Budhram-Mahadeo, V.S., Bowen, S., Lee, S., Perez-Sanchez, C., Ensor, E., Morris, P.J. and Latchman, D.S.
Notes: Previously, the POU domain of Brn-3a was shown to interact with p53 and increase cell survival. In this article, the authors explored the possibility that Brn-3b, which shares a POU domain 95% identical to Brn-3a, may interact with p53 and affect its role in apoptosis. To test the protein:protein interaction, GST-Brn-3b fusion protein was bound to glutathione Sepharose beads and incubated with 35S-methionine labeled full-length or truncated p53, prepared using the TNT® T7 rabbit reticulocyte lysate. The luciferase control included in the kit was used as the noninteracting protein control. After washing, the bound proteins were resolved by 12% SDS-PAGE, and the bands examined by radiography. To examine the effect of Brn-3b on two p53-regulated genes, Bax and p21cip1/waf1, ND7 cells were transiently transfected with empty vector, Brn-3b, Brn-3a or p53, or Brn-3 with p53. The reporter gene cotransfected was under the control of wildtype Bax, wildtype p21cip1/waf1, or mutant Bax. A control vector (Renilla luciferase driven by the thymidine kinase promoter) was used for normalization. Forty-eight hours posttransfection, the cells were harvested and reporter levels assessed using the Dual-Luciferase® Reporter Assay System. (3597)