Fig. 2

PIK3CA and PIK3R2 are direct target genes of ARID4B. a, b ChIP-Seq analysis shows enrichment of ARID4B binding to the promoters of PIK3CA (a) and PIK3R2 (b) in PC3 cells. Orange lines indicate the ARID4B binding regions. c, d Recruitment of ARID4B (c) and histone H1 (d) to the promoters of PIK3CA, PIK3R2, and MYOD1 in control and ARID4BKO PC3 cells were analyzed by ChIP-qPCR analyses using anti-ARID4B (c) or anti-H1 (d) antibodies. Normal rabbit IgG was used for comparison. e Chromatin accessibility of the PIK3CA, PIK3R2, and MYOD1 promoters to micrococcal nuclease (MNase) digestion. The PCR products on the promoter region of each gene detected by specific primer sets in qPCR are as follows: PIK3CA (PCR products 1 and 2), PIK3R2 (PCR products 3–5), and MYOD1 (c–e). See Supplementary Fig. 4e for details on regions of qPCR products. Data are means ± SEM from three experiments performed in triplicate (c–e). *P < 0.05; **P < 0.01; ***P < 0.001; NS no significant differences; Statistical analysis: t test (c–e). f A schematic representation of how ARID4B controls chromatin condensation to regulate the promoter activities of PIK3CA and PIK3R2. ARID4B maintains a relaxed chromatin structure on the promoters, leading to gene activation. Loss of ARID4B results in occupancy of histone H1 on the promoters and chromatin condensation, leading to suppression of gene transcription