Biomedical subjects

David M Heery

Publications and source records attributed to David M Heery.

12 recordsLinked to original sources

PubMed2006

Pharmacological targeting of lysine acetyltransferases in human disease: a progress report.

Lysine acetyltransferases (LATs) are a structurally disparate group of enzymes involved in regulating transcription by participating as cofactors in transcriptional regulatory complexes, and by acetylation of lysine residues in histones and other proteins. Aberrant LAT function probably plays an important part in the pathogenesis of certain cancers, especially leukaemias and endocrine tumours. However, LAT activity might also be an important drug target in a range of other indications, including inflammatory lung diseases, viral infections and metabolic disorders. At present, comparatively few LAT inhibitors are known, but progress regarding the understanding of their structural and functional biology is now beginning to reveal LATs as promising new epigenetic drug targets.

Acetyltransferases↗

PubMed2006

ZNF366 is an estrogen receptor corepressor that acts through CtBP and histone deacetylases.

The regulation of gene expression by estrogen receptor-alpha (ERalpha) requires the coordinated and temporal recruitment of diverse sets of transcriptional co-regulator complexes, which mediate nucleosome remodelling and histone modification. Using ERalpha as bait in a yeast two-hybrid screen, we have identified a novel ERalpha-interacting protein, ZNF366, which is a potent corepressor of ERalpha activity. The interaction between ZNF366 and ERalpha has been confirmed in vitro and in vivo, and is mediated by the zinc finger domains of the two proteins. Further, we show that ZNF366 acts as a corepressor by interacting with other known ERalpha corepressors, namely RIP140 and CtBP, to inhibit expression of estrogen-responsive genes in vivo. Together, our results indicate that ZNF366 may play an important role in regulating the expression of genes in response to estrogen.

Adaptor Proteins, Signal Transducing↗

PubMed2006

Functional interaction of CREB binding protein (CBP) with nuclear transport proteins and modulation by HDAC inhibitors.

Nuclear transport proteins such as CSE1, NUP93 and Importin-alpha have recently been shown to be chromatin-associated proteins in yeast, which have unexpected functions in gene regulation. Here we report interactions between the mammalian histone acetyltransferase CBP with nuclear transport proteins CAS (a CSE1 homologue) and Importin-alpha (Impalpha) and NUP93. CAS was found to bind the SRC1 interaction domain (SID) of CBP via a leucine-rich motif in the N-terminus of the protein, that is conserved in other SID-binding proteins. Coimmunoprecipitation experiments also revealed that CBP and Impalpha proteins form a complex. As Impalpha is a known acetylation target of CBP/p300, and is recycled to the cytoplasm via the exportin CAS, we investigated whether HDAC inhibitors would alter the subcellular localization of these proteins. Treatment of COS-1 cells with the HDAC inhibitors trichostatin A or sodium butyrate resulted in sequestration of Impalpha in the nuclear envelope, accumulation of CAS in nuclear aggregates, and an increased number of CBP-containing PML bodies per cell. In addition, HDACi treatment appeared to enhance the association of Impalpha and CBP in coimmunoprecipitation experiments. Our results provide evidence for novel functional interactions between the chromatin modification enzyme CBP and nuclear transport proteins in mammalian cells.

Active Transport, Cell Nucleus↗

PubMed2006

Effects of glucocorticoids on STAT4 activation in human T cells are stimulus-dependent.

Glucocorticoids affect the immune system by a number of mechanisms, including modulation of cytokine production in lymphocytes. Glucocorticoids suppress T helper cell type 1 immune responses by decreasing the ability of T cells to respond to interleukin (IL)-12, a major inducer of interferon (IFN)-gamma. IFN-beta increases the expression of the anti-inflammatory cytokine IL-10 and suppresses IL-12. Signaling pathways through IFN-beta and the IL-12 receptor (IL-12R) involve activation by phosphorylation of signal transducer and activator of transcription 4 (STAT4). Our aim was to investigate the effects of dexamethasone on STAT4 activation by IFN-beta and IL-12 in human T cell blasts. We report that dexamethasone decreases IL-12-induced STAT4 phosphorylation and IFN-gamma production and enhances IFN-beta-induced STAT4 activation and IL-10 production. These effects are associated with a down-regulation of IL-12Rbeta1 expression but an up-regulation of IFN-betaR. These results indicate that the effect of glucocorticoids on the STAT4 signaling pathway depends on the stimulus activating that pathway.

