Biomedical subjects

Sachiko Matsuda

Publications and source records attributed to Sachiko Matsuda.

5 recordsLinked to original sources

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↗

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↗