Nuclear hormonal receptors

Table 2 Raw Data and Posterior Modes from Dirichlet Mixtures for a Six Amino Acid Segment of Nuclear Hormone Receptors ...

The antagonist-induced conformation of nuclear hormone receptors attracts co-repressors like Nco/SMRT (nuclear hormone receptor co-repressor/silencing mediator of retinoid and thyroid receptors) which further recruit other nuclear proteins with histone deacetylase activity. Their action leads to chromatin condensation, thus preventing the general transcription apparatus from binding to promoter regions. 

Ekins S, Kirillov E, Rakhmatulin FA, Nikolskaya T. A novel method for visualizing nuclear hormone receptor networks relevant to drug metabolism. Drug Metab Dispos 2005 33 474-81. 

Schapira M, Raaka BM, Samuels HH, Abagyan R. Rational discovery of novel nuclear hormone receptor antagonists. Proc Natl Acad Sci USA 2000 97 1008-13. 

The nuclear receptor superfamily consists of a diverse set of transcription factors that were discovered because of a sequence similarity in their DNA-binding domains. This family, now with more than 50 members, includes the nuclear hormone receptors discussed above, a number of other receptors whose ligands were discovered after the receptors were identified, and many putative or orphan receptors for which a ligand has yet to be discovered. 

SaOS-2 osteoblasts (Kim et al., 2003). Such an effect was shown to be dependent on the stage of cell differentiation. The mechanism of the differentiating activity of lycopene is still unclear. One of the most reliable hypothesis is that the carotenoid may activate the expression of nuclear hormone receptors, such as RAR and RXR (Sharoni et al., 2002). 

Kostrouchova, M., Krause, M., Kostrouch, Z. and Rail, J.E. (1998) CHR3 a Caenorhabditis elegans orphan nuclear hormone receptor required for proper epidermal development and molting. Development 125,1617-1626. 

Once nuclear hormone receptors are bound to their hormone, they are capable of being integrated directly into the machinery that regulates the transcription of specific genes. This action is more direct, and apparently more... 

This chapter reviews the main characteristics of two of the better known members of the nuclear hormone receptor family estrogen receptors a and ft (ERa and ER/i). First, the different functional regions harbored by the molecule of the receptor are described. These properties will be used to describe the cellular, molecular, and other consequences that derive from the interactions of receptors with their own hormone, other proteins, or DNA. 

In the 1980s, Jensen and others obtained monoclonal antibodies against several of the nuclear hormone receptors (Dfaz-Chico et al. 1988 Jordan et al. 1990). These antibodies permitted the introduction of immunohistochemical techniques in the study of receptors. Consequently, King and Greene verified... 

The zinc fingers are common structures among the transcription factors. Nevertheless, the coordination with zinc is more frequently produced between two histidine residues and two neighboring cysteines than when it is among four cysteine residues, as occurs in the nuclear hormone receptors. The zinc fingers provide an optimum architecture for the mutual recognition between specific sequences of amino acids and nucleotides. In the case of the nuclear receptors, the interaction occurs between particular amino acids of the DBD and guanine residues of the DNA sequence (Fig. 1.7). 

The final phase of action of the hormones that utilize nuclear hormone receptors lies in the modification of the gene transcription. In spite of the enormous... 

The chemical structure of the substances capable of interacting with a determinate nuclear receptor is tremendously varied. For now no pattern exists that permits one to assure that a particular substance is going to interact with the receptor to produce an agonist or antagonist effect. In recent years the concept of endocrine disruptors has been introduced to describe the substances that are capable of modifying the endocrine equilibrium. Some of them act by binding with nuclear hormone receptors, while others interfere with the processes of regulation of hormone secretion (Lathers 2002 Melnick et al. 2002 Nakata 2002 Powles 2002 Brown et al. 2002 Sonnenschein et al. 1998). 

An example of the complexity involved in the regulation of nuclear hormone receptors is shown in the case of the ER in the liver. Its synthesis is induced by estradiol, growth hormone, thyroid hormones, and glucocorticoids. 

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