Gene expression/regulation tissue-specific

However, promoters are not the only types of cis-acting DNA sequences. Eukaryotes and their viruses also contain enhancers. These DNA sequences, although not promoters themselves, can enormously increase the effectiveness of promoters. Interestingly, the positions of enhancers relative to promoters are not fixed they can vary substantially. Enhancers play key roles in regulating gene expression in a specific tissue or developmental stage (Section 31.2.4). 

Ball, H.J., Shine, J. Herzog, H. (1996) Multiple promoters regulate tissue-specific expression of the human NPY-Y1 receptor gene. J. Biol. Chem. 270, 27 272-27 276. 

In addition to the stimulus-specific characteristics, different ACC synthase genes show various tissue-specific or developmentally regulated expression patterns. 

The picture emerging is that of a sophisticated set of control mechanisms that regulate tissue-specific expression and developmental expression through a number of cis-acting control elements adjacent to the structural genes a number of proteins then bind specifically to these control elements. 

Originally described in the immune system, NFAT proteins comprise a family of transcriptional factors that play key roles in many cellular processes that control not only immune responses but also the development, regulation, and differentiation of many other tissues. Activation of NFAT proteins results in the expression of specific sets of genes that regulate multiple cell functions [1,2]. 

Regulatory regions are transcriptional control sequences, which consist of promoters, response elements, enhancers and possibly silencers, located upstream of the start site of transcription. The overall effect on gene transcription is a sum of the contributions of these elements and the activities of proteins recruited to these sites. Promoters are located immediately upstream of the start site and initiate transcription. They often contain tissue- or cell-specific elements if the gene is not ubiquitously expressed. Enhancers are positive regulatory elements which function independently of orientation and distance from the genes they regulate. 

The processing of hnRNA molecules is a site for regulation of gene expression. Alternative patterns of RNA splicing result from tissue-specific adaptive and developmental control mechanisms. As mentioned... 

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