Alterations in the expression of the genes that control stem cell differentiation and self-renewal often contribute to tumorigenesis. Our laboratory has studied the mechanisms by which retinoids (vitamin A (retinol) and its derivatives and metabolites), control gene expression in both normal stem cells and in tumors. Over this past grant period we have developed evidence that: a) the polycomb group (PcG) protein(s) play a major role in repressing retinoid signaling in embryonic stem (ES) cells;b) these polycomb mediated inhibitory signals are altered in tumor cells;and c) specific retinoid receptors act in concert with transcriptional coactivators in a gene specific context. Our immediate goal in the next grant period is to delineate the mechanisms by which the polycomb group mediated transcriptional repressive pathways and the retinoid transcriptional signaling pathways intersect.
Our Specific Aims for the next grant period: 1) We will elucidate the mechanisms by which the polycomb proteins inhibit retinoid transcriptional activation and retinoic acid induced cell differentiation. This will be accomplished by a combination of ChIP (chromatin immunoprecipitation) assays;overexpression or reduced expression of key transcriptional regulatory proteins such as pCIP (SRC3), EZH2, SUZ12, and JMJD3 in F9 and ES Wt and RAR1, 2, and 3 null cells;and deletion of DNA regulatory elements such as the Hoxa1 RARE, followed by analysis of PcG protein binding. We also propose a comparison of 3T3 cells with H-Ras transformed 3T3 cells to assess how an oncogenic protein perturbs retinoid signaling. 2) We plan to define the domains of the specific retinoic acid receptors (RARs) 1, 2, and 3 (i.e. the receptors for all-trans retinoic acid (RA) and other retinoids) and the coactivators for these receptors that control the transcriptional events which result in cell differentiation (and, thus, aid in inhibiting tumor cell proliferation). 3) Finally, as part of our goal of understanding retinoid regulation of stem cell differentiation, we will undertake a genome-wide search for primary target genes of the RARs through the use of ChIP-on-chip (tiling) arrays or ChIP-seq technology. This approach will allow us to obtain key information about the genes transcriptionally activated as ES cells differentiate along different pathways. For these proposed experiments we will utilize (a) murine ES and teratocarcinoma stem cell lines with both alleles of each of the individual RARs """"""""knocked out"""""""" by homologous recombination;(b) ES cell lines with some of the """"""""downstream"""""""" RAR target genes """"""""knocked out"""""""";and (c) mice that have each of the individual RARs knocked out by homologous recombination. This proposed research will increase our knowledge of the molecular mechanisms by which signaling by retinoids is accomplished, provide new knowledge that will be useful for improvement of 'differentiation therapy'for cancer, delineate the mechanisms by which retinoids signal so that we will understand why some tumors are resistant to retinoid therapy, and allow us to manipulate the expression or function of polycomb repressive proteins to increase the effectiveness of retinoid based therapies and differentiation strategies for stem cells.

Public Health Relevance

Cancer is a dangerous and dreaded disease. This research project will allow us to understand how normal mouse stem cells differentiate or mature in response to vitamin A, a vitamin required for health and without which we would all die. Our new research findings will allow us to improve therapies for cancer treatment, including new therapies in which chemicals related to vitamin A force cancer cells to differentiate and become more like normal cells (differentiation therapy for cancer).

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
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Chemo/Dietary Prevention Study Section (CDP)
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Ogunbiyi, Peter
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Weill Medical College of Cornell University
Schools of Medicine
New York
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Laursen, Kristian B; Gudas, Lorraine J (2018) Combinatorial knockout of RAR?, RAR?, and RAR? completely abrogates transcriptional responses to retinoic acid in murine embryonic stem cells. J Biol Chem 293:11891-11900
Quintero, Cynthia M; Laursen, Kristian B; Mongan, Nigel P et al. (2018) CARM1 (PRMT4) Acts as a Transcriptional Coactivator during Retinoic Acid-Induced Embryonic Stem Cell Differentiation. J Mol Biol 430:4168-4182
Simandi, Zoltan; Horvath, Attila; Wright, Lyndsey C et al. (2016) OCT4 Acts as an Integrator of Pluripotency and Signal-Induced Differentiation. Mol Cell 63:647-661
Trasino, Steven E; Tang, Xiao-Han; Jessurun, Jose et al. (2016) A retinoic acid receptor ?2 agonist reduces hepatic stellate cell activation in nonalcoholic fatty liver disease. J Mol Med (Berl) 94:1143-1151
Trasino, S E; Tang, X-H; Jessurun, J et al. (2016) Retinoic acid receptor ?2 agonists restore glycaemic control in diabetes and reduce steatosis. Diabetes Obes Metab 18:142-51
Nilsson, Emeli M; Laursen, Kristian B; Whitchurch, Jonathan et al. (2015) MiR137 is an androgen regulated repressor of an extended network of transcriptional coregulators. Oncotarget 6:35710-25
Orfali, Nina; O'Donovan, Tracey R; Nyhan, Michelle J et al. (2015) Induction of autophagy is a key component of all-trans-retinoic acid-induced differentiation in leukemia cells and a potential target for pharmacologic modulation. Exp Hematol 43:781-93.e2
Trasino, Steven E; Tang, Xiao-Han; Jessurun, Jose et al. (2015) Obesity Leads to Tissue, but not Serum Vitamin A Deficiency. Sci Rep 5:15893
Trasino, Steven E; Benoit, Yannick D; Gudas, Lorraine J (2015) Vitamin A deficiency causes hyperglycemia and loss of pancreatic ?-cell mass. J Biol Chem 290:1456-73
Laursen, Kristian B; Kashyap, Vasundhra; Scandura, Joseph et al. (2015) An alternative retinoic acid-responsive Stra6 promoter regulated in response to retinol deficiency. J Biol Chem 290:4356-66

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