Dexamethasone↗

PubMed2006

MOZ-TIF2 alters cofactor recruitment and histone modification at the RARbeta2 promoter: differential effects of MOZ fusion proteins on CBP- and MOZ-dependent activators.

MOZ-TIF2 and MOZ-CBP are leukemogenic fusion proteins associated with therapy-induced acute myeloid leukemia. These proteins are thought to subvert normal gene expression in differentiating hematopoietic progenitor cells. We have previously shown that MOZ-TIF2 inhibits transcription by CREB-binding protein (CBP)/p300-dependent activators such as nuclear receptors and p53. Here we have shown that MOZ-TIF2 associates with the RARbeta2 promoter in vivo, resulting in altered recruitment of CBP/p300, aberrant histone modification, and down-regulation of the RARbeta2 gene. In contrast, MOZ-TIF2 up-regulated transcription mediated by the MOZ/MYST3-dependent activator AML1/RUNX1. Both wild type MOZ and MOZ-TIF2 were found to colocalize with AML1, and MOZ-TIF2 was recruited to an AML1 target promoter. A MOZ-CBP fusion protein showed similar functions to MOZ-TIF2 in that it inhibited retinoic acid receptor-mediated transcription but enhanced AML1 reporter activation. Although it contains almost the entire CBP sequence, MOZ-CBP does not appear to associate with PML bodies. In summary, our results indicate that leukemogenic MOZ fusion proteins have differential effects on the activities of CBP-dependent and MOZ-dependent activators because of their ability to alter cofactor recruitment and chromatin modification at target promoters.

Animals↗

PubMed2006

Structural diversity in p160/CREB-binding protein coactivator complexes.

Ligand-induced transcription by nuclear receptors involves the recruitment of p160 coactivators such as steroid receptor coactivator 1 (SRC1), in complex with histone acetyltransferases such as CREB-binding protein (CBP) and p300. Here we describe the solution structure of a complex formed by the SRC1 interaction domain (SID) of CBP and the activation domain (AD1) of SRC1, both of which contain four helical regions (Calpha1, Calpha2, Calpha3, and Calpha3' in CBP and Salpha1, Salpha2', Salpha2, and Salpha3 in SRC1). A tight four-helix bundle is formed between Salpha1, Calpha1, Calpha2, and Calpha3 that is capped by Salpha3. In contrast to the structure of the AD1 domain of the related p160 protein ACTR in complex with CBP SID, the sequences forming Salpha2' and Salpha2 in SRC1 AD1 are not involved in the interface between the two domains but rather serve to position Salpha3. Thus, although the CBP SID domain adopts a similar fold in complex with different p160 proteins, the topologies of the AD1 domains are strikingly different, a feature that is likely to contribute to functional specificity of these coactivator complexes.

Amino Acid Sequence↗

PubMed2006

MOZ fusion proteins in acute myeloid leukaemia.

MOZ (monocytic leukaemia zinc finger protein; also known as ZNF220 or MYST3) is a member of the MYST family of protein acetyltransferases. Chromosomal translocations involving the MOZ gene are associated with AML (acute myeloid leukaemia), suggesting that it has a role in haematopoiesis. Recurrent reciprocal translocations fuse the MOZ gene [or the gene encoding MORF (MOZ-related factor); also known as MYST4] to genes encoding the nuclear receptor co-activators CBP [CREB (cAMP response element-binding protein)-binding protein], p300 or the p160 protein TIF2 (transcription intermediary factor 2). The resulting fusion proteins can transform haematopoietic progenitors in vitro, and induce myeloproliferative disease in mice. Recent insights into the molecular mechanisms underlying these effects indicate that MOZ fusion proteins interfere with the activities of transcription factors such as nuclear receptors, p53 and Runx proteins. Our studies suggest that subverting the function of cellular CBP and p300 proteins may play a key role in this process. Here we review the recent progress in understanding the role of MOZ fusion proteins in the aetiology of AML.

