Characterization of FIII/YY1, a Xenopus laevis Conserved Zinc-Finger Protein Binding to the First Exon of L1 and L14 Ribosomal Protein Genes

Pisaneschi, Giuseppe; Ceccotti, Sabrina; Falchetti, Mario; Fiumicino, Silvia; Carnevali, Francesca; Beccari, E

doi:10.1006/bbrc.1994.2797

Cited by 38 publications

(29 citation statements)

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“…One possibility is that YY1 may establish a threshold which must be overcome by c-Myc in order to stimulate cell growth. This would be consistent with the notion that YY1 is ubiquitously and constitutively expressed at relatively high levels under most conditions studied (Hariharan et al, 1991;Hahn, 1992;Shrivastava and Calame, 1994;Pisaneschi et al, 1994;Austen et al, 1997). Such a mechanism could be operating during the G0 to G1 transition or upon induction of dierentiation when the levels of c-Myc are modulated and the ratio between c-Myc and YY1 is changed.…”

Section: Discussionsupporting

confidence: 86%

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YY1 can inhibit c-Myc function through a mechanism requiring DNA binding of YY1 but neither its transactivation domain nor direct interaction with c-Myc

et al. 1998

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The proto-oncoprotein c-Myc and the multifunctional transcriptional regulator YY1 have been shown previously to interact directly in a manner that excludes Max from the complex (Shrivastava et al., 1993). As binding to Max is necessary for all known c-Myc activities we have analysed the in¯uence of YY1 on cMyc function. We demonstrate that YY1 is a potent inhibitor of c-Myc transforming activity. The region in YY1 required for inhibition corresponds to a functional DNA-binding domain and is distinct from the domains necessary for direct binding to c-Myc. Furthermore the transactivation domain of YY1 was not necessary suggesting that gene regulation by YY1, for example through DNA bending or displacement of regulators from DNA, could be the cause for the negative regulation of c-Myc. This model of indirect regulation of c-Myc by YY1 was supported by the ®nding that although YY1 did not bind to the c-Myc transactivation domain (TAD) in vitro it was able to inhibit transactivation by Gal4-MycTAD fusion proteins in transient transfections. As for the inhibition of transformation, an intact DNA-binding domain of YY1 was necessary and sucient for this eect. In addition YY1 did not alter c-Myc/Max DNA binding, further supporting an indirect mode of action. Our ®ndings point to a role of YY1 as a negative regulator of cell growth with a possible involvement in tumor suppression.

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Section: Discussionsupporting

confidence: 86%

“…YY1 is a Zn-®nger transcription factor which is ubiquitously expressed and well conserved in evolution (Hariharan et al, 1991;Hahn, 1992;Shrivastava and Calame, 1994;Pisaneschi et al, 1994;Austen et al, 1997). YY1 has been implicated in the regulation of a wide range of dierent promoters through various mechanisms.…”

Section: Introductionmentioning

confidence: 99%

YY1 can inhibit c-Myc function through a mechanism requiring DNA binding of YY1 but neither its transactivation domain nor direct interaction with c-Myc

et al. 1998

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“…These features are commonly observed in activation domains of other transcription factors (34). It is interesting that the Xenopus laevis YY1 protein lacks the consecutive histidine stretch but contains both amino acid segments that we determined to be involved in transcriptional activation (35). It will be interesting to determine whether the Xenopus YY1 homologue can function as a transcriptional activator similar to the human form.…”

Section: Discussionmentioning

confidence: 83%

Characterization of Functional Domains within the Multifunctional Transcription Factor, YY1

