scholarly journals Thyroid hormone receptors regulate adipogenesis and carcinogenesis via crosstalk signaling with peroxisome proliferator-activated receptors

2009 ◽  
Vol 44 (3) ◽  
pp. 143-154 ◽  
Author(s):  
Changxue Lu ◽  
Sheue-Yann Cheng
Keyword(s):  
Thyroid Hormone ◽  
Target Gene ◽  
Molecular Mechanisms ◽  
Hormone Receptors ◽  
Thyroid Hormone Receptors ◽  
Peroxisome Proliferator ◽  
Cellular Functions ◽  
Biological Impact ◽  
Hormone Response Elements ◽  
Peroxisome Proliferator Activated Receptors

Peroxisome proliferator-activated receptors (PPARs) and thyroid hormone receptors (TRs) are members of the nuclear receptor superfamily. They are ligand-dependent transcription factors that interact with their cognate hormone response elements in the promoters to regulate respective target gene expression to modulate cellular functions. While the transcription activity of each is regulated by their respective ligands, recent studies indicate that via multiple mechanisms PPARs and TRs crosstalk to affect diverse biological functions. Here, we review recent advances in the understanding of the molecular mechanisms and biological impact of crosstalk between these two important nuclear receptors, focusing on their roles in adipogenesis and carcinogenesis.

scholarly journals Thyroid hormone-mediated negative transcriptional regulation of Necdin expression

2006 ◽  
Vol 36 (3) ◽  
pp. 517-530 ◽  
Author(s):  
Maria Nygård ◽  
Nathalie Becker ◽  
Barbara Demeneix ◽  
Katarina Pettersson ◽  
Maria Bondesson
Keyword(s):  
Thyroid Hormone ◽  
Histone Deacetylases ◽  
Molecular Mechanisms ◽  
Hormone Receptors ◽  
Thyroid Hormone Receptors ◽  
Developmentally Regulated ◽  
Hormone Response Elements ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
Sequence Position

Unliganded thyroid hormone receptors (apoTRs) repress transcription of hormone-activated genes by recruiting corepressors to the promoters. In contrast, on promoters containing so-called negative thyroid hormone response elements (nTREs), apoTRs activate transcription. A number of different molecular mechanisms have been described as to how apoTRs activate transcription varying with the target gene of the study. Here we demonstrate that thyroid hormone regulates the transcription of the Necdin gene, a developmentally regulated candidate gene for the genomic imprinting-associated neurobehavioural disorder, Prader–Willi syndrome. ApoTRs activate Necdin expression through an nTRE in its promoter, downstream of the transcription start site. The nTRE of the Necdin gene resembles the nTREs of the TSHβ genes of the hypothalamus–pituitary–thyroid axis in the sequence, position in the promoter, and mode of activation. We show that this group of nTRE-driven genes shares the requirements for binding of the retinoic X receptor and nuclear receptor corepressor/silencing mediator of retinoid and thyroid hormone receptors (NCoR/SMRT) for full ligand-independent activation, whereas there is no need for association of the p160 family of coactivators. In accordance with the requirement for corepressors, Necdin expression is influenced by deacetylase activity, suggesting that histone deacetylases and corepressors as well could function as activators of transcription, depending on the promoter context.

scholarly journals Determinants of target gene specificity for steroid/thyroid hormone receptors

Cell ◽  
1989 ◽  
Vol 57 (7) ◽  
pp. 1139-1146 ◽  
Author(s):  
Kazuhiko Umesono ◽  
Ronald M. Evans
Keyword(s):  
Thyroid Hormone ◽  
Target Gene ◽  
Hormone Receptors ◽  
Thyroid Hormone Receptors

scholarly journals Molecular Mechanisms and Genome-Wide Aspects of PPAR Subtype Specific Transactivation

PPAR Research ◽  
2010 ◽  
Vol 2010 ◽  
pp. 1-12 ◽  
Author(s):  
Anne Bugge ◽  
Susanne Mandrup
Keyword(s):  
Energy Homeostasis ◽  
Target Gene ◽  
Molecular Mechanisms ◽  
Fat Metabolism ◽  
Special Focus ◽  
Peroxisome Proliferator ◽  
Subtype Specificity ◽  
Genome Wide ◽  
Peroxisome Proliferator Activated Receptors

