Dimerization-induced corepressor binding and relaxed DNA-binding specificity are critical for PML/RARA-induced immortalization (original) (raw)
Related papers
Molecular and Cellular Biology, 2003
PML-RAR is an oncogenic transcription factor forming in acute promyelocytic leukemias (APL) because of a chromosomal translocation. Without its ligand, retinoic acid (RA), PML-RAR functions as a constitutive transcriptional repressor, abnormally associating with the corepressor-histone deacetylase complex and blocking hematopoietic differentiation. In the presence of pharmacological concentrations of RA, PML-RAR activates transcription and stimulates differentiation. Even though it has been suggested that chromatin alteration is important for APL onset, the PML-RAR effect on chromatin of target promoters has not been investigated. Taking advantage of the Xenopus oocyte system, we compared the wild-type transcription factor RARα with PML-RAR as both transcriptional regulators and chromatin structure modifiers. Without RA, we found that PML-RAR is a more potent transcriptional repressor that does not require the cofactor RXR and produces a closed chromatin configuration. Surprisingly,...
Blood, 1998
Typical acute promyelocytic leukemia (APL) is associated with expression of the PML-RARα fusion protein and responsiveness to treatment with all-trans retinoic acid (ATRA). A rare, but recurrent, APL has been described that does not respond to ATRA treatment and is associated with a variant chromosomal translocation and expression of the PLZF-RARα fusion protein. Both PML- and PLZF-RARα possess identical RAR sequences and inhibit ATRA-induced gene transcription as well as cell differentiation. We now show that the above-mentioned oncogenic fusion proteins interact with the nuclear receptor corepressor N-CoR and, in comparison with the wild-type RARα protein, their interactions display reduced sensitivities to ATRA. Although pharmacologic concentration of ATRA could still induce dissociation of N-CoR from PML-RARα, it had a very little effect on its association with the PLZF-RARα fusion protein. This ATRA-insensitive interaction between N-CoR and PLZF-RARα was mediated by the N-termi...
Retinoic Acid Receptor Fusion to PML Affects Its Transcriptional and Chromatin-Remodeling Properties
Molecular and Cellular Biology, 2003
PML-RAR is an oncogenic transcription factor forming in acute promyelocytic leukemias (APL) because of a chromosomal translocation. Without its ligand, retinoic acid (RA), PML-RAR functions as a constitutive transcriptional repressor, abnormally associating with the corepressor-histone deacetylase complex and blocking hematopoietic differentiation. In the presence of pharmacological concentrations of RA, PML-RAR activates transcription and stimulates differentiation. Even though it has been suggested that chromatin alteration is important for APL onset, the PML-RAR effect on chromatin of target promoters has not been investigated. Taking advantage of the Xenopus oocyte system, we compared the wild-type transcription factor RAR␣ with PML-RAR as both transcriptional regulators and chromatin structure modifiers. Without RA, we found that PML-RAR is a more potent transcriptional repressor that does not require the cofactor RXR and produces a closed chromatin configuration. Surprisingly, repression by PML-RAR occurs through a further pathway that is independent of nucleosome deposition and histone deacetylation. In the presence of RA, PML-RAR is a less efficient transcriptional activator that is unable to modify the DNA nucleoprotein structure. We propose that PML-RAR, aside from its ability to recruit aberrant quantities of histone deacetylase complexes, has acquired additional repressive mechanisms and lost important activating functions; the comprehension of these mechanisms might reveal novel targets for antileukemic intervention.
The EMBO …, 1996
The block of terminal differentiation is a prominent feature of acute promyelocytic leukemia (APL) and its release by retinoic acid correlates with disease remission. Expression of the APL-specific PML/RARa fusion protein in hematopoietic precursor cell lines blocks terminal differentiation, suggesting that PML/ RARa may have the same activity in APL blasts. We expressed different PML/RARa mutants in U937 and TF-1 cells and demonstrated that the integrity of the PML protein dimerization and RARa DNA binding domains is crucial for the differentiation block induced by PMLJRARc, and that these domains exert their functions only within the context of the fusion protein. Analysis of the in vivo dimerization and cell localization properties of the PML/RARa mutants revealed that PML/RARa-PML and PML/RARa-RXR heterodimers are not necssary for PML/RARa activity on differentiation. We propose that a crucial mechanism underlying PML/RARa oncogenic activity is the deregulation of a transcription factor, RARa, through its fusion with the dimerization interface of another nuclear protein, PML.
