Phorbol 12-myristate 13-acetate promotes nuclear translocation of hepatic steroid response element binding protein-2

2016 ◽  
Vol 75 ◽  
pp. 1-10 ◽  
Author(s):  
Tsz Yan Wong ◽  
Yan Qin Tan ◽  
Shu-mei Lin ◽  
Lai K. Leung
Keyword(s):  
Nuclear Translocation ◽  
Binding Protein ◽  
Response Element ◽  
Steroid Response ◽  
Element Binding Protein

scholarly journals Adrenergic Regulation of the Distribution of Transducer of Regulated cAMP-Response Element-Binding Protein (TORC2) in Rat Pinealocytes

Endocrinology ◽  
2011 ◽  
Vol 152 (9) ◽  
pp. 3440-3450 ◽  
Author(s):  
R. Kanyo ◽  
N. Amyotte ◽  
J. McTague ◽  
C. L. Chik ◽  
A. K. Ho
Keyword(s):  
Pineal Gland ◽  
Protein Phosphatase ◽  
Nuclear Translocation ◽  
Binding Protein ◽  
Camp Response Element Binding ◽  
Camp Response Element ◽  
Response Element ◽  
Adrenergic Antagonist ◽  
Element Binding Protein ◽  
Rat Pineal Gland

Transducers of regulated cAMP-response element-binding protein (CREB) activity (TORC) are coactivators that can increase CREB transcriptional activity, suggesting that TORC may regulate the transcription of Aanat, a CREB-target gene. In the present study, we focused on the regulation of TORC2 and its role in Aanat transcription in the rat pineal gland. Although there was no endogenous Torc2 mRNA rhythm in the rat pineal gland and treatment of cultured pinealocytes with norepinephrine (NE) had no effect on the mRNA level of Torc2, the phosphorylation state and intracellular distribution of TORC2 protein were regulated by NE. Immunoblot analysis combined with cytosolic/nuclear fractionation or phosphatase treatment showed that TORC2 protein was rapidly dephosphorylated and translocated to the nucleus after NE stimulation in rat pinealocytes. Similar dephosphorylation of TORC2 also occurred nocturnally in the rat pineal gland. The NE-mediated TORC2 dephosphorylation was blocked by cotreatment with propranolol (a β-adrenergic antagonist) but not prazosin (an α1-adrenergic antagonist) and mimicked by dibutyryl cAMP, indicating the participation of the β-adrenergic receptor/cAMP pathway. Studies with protein phosphatase inhibitors showed that only okadaic acid and calyculin A were effective in blocking the NE-mediated TORC2 dephosphorylation, suggesting the involvement of protein phosphatase 2A in this dephosphorylation. Moreover, TORC2 overexpression had an enhancing effect on NE-stimulated Aanat transcription. Together, these results indicate that NE stimulation causes nuclear translocation of TORC2 by dephosphorylating the protein through a β-adrenoceptor/cAMP mechanism and that nuclear localization of TORC2 appears to regulate Aanat transcription by NE in the rat pineal gland.

scholarly journals Involvement of Transducer of Regulated cAMP Response Element-Binding Protein Activity on Corticotropin Releasing Hormone Transcription

Endocrinology ◽  
2010 ◽  
Vol 151 (3) ◽  
pp. 1109-1118 ◽  
Author(s):  
Ying Liu ◽  
Ana G. Coello ◽  
Valery Grinevich ◽  
Greti Aguilera
Keyword(s):  
Promoter Activity ◽  
Nuclear Translocation ◽  
Binding Protein ◽  
Primary Cultures ◽  
Camp Response Element Binding ◽  
Neuronal Cultures ◽  
Dependent Manner ◽  
Camp Response Element ◽  
Response Element ◽  
Element Binding Protein

We have recently shown that phospho-cAMP response element-binding protein (CREB) is essential but not sufficient for activation of CRH transcription, suggesting the requirement of a coactivator. Here, we test the hypothesis that the CREB coactivator, transducer of regulated CREB activity (TORC), is required for activation of CRH transcription, using the cell line 4B and primary cultures of hypothalamic neurons. Immunohistochemistry and Western blot experiments in 4B cells revealed time-dependent nuclear translocation of TORC1,TORC 2, and TORC3 by forskolin [but not by the phorbol ester, phorbol 12-myristate 13-acetate (PMA)] in a concentration-dependent manner. In reporter gene assays, cotransfection of TORC1 or TORC2 potentiated the stimulatory effect of forskolin on CRH promoter activity but had no effect in cells treated with PMA. Knockout of endogenous TORC using silencing RNA markedly inhibited forskolin-activated CRH promoter activity in 4B cells, as well as the induction of endogenous CRH primary transcript by forskolin in primary neuronal cultures. Coimmunoprecipitation and chromatin immunoprecipitation experiments in 4B cells revealed association of CREB and TORC in the nucleus, and recruitment of TORC2 by the CRH promoter, after 20-min incubation with forskolin. These studies demonstrate a correlation between nuclear translocation of TORC with association to the CRH promoter and activation of CRH transcription. The data suggest that TORC is required for transcriptional activation of the CRH promoter by acting as a CREB coactivator. In addition, cytoplasmic retention of TORC during PMA treatment is likely to explain the failure of phorbolesters to activate CRH transcription in spite of efficiently phosphorylating CREB.

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