Phosphorylation is involved in transcriptional activation by the 1,25-dihydroxyvitamin D3 receptor

Darwish, Hisham M.; Burmester, James K.; Moss, Valerie; DeLuca, Hector F.

doi:10.1016/0005-2760(93)90213-s

Cited by 48 publications

(14 citation statements)

References 35 publications

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“…The effects ofthe phosphatase inhibitor okadaic acid include both an accumulation of phosphorylated VDR and transactivation. The addition of 1,25-(OH)2D3 to the okadaic acid-treated cells results in twice the transactivation effect detected with okadaic acid treatment alone (24). This evidence lends support for the formation of a VDR-NAF-DRE intermediate in the absence of ligand, since the presence of these compounds mimic the 1,25-(OH)2D3-induced phosphorylation effect.…”

Section: Methodsmentioning

confidence: 54%

See 1 more Smart Citation

Vitamin D-influenced gene expression via a ligand-independent, receptor-DNA complex intermediate.

Ross

Darwish²,

Moss³

et al. 1993

Proc. Natl. Acad. Sci. U.S.A.

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Section: Methodsmentioning

confidence: 54%

“…5, dashed arrow). The effect of 8-bromo-cAMP, an activator of protein kinase A, includes the transactivation ofgene expression in the absence of exogenous 1,25-(OH)2D3 (24). Upon the addition of 1,25-(OH)2D3 to cells treated with 8-bromo-cAMP there is an additive effect in enhanced gene expression mediated by VDR.…”

Section: Methodsmentioning

confidence: 99%

Vitamin D-influenced gene expression via a ligand-independent, receptor-DNA complex intermediate.

Ross

Darwish²,

Moss³

et al. 1993

Proc. Natl. Acad. Sci. U.S.A.

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“…The requirements for TR/PKA synergy also differ from those of other nuclear receptors in that it occurs only in the liganded state, whereas other studies found that PKA activates the unliganded progesterone, vitamin D, and estrogen receptors and RAR, mimicking the transcriptional effects of their cognate ligands (18,19,51). Our TRE-TKCAT reporter plasmids have a deletion of an AP-1-like regulatory site found in the backbone of the pUC plasmid (33); this site in TRE-TKCAT constructs conveyed forskolin activation to unliganded TRs (data not shown).…”

Section: Discussionmentioning

confidence: 94%

Thyroid Hormone Activation of Transcription Is Potentiated by Activators of cAMP-dependent Protein Kinase

Leitman

Costa

Graf

et al. 1996

Journal of Biological Chemistry

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We characterized the cross-talk between activators of protein kinase A (PKA) and thyroid hormone (T 3 ) in T 3 receptor (TR)-mediated transcription. U937 cells were cotransfected with a plasmid expressing the TR and a reporter plasmid containing a T 3 response element (TRE) oriented either as a direct repeat or as a palindrome upstream of the thymidine kinase promoter linked to the chloramphenicol acetyltransferase gene. T 3 activated transcription by 10-fold. T 3 response was potentiated 2.5-3-fold by activators of PKA, but an activator of protein kinase C or of guanylate kinase was ineffective. In the absence of T 3 , activators of PKA had no effect on transcription. TR heterodimerization with the retinoid X receptor may facilitate T 3 /PKA cross-talk because coexpression of the retinoid X receptor potentiated cross-talk. Synergy was not observed in JEG-3, F9, CV-1, HeLa, L929, and HTC cells, indicating that it may require cell-specific factors. Synergy required the DNAand ligand-binding domains, but not the amino-terminal domain, indicating that T 3 -and TRE-induced conformational changes on the TR are essential for cross-talk. PKA phosphorylated the TR in vitro, suggesting that, like other nuclear receptors, the TR is a target for PKA. These results imply that PKA cross-talks with T 3 at the level of the TRE-bound TR, enhancing its transcriptional activity in a cell-specific manner.Thyroid hormones promote diverse actions on development and differentiation of many tissues in vertebrates by binding to thyroid hormone (T 3 ) 1 receptors (TRs) (1). TRs are one of the ligand-regulated transcription factors in the nuclear receptor superfamily that includes receptors for steroids, vitamins, peroxisomal proliferators, and "orphan" receptors for which no ligands have been identified (2-6). Two genes code for TRs, but differential RNA splicing or promoter usage generates four isoforms: TR␣1, TR␣2, TR␤1, and TR␤2 (3, 5, 6). Like other nuclear receptor superfamily members, TRs contain three major modular domains (2-6). The amino-terminal domain is presumably involved in transcriptional activation. The DNAbinding domain (DBD) directs receptor binding to specific thyroid hormone response elements (TREs), where TRs bind as monomers, homodimers, or heterodimers commonly with retinoid X receptors (RXRs) (7,8). The ligand-binding domain (LBD) binds T 3 and participates in other functions such as dimerization and transcriptional activation or repression (2-6).The actions of nuclear receptors are known to be influenced by second messenger signaling systems such as those that affect the activity of adenylate cyclase/3Ј,5Ј-cAMP-dependent protein kinase (PKA) and phospholipase/protein kinase C (PKC) (9 -13). Thus, PKA enhances ligand-dependent transcriptional activation of glucocorticoid, retinoic acid (RAR), estrogen, progesterone, and vitamin D receptors (11, 14 -19). PKA has also been shown to phosphorylate the RAR (16,17) and the progesterone receptor (20). Phosphorylation of nuclear receptors has been directly implicated in ...

