Transcriptional regulation by HMGN proteins

Abstract

High mobility group nucleosomal proteins (HMGNs) are small non-histone proteins associated with chromatin. HMGNs have the unique ability to bind to nucleosomes with higher affinity than to naked DNA [1]. They have been studied extensively for their ability to modulate transcription. Although initially viewed as general transcriptional activators on chromatin templates, it is now appreciated that they are instead highly specific modulators of gene expression. We review the mechanisms for targeting HMGNs to specific genes and for how they subsequently regulate transcription.

Figure 1. Rapid and transient association of pSer6HMGN1 with the TFF1 promoter upon estrogen induction

MCF-7 cells were cultured under estrogen-deprived conditions and then treated with 100 nM 17-β-estradiol (E2) for the indicated times. (A) ChIP using antibodies against pSer6HMGN1. Input DNA and immunoprecipitated DNA were quantified by real time PCR using the primers described previously [26]. The amount of binding of protein to a specific promoter or gene region is expressed as percentage of DNA immunoprecipitated by either the specific antibody or IgG (right most set of bars), as compared to the total chromosomal DNA before immunoprecipitation. Error bars represent standard deviation from two independent experiments. (B) Immunoblotting from a representative experiment, showing the levels of total cellular pSer6HMGN1 and HMGN1 with and without estrogen treatment.