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Loss of CAK phosphorylation of RAR{alpha} mediates transcriptional control of retinoid-induced cancer cell differentiation.

ABSTRACT: Although the role of the classic retinoic acid (RA)-induced genomic pathway in cancer cell differentiation is well recognized, the underlying mechanisms remain to be dissected. Retinoic acid receptor alpha (RARalpha) is a transcription factor activated by RA, and its serine 77 (RARalphaS77) is the main residue phosphorylated by the cyclin-dependent kinase (CDK)-activating kinase (CAK) complex. We report here that in both human myeloid leukemia and mouse embryonic teratocarcinoma stem cells, either RA-suppressed CAK phosphorylation of RARalpha or mutation of RARalphaS77 to alanine (RARalphaS77A) coordinates CAK-dependent G(1) arrest with cancer cell differentiation by transactivating RA-target genes. Both hypophosphorylated RARalpha and RARalphaS77A reduce binding to retinoic acid-responsive elements (RARE) in the promoters of RA-target genes while stimulating gene transcription. The enhanced transactivation and reduced RARalpha-chromatin interaction are accompanied by RARalpha dissociation from the transcriptional repressor N-CoR and are association with the coactivator NCoA-3. Such effects of decreased CAK phosphorylation of RARalphaS77 on mediating RA-dependent transcriptional control of cancer cell differentiation are examined correspondingly in both RA-resistant myeloid leukemia and embryonic teratocarcinoma stem RARalpha(-/-) cells. These studies demonstrate, for the first time, that RA couples G(1) arrest to transcriptional control of cancer cell differentiation by suppressing CAK phosphorylation of RARalpha to release transcriptional repression.-Wang, A., Alimova, I. N., Luo, P. Jong, A., Triche, T. J., Wu, L. Loss of CAK phosphorylation of RARalpha mediates transcriptional control of retinoid-induced cancer cell differentiation.

SUBMITTER: Wang A

PROVIDER: S-EPMC2830139 | biostudies-literature | 2010 Mar

REPOSITORIES: biostudies-literature

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Loss of CAK phosphorylation of RAR{alpha} mediates transcriptional control of retinoid-induced cancer cell differentiation.

Wang Anxun A Alimova Irina N IN Luo Peihua P Jong Ambrose A Triche Timothy J TJ Wu Lingtao L

FASEB journal : official publication of the Federation of American Societies for Experimental Biology 20091116 3

Although the role of the classic retinoic acid (RA)-induced genomic pathway in cancer cell differentiation is well recognized, the underlying mechanisms remain to be dissected. Retinoic acid receptor alpha (RARalpha) is a transcription factor activated by RA, and its serine 77 (RARalphaS77) is the main residue phosphorylated by the cyclin-dependent kinase (CDK)-activating kinase (CAK) complex. We report here that in both human myeloid leukemia and mouse embryonic teratocarcinoma stem cells, eith ...[more]

PMID: 19917671

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Project description:Understanding the mechanisms of controlled expansion and differentiation of basal progenitor cell populations during organogenesis is essential for developing targeted regenerative therapies. Since the cytokeratin 5-positive (K5+) basal epithelial cell population in the salivary gland is regulated by retinoic acid signaling, we interrogated how isoform-specific retinoic acid receptor (RAR) signaling impacts the K5+ cell population during salivary gland organogenesis to identify RAR isoform-specific mechanisms that could be exploited in future regenerative therapies. In this study, we utilized RAR isoform-specific inhibitors and agonists with murine submandibular salivary gland organ explants. We determined that RAR? and RAR? have opposing effects on K5+ cell cycle progression and cell distribution. RAR? negatively regulates K5+ cells in both whole organ explants and in isolated epithelial rudiments. In contrast, RAR? is necessary but not sufficient to positively maintain K5+ cells, as agonism of RAR? alone failed to significantly expand the population. Although retinoids are known to stimulate differentiation, K5 levels were not inversely correlated with differentiated ductal cytokeratins. Instead, RAR? agonism and RAR? inhibition, corresponding with reduced K5, resulted in premature lumenization, as marked by prominin-1. With lineage tracing, we demonstrated that K5+ cells have the capacity to become prominin-1+ cells. We conclude that RAR? and RAR? reciprocally control K5+ progenitor cells endogenously in the developing submandibular salivary epithelium, in a cell cycle-dependent manner, controlling lumenization independently of keratinizing differentiation. Based on these data, isoform-specific targeting RAR? may be more effective than pan-RAR inhibitors for regenerative therapies that seek to expand the K5+ progenitor cell pool.RAR? and RAR? reciprocally control K5+ progenitor cell proliferation and distribution in the developing submandibular salivary epithelium in a cell cycle-dependent manner while regulating lumenization independently of keratinizing differentiation.

Dataset Information

Loss of CAK phosphorylation of RAR{alpha} mediates transcriptional control of retinoid-induced cancer cell differentiation.

Publications

Loss of CAK phosphorylation of RAR{alpha} mediates transcriptional control of retinoid-induced cancer cell differentiation.

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