Identification of novel functional TBP-binding sites and general factor repertoires

We performed a comprehensive ChIP-on-chip analysis for 28 transcription factors on a large set of known and novel TBP binding sites experimentally identified via ChIP-cloning. A large fraction of identified TBP binding sites is located in introns or lacks a gene/mRNA annotation and found to direct transcription. Distinct profiles for general transcription factors and TAF-containing complexes were uncovered for RNAP II promoters located in CpG- and non-CpG islands suggesting distinct transcription initiation pathways. Keywords: TBP, Promoter, ChIP-on-chip, transcription factor profiling DNA fragments from ChIP with TBP antibodies and human U2OS cells were cloned, amplified and printed on glass slides to obtain TBP-binding sites microarray. ChIP has been performed with 28 antibodies against transcripton factors and histone marks, DNA from ChIP and input was amplified and hybridyzed on the TBP-binding sites microarray. The median ChIP/input ratios were normalized to median value of negative controls (myoglobin exons and promoter), averaged between 2 hybridizations and calculated as log2. For correlation analysis those targets with TBP ratio >2 were selected. Additionally, these targets were split to 2 datasets which contain targets overlapped and non-ovelapped with CpG islands (alignment and definition of UCSC genome browser).