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“…Assuming that at least four protein kinases modulate hVDR activity, possibly including MAPK, it is reasonable that cell-speci®c expression and activation of these kinases, at least one of which (CK2) may be cell-cycle dependent [Bosc et al, 1999], could account for the reported differences in the functional impact of VDR phosphorylation [Darwish et al, 1993;Hsieh et al, 1993;Jurutka et al, 1993aJurutka et al, , 1996Desai et al, 1995;Matkovits and Christakos, 1995;Nakajima et al, 2000]. Despite the fact that in previous studies VDRs from different species were employed, as were a number of distinct promoter-reporter constructs, it is still possible to rationalize the current results within the context of the con¯icting observations of Desai et al [1995] and Matkovits and Christakos [1995].…”

Section: Discussionmentioning

confidence: 99%

Isolation of baculovirus‐expressed human vitamin D receptor: DNA responsive element interactions and phosphorylation of the purified receptor

Jurutka

MacDonald

Nakajima

et al. 2002

J of Cellular Biochemistry

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Two controversial aspects in the mechanism of human vitamin D receptor (hVDR) action are the possible significance of VDR homodimers and the functional role of receptor phosphorylation. To address these issues, milligram quantities of baculovirus-expressed hVDR were purified to 97% homogeneity, and then tested for binding to the rat osteocalcin vitamin D responsive element (VDRE) via electrophoretic mobility shift and half-site competition assays in the presence or absence of a CV-1 nuclear extract containing retinoid X receptor (RXR). Methylation interference analysis revealed that both the hVDR homodimer and the VDR-RXR heterodimer display similar patterns of VDRE G-base protection. However, in competition studies, the relative dissociation of the homodimeric hVDR complex from the VDRE was extremely rapid (t1/2 < 30 s) compared to the dissociation of the heteromeric complex (t1/2 > 5 min), thus illustrating the relative instability and low affinity of homodimeric VDR binding to DNA. These results indicate that VDR-RXR heterodimers are the preferred VDRE binding species. Further, two dimensional gel electrophoresis of hVDR demonstrated several isoelectric forms of the receptor, suggesting that it is subject to multiple phosphorylation events. In vitro kinase assays confirmed that purified hVDR is an efficient substrate for protein kinases A and Cbeta, as well as casein kinase II. In vivo studies of the expressed receptor in intact cells, namely baculovirus vector infected Sf9 insect cells and transfected mammalian COS-7 cells, demonstrated that hVDR was phosphorylated in a hormone-enhanced fashion. Functional consequences of hVDR phosphorylation were suggested by the observations that: (i) potato acid phosphatase (PAP)-treated hVDR no longer interacted with the VDRE as either a homodimer or a heteromeric complex with RXR, and (ii) treatment of transfected COS-7 cells with a phosphatase inhibitor (okadaic acid) along with 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) resulted in a synergistic enhancement of both hVDR phosphorylation and transactivation of a VDRE-linked reporter gene, compared to the effect of treatment with either agent alone. These studies point to a significant role for phosphorylation of VDR in regulating high-affinity VDR-RXR interactions with VDREs, and also in modulating 1,25(OH)2D3-elicited transcriptional activation in target cells.

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Phosphorylation is involved in transcriptional activation by the 1,25-dihydroxyvitamin D3 receptor

Cited by 48 publications

References 35 publications

Vitamin D-influenced gene expression via a ligand-independent, receptor-DNA complex intermediate.

Vitamin D-influenced gene expression via a ligand-independent, receptor-DNA complex intermediate.

Thyroid Hormone Activation of Transcription Is Potentiated by Activators of cAMP-dependent Protein Kinase

Isolation of baculovirus‐expressed human vitamin D receptor: DNA responsive element interactions and phosphorylation of the purified receptor

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