Hormone responsive elements HREs

Figure 39-11. Location of hormone response elements (HREs) A, B, and C using the reporter gene-transfection approach. A family of reporter genes, constructed as described in Figure 39-10, can be transfected individually into a recipient cell. By analyzing when certain hormone responses are lost in comparison to the 5 deletion, specific hormone-responsive elements can be located.

Table 43-1. The DNA sequences of several hormone response elements (HREs). ...

Several Hormone Response Elements (HREs) Have Been Defined... 

The identification of the few genes regulated by hormones, among the multitude of the genes that are expressed in each cell, is a first-order problem. What makes the identification possible is the existence of some short specific sequences of DNA, situated in the promoter region of each gene, that are recognized by the dimer of the hormone receptor. These sequences are called hormone response elements (HRE) (Seiler-Tuyns et al. 1986 Tzukerman et al. 1994). 

Second messengers often involved Protein kinases activated Hormone-receptor complex binds hormone response elements (HRE, of enhancer regions) inDNA... 

In the nucleus, the hormone-receptor complex binds to nucleotide sequences known as hormone response elements (HREs). These are short palindromic DNA segments that usually promote transcription as enhancer elements (see p. 244). The illustration shows the HRE for glucocorticoids (GRE ... 

The first crystal structure of the LED of the AR in complex with metri-bolone (R1881) was solved by Matias and colleagues in 2000 [38]. The LED has a similar three-dimensional structure to the other agonist-bound steroid receptors, namely the ERa, ERj6 and the PR [38]. The fact that all steroid hormone receptors bind similar hormone response elements (HREs) stands in sharp contrast to the specific activities elicited by application of the steroid... 

Fig. 4.4. The principle of signal transduction by nuclear receptors. Nuclear receptors are ligand-controlled transcription factors that bind cognate DNA sequences, or hormone responsive elements (HRE). The hormone acts as a regulating ligand. Most nuclear receptors bind their cognate HREs, which tend to be symmetrically organized, as homo- or heterodimers. The DNA-bound, activated receptor stimulates transcription initiation via direct or indirect protein-protein interactions with the transcription initiation complex. The arrows demonstrate the different possible configurations of the HRE (see also 4.6). H hormone Hsp heat shock protein.

The steroid hormone receptors are sequence specific DNA binding proteins whose cognate DNA elements are termed hormone responsive elements" (HREs). The HREs known to date possess a common structure. They are composed primarily of two copies of a hexamer sequence. In table 4.1 are listed the hexamer sequences of the HREs of important nuclear receptors. 

Hormone binding changes the conformation of Rec it forms homo-or heterodimers with other hormone-receptor complexes and binds to specific regulatory regions called hormone response elements (HREs) in the DNA adjacent to specific genes. 

Regulation of the LDL receptor gene involves a hormone-response element (HRE, see p. 238).] Third, if the cholesterol is not required immediately for some structural or synthetic purpose, it is esterified by acyl CoA cholesterol acyltransferase (ACAT, AC AT transfers a fatty acid from a fatty acyl CoA derivative to cholesterol, producing a cholesteryl ester that can be stored in the cell (Figure 18.21). The activity of ACAT is enhanced in the presence of increased intracellular cholesterol. 

Activation of transcription by interaction of steroid hormone-receptor complex with hormone response element (HRE). 

Activation of steroid hormone receptors by the hormone. In the absence of the hormone, the steroid receptors are complexed through the hormone-binding domain to another protein known as heat shock protein 90 (hsp90). Both the hormone-binding domain and the hsp90 prevent functional interaction of the receptor with DNA. Binding of the hormone frees the receptor from hsp90 and promotes dimerization of the receptor, which can then bind to the palindromic hormone response element (HRE) and activate transcription. 

Fig. 1. A model for the mechanism whereby steroid hormones regulate rates of gene transcription. Steroids (S) bind with receptors (R) to form a steroid-receptor complex that interacts with DNA sequences called hormone response elements (HRE). These HREs are at variable distances from the gene promoter which frequently consists of upstream promoter elements (UPE) and conserved elements such as TATA box (TATA).

Mammalian nuclear receptors regulate the expression or activation of target genes from promoter sequences that contain either a palindromic or a direct repeat DNA sequence collectively termed hormone response elements (HREs). Most nnclear receptors bind to HREs as either a homodimer... 

When the hormone-receptor complex is activated, it binds to a regulatory element (i.e., hormone response element [HRE]) on DNA that stimulates or inhibits the synthesis of mRNA (see Figure 8-7). 

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