Using chromatin immunoprecipitation to monitor 1α,25-dihydroxyvitamin D3-dependent chromatin activity on the human CYP24 promoter

We applied the chromatin immunoprecipitation (ChIP) method for the analysis of 1alpha,25-dihydroxyvitamin D-3 (1,25-D-3)-dependent chromatin activity on the human 24-hydroxylase (CYP24) promoter in MCF-7 human breast cancer cells. In this pilot study we concentrated on the proximal promoter (+22 to -424) of the CYP24 gene, which includes the known 1,25-D-3 response element (VDRE) cluster. A constitutively active region of the human histone 4a gene (-40 to +285) served for normalization. Chromatin activity snapshots were taken 0, 30, 60, 120, 180, 240 and 300 min after the onset of stimulation with 1,25-D-3 and anti-acetylated histone 4 antibodies were used for ChIP. Our results suggest that ChIP is suitable for monitoring 1,25-D-3-dependent changes of chromatin organization and can be used to reveal information about chromatin activity in living cells. (C) 2004 Elsevier Ltd. All rights reserved.