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Role of Abcg2 During Mouse Embroyonic Stem Cell Diffferentiation
Rosen, Mitch, K. Chandler, S. Jeffay, H. Nichols, M. Hoopes, AND S. Hunter. Role of Abcg2 During Mouse Embroyonic Stem Cell Diffferentiation. Presented at ToxCast Data Summit, RTP, NC, September 29 - 30, 2014.
To be presented at the ToxCast Data Summit
Role of Abcg2 During Mouse Embryonic Stem Cell Differentiation. Abcg2 is a multidrug resistance ATP-binding cassette (ABC) transporter whose activity may be considered a hallmark of stem cell plasticity. The role of Abcg2 during early embryogenesis, however, is unclear. Studies done with mouse embryonic stem cells (mESCs) suggest that inhibition of Abcg2 by either chemical means or RNAi may reduce colony expansion of pluripotent cells and promote differentiation. Our group also observed a correlation between xenobiotics that alter mESC differentiation and chemicals that induce expression of ABCGg2 in primary human hepatocytes (ToxCast assay). On the other hand, knockout mice display a normal phenotype unless challenged by certain toxicants. Chemical inhibitors of Abcg2, such as K0143 and fumitremorgin C (FTC) were utilized to evaluate the role of Abcg2 in cultured J1 cells. MK571 and verapamil, inhibitors of Abcc1 and Abcb1, respectively, were utilized as well. Based on cellular accumulation of the Abcg2 substrate, pheophorbide A, maximum inhibition of Abcg2 was observed at approximately 1µm K0143 or FTC. Neither verapamil nor MK571 had a notable effect on Abcg2 function. While growth and differentiation of mESC could be affected by FTC, K0143, and verapamil at concentrations greater than 10 µm, lower concentrations did not influence cell proliferation or alter the expression of selected pluripotency/lineage markers on the appropriate days of culture (culture days 2, 4, 6, 9). These transcript markers included Pou5f1, Nanog, T, Gsc, Bmp4, Nes, Ncam1, Des, Ttr, Gata4, Abcg2, Myl4, and Myl7. Hence, Abcg2 does not appear to play a fundamental role in mESC differentiation based on observations in an adherent culture system. The possibility that Abcg2 plays a role in protecting embryonic cells from damage caused by xenobiotics, or that regulation of this efflux transporter by exogenous compounds may affect early differentiation is being considered. (Funded by U.S. EPA. This research does not reflect EPA policy.)