Abstract
Tpit/Pitx-responsive element (Tpit/PitxR-E), which binds transcription factors Tpit and Pitx1, confers cell-type specific expression of proopiomelanocortin (POMC) gene in pituitary corticotrops where the gene expression is mainly regulated by corticotropin-releasing hormone (CRH) and glucocorticoids (Gcs). CRH stimulates POMC gene expression, which is mediated by the accumulation of intracellular cAMP and requires binding of Nur factors to Nur-responsive element (NurRE). Gcs antagonize NurRE-dependent POMC gene expression through direct interaction between glucocorticoid receptors and Nur factors. We examined whether Tpit/ PitxRE and NurRE are involved in CRH/cAMP-induced activation and Gc-induced repression of POMC gene expression by reporter assay in AtT-20 corticotropic cells. Deletion and mutation of Tpit/PitxR-E markedly reduced basal activity of the promoter, and those of NurRE decreased the levels of the CRH/cAMP-induced activation. Nifedipine, KN-62, and W-7, specific inhibitors of the L-type calcium channel, calmoduhn-dependent protein kinase II, and calmodulin respectively, attenuated CRH/cAMP-induced activation of promoters with three copies of either Tpit/PitxRE or NurRE, indicating that both Tpit/PitxRE and NurRE mediate CRH-induced activation of POMC gene expression in a calcium-dependent manner. Deletion and mutation of Tpit/PitxRE abolished dexamethasone (DEX)-induced repression of POMC gene expression, while those of NurRE did not, indicating that Tpit/PitxRE predominantly mediates Gc-induced repression of POMC transcription. However, DEX treatment attenuated activities of promoters with three copies of either Tpit/PitxRE or NurRE, suggesting that Gcs act at NurRE as well as Tpit/ PitxRE to repress POMC gene expression. We conclude that Tpit/PitxRE is an important element by which CRH and Gcs regulate the POMC gene expression.
| Original language | English |
|---|---|
| Pages (from-to) | 279-290 |
| Number of pages | 12 |
| Journal | Journal of Endocrinology |
| Volume | 193 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - May 2007 |
Fingerprint
ASJC Scopus subject areas
- Endocrinology
- Endocrinology, Diabetes and Metabolism
Cite this
Corticotropin-releasing hormone or dexamethasone regulates rat proopiomelanocortin transcription through Tpit/Pitx-responsive element in its promoter. / Murakami, Itsuo; Takeuchi, Sakae; Kudo, Toshiyuki; Sutou, Shizuyo; Takahashi, Sumio.
In: Journal of Endocrinology, Vol. 193, No. 2, 05.2007, p. 279-290.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Corticotropin-releasing hormone or dexamethasone regulates rat proopiomelanocortin transcription through Tpit/Pitx-responsive element in its promoter
AU - Murakami, Itsuo
AU - Takeuchi, Sakae
AU - Kudo, Toshiyuki
AU - Sutou, Shizuyo
AU - Takahashi, Sumio
PY - 2007/5
Y1 - 2007/5
N2 - Tpit/Pitx-responsive element (Tpit/PitxR-E), which binds transcription factors Tpit and Pitx1, confers cell-type specific expression of proopiomelanocortin (POMC) gene in pituitary corticotrops where the gene expression is mainly regulated by corticotropin-releasing hormone (CRH) and glucocorticoids (Gcs). CRH stimulates POMC gene expression, which is mediated by the accumulation of intracellular cAMP and requires binding of Nur factors to Nur-responsive element (NurRE). Gcs antagonize NurRE-dependent POMC gene expression through direct interaction between glucocorticoid receptors and Nur factors. We examined whether Tpit/ PitxRE and NurRE are involved in CRH/cAMP-induced activation and Gc-induced repression of POMC gene expression by reporter assay in AtT-20 corticotropic cells. Deletion and mutation of Tpit/PitxR-E markedly reduced basal activity of the promoter, and those of NurRE decreased the levels of the CRH/cAMP-induced activation. Nifedipine, KN-62, and W-7, specific inhibitors of the L-type calcium channel, calmoduhn-dependent protein kinase II, and calmodulin respectively, attenuated CRH/cAMP-induced activation of promoters with three copies of either Tpit/PitxRE or NurRE, indicating that both Tpit/PitxRE and NurRE mediate CRH-induced activation of POMC gene expression in a calcium-dependent manner. Deletion and mutation of Tpit/PitxRE abolished dexamethasone (DEX)-induced repression of POMC gene expression, while those of NurRE did not, indicating that Tpit/PitxRE predominantly mediates Gc-induced repression of POMC transcription. However, DEX treatment attenuated activities of promoters with three copies of either Tpit/PitxRE or NurRE, suggesting that Gcs act at NurRE as well as Tpit/ PitxRE to repress POMC gene expression. We conclude that Tpit/PitxRE is an important element by which CRH and Gcs regulate the POMC gene expression.
AB - Tpit/Pitx-responsive element (Tpit/PitxR-E), which binds transcription factors Tpit and Pitx1, confers cell-type specific expression of proopiomelanocortin (POMC) gene in pituitary corticotrops where the gene expression is mainly regulated by corticotropin-releasing hormone (CRH) and glucocorticoids (Gcs). CRH stimulates POMC gene expression, which is mediated by the accumulation of intracellular cAMP and requires binding of Nur factors to Nur-responsive element (NurRE). Gcs antagonize NurRE-dependent POMC gene expression through direct interaction between glucocorticoid receptors and Nur factors. We examined whether Tpit/ PitxRE and NurRE are involved in CRH/cAMP-induced activation and Gc-induced repression of POMC gene expression by reporter assay in AtT-20 corticotropic cells. Deletion and mutation of Tpit/PitxR-E markedly reduced basal activity of the promoter, and those of NurRE decreased the levels of the CRH/cAMP-induced activation. Nifedipine, KN-62, and W-7, specific inhibitors of the L-type calcium channel, calmoduhn-dependent protein kinase II, and calmodulin respectively, attenuated CRH/cAMP-induced activation of promoters with three copies of either Tpit/PitxRE or NurRE, indicating that both Tpit/PitxRE and NurRE mediate CRH-induced activation of POMC gene expression in a calcium-dependent manner. Deletion and mutation of Tpit/PitxRE abolished dexamethasone (DEX)-induced repression of POMC gene expression, while those of NurRE did not, indicating that Tpit/PitxRE predominantly mediates Gc-induced repression of POMC transcription. However, DEX treatment attenuated activities of promoters with three copies of either Tpit/PitxRE or NurRE, suggesting that Gcs act at NurRE as well as Tpit/ PitxRE to repress POMC gene expression. We conclude that Tpit/PitxRE is an important element by which CRH and Gcs regulate the POMC gene expression.
UR - http://www.scopus.com/inward/record.url?scp=34250318916&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=34250318916&partnerID=8YFLogxK
U2 - 10.1677/JOE-06-0143
DO - 10.1677/JOE-06-0143
M3 - Article
VL - 193
SP - 279
EP - 290
JO - Journal of Endocrinology
JF - Journal of Endocrinology
SN - 0022-0795
IS - 2
ER -