Meloni, A., Fiorillo, E., Corda, D., Incani, F., Serra, M.L., Contini, A., Cao, A. and Rosatelli, M.C.
Notes: The authors used a yeast two-hybrid system to identify proteins that interact with the autoimmune regulator (AIRE) protein. DAXX, a multifunctional protein involved in apoptosis and transcription regulation, interacts with AIRE, as shown through coimmunoprecipitation and colocalization studies. Colocalization of AIRE and DAXX in HeLa cells was demonstrated by confocal microscopy using a Monster Green® Fluorescent Protein-AIRE fusion protein and endogenous DAXX, which was detected using an anti-DAXX primary antibody and an anti-rabbit secondary antibody conjugated with Texas Red fluorophore. However, AIRE and DAXX did not interact in vitro in a GST pull-down assay using a GST-AIRE construct, radiolabeled DAXX protein expressed in a TNT® system, and MagneGST™ Glutathione Particles, leading the authors to speculate that the interaction is weak or there are scaffold proteins required for protein interaction. To examine the effect of DAXX on AIRE transcriptional activity, the authors transfected COS-1 and HeLa cells with AIRE and DAXX expression constructs and a luciferase reporter plasmid with the human insulin promoter, then performed Dual Luciferase® Reporter Assays. AIRE induced transcription of the insulin promoter, but coexpression of DAXX suppressed this transcriptional activation. (4153)