A negative regulatory element in the promoter region of the rat <i>α</i>2A-adrenergic receptor gene overlaps an SP1 consensus binding site

Handy, Diane E.; Zanella, Maria Teresa; Kanemaru, Ai; Tavares, Agostinho; Flordellis, Christos S.; Gavras, Haralambos

doi:10.1042/bj3110541

Cited by 20 publications

(12 citation statements)

References 29 publications

(27 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Reporter assays in C6 cells have uncovered the existence of both negative (¹978 to ¹609) and positive (¹569 to ¹247) regulatory domains on the ␣ 2D/A -AR promoter. Previous studies have identified negative regulatory domains on the human promoters (Handy & Gavras 1992; using HT29, a human adenocarcinoma cell line) and rat promoters (Yang et al 1997;using vascular smooth muscle cells;Handy et al 1995 in RINm5F, a rat insulinoma cell line), that are localized to regions different from that reported in the present study. The deletion of these domains results in 2-3-fold higher activity (Handy et al 1995;Yang et al 1997).…”

Section: Basal Transcriptional Features Of the ␣ 2d/a -Ar Genecontrasting

confidence: 42%

See 1 more Smart Citation

α_2D/A‐adrenergic receptor gene induction in the retina by phorbol ester: involvement of an AP‐2 element

Venkataraman¹,

Duda²,

Sharma³

1999

Genes to Cells

View full text Add to dashboard Cite

show abstract

Section: Basal Transcriptional Features Of the ␣ 2d/a -Ar Genecontrasting

confidence: 42%

“…3,B-D). This magnitude of suppression is a remarkable feature of the negative regulatory domain of the bovine promoter, in contrast to those of the human (Handy & Gavras 1992) and rat (Handy et al 1995;Yang et al 1997) genes. (Figs 1, 2 and 4).…”

Section: Basal Transcriptional Features Of the ␣ 2d/a -Ar Genementioning

confidence: 94%

α_2D/A‐adrenergic receptor gene induction in the retina by phorbol ester: involvement of an AP‐2 element

Venkataraman¹,

Duda²,

Sharma³

1999

Genes to Cells

View full text Add to dashboard Cite

show abstract

“…One possible explanation for Cbox-mediated repression is that other members of the Sp family [4,10] or Sp1-related zinc finger proteins [13][14][15]19] are involved by competitive binding and Sp1 replacement [12,13,35]. For example, Sp3 is an Sp family member that acts as a repressor [4] using a portable repressor domain [7,36], and binds to the same element as Sp1 [1,2].…”

Section: Discussionmentioning

confidence: 99%

Sp1 acts as a repressor of the human adenine nucleotide translocase-2 (ANT2) promoter

Zaid¹,

Hodný²,

Li³

et al. 2001

Eur J Biochem

View full text Add to dashboard Cite

The human adenine nucleotide translocator-2 promoter is activated by adjacent Sp1 activation elements centered at nucleotides 279 and 268 (Abox and Bbox, respectively), and is repressed by Sp1 bound to a GC element (Cbox) that lies adjacent to transcription start. Here, we address the mechanism of this unique Sp1-mediated repression using transfected Drosophila SL2 and mammalian cell lines. We show that repression is not due to steric interference with assembly of the transcription machinery, as Sp1 bound to the Cbox can, under certain conditions, activate the promoter. Furthermore, ectopic expression of Sp1 deletion mutants in SL2 cells demonstrates that both the Sp1-mediated repression and activation require the D transactivation domain of Sp1 bound to the Cbox. In addition, repression of ABbox-mediated activation is eliminated by separating the Abox and Bbox. Thus, for Cbox-bound Sp1 to repress, Sp1 must be precisely positioned at the region of the ABboxes. Together, these data suggest that the D transactivation domain mediates interactions by Sp1 complexes on separate GC elements that results in repression of the activating Sp1 species.Keywords: mitochondrial promoter; transcription repression; adenine nucleotide translocator; Sp1.Sp1 is the prototype member of a family of four [1,2] [6,7] that accounts at least partially for the observations that, unlike Sp1 and Sp4, Sp3 functions as a repressor [4,8].Although Sp1 bears no repression domain or motifs, Sp1 protein or Sp1 binding elements are often involved in the negative regulation of specific genes. Recently, it was shown that Sp1 can direct repression of specific promoters by targeting corepressor (histone deactylase) to chromatin [9]. However, in most cases such negative regulation can be accounted for by binding-site competition and Sp1 replacement by Sp3 [4,10,11] or other Sp-like inhibitor proteins [12][13][14][15]. Inhibitory complex formation has also been reported between Sp1 and other transfactors [16 -19]. These presumably mask the Sp1 activation domain sites. However, the results of several experiments suggest that negative regulation can also be exerted between separate GC elements that bind Sp proteins [20 -25]. The mechanism of such repression is not yet clear.In our studies on the promoter region of the human adenine nucleotide translocator-2 (ANT2) gene [25,26], we identified a unique Sp1-dependent repressor site (the Cbox) located at the transcription start site that appears to prevent activation by Sp1 bound to the major activating elements (the Abox and Bbox). Because of the location of the Cbox, we proposed that Sp1 might act sterically to prevent assembly of the preinitiation complex or recruitment of the polymerase complex to initiation start. In the present study, we provide evidence that this is not the case. Rather, our data support a mechanism of repression in which Sp1 bound to the repressor element near the transcription start site is able to attenuate activation by Sp1 bound to upstream activation elements. E X P E R I M E N T ...

