The Role of Retinoic Acid Receptors in Myeloid Differentiation

2003 ◽  
pp. 149-161
Author(s):  
Steven J. Collins ◽  
Barton S. Johnson ◽  
Louise E. Purton
Keyword(s):  
Retinoic Acid ◽  
Retinoic Acid Receptors ◽  
Myeloid Differentiation

scholarly journals PML-RAR Binds to the +7kb Enhancer of CEBPE and Inhibits Its Expression

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 43-43
Author(s):  
Pavithra Shyamsunder ◽  
Shree Pooja Sridharan ◽  
Pushkar Dakle ◽  
Zeya Cao ◽  
Vikas Madan ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Regulatory Element ◽  
Promyelocytic Leukemia ◽  
Luciferase Reporter ◽  
Myeloid Differentiation ◽  
Atra Treatment ◽  
Granulocytic Differentiation ◽  
Nb4 Cells ◽  
Acute Myeloid

Acute promyelocytic leukemia (APL) is a unique subtype of acute myeloid leukemia (AML). The disease is identified by distinctive morphology and is distinguished by a balanced reciprocal translocation between chromosomes 15 and 17. This aberration leads to the fusion between promyelocytic leukemia (PML) gene located on chromosome 15q21, and retinoic acid receptor α (RARA) gene from chromosome 17q21, leading to the resultant chimeric onco-fusion protein PML-RARA, which is detectable in more than 95% patients and disturbs proper promyelocytic differentiation. All-trans retinoic acid (ATRA) can induce granulocytic differentiation in APL and is used to treat APL patients. Genes containing PML-RARA-targeted promoters are transcriptionally suppressed in APL and most likely constitute a major mechanism of transcriptional repression occurring in APL. A growing body of evidence points to the role of distal regulatory elements, including enhancers, in the control of gene expression. In order to understand the unique sets of enhancers that might be under the control of PML-RAR and crucial for granulocytic differentiation of NB4 cells, we analysed the enhancer landscape of control and ATRA treated NB4 cells. H3K9Ac mapping identified a repertoire of enhancers that were gained in NB4 cells treated with ATRA. Closer investigation of these enhancer elements revealed enrichment of H3K9Ac signals around major drivers of myeloid differentiation. Of note, we identified a gain in enhancer signature for a region about 7kb downstream of the CEBPE gene. Our previous studies identified a novel enhancer for CEBPE in murine hematopoietic cells, which was 6 downstream of CEBPE core promoter. It appears that the +7kb region we identified in human APL cells may be analogous to the murine enhancer. We also observed that PML-RAR binds this +7kb region and ATRA treatment of NB4 cells displaced binding of PML-RAR from the + 7kb region, suggestive of a transcriptional repressive effect of PML-RAR at such enhancer elements. To test the transcription regulating potential of this +7kb region, we used catalytically inactive Cas9 fused to Krüppel associated box (KRAB) domain (dCas9-KRAB). We designed three guide RNAs covering this regulatory region. The sgRNAs effectively repressed expression of CEBPE accompanied by lowered granulocytic differentiation of these guide RNA targeted NB4 cells after ATRA treatment. To explore transcription factor (TF) occupancy at this +7 kb region, we analysed public available ChIP-seq datasets for hematopoiesis-specific factors. Analysis revealed that the +7kb region was marked by an open chromatin signature, accompanied by binding of a majority of hematopoietic TFs around this putative regulatory element with concurrent binding of EP300. Strikingly we noticed binding of CEBPA, CEBPB and CEBPE at this regulatory element. To assess whether binding of these members of the CEBP family of TFs is functionally relevant, luciferase reporter and electrophoretic mobility shift assays (EMSA) were performed. Co expression of the CEBP TFs led to significant induction of luciferase expression, and this data was further confirmed using EMSA assays. Based on these observations, we propose that PML-RAR blocks granulocytic differentiation by occupying this +7kb enhancer of CEBPE, hinders binding of other cell type/lineage specific TFs, and blocks CEBPE expression. When cells are stimulated with ATRA, PML-RAR is displaced from the CEBPE enhancer, allowing for efficient binding of myeloid-specific TFs. This results in increased CEBPE expression, which in turn promotes efficient granulocytic differentiation. The findings from our study expands our current understanding of the mechanism of differentiation therapy, the role of onco-fusion proteins in inhibiting myeloid differentiation, and may provide new therapeutic approaches to many acute myeloid leukemias. Disclosures Ong: National University of Singapore: Other: Royalties.

