The Polymorphic N Terminus in Human Vitamin D Receptor Isoforms Influences Transcriptional Activity by Modulating Interaction with Transcription Factor IIB

Jurutka, Peter W.; Remus, L. S.; Whitfield, G. Kerr; Thompson, Paul D.; Hsieh, Jui Cheng; Zitzer, Heike; Tavakkoli, P.; Galligan, Michael A.; Dang, Hope; Haussler, Carol A.; Haussler, Mark R.

doi:10.1210/mend.14.3.0435

Cited by 287 publications

(63 citation statements)

References 62 publications

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“…The reinstatement of interactions upon ligand treatment may result from a conformational change that brings additional interacting regions into play. This proposal is consistent with a requirement for hVDR helix H1 residues 116 -165 for SKIP/ NCoA-62 interaction (7), and for sites in the DNA binding and ligand binding domains of VDR for TFIIB and RXR interactions (22)(23)(24)(25)(26).…”

Section: Vdr Helix H10 Mutations Inhibit Transactivation Function-effsupporting

confidence: 85%

Interactions of SKIP/NCoA-62, TFIIB, and Retinoid X Receptor with Vitamin D Receptor Helix H10 Residues

Barry¹,

Leong²,

Church³

et al. 2003

Journal of Biological Chemistry

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The vitamin D receptor (VDR) is a ligand-dependent transcription factor that heterodimerizes with retinoid X receptor (RXR) and interacts with the basal transcription machinery and transcriptional cofactors to regulate target gene activity. The p160 coactivator GRIP1 and the distinct coregulator Ski-interacting protein (SKIP)/NCoA-62 synergistically enhance ligand-dependent VDR transcriptional activity. Both coregulators bind directly to and form a ternary complex with VDR, with GRIP1 contacting the activation function-2 (AF-2) domain and SKIP/NCoA-62 interacting through an AF-2 independent interface. It was previously reported that SKIP/NCoA-62 interaction with VDR was independent of the heterodimerization interface (specifically, helices H10/H11). In contrast, the present study defines specific residues within a conserved and surface-exposed region of VDR helix H10 that are required for interaction with SKIP/NCoA-62 and for full ligand-dependent transactivation activity. SKIP/NCoA-62, the basal transcription factor TFIIB, and RXR all interacted with VDR helix H10 mutants at reduced levels compared with wild type in the absence of ligand and exhibited different degrees of increased interaction upon ligand addition. Thus, SKIP/ NCoA-62 interacts with VDR at a highly conserved region not previously associated with coregulator binding to regulate transactivation by a molecular mechanism distinct from that of p160 coactivators. The vitamin D receptor (VDR)1 is a ligand-dependent transcription factor important in the regulation of calcium homeostasis, development, cell growth, and differentiation. VDR belongs to the nuclear receptor superfamily, members of which share a common modular structure including a highly conserved DNA binding domain (DBD) and a conserved ligand binding domain (LBD). The LBD has a predominantly ␣-helical structure with an activation function-2 (AF-2) domain in the COOH-terminal helix (H12). The LBD is the main site of VDR interaction with its heterodimer partner retinoid X receptor (RXR) and basal transcription factors, and the AF-2 domain in combination with the hydrophobic cleft forms an interaction surface for transcriptional corepressors and coactivators (1, 2). In the absence of its ligand 1,25-dihydroxyvitamin D 3

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Section: Vdr Helix H10 Mutations Inhibit Transactivation Function-effsupporting

confidence: 85%

Interactions of SKIP/NCoA-62, TFIIB, and Retinoid X Receptor with Vitamin D Receptor Helix H10 Residues

Barry¹,

Leong²,

Church³

et al. 2003

Journal of Biological Chemistry

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“…Similarly, speci®c VDR and ER polymorphisms are linked to bone mineral density in postmenopausal women (Gennari et al, 1998;Deng et al, 1998) and to the regulation of infant growth (Suarez et al, 1998). Also, VDR polymorphisms are associated with increased risk for prostate cancer and the progression of breast cancer, possible as a result of altered transcriptional activity (Ingles et al, 1997;Lundin et al, 1999;Jurutka et al, 2000). In addition, most recently, BRCA1 was found to inhibit ERdependent transcriptional pathways, thereby suggesting a mechanism for BRCA1 to suppress proliferation of estrogen-dependent mammary epithelial cells (Fan et al, 1999).…”

Section: Discussionmentioning

confidence: 99%

The anti-proliferative effects of 1α,25(OH)2D3 on breast and prostate cancer cells are associated with induction of BRCA1 gene expression

