Figure 1. Screen for Bhlhb5 target genes identifies the PR/SET-domain protein, Prdm8.

A) Affymetrix microarray-based gene profiling was performed to identify genes that are misexpressed in the dorsal telencephalon of Bhlhb5^−/− mice. Three embryonic stages (E13.5, E15.5 and E17.5) were investigated, and each time point was analyzed using three independent pairs of littermate mice. Using a false discovery rate (FDR) of 0.05 or less, we identified a total of eight genes, and all of these genes were up-regulated in Bhlhb5^−/− mice (also see Figures 7A and S1). Of these, Prdm8 (shown) was the most significantly misregulated. Data are mean +/− SEM, with wild type (WT) in black and Bhlhb5^−/− in red, as indicated. B) Quantitative PCR confirms that Prdm8 mRNA transcripts are upregulated in the dorsal telencephalon of Bhlhb5^−/− mice relative to WT littermates at E17.5. Data are normalized to WT and are presented as mean +/− SEM of biological replicates. * indicates significant difference relative to controls (p < 0.05, t-test). C) Prdm8 protein is upregulated in the cortex of Bhlhb5^−/− mice at E16.5. Matched coronal sections were stained with a Prdm8 antibody raised against a GST-Prdm8 fusion protein. Also see Figure S4 for details on the generation of Prdm8 antibodies and Figure S6 for further analysis of the upregulation of Prdm8 in other regions of the nervous system and at other times during development.