Gene Expression Analysis of Bexarotene Differentiated Acute Myeloid Leukemias Identifies Known and Novel Gene Targets.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1199-1199
Author(s):  
Patricia Vanessa Sanchez ◽  
Reid P Bissonnette ◽  
Donald E Tsai ◽  
Martin Carroll
Keyword(s):  
Transcription Factor ◽  
Retinoic Acid ◽  
Cell Differentiation ◽  
Cell Lines ◽  
Leukemic Cell ◽  
Myeloid Differentiation ◽  
Induced Differentiation ◽  
Pparγ Agonist ◽  
Acute Myeloid

Abstract Despite advances in understanding the molecular pathogenesis of acute myeloid leukemia (AML), therapy for relapsed disease remains inadequate with high mortalities. Clinicians at the University of Pennsylvania have demonstrated that the FDA approved retinoid X receptor (RXR) agonist bexarotene (Targretin™) stimulates leukemic cell differentiation in a subset patents with relapsed AML leading to clinical responses. This underscores the importance of identifying the mechanism by which bexarotene induces differentiation in AML in order to enhance the efficacy of this therapeutic approach. To understand the role of bexarotene and RXR receptors in leukemic cell differentiation, we initially utilized a pharmacogenetic approach to study the effects of bexarotene on AML cell lines using combinations of bexarotene with other differentiation induction agents. These studies demonstrate that bexarotene induces myeloid differentiation in MOLM14, HL60, THP-1, and NB4 cell lines but not in the myeloblastic cell line KG1a. Combination treatment of AML cell lines with bexarotene in combination with all trans retinoic acid (ATRA) enhanced differentiation suggesting that the mechanism of action for bexarotene is through RARα (retinoic acid receptor)/RXRα heterodimer stimulation. Consistent with this, differentiation induced by the drug combination was effectively blocked by the RAR antagonist, LG100815 and partially blocked by the RXR antagonist, LG101208. In contrast, bexarotene does not cooperate with valproic acid, theophylline, the PPARγ agonist rosiglitazone, or the LXR agonist T0901317. Preliminary data from quantitative RT-PCR and Affymetrix microarray analysis of bexarotene responsive AML cell lines at 3, 6, 12, and 96 hours post treatment has identified a subset of genes potentially regulated by bexarotene. CEBPε, a transcription factor known to play a critical role in granulopoiesis and PIM-1, a known oncogenic transcription factor, were among the genes that were significantly upregulated after bexarotene treatment of AML cells. Analysis of the functional role of C/EBPε in retinoid induced differentiation will be presented. Overall, this data supports the hypothesis that bexarotene, like ATRA, induces myeloid differentiation through activation of a RAR/RXR heterodimeric partner. However, other data suggests the presence of RAR independent pathways of signaling. LG100268, a pure RXR agonist induced myeloid differentiaton although not as robustly as bexarotene. Analysis of RAR and RXR mRNA expression in AML cell lines demonstrates that bexarotene does not induce expression of RARβ or p21, known targets induced by ATRA during myeloid differentiation. Chromatin immunoprecipitation assays demonstrate RXRα occupancy at RARβ and p21 promoter regions containing retinoid response elements (RARE). However, expression of these genes does not correlate with bexarotene-induced differentiation. This data suggests that although their expression has been linked to ATRA responsiveness, induction of RARβ and p21 expression is not necessary for retinoid induced myeloid differentiation. In summary, bexarotene induces myeloid differentiation through RAR dependent and independent pathways. Further analysis of the signaling events necessary for induction of myeloid differentiation by bexarotene may allow for improved selection of patients with AML who will respond to bexarotene.