The peroxisome proliferator-activated receptors (PPARs) are central regulators of fat metabolism, energy homeostasis, proliferation, and inflammation. The three PPAR subtypes, PPAR, /, and activate overlapping but also very different target gene programs. This review summarizes the insights into PPAR subtype-specific transactivation provided by genome-wide studies and discusses the recent advances in the understanding of the molecular mechanisms underlying PPAR subtype specificity with special focus on the regulatory role of AF-1.

scholarly journals Identification and characterization of RanBPM, a novel coactivator of thyroid hormone receptors

2006 ◽  
Vol 36 (2) ◽  
pp. 313-325 ◽  
Author(s):  
Marie-Belle Poirier ◽  
Liette Laflamme ◽  
Marie-France Langlois
Keyword(s):  
Thyroid Hormone ◽  
Mammalian Cells ◽  
Hormone Receptors ◽  
Thyroid Hormone Receptors ◽  
Luciferase Reporter ◽  
Glutathione S Transferase ◽  
Hormone Response Elements ◽  
Over Expression ◽  
Protein Partner ◽  
Dose Dependent Fashion

Thyroid hormone receptors (TRs) are transcription factor members of the nuclear receptor superfamily. The transcriptional activity of TRs is controlled by thyroid hormones and cell-specific coregulators. Using the yeast two-hybrid system, we identified RanBPM as a new protein partner for TRs. RanBPM was initially discovered as an interacting partner for Ran, and was also shown to be a protein partner and coactivator of the androgen receptor. The novel interaction between RanBPM and TR isoforms was addressed by glutathione-S-transferase (GST) pull-down assays and co-immunoprecipitation in intact mammalian cells, where RanBPM was shown to bind TRs in a ligand-independent fashion. We also studied the regions implicated in the interaction with deletion mutants: the principal interacting region of RanBPM is comprised within its carboxyl-terminal end and the TR DNA-binding domain is sufficient to mediate the interaction. To investigate the potential role of RanBPM in thyroid hormone action, transient transfections with luciferase reporter genes were performed in CV-1 cells. We found that the over-expression of RanBPM increases the activation of TRETK- and DR+4-positive thyroid hormone response elements. Interestingly, over-expression of the truncated protein RanBPM55, which lacks the N-terminal polyglutaminated region but binds TRs, decreased the fold activation by almost 80%. Furthermore, we performed competition assays using transient transfection of RanBPM and increasing amounts of RanBPM55. This revealed that the stimulating effect on TR transactivation by the full-length protein is inhibited in a dose-dependent fashion by RanBPM55. This suggests that although the polyglutaminated region of RanBPM is not required for the binding to TRs, it is required for the stimulation of TR transactivation. Taken together, our results provide evidence that RanBPM is a potent novel coactivator for thyroid hormone receptors.

scholarly journals The Role of Peroxisome Proliferator-Activated Receptors in the Esophageal, Gastric, and Colorectal Cancer

PPAR Research ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Alessandra Fucci ◽  
Tommaso Colangelo ◽  
Carolina Votino ◽  
Massimo Pancione ◽  
Lina Sabatino ◽  
...  
Keyword(s):  
Gastrointestinal Tract ◽  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Molecular Targets ◽  
Predictive Biomarkers ◽  
Cancer Development ◽  
Peroxisome Proliferator ◽  
Cellular Functions ◽  
Peroxisome Proliferator Activated Receptors

Tumors of the gastrointestinal tract are among the most frequent human malignancies and account for approximately 30% of cancer-related deaths worldwide. Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that control diverse cellular functions such as proliferation, differentiation, and cell death. Owing to their involvement in so many processes, they play crucial roles also in the development and physiology of the gastrointestinal tract. Consistently, PPARs deregulation has been implicated in several pathophysiological conditions, including chronic inflammation and cancer development. This paper summarizes the current knowledge on the role that the various PPAR isoforms play in the pathogenesis of the esophageal, gastric, and intestinal cancer. Elucidation of the molecular mechanisms underlying PPARs' signaling pathways will provide insights into their possible use as predictive biomarkers in the initial stages of the process. In addition, this understanding will provide the basis for new molecular targets in cancer therapy and chemoprevention.

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