Animals↗

PubMed2005

T:G mismatch-specific thymine-DNA glycosylase (TDG) as a coregulator of transcription interacts with SRC1 family members through a novel tyrosine repeat motif.

Gene activation involves protein complexes with diverse enzymatic activities, some of which are involved in chromatin modification. We have shown previously that the base excision repair enzyme thymine DNA glycosylase (TDG) acts as a potent coactivator for estrogen receptor-alpha. To further understand how TDG acts in this context, we studied its interaction with known coactivators of nuclear receptors. We find that TDG interacts in vitro and in vivo with the p160 coactivator SRC1, with the interaction being mediated by a previously undescribed motif encoding four equally spaced tyrosine residues in TDG, each tyrosine being separated by three amino acids. This is found to interact with two motifs in SRC1 also containing tyrosine residues separated by three amino acids. Site-directed mutagenesis shows that the tyrosines encoded in these motifs are critical for the interaction. The related p160 protein TIF2 does not interact with TDG and has the altered sequence, F-X-X-X-Y, at the equivalent positions relative to SRC1. Substitution of the phenylalanines to tyrosines is sufficient to bring about interaction of TIF2 with TDG. These findings highlight a new protein-protein interaction motif based on Y-X-X-X-Y and provide new insight into the interaction of diverse proteins in coactivator complexes.

Amino Acid Motifs↗

PubMed2005

MOZ-TIF2 inhibits transcription by nuclear receptors and p53 by impairment of CBP function.

Chromosomal rearrangements associated with acute myeloid leukemia (AML) include fusions of the genes encoding the acetyltransferase MOZ or MORF with genes encoding the nuclear receptor coactivator TIF2, p300, or CBP. Here we show that MOZ-TIF2 acts as a dominant inhibitor of the transcriptional activities of CBP-dependent activators such as nuclear receptors and p53. The dominant negative property of MOZ-TIF2 requires the CBP-binding domain (activation domain 1 [AD1]), and coimmunoprecipitation and fluorescent resonance energy transfer experiments show that MOZ-TIF2 interacts with CBP directly in vivo. The CBP-binding domain is also required for the ability of MOZ-TIF2 to extend the proliferative potential of murine bone marrow lineage-negative cells in vitro. We show that MOZ-TIF2 displays an aberrant nuclear distribution and that cells expressing this protein have reduced levels of cellular CBP, leading to depletion of CBP from PML bodies. In summary, our results indicate that disruption of the normal function of CBP and CBP-dependent activators is an important feature of MOZ-TIF2 action in AML.

Acetyltransferases↗

PubMed2004

A Conserved alpha-helical motif mediates the binding of diverse nuclear proteins to the SRC1 interaction domain of CBP.

CREB-binding protein (CBP) and p300 contain modular domains that mediate protein-protein interactions with a wide variety of nuclear factors. A C-terminal domain of CBP (referred to as the SID) is responsible for interaction with the alpha-helical AD1 domain of p160 coactivators such as the steroid receptor coactivator (SRC1), and also other transcriptional regulators such as E1A, Ets-2, IRF3, and p53. Here we show that the pointed (PNT) domain of Ets-2 mediates its interaction with the CBP SID, and describe the effects of mutations in the SID on binding of Ets-2, E1A, and SRC1. In vitro binding studies indicate that SRC1, Ets-2 and E1A display mutually exclusive binding to the CBP SID. Consistent with this, we observed negative cross-talk between ERalpha/SRC1, Ets-2, and E1A proteins in reporter assays in transiently transfected cells. Transcriptional inhibition of Ets-2 or GAL4-AD1 activity by E1A was rescued by co-transfection with a CBP expression plasmid, consistent with the hypothesis that the observed inhibition was due to competition for CBP in vivo. Sequence comparisons revealed that SID-binding proteins contain a leucine-rich motif similar to the alpha-helix Aalpha1 of the SRC1 AD1 domain. Deletion mutants of E1A and Ets-2 lacking the conserved motif were unable to bind the CBP SID. Moreover, a peptide corresponding to this sequence competed the binding of full-length SRC1, Ets-2, and E1A proteins to the CBP SID. Thus, a leucine-rich amphipathic alpha-helix mediates mutually exclusive interactions of functionally diverse nuclear proteins with CBP.

