Conformationally Defined 6-s-trans-Retinoic Acid Analogs. 3. Structure−Activity Relationships for Nuclear Receptor Binding, Transcriptional Activity, and Cancer Chemopreventive Activity

1996 ◽  
Vol 39 (19) ◽  
pp. 3625-3635 ◽  
Author(s):  
Donald D. Muccio ◽  
Wayne J. Brouillette ◽  
Muzaffar Alam ◽  
Michael F. Vaezi ◽  
Brahma P. Sani ◽  
...  
1995 ◽  
Vol 38 (13) ◽  
pp. 2302-2310 ◽  
Author(s):  
Muzaffar Alam ◽  
Valdimir Zhestkov ◽  
Brahma P. Sani ◽  
Pratap Venepally ◽  
Arthur A. Levin ◽  
...  

ChemInform ◽  
2010 ◽  
Vol 27 (52) ◽  
pp. no-no
Author(s):  
R. L. BEARD ◽  
D. F. COLON ◽  
T. K. SONG ◽  
P. J. A. DAVIES ◽  
D. M. KOCHHAR ◽  
...  

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2727-2727
Author(s):  
Mitsuhiro Ito ◽  
Norinaga Urahama ◽  
Akiko Sada ◽  
Kimikazu Yakushijin ◽  
Katsuya Yamamoto ◽  
...  

Abstract The TRAP/Mediator complex, the metazoan counterpart of the yeast Mediator complex, is master transcriptional regulatory complex composed of approximately 30 subunits. It was originally isolated as a thyroid hormone receptor (TR)-associated protein (TRAP) complex that mediates TR-activated transcription from DNA templates in vitro and probably acts in vivo after the action of other receptor-interacting coactivators involved in chromatin remodeling. The TRAP220/MED1 subunit of the TRAP/Mediator complex is proposed to act on a variety of major and specific biological events, including growth, differentiation and homeostasis, through physical interaction with nuclear receptors. The vitamin D receptor (VDR) and retinoic acid receptor (RAR), coupled with retinoid X receptor (RXR), are nuclear receptors which have important roles for monopoiesis and granulopoiesis, respectively. In this study, we present the functional role of TRAP220/MED1 in nuclear receptor-mediated monopoiesis and granulopoiesis. Since TRAP220 knockout (Trap220-/-) mice were mortalities during the early embryonic period before definitive hematopoiesis within the hepatic primordia becomes dominant, the function of TRAP220/MED1 in adult hematopoiesis was mostly unknown. However, these embryos appeared to have normal composition of nucleated erythroid cells. Therefore, the E9.0 yolk sac-derived hematopoietic precursor cells were used to differentiate into definitive hematopoietic colony forming units within the methylcellulose blood cell culture. The number of monocytic colonies (CFU-M) was significantly lower in knockouts than in wild type controls, while the numbers of other types of colonies (CFU-GEMM, CFU-GM, CFU-G and CFU-E) were comparable. Hence, TRAP220/MED1 appeared to be indispensable for optimal monocytic differentiation. Next, the HL-60 acute promyelocytic leukemia cells were used to elucidate directly and mechanistically the roles of TRAP220/MED1 in RAR- and VDR-dependent differentiation of the hematopoietic precursor cells into granulocytic and monocytic lineage cells. The expression of the TRAP220/MED1 subunit as well as other TRAP/Mediator subunits was induced when the cells were treated with their ligands, all-trans retinoic acid and 1,25-dihydroxyvitamin D3. Flow cytometric analyses showed that HL-60 cells, wherein TRAP220/MED1 was down-regulated, did not differentiate efficiently into monocytes and granulocytes by stimulation with 1,25-dihydroxyvitamin D3 and all-trans retinoic acid, correspondingly. The expression of direct target genes of VDR or RAR, as well as the differentiation marker genes, was low in the knockdown cells by stimulation with these ligands. In contrast, 12-O-tetradecanoylphorbol-13-acetate (TPA)- and dimethylsulphoxide (DMSO)-mediated monocytic and myeloid differentiation, which bypasses nuclear receptor-mediated signaling pathways, was not affected in knockdown cells. Collectively, these results indicated an indispensable role of TRAP220/MED1 in the optimal VDR- and RAR-mediated myelomonocytic differentiation processes in mammalian hematopoiesis.


Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4247-4247
Author(s):  
Jean-Noel Bastie ◽  
Nicole Balitrand ◽  
Isabelle Guillemot ◽  
Christine Chomienne ◽  
Laurent Delva

Abstract All-trans-retinoic acid (RA) and 1alpha,25-dihydroxyvitamin D3 (1,25D3) are involved in the control of hematopoiesis and have been suggested to play a role in cellular differentiation and are as such potent inducers of differentiation of myeloid leukemia cells. In this study, we have shown that in promyelocytic NB4 cells, addition of 1,25D3 enhances terminal granulocytic RA-dependent differentiation concomitant with the enhanced activation of the RA-transcriptional activity through an RARbeta promoter. By EMSA and ChIP assays, we further demonstrate that while both VDR and RAR are bound to the RARbeta promoter in NB4 cells, addition of 1,25D3 increases VDR binding to this promoter while that of RA induces the release of VDR and increases the binding of RAR. Thus, contrary to normal myeloid cells, 1,25D3 does not act as a transrepressor of RA-transcriptional activity in leukemic cells suggesting that transcriptional regulation of RA-target genes may be modified in malignant cells. In promyelocytic leukemic cells the combination of 1,25D3 and RA results in both enhanced transactivation and differentiation.


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