Chapter 8 - Regulation of transcription factor activity

Abstract

The regulation of synthesis of a particular factor is used primarily in cases of factors which mediate tissue specific or developmentally regulated gene expression, where a factor is only required in a small proportion of cell types and is never required in most cell types. The rapid induction of transcription in response to inducers of gene expression is primarily achieved by the activation of preexisting inactive forms of transcription factors that are present in most cell types since this process, although more metabolically expensive, provides the required rapidity in response. In many cases of inducible gene expression, which involve activation of preexisting factors, such activation is supplemented by the slower process of synthesizing new factor in response to the inducing agent. The phorbol ester-induced increase in the DNA binding of preexisting Jun protein is supplemented by increased synthesis of both Fos and Jun following phorbol ester treatment. The activation of NFκB by dissociation from IB following treatment with substances such as phorbol esters which activate T cells supplemented by increased synthesis of NFκB and its corresponding mRNA following T cell activation, whilst increased synthesis of IB itself occurs in response to glucocorticoid.