scholarly journals The Pleiotropic Role of Retinoic Acid/Retinoic Acid Receptors Signaling: From Vitamin A Metabolism to Gene Rearrangements in Acute Promyelocytic Leukemia

2019 ◽  
Vol 20 (12) ◽  
pp. 2921 ◽  
Author(s):  
Conserva ◽  
Anelli ◽  
Zagaria ◽  
Specchia ◽  
Albano
Keyword(s):  
Retinoic Acid ◽  
Acute Promyelocytic Leukemia ◽  
Chromosomal Rearrangements ◽  
Therapy Response ◽  
Promyelocytic Leukemia ◽  
Retinoic Acid Receptors ◽  
Hematopoietic Stem ◽  
Vitamin A Metabolism ◽  
Hematological Neoplasms

The family of retinoic acid receptors (RARs: RARα, -β, and -γ) has remarkable pleiotropy characteristics, since the retinoic acid/RARs pathway is involved in numerous biological processes not only during embryonic development, but also in the postnatal phase and during adulthood. In this review, we trace the roles of RA/RARs signaling in the immune system (where this pathway has both an immunosuppressive role or is involved in the inflammatory response), in hematopoiesis (enhancing hematopoietic stem cell self-renewal, progenitor cells differentiation or maintaining the bone marrow microenvironment homeostasis), and in bone remodeling (where this pathway seems to have controversial effects on bone formation or osteoclast activation). Moreover, in this review is shown the involvement of RAR genes in multiple chromosomal rearrangements generating different fusion genes in hematological neoplasms, with a particular focus on acute promyelocytic leukemia and its variant subtypes. The effect of different RARs fusion proteins on leukemic transformation, on patients’ outcome, and on therapy response is also discussed.

The role of retinoic acid receptors in activated hepatic stellate cells

2013 ◽  
Vol 81 (2) ◽  
pp. 222-224 ◽  
Author(s):  
Yoshihiro Mezaki ◽  
Mayako Morii ◽  
Taku Hebiguchi ◽  
Kiwamu Yoshikawa ◽  
Noriko Yamaguchi ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Hepatic Stellate Cells ◽  
Stellate Cells ◽  
Retinoic Acid Receptors ◽  
Activated Hepatic Stellate Cells

Defective lens fiber differentiation and pancreatic tumorigenesis caused by ectopic expression of the cellular retinoic acid-binding protein I

Development ◽  
1993 ◽  
Vol 119 (2) ◽  
pp. 363-375
Author(s):  
A.V. Perez-Castro ◽  
V.T. Tran ◽  
M.C. Nguyen-Huu
Keyword(s):  
Retinoic Acid ◽  
Binding Proteins ◽  
Binding Protein ◽  
Ectopic Expression ◽  
Retinoic Acid Receptors ◽  
Acid Binding Protein ◽  
Trans Retinoic Acid ◽  
All Trans Retinoic Acid ◽  
Retinoic Acid Binding Proteins

All-trans retinoic acid, a metabolite of retinol, is a possible morphogen in vertebrate development. Two classes of cellular proteins, which specifically bind all-trans retinoic acid, are thought to mediate its action: the nuclear retinoic acid receptors (RAR alpha, beta, gamma), and the cytoplasmic binding proteins known as cellular retinoic acid-binding proteins I and II (CRABP I and II). The function of the retinoic acid receptors is to regulate gene transcription by binding to DNA in conjunction with the nuclear retinoid X receptors (RXR alpha, beta, gamma), which in turn have 9-cis retinoic acid as a ligand. Several lines of evidence suggest that the role of the cellular retinoic acid-binding proteins is to control the concentration of free retinoic acid reaching the nucleus in a given cell. Here, we have addressed the role of the cellular retinoic acid-binding protein I in development by ectopically expressing it in the mouse lens, under the control of the alpha A-crystallin promoter. We show that this ectopic expression interferes with the development of the lens and with the differentiation of the secondary lens fiber cells, causing cataract formation. These results suggest that correct regulation of intracellular retinoic acid concentration is required for normal eye development. In addition, the generated transgenic mice also present expression of the transgene in the pancreas and develop pancreatic carcinomas, suggesting that overexpression of the cellular retinoic acid-binding protein is the cause of the tumors. These results taken together provide evidence for a role of the cellular retinoic acid-binding protein in development and cell differentiation. The relevance of these findings to the possible role of the cellular retinoic acid-binding proteins in the transduction of the retinoic acid signal is discussed.

