein was coexpressed with the differentiation marker stage-specific embryonic antigen-1 of hESCs, following constant BMP-4 signaling at days 4 and 6. This expression was tightly correlated with the downregulation of two microRNAs (miRNAs) (i.e., hsa-miR-519c and hsa-miR-520h). Transfection of miRNA mimics and inhibitors of these two miRNAs confirmed their direct involvement in the regulation ABCG2 translation. Our findings clarify the controversy regarding the expression of the ABCG2 gene and also provide new insights into translational control of the expression of membrane transporter mRNAs by miRNAs in hESCs. STEM Cells2012;30:2175–2187

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