An auxiliary peptide required for the function of two activation domains in upstream stimulatory factor 2 (USF2) transcription factor

Gourdon, Laurence; Lefrançois‐Martinez, Anne‐Marie; Viollet, Benoı̂t; Martinez, Antoine; Kahn, Axel; Raymondjean, Michel

doi:10.1046/j.1365-4624.1997.00014.x

Cited by 3 publications

(3 citation statements)

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“…N-terminal trans-activation domains identified in human and mouse USFs (25)(26)(27). The bovine USF2 region spanning from Met 1 to Pro 149 proved to contain a key element(s) involved in regulating basal PGHS-2 promoter activity, whereas bovine USF1 region from Met 1 to Gly 129 and USF2 region from Met 1 to Pro 220 appeared central for forskolin-inducible promoter activation.…”

Section: Discussionmentioning

confidence: 98%

“…Another very well conserved domain between USF1 and USF2 is a small domain termed USF-specific region (USR) that is located immediately upstream of the basic region and involved in nuclear localization and context-dependent transcriptional activation (25). In contrast, the N-terminal regions of USF1 and USF2 are much more divergent, but were shown to contain additional transactivation domains (25)(26)(27). USF proteins are ubiquitous transcription factors that play a key role during embryonic development (28) and that are known to activate or repress the expression of various genes (29 -35).…”

mentioning

confidence: 99%

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Molecular Characterization and Role of Bovine Upstream Stimulatory Factor 1 and 2 in the Regulation of the Prostaglandin G/H Synthase-2 Promoter in Granulosa Cells

Sayasith

Bouchard

Sawadogo

et al. 2004

Journal of Biological Chemistry

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The transcriptional activation of the prostaglandin G/H synthase-2 (PGHS-2) gene in granulosa cells is required for ovulation. To directly study the ability of upstream stimulatory factor 1 (USF1) and USF2 to trans-activate the bovine PGHS-2 promoter in granulosa cells, USF1 or USF2 expression vectors were cotransfected with the PGHS-2/luciferase (LUC) chimeric construct, ؊149/؊2PGHS-2.LUC. Results revealed that overexpression of USF1 or USF2 caused a marked and significant increase in basal and forskolin-inducible promoter activities (p < 0.05), and these effects were dependent on the presence of a consensus E-box ciselement within the promoter fragment. Co-transfections with different N-and C-terminal truncated USF mutants led to significant reductions in promoter activation, as compared with full-length constructs (p < 0.05), thus allowing identification of putative bovine USF functional domains. Overexpression of a USF2 truncated mutant lacking the first 220 residues (U2⌬1-220) acted as a dominant negative mutant and blocked endogenous and USF-stimulated PGHS-2 promoter activation. Interestingly, transfections with U2⌬1-220 blocked the forskolin-dependent induction of PGHS-2 mRNA in granulosa cells, whereas transfections with full-length USF2 increased PGHS-2 transcript levels. Immunoblot analyses confirmed overexpression of full-length and truncated USF proteins, and electrophoretic mobility shift assays (EMSAs) and supershift EMSAs established that the observed effects were dependent on specific interactions between USF proteins and the consensus E-box cis-element. Stimulation of cells with forskolin increased, whereas treatment of extracts with phosphatase decreased USF binding activities to the E-box. Thus, this study presents for the first time direct evidence for a role of USF proteins in the regulation of the PGHS-2 promoter in preovulatory granulosa cells.Prostaglandins are key mediators of inflammation, and the process of ovulation shares numerous signs of an acute inflammatory reaction, including hyperemia, edema, emigration of leukocytes, and induction of proteolytic and collagenolytic activities (1, 2). Likewise, there is a marked increase in intrafollicular levels of prostaglandin E 2 (PGE 2 ) 1 and PGF 2␣ just prior to ovulation, and inhibitors of prostaglandin synthesis were shown to block ovulation in several species (3-6). Prostaglandin G/H synthase (PGHS, also known as COX) is the first rate-limiting enzyme in the biosynthesis of all prostaglandins from arachidonic acid, and two PGHS isoforms derived from distinct genes located on separate chromosomes have been characterized, and are referred to as PGHS-1 and PGHS-2 (7-9). A third PGHS isoform produced as an alternate splice variant of the PGHS-1 gene was recently identified as PGHS-3 (10). Several studies have established that the increase in follicular prostaglandin synthesis prior to ovulation is caused by a selective, gonadotropin-dependent induction of . Within the preovulatory follicle, the enzyme was shown to be induced exclusively i...

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Section: Discussionmentioning

confidence: 98%

mentioning

confidence: 99%

Molecular Characterization and Role of Bovine Upstream Stimulatory Factor 1 and 2 in the Regulation of the Prostaglandin G/H Synthase-2 Promoter in Granulosa Cells

Sayasith

Bouchard

Sawadogo

et al. 2004

Journal of Biological Chemistry

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“…Like Sp1, the USF1, and USF2 proteins are ubiquitously expressed transcription factors (Sirito et al, 1994;Gourdon et al, 1997;Ismail et al, 1999). They can function as either activators or repressors of target genes.…”

Section: Discussionmentioning

confidence: 99%

Cooperative E‐box regulation of human GLI1 by TWIST and USF

Villavicencio

Yoon

Frank

et al. 2002

Genesis

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Sonic hedgehog signaling plays a critical role in vertebrate patterning, and signaling defects are associated with severe birth defects and cancer in man. GLI1 encodes a critical transcription activator in this pathway. GLI1 is expressed in human basal cell carcinomas and sarcomas. Despite the significance of the GLI1 gene in human disease, few immediate upstream regulators of GLI1 expression are known. We previously demonstrated that a 5' region, including 5' flanking sequence, an untranslated exon, and 425 bp of the first intron, regulates the human GLI1 gene. Here we show that inactivating mutations in E-box, GC box, AP-2, GATA, GSG, PuF, and Zeste sites identified three critical regulatory elements, including a GC box that binds Sp1 and two intronic E-boxes that bind USF proteins or Twist. Expression of Twist but not a frame shift mutation of Twist activates the wild-type human GLI1 regulatory sequences but not with inactivating mutations of the E-boxes. Twist activates GLI1 reporter expression through E-box +482 but requires binding of USF proteins to E-box +157. Twist mutations cause human birth defects and Twist is overexpressed in many rhabdomyosarcomas, suggesting that one of Twist's primary roles is the regulation of GLI1.

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