scholarly journals Isoform-Specific Transcriptional Regulation by Thyroid Hormone Receptors: Hormone-Independent Activation Operates through a Steroid Receptor Mode of Coactivator Interaction

2001 ◽  
Vol 15 (7) ◽  
pp. 1170-1185 ◽  
Author(s):  
Zhihong Yang ◽  
Martin L. Privalsky
Keyword(s):  
Thyroid Hormone ◽  
Transcriptional Activation ◽  
Hormone Receptors ◽  
Steroid Hormone ◽  
Expression Patterns ◽  
Steroid Receptor ◽  
Steroid Hormone Receptors ◽  
Thyroid Hormone Receptors ◽  
Interaction Domain ◽  
Specific Expression

Abstract Thyroid hormone receptors (T3Rs) are hormone-regulated transcription factors that play important roles in vertebrate homeostasis, differentiation, and development. T3Rs are synthesized as multiple isoforms that display tissue-specific expression patterns and distinct transcriptional properties. Most T3R isoforms associate with coactivator proteins and mediate transcriptional activation only in the presence of thyroid hormone. The pituitary-specific T3Rβ-2 isoform departs from this general rule and is able to interact with p160 coactivators, and to mediate transcriptional activation in both the absence and presence of hormone. We report here that this hormone-independent activation is mediated by contacts between the unique N terminus of T3Rβ-2 and an internal interaction domain in the SRC-1 (steroid receptor coactivator-1) and GRIP-1 (glucocorticoid receptor interacting protein 1) coactivators. These hormone-independent contacts between T3Rβ-2 and the p160 coactivators are distinct in sequence and function from the LXXLL motifs that mediate hormone-dependent transcriptional activation and resemble instead a mode of coactivator recruitment previously observed only for the steroid hormone receptors and only in the presence of steroid hormone. Our results suggest that the transcriptional properties of the different T3R isoforms represent a combinatorial mixture of repression, antirepression, and hormone-independent and hormone-dependent activation functions that operate in conjunction to determine the ultimate transcriptional outcome.

scholarly journals Characteristics and Expression Pattern of MYC Genes in Triticum aestivum, Oryza sativa, and Brachypodium distachyon

Plants ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 274 ◽  
Author(s):  
Shoukun Chen ◽  
Hongyan Zhao ◽  
Tengli Luo ◽  
Yue Liu ◽  
Xiaojun Nie ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Leucine Zipper ◽  
Brachypodium Distachyon ◽  
Expression Patterns ◽  
Terminal Region ◽  
Gene Promoters ◽  
Interaction Domain ◽  
Specific Expression ◽  
Systematic Analysis ◽  
Transcriptional Activation Domain

Myelocytomatosis oncogenes (MYC) transcription factors (TFs) belong to basic helix-loop-helix (bHLH) TF family and have a special bHLH_MYC_N domain in the N-terminal region. Presently, there is no detailed and systematic analysis of MYC TFs in wheat, rice, and Brachypodium distachyon. In this study, 26 TaMYC, 7 OsMYC, and 7 BdMYC TFs were identified and their features were characterized. Firstly, they contain a JAZ interaction domain (JID) and a putative transcriptional activation domain (TAD) in the bHLH_MYC_N region and a BhlH region in the C-terminal region. In some cases, the bHLH region is followed by a leucine zipper region; secondly, they display tissue-specific expression patterns: wheat MYC genes are mainly expressed in leaves, rice MYC genes are highly expressed in stems, and B. distachyon MYC genes are mainly expressed in inflorescences. In addition, three types of cis-elements, including plant development/growth-related, hormone-related, and abiotic stresses-related were identified in different MYC gene promoters. In combination with the previous studies, these results indicate that MYC TFs mainly function in growth and development, as well as in response to stresses. This study laid a foundation for the further functional elucidation of MYC genes.

scholarly journals Inhibition of Estrogen Receptor Action by the Orphan Receptor SHP (Short Heterodimer Partner)

1998 ◽  
Vol 12 (10) ◽  
pp. 1551-1557 ◽  
Author(s):  
Wongi Seol ◽  
Bettina Hanstein ◽  
Myles Brown ◽  
David D. Moore
Keyword(s):  
Estrogen Receptor ◽  
Thyroid Hormone ◽  
Transcriptional Activation ◽  
Hormone Receptors ◽  
Thyroid Hormone Receptor ◽  
Orphan Receptor ◽  
Estrogen Signaling ◽  
Dependent Manner ◽  
Interaction Domain ◽  
Short Heterodimer Partner

Abstract SHP (short heterodimer partner) is an unusual orphan receptor that lacks a conventional DNA-binding domain. Previous results have shown that it interacts with several other nuclear hormone receptors, including the retinoid and thyroid hormone receptors, and inhibits their ligand-dependent transcriptional activation. Here we show that SHP also interacts with estrogen receptors and inhibits their function. In mammalian and yeast two-hybrid systems as well as glutathione-S-transferase pull-down assays, SHP interacts specifically with estrogen receptor-α (ERα) in an agonist-dependent manner. The same assay systems using various deletion mutants of SHP map the interaction domain with ERα to the same SHP sequences required for interaction with the nonsteroid hormone receptors such as retinoid X receptor and thyroid hormone receptor. In transient cotransfection assays, SHP inhibits estradiol -dependent activation by ERα by about 5-fold. In contrast, SHP interacts with ERβ independent of ligand and reduces its ability to activate transcription by only 50%. These data suggest that SHP functions to regulate estrogen signaling through a direct interaction with ERα.

scholarly journals Hsp90 Heterocomplexes Regulate Steroid Hormone Receptors: From Stress Response to Psychiatric Disease

2018 ◽  
Vol 20 (1) ◽  
pp. 79 ◽  
Author(s):  
Jeremy Baker ◽  
Ilayda Ozsan ◽  
Santiago Rodriguez Ospina ◽  
Danielle Gulick ◽  
Laura Blair
Keyword(s):  
Stress Response ◽  
Hormone Receptors ◽  
Steroid Hormone ◽  
Steroid Receptor ◽  
Steroid Hormone Receptors ◽  
Psychiatric Disease ◽  
Post Traumatic Stress ◽  
Fk506 Binding Protein ◽  
Structural Regulation ◽  
And Function

The hypothalamus-pituitary-adrenal (HPA) axis directly controls the stress response. Dysregulation of this neuroendocrine system is a common feature among psychiatric disorders. Steroid hormone receptors, like glucocorticoid receptor (GR), function as transcription factors of a diverse set of genes upon activation. This activity is regulated by molecular chaperone heterocomplexes. Much is known about the structure and function of these GR/heterocomplexes. There is strong evidence suggesting altered regulation of steroid receptor hormones by chaperones, particularly the 51 kDa FK506-binding protein (FKBP51), may work with environmental factors to increase susceptibility to various psychiatric illnesses including post-traumatic stress disorder (PTSD), major depressive disorder (MDD), and anxiety. This review highlights the regulation of steroid receptor dynamics by the 90kDa heat shock protein (Hsp90)/cochaperone heterocomplexes with an in depth look at how the structural regulation and imbalances in cochaperones can cause functional effects on GR activity. Links between the stress response and circadian systems and the development of novel chaperone-targeting therapeutics are also discussed.

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