I N THE LATE 1980s and early 1990s, the elucidation of the molecular basis of acute promyelocytic leukemia (APL) emerged as a paradigm for the connection between the bench and bedside. At that time, it became apparent that APL was, among the forms of acute myeloid leukemia, uniquely sensitive to all-trans retinoic acid (ATRA) 1,2 and clinical trials indicated that ATRA induced complete remissions by differentiation and eventual elimination of the malignant clone (reviewed previously 3-8 ). In 1991, it was discovered that the consistent chromosomal translocation of APL, t(15:17), 9 fused the retinoic acid receptor ␣ (RAR␣) gene to the promyelocytic leukemia (PML) gene on chromosome 15, yielding the fusion protein PML-RAR␣. 10-15 These data suggested that disruption of RAR␣ function was the major cause of APL. According to this line of reasoning, retinoic acid in pharmacological doses could then overcome this pathology, leading to in vivo differentiation and clinical remission. Although this hypothesis is essentially correct, 7 years of intense investigation of the APL model have begun to uncover a more complicated picture.
Proceedings of the National Academy of Sciences, 1999
Acute promyelocytic leukemia (APL) is characterized by a specific chromosome translocation involving RAR α and one of four fusion partners: PML , PLZF , NPM , and NuMA genes. To study the leukemogenic potential of the fusion genes in vivo , we generated transgenic mice with PLZF–RAR α and NPM–RAR α. PLZF–RAR α transgenic animals developed chronic myeloid leukemia-like phenotypes at an early stage of life (within 3 months in five of six mice), whereas three NPM–RAR α transgenic mice showed a spectrum of phenotypes from typical APL to chronic myeloid leukemia relatively late in life (from 12 to 15 months). In contrast to bone marrow cells from PLZF–RAR α transgenic mice, those from NPM–RAR α transgenic mice could be induced to differentiate by all- trans -retinoic acid (ATRA). We also studied RARE binding properties and interactions between nuclear corepressor SMRT and various fusion proteins in response to ATRA. Dissociation of SMRT from different receptors was observed at ATRA conce...
Forced retinoic acid receptor α homodimers prime mice for APL-like leukemia
Cancer Cell, 2006
RARA becomes an acute promyelocytic leukemia (APL) oncogene by fusion with any of five translocation partners. Unlike RARa, the fusion proteins homodimerize, which may be central to oncogenic activation. This model was tested by replacing PML with dimerization domains from p50NFkB (p50-RARa) or the rapamycin-sensitive dimerizing peptide of FKBP12 (F3-RARa). The X-RARa fusions recapitulated in vitro activities of PML-RARa. For F3-RARa, these properties were rapamycin sensitive. Although in vivo the artificial fusions alone are poor initiators of leukemia, p50-RARa readily cooperates with an activated mutant CDw131 to induce APL-like disease. These results demonstrate that the dimerization interface of RARa fusion partners is a critical element in APL pathogenesis while pointing to other features of PML for enhancing penetrance and progression.
Leukemia, 2011
In acute promyelocytic leukemia (APL) the retinoic acid receptor alpha (RARa) becomes an oncogene through the fusion with several partners, mostly with promyelocytic leukemia protein (PML), all of which have in common the presence of a self-association domain. The new fusion proteins, therefore, differently from the wild-type RARa, which forms only heterodimers with retinoic X receptor alpha, are also able to homooligomerize. The presence of such a domain has been suggested to be crucial for the leukemogenic potential of the chimeric proteins found in APL blasts. Whether or not any selfassociation domain is sufficient to bestow a leukemogenic activity on RARa is still under investigation. In this work, we address this question using two different X-RARa chimeras, where X represents the coiled-coil domain of PML (CC-RARa) or the oligomerization portion of the yeast transcription factor GCN4 (GCN4-RARa). We demonstrate that in vitro both proteins have transforming potential, and recapitulate the main PML-RARa biological properties, but CC-RARa is uniquely able to disrupt PML nuclear bodies. Indeed, in vivo only the CC-RARa chimera induces efficiently APL in a murine transplantation model. Thus, the PML CC domain represents the minimal structural determinant indispensable to transform RARa into an oncogenic protein.
The EMBO journal, 1996
The block of terminal differentiation is a prominent feature of acute promyelocytic leukemia (APL) and its release by retinoic acid correlates with disease remission. Expression of the APL-specific PML/RARalpha fusion protein in hematopoietic precursor cell lines blocks terminal differentiation, suggesting that PML/ RARalpha may have the same activity in APL blasts. We expressed different PML/RARalpha mutants in U937 and TF-1 cells and demonstrated that the integrity of the PML protein dimerization and RARalpha DNA binding domains is crucial for the differentiation block induced by PML/RARalpha, and that these domains exert their functions only within the context of the fusion protein. Analysis of the in vivo dimerization and cell localization properties of the PML/RARalpha mutants revealed that PML/RARalpha--PML and PML/RARalpha--RXR heterodimers are not necessary for PML/RARalpha activity on differentiation. We propose that a crucial mechanism underlying PML/RARalpha oncogenic act...