Bushmeyer

Park

Atchison

1995

Journal of Biological Chemistry

130

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YY1 is a multifunctional transcription factor capable of either activation or repression of transcription. Using a series of mutant proteins, we have characterized domains responsible for activation or repression. We found that the YY1 transcriptional activation domain lies near the amino terminus and requires amino acids 16 -29 and 80 -100 for maximal activity. The region between residues 16 and 29 has the potential to form an acidic amphipathic helix, whereas residues between 80 and 100 are rich in proline and glutamine. The YY1 repression domain lies near the carboxyl terminus and is embedded within the YY1 zinc finger region necessary for binding to DNA. Deletion of YY1 amino acids, which include zinc fingers 3 and 4, abolishes repression. However, site-directed mutagenesis, progressive deletion, and internal deletion mutant analyses indicate that the normal structures of zinc fingers 3 and 4 are not required for repression.YY1 (variously called NF-E1, ␦, or UCRBP; Refs. 1-4), is a multifunctional transcription factor that can either activate or repress transcription. Repression has been observed in the context of the immunoglobulin 3Ј enhancer, the Moloney murine leukemia virus long terminal repeat, the adeno-associated virus P5 promoter, the skeletal ␣-actin promoter, the ␤-casein promoter, ⑀-and ␥-globin genes, the serum amyloid A1 promoter, the human immunodeficiency virus promoter, and the human papilloma virus type 18 promoter (1, 4 -13; reviewed in ref. 14). In contrast YY1 can activate the c-Myc promoter, the ribosomal protein L30 and L32 promoters, and the intracisternal A-particle upstream promoter element (15-18). Interestingly, YY1 can either activate or repress some promoters depending upon either promoter architecture or intracellular milieu. For instance, YY1 typically represses the adeno-associated virus P5 promoter, but can be converted into a potent transcriptional activator in the presence of adenovirus E1A protein (1). YY1 can also either activate or repress the c-Fos promoter based on the orientation or the position of a YY1 binding site within the promoter (19). Finally, YY1 can either repress or activate the human papilloma virus type 18 promoter depending upon the presence of an adjacent DNA sequence that binds to a distinct nuclear factor (6).The mechanism of YY1 function is presently unclear. In some cases, YY1 binding appears to preclude the binding of activator proteins. For instance, YY1 binding competes with the binding of NF-B to an overlapping -sequence in the serum amyloid A1 promoter (13). Similarly, YY1 competes with serum response factor binding in the ␣-actin promoter, GATA-1 binding in the ⑀-globin promoter, and with binding of a lactation-associated factor in the ␤-casein promoter (7, 9 -11). YY1 function may also relate to its ability to bend DNA (19). In other cases, the function of YY1 appears to be controlled by interaction with other proteins such as adenoviral E1A, c-Myc, or switch binding protein (1,6,20). Interestingly, loss of YY1 binding sites in the human pap...

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“…1). It is expressed in a wide variety of different cell types and shows a high degree of sequence similarity among divergent organisms (2)(3)(4)(5). The mammalian YY1 protein (414 aa) contains four C-terminal zinc fingers, an N-terminal bipartite transcriptional activation domain, and a number of domains that function to mediate interactions with other proteins (6).…”

Section: Yin Yang 1 (Yy1mentioning

confidence: 99%

“…The mammalian YY1 protein (414 aa) contains four C-terminal zinc fingers, an N-terminal bipartite transcriptional activation domain, and a number of domains that function to mediate interactions with other proteins (6). The Xenopus YY1 cDNA is highly conserved, but the predicted protein is somewhat smaller at 373 aa (4).…”

Section: Yin Yang 1 (Yy1mentioning

confidence: 99%

Expression, Activity, and Subcellular Localization of the Yin Yang 1 Transcription Factor in Xenopus Oocytes and Embryos

Ficzycz

Eskiw

Meyer

et al. 2001

Journal of Biological Chemistry

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Yin Yang 1 (YY1) is a multifunctional transcription factor that acts as an activator, repressor, or initiator of transcription of numerous cellular and viral genes. Previous studies in tissue culture model systems suggest YY1 plays a role in development and differentiation in multiple cell types, but the biological role of YY1 in vertebrate oocytes and embryos is not well understood. Here we analyzed expression, activity, and subcellular localization profiles of YY1 during Xenopus laevis development. Abundant levels of YY1 mRNA and protein were detected in early stage oocytes and in all subsequent stages of oocyte and embryonic development through to swimming larval stages. The DNA binding activity of YY1 was detected only in early oocytes (stages I and II) and in embryos after the midblastula transition (MBT), which suggested that its potential to modulate gene expression may be specifically repressed in the intervening period of development. Experiments to determine transcriptional activity showed that addition of YY1 recognition sites upstream of the thymidine kinase promoter had no stimulatory or repressive effect on basal transcription in oocytes and post-MBT embryos. Although the apparent transcriptional inactivity of YY1 in oocytes could be explained by the absence of DNA binding activity at this stage of development, the lack of transcriptional activity in post-MBT embryos was not expected given the ability of YY1 to bind its recognition elements. Subsequent Western blot and immunocytochemical analyses showed that YY1 is localized in the cytoplasm in oocytes and in cells of developing embryos well past the MBT. These findings suggest a novel mode of YY1 regulation during early development in which the potential transcriptional function of the maternally expressed factor is repressed by cytoplasmic localization.

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Characterization of FIII/YY1, a Xenopus laevis Conserved Zinc-Finger Protein Binding to the First Exon of L1 and L14 Ribosomal Protein Genes

Cited by 38 publications

References 0 publications

YY1 can inhibit c-Myc function through a mechanism requiring DNA binding of YY1 but neither its transactivation domain nor direct interaction with c-Myc

YY1 can inhibit c-Myc function through a mechanism requiring DNA binding of YY1 but neither its transactivation domain nor direct interaction with c-Myc

Characterization of Functional Domains within the Multifunctional Transcription Factor, YY1

Expression, Activity, and Subcellular Localization of the Yin Yang 1 Transcription Factor in Xenopus Oocytes and Embryos

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