Groucho/transducin-like Enhancer of split (TLE) family members interact with the yeast transcriptional co-repressor SSN6 and mammalian SSN6-related proteins: implications for evolutionary conservation of transcription repression mechanisms

The yeast proteins TUP1 and SSN6 form a transcription repressor complex tha t is recruited to different promoters via pathway-specific DNA-binding prot eins and regulates the expression of a variety of genes. TUP1 is functional ly related to invertebrate and vertebrate transcriptional repressors of the Groucho/transducin-like Enhancer of split (TLE) family. The aim was to exa mine whether similar mechanisms underlie the transcription repression funct ions of TUP1 and Groucho/TLEs by determining whether TLE family members can interact with yeast SSN6 and mammalian SSN6-like proteins. It is shown in the present work that SSN6 binds to TLE1 and mediates transcriptional repre ssion when expressed in mammalian cells. Moreover, TLE1 and TLE2 interact w ith two mammalian proteins related to SSN6, designated as the products of t he ubiquitously transcribed tetratricopeptide-repeat genes on the Y (or X) chromosomes (UTY/X). These findings suggest that mammalian TLE and UTY/X pr oteins may mediate repression mechanisms similar to those performed by TUP1 -SSN6 in yeast.