et al. 2000

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The anti-proliferative action of the seco-steroid hormone 1a,25-dihydroxyvitamin D 3 [1a,25(OH) 2 D 3 ] extends to some, but not all breast and prostate cancer cell lines. By elucidating the molecular mechanisms mediating the sensitivity of these cells, we can identify critical target genes regulated directly or indirectly by 1a,25(OH) 2 D 3 and pathways potentially disrupted during transformation. In this study, we demonstrated the induction of expression of BRCA1 mRNA and protein as well as transcriptional activation from the BRCA1-promoter by 1a,25(OH) 2 D 3 in the sensitive breast cancer cell line MCF-7. This was not observed in the 1a,25(OH) 2 D 3 -resistant breast cancer cell line MDA-MB-436. The induction of BRCA1 mRNA was blocked by cyclohexamide. This indicated that transcriptional activation was mediated indirectly by the vitamin D receptor (VDR). Inhibition of VDR protein levels by stable transformation of the anti-sense VDR in MCF-7 reduced the sensitivity of MCF-7 to 1a,25(OH) 2 D 3 by 50-fold. In addition, the induction of BRCA1 protein and transcriptional activation of a BRCA1 promoter-luciferase reporter construct was abrogated in the stable transformant with the greatest reduction of VDR levels. Examination of other breast and prostate cancer cell lines revealed that sensitivity to the anti-proliferative eects of 1a,25(OH) 2 D 3 was strongly associated with an ability to modulate BRCA1 protein. Furthermore, the expression of the estrogen receptor in these cell lines strongly correlated with their sensitivity to 1a,25(OH) 2 D 3 and their ability to modulate BRCA1 expression. Taken together, our data support a model whereby the anti-proliferative eects of 1a,25(OH) 2 D 3 are mediated, in part, by the induction of BRCA1 gene expression via transcriptional activation by factors induced by the VDR and that this pathway is disrupted during the development of prostate and breast cancers.

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“…Hr was detected by Western analysis with either Hr-or Myc-specific antisera as described (30). VDR was detected with VDR-specific antibody 9A7␥ (47,49).…”

Section: Methodsmentioning

confidence: 99%

Physical and Functional Interaction between the Vitamin D Receptor and Hairless Corepressor, Two Proteins Required for Hair Cycling

Hsieh

Sisk

Jurutka

et al. 2003

Journal of Biological Chemistry

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207

201

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Both the vitamin D receptor (VDR) and hairless (hr) genes play a role in the mammalian hair cycle, as inactivating mutations in either result in total alopecia. VDR is a nuclear receptor that functions as a ligand-activated transcription factor, whereas the hairless gene product (Hr) acts as a corepressor of both the thyroid hormone receptor (TR) and the orphan nuclear receptor, ROR␣. In the present study, we show that VDR-mediated transactivation is strikingly inhibited by coexpression of rat Hr. The repressive effect of Hr is observed on both synthetic and naturally occurring VDR-responsive promoters and also when VDR-mediated transactivation is augmented by overexpression of its heterodimeric partner, retinoid X receptor. Utilizing in vitro pull down methods, we find that Hr binds directly to VDR but insignificantly to nuclear receptors that are not functionally repressed by Hr. Coimmunoprecipitation data demonstrate that Hr and VDR associate in a cellular milieu, suggesting in vivo interaction. The Hr contact site in human VDR is localized to the central portion of the ligand binding domain, a known corepressor docking region in other nuclear receptors separate from the activation function-2 domain. Coimmunoprecipitation and functional studies of Hr deletants reveal that VDR contacts a C-terminal region of Hr that includes motifs required for TR and ROR␣ binding. Finally, in situ hybridization analysis of hr and VDR mRNAs in mouse skin demonstrates colocalization in cells of the hair follicle, consistent with a hypothesized intracellular interaction between these proteins to repress VDR target gene expression, in vivo.Nuclear receptors comprise a family of ligand-activated transcription factors that coordinate physiological and developmental processes by regulating specific changes in gene expression (1, 2). The vitamin D receptor (VDR) 1 mediates signaling by 1,25-dihydroxyvitamin D 3 (1,25(OH) 2 D 3 ) and is a member of the thyroid hormone/retinoic acid receptor subfamily of nuclear receptors that heterodimerize with the retinoid X receptor (RXR) on direct repeat hormone-responsive elements in the promoters of regulated genes (3, 4). Binding of liganded VDR⅐RXR to a vitamin D-responsive element (VDRE) in target genes such as osteocalcin, osteopontin, and vitamin D 24-hydroxylase (CYP24) is accompanied by the recruitment of coactivator proteins (5). VDR coactivators such as steroid receptor coactivator-1 (6), NCoA-62 (7), and vitamin D receptor interacting protein 205 (8) stimulate transcriptional activation by facilitating chromatin remodeling and/or attraction of RNA polymerase II. Although some unliganded nuclear receptors (thyroid hormone and retinoic acid receptors) can mediate repression through association with corepressors such as nuclear receptor corepressor (N-CoR) (9) and silencing mediator for retinoic acid and thyroid hormone receptors (SMRT) (10), evidence suggests that VDR does not associate strongly with these corepressors (9 -12).Targeted gene deletion studies in mice (13, 14) and inactivat...

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The Polymorphic N Terminus in Human Vitamin D Receptor Isoforms Influences Transcriptional Activity by Modulating Interaction with Transcription Factor IIB

Cited by 287 publications

References 62 publications

Interactions of SKIP/NCoA-62, TFIIB, and Retinoid X Receptor with Vitamin D Receptor Helix H10 Residues

Interactions of SKIP/NCoA-62, TFIIB, and Retinoid X Receptor with Vitamin D Receptor Helix H10 Residues

The anti-proliferative effects of 1α,25(OH)2D3 on breast and prostate cancer cells are associated with induction of BRCA1 gene expression

Physical and Functional Interaction between the Vitamin D Receptor and Hairless Corepressor, Two Proteins Required for Hair Cycling

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