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  • 1
    Electronic Resource
    Electronic Resource
    The yeast SIN3 gene product negatively regulates the activity of the human progesterone receptor and positively regulates the activities of GAL4 and the HAP1 activator (1994)
    Springer
    Molecular genetics and genomics 245 (1994), S. 724-733 
    Details
    ISSN: 1617-4623
    Keywords: SIN3 protein ; SIN3 protein ; GAL4 ; HAP1 ; Gene regulation ; Transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The activation of gene transcription in eukaryotic organisms is regulated by sequence-specific DNA-binding proteins as well as by non-DNA-binding proteins. In this report we describe the modulatory functions of a non-DNA-binding protein, SIN3 (also known as SDI1, UME4, RPD1, and GAM2) on the transactivation properties of the human progesterone receptor (hPR), GAL4, and the HAPl activator in yeast. Our data suggest that SIN3 is a dual function protein. It negatively regulates the transcriptional activities of hPR-A and hPR-B by affecting the N-terminal activation domain (AFI). SIN3 positively regulates the transcriptional activities of GAL4 and the HAP1 activator. However, it has no effect on the transcriptional activities of the human glucocorticoid receptor (hGR) and GCN4. The SIN3 protein contains four copies of a paired amphipathic helix (PAH) motif. Deletion analysis of the SIN3 PAH motifs shows that the PAH3 motif is essential for SIN3-mediated regulation of hPR, GAL4, and the HAPI activator. In constrast, the PAH 1, PAH2, and PAH4 motifs are not required for SIN3-mediated regulation of these activators. Additionally, we examined the mechanism(s) by which the SIN3 protein modulate the activities of various activators. We are unable to demonstrate the direct interaction of SIN3 protein with these activators using the yeast two-hybrid system or co-immunoprecipitation. These data suggest that SIN3 regulates the transactivation functions of hPR, GAL4, and the HAP1 activator by an indirect mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297279
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The ER-positive / PgR-negative breast cancer phenotype is not associated with mutations within the DNA binding domain (1993)
    Springer
    Breast cancer research and treatment 26 (1993), S. 191-202 
    Details
    ISSN: 1573-7217
    Keywords: estrogen receptor ; breast cancer ; DNA binding domain ; gel-retardation analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have used in vitro DNA binding assays as a measure of estrogen receptor (ER) function in human breast tumors. We found that the majority of ER+ (25 ER+/progesterone receptor [PgR]+, and 25 ER+/PgR−) tumors we examined were capable of binding consensus estrogen response element (ERE) oligonucleotides in this assay system. We found significant proteolytic activity in many of the tumors such that protease inhibitors were found to be essential during the preparation of tumor extracts. We next applied direct sequence analysis of the ER DNA binding domain of several of these tumors, and determined that the ER+/PgR− breast tumors did not contain mutations within the DNA binding domain which might explain their apparent discordant receptor phenotype. We did identify an alternatively spliced ER variant missing exon 3 of the DNA binding domain. This variant was unable to function as a transcriptional inducer of an estrogen-responsive reporter in a yeast assay system. Furthermore, the exon 3 ER deletion variant was expressed at equivalent levels in all of the ER+ breast tumors, so that it does not appear to be involved in the evolution of the ER+/PgR− breast cancer phenotype.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00689692
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  • 3
    Electronic Resource
    Electronic Resource
    The dual function steroid receptor coactivator/ubiquitin protein-ligase integrator E6-AP is overexpressed in mouse mammary tumorigenesis (2000)
    Springer
    Breast cancer research and treatment 62 (2000), S. 185-195 
    Details
    ISSN: 1573-7217
    Keywords: steroid receptor coactivators ; mammary gland ; mammary tumorigenesis ; E6-AP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Steroid receptor coactivator and corepressor proteins are important mediators of steroid receptor function. Changes in the expression or activity of these limiting cofactors can contribute to the etiology of steroidal cancers. Using a mouse mammary model of multistage tumorigenesis we have examined whether the expression of select steroid receptor coactivators is altered. The 10 kb transcript of the novel dual function steroid receptor coactivator/ubiquitin protein-ligase integrator E6-AP is overexpressed 2.5–4.5 fold in the mammary tumors but not in the precursor steps of tumorigenesis; that is, immortal ductal and alveolar hyperplastic outgrowths. The over expression is striking because the 10 kb transcript is expressed to variable levels in other wild type tissues like the uterus, ovary, testis, kidney and brain but is undetectable in normal virgin mammary gland and the prostate gland. The E6-AP overexpression in the mammary tumors is substantiated by western blot analysis and immunohistochemical analysis. Absence of ER and PR in these tumors in the presence of high levels of E6-AP could contribute to steroid receptor-independent function and tumorigenesis. There is no obvious correlation between p53 (a well-characterized substrate of E6-AP) status (wt vs. mutant) and levels of E6-AP in the mouse mammary tumors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006410111706
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    Paper (German National Licenses)
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