show abstract

“…Several recent reports have suggested a similar negative regulatory role for bound Sp1 (53)(54)(55). How this occurs is unclear, but one mechanism may involve its interactions with other nuclear elements.…”

Section: Ectopic Reinsertion Of the ϫ150 To ϫ101 Bp Region Immediatelmentioning

confidence: 96%

An Sp1-binding Silencer Element Is a Critical Negative Regulator of the Megakaryocyte-specific αIIb Gene

Shou¹,

Baron²,

Poncz³

1998

Journal of Biological Chemistry

View full text Add to dashboard Cite

The Sp1 family of transcription factors are often involved in the regulated expression of TATA-less genes, frequently enhancing gene transcription. In this paper, we demonstrate that an Sp1-binding element inhibits the expression of the megakaryocyte-specific ␣ IIb gene in all cell lines tested and that this inhibition is actively overcome only in megakaryocyte-like cell lines. We had noted previously in primary megakaryocytes that a 50-base pair (bp) deletion from ؊150 to ؊101 bp in the rat ␣ IIb promoter region resulted in increased expression. We now show that deletion of this region markedly increased expression in both megakaryocytic and nonmegakaryocytic cell lines, eliminating the tissue specificity of the ␣ IIb promoter. Electrophoretic mobility shift assays (EMSA) defined a single complex, which bound to a ؊145 to ؊125 bp subregion. Point mutations within this region, localized the critical point of binding around bases ؊136/؊135, and expression studies showed that introduction of the ؊136/؊135 mutation into the rat ␣ IIb promoter had a comparable result to that seen with the 50-bp deletion. EMSA studies with the homologous human ␣ IIb promoter region gave an identical migrating band. Southwestern blots of HeLa nuclear proteins with both the rat ؊145 to ؊125 DNA and its human homologue bound to a single ϳ110-kDa protein, the known molecular weight of Sp1. Confirmation that this region of the ␣ IIb gene promoter bound Sp1 was accomplished using EMSA studies with an Sp1 consensus probe, antiSp1 and -Sp3 antibodies, and recombinant Sp1 protein.Further support for the role of Sp1 in the silencing of the ␣ IIb promoter was obtained using a Gal4 binding site substitution for the silencer region of ␣ IIb and co-expression of near full-length Sp1/Gal4 fusion protein expression vectors. Ectopic reinsertion of the ؊150 to ؊101 bp region, back into the ؊150 to ؊101 bp deleted promoter, enhanced rather than decreased expression, suggesting that Sp1's inhibitory role at ؊136/؊135 depends on its local interactions. In summary, we believe that we have identified a cross-species, non-consensus Sp1-binding site that binds Sp1 and that acts as a silencer of ␣ IIb expression in many cell lines. A model is presented as to how this Sp1-binding silencer element contributes to the megakaryocyte-specific expression of ␣ IIb gene.Platelets have a central role in thrombus formation. These anuclear cytoplasmic fragments are derived from bone marrow megakaryocytes and are highly differentiated (1). One of the specialized features found on the platelet membrane is the ␣ IIb /␤ 3 (also known as glycoprotein IIb/IIIa or CD41b) integrin receptor (2). This receptor is densely packed on the platelet surface. Following platelet activation, this receptor binds fibrinogen and plays an important role in platelet aggregation (2). Normally, ␣ IIb /␤ 3 is only found on developing megakaryocytes and circulating platelets. This is due to the tissue-specific nature of the ␣ IIb subunit. While ␤ 3 is expressed in several different cell types (3), ...

show abstract

A negative regulatory element in the promoter region of the rat α2A-adrenergic receptor gene overlaps an SP1 consensus binding site

Cited by 20 publications

References 29 publications

α_2D/A‐adrenergic receptor gene induction in the retina by phorbol ester: involvement of an AP‐2 element

α_2D/A‐adrenergic receptor gene induction in the retina by phorbol ester: involvement of an AP‐2 element

Sp1 acts as a repressor of the human adenine nucleotide translocase-2 (ANT2) promoter

An Sp1-binding Silencer Element Is a Critical Negative Regulator of the Megakaryocyte-specific αIIb Gene

Contact Info

Product

Resources

About

A negative regulatory element in the promoter region of the rat α2A-adrenergic receptor gene overlaps an SP1 consensus binding site

Cited by 20 publications

References 29 publications

α2D/A‐adrenergic receptor gene induction in the retina by phorbol ester: involvement of an AP‐2 element

α2D/A‐adrenergic receptor gene induction in the retina by phorbol ester: involvement of an AP‐2 element

Sp1 acts as a repressor of the human adenine nucleotide translocase-2 (ANT2) promoter

An Sp1-binding Silencer Element Is a Critical Negative Regulator of the Megakaryocyte-specific αIIb Gene

Contact Info

Product

Resources

About

α_2D/A‐adrenergic receptor gene induction in the retina by phorbol ester: involvement of an AP‐2 element

α_2D/A‐adrenergic receptor gene induction in the retina by phorbol ester: involvement of an AP‐2 element