Adenovirus E1A Proteins↗

PubMed2003

An extended LXXLL motif sequence determines the nuclear receptor binding specificity of TRAP220.

The interaction of coactivators with the ligand-binding domain of nuclear receptors (NRs) is mediated by amphipathic alpha-helices containing the signature motif LXXLL. TRAP220 contains two LXXLL motifs (LXM1 and LXM2) that are required for its interaction with NRs. Here we show that the nuclear receptor interaction domain (NID) of TRAP220 interacts weakly with Class I NRs. In contrast, SRC1 NID binds strongly to both Class I and Class II NRs. Interaction assays using nine amino acid LXXLL core motifs derived from SRC1 and TRAP220 revealed no discriminatory NR binding preferences. However, an extended LXM1 sequence containing amino acids -4 to +9, (where the first conserved leucine is +1) showed selective binding to thyroid hormone receptor and reduced binding to estrogen receptor. Replacement of either TRAP220 LXXLL motif with the corresponding 13 amino acids of SRC1 LXM2 strongly enhanced the interaction of the TRAP220 NID with the estrogen receptor. Mutational analysis revealed combinatorial effects of the LXM1 core and flanking sequences in the determination of the NR binding specificity of the TRAP220 NID. In contrast, a mutation that increased the spacing between TRAP220 LXM1 and LXM2 had little effect on the binding properties of this domain. Thus, a 13-amino acid sequence comprising an extended LXXLL motif acts as the key determinant of the NR binding specificity of TRAP220. Finally, we show that the NR binding specificity of full-length TRAP220 can be altered by swapping extended LXM sequences.

Amino Acid Motifs↗

PubMed2001

Functional interaction of STAT3 transcription factor with the coactivator NcoA/SRC1a.

Signal transducer and activator of transcription 3 (STAT3) transcription factors are cytoplasmic proteins that induce gene activation in response to cytokine receptor stimulation. Following tyrosine phosphorylation, STAT3 proteins dimerize, translocate to the nucleus, and activate specific target genes. This transcriptional activation by STAT3 proteins has been shown to require the recruitment of coactivators such as CREB-binding protein (CBP)/p300. In the present study, we show that steroid receptor coactivator 1, NcoA/SRC1a, originally identified as a nuclear receptor coactivator, also functions as a coactivator of STAT3 proteins. In coimmunoprecipitations, NcoA/SRC1a was found to associate with STAT3 following IL-6 stimulation of HepG2 hepatoma cells. Pull-down experiments indicated that the N-terminal part of NcoA/SRC1a associates with the activation domain of STAT3. Overexpression of NcoA/SRC1a or its SRC1e isoform enhanced transcriptional activation by STAT3 proteins in transient transfection experiments. This ability of NcoA/SRC1a to enhance STAT3 activity is dependent upon the presence of the CBP-interacting domain, activation domain 1. Using chromatin immunoprecipitation assays, we found that STAT3, NcoA/SRC1a, and CBP/p300 are simultaneously recruited to the p21(waf1) promoter following interleukin-6 stimulation. Taken together, these data suggest that CBP/p300 and NcoA/SRC1a may function in a common pathway to regulate STAT3 transcriptional activity.

Base Sequence↗