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Mol. Cell. Biol., Feb 1995, 843-851, Vol 15, No. 2
JF Boylan, T Lufkin, CC Achkar, R Taneja, P Chambon and LJ Gudas
F9 embryonic teratocarcinoma stem cells differentiate into an epithelial
cell type called extraembryonic endoderm when treated with retinoic acid
(RA), a derivative of retinol (vitamin A). This differentiation is
presumably mediated through the actions of retinoid receptors, the RARs and
RXRs. To delineate the functions of each of the different retinoid
receptors in this model system, we have generated F9 cell lines in which
both copies of either the RAR alpha gene or the RAR gamma gene are
disrupted by homologous recombination. The absence of RAR alpha is
associated with a reduction in the RA-induced expression of both the
CRABP-II and Hoxb-1 (formerly 2.9) genes. The absence of RAR gamma is
associated with a loss of the RA-inducible expression of the Hoxa-1
(formerly Hox-1.6), Hoxa-3 (formerly Hox-1.5), laminin B1, collagen IV
(alpha 1), GATA-4, and BMP-2 genes. Furthermore, the loss of RAR gamma is
associated with a reduction in the metabolism of all- trans-RA to more
polar derivatives, while the loss of RAR alpha is associated with an
increase in metabolism of RA relative to wild-type F9 cells. Thus, each of
these RARs exhibits some specificity with respect to the regulation of
differentiation-specific gene expression. These results provide an
explanation for the expression of multiple RAR types within one cell type
and suggest that each RAR has specific functions.
Copyright © 1995, American Society for Microbiology
Targeted disruption of retinoic acid receptor alpha (RAR alpha) and RAR gamma results in receptor-specific alterations in retinoic acid- mediated differentiation and retinoic acid metabolism
Department of Pharmacology, Cornell University Medical College, New York, New York 10021.
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