The role of retinoic acid receptors in neurite outgrowth from different populations of embryonic mouse dorsal root ganglia

2000 ◽  
Vol 113 (14) ◽  
pp. 2567-2574
Author(s):  
J. Corcoran ◽  
B. Shroot ◽  
J. Pizzey ◽  
M. Maden
Keyword(s):  
Retinoic Acid ◽  
Neurite Outgrowth ◽  
Dorsal Root ◽  
Retinoic Acid Receptors ◽  
Embryonic Mouse ◽  
Different Populations ◽  
Alpha Beta ◽  
Beta 2 ◽  
X Receptors

Dorsal root ganglion (DRG) neurons can be categorised into at least three types, based upon their neurotrophin requirement for survival. We have analysed the expression of the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs) in NGF, NT-3 and BDNF dependent neurons isolated from embryonic day (E)13.5 mouse DRG. We show that each population of neurons expressed each of the three RXRs, (alpha), (beta) and (gamma); however, whilst the NGF and NT-3 dependent neurons expressed each of the RARs (alpha), (beta) and (gamma), the BDNF dependent neurons only expressed RAR(alpha) and (beta). When retinoic acid was added to each of the neuronal classes only the NGF and NT-3 dependent neurons responded by extending neurites, and this response involved the upregulation of RAR(beta)(2). This specificity was confirmed by the use of receptor-selective agonists as only a RAR(beta)-selective compound stimulated neurite outgrowth. These results suggest a role for RA acting via RAR(beta)(2) in the outgrowth of neurites.

Hindbrain patterning involves graded responses to retinoic acid signalling

Development ◽  
2001 ◽  
Vol 128 (12) ◽  
pp. 2199-2208 ◽  
Author(s):  
Valérie Dupé ◽  
Andrew Lumsden
Keyword(s):  
Retinoic Acid ◽  
Neural Tube ◽  
Retinoic Acid Receptors ◽  
Chick Embryos ◽  
Anteroposterior Axis ◽  
Retinoic Acid Signalling ◽  
Graded Responses ◽  
Acid Deficiency ◽  
Precise Role

Several recent studies have shown that retinoic acid signalling is required for correct patterning of the hindbrain. However, the data from these studies are disparate and the precise role of retinoic acid signalling in patterning the anteroposterior axis of the neural tube remains uncertain. To help clarify this issue, we have cultured a staged series of chick embryos in the presence of an antagonist to the all three retinoic acid receptors. Our data indicate that retinoic acid is the transforming signal involved in the expansion of posterior hindbrain structures. We find that the hindbrain region of the neural tube down to the level of the sixth somite acquires the identity of rhombomere 4 when retinoic acid signalling is blocked. Specification of future rhombomere boundaries has a retinoic acid dependency between stage 5 and stage 10+ that is lost progressively in an anterior-to-posterior sequence. Furthermore, the application of various concentrations of antagonist shows that successively more posterior rhombomere boundaries require progressively higher concentration of endogenous retinoic acid for their correct positioning, a result that strengthens the hypothesis that a complex retinoid gradient acts to pattern the posterior hindbrain. Our dissection of early retinoic acid functions allows us to re-interpret the wide disparity of hindbrain phenotypes previously observed in various models of retinoic acid deficiency.

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