Identification and Characterization of the Protein Interaction between ASXL2 and WTIP
thesisposted on 02.03.2015, 00:00 by Farida F. Khan
Epigenetics refers to mechanisms that alter gene expression patterns without changes to the DNA sequence. Polycomb group (PcG) and trithorax group (TrxG) proteins are epigenetic factors that function in transcriptional repression and activation, respectively. ASXL2 is an epigenetic factor involved in PcG-mediated gene regulation in the heart. Using a mutant mouse model, our lab has shown that ASXL2 is required for proper heart development and function. Here, I show evidence that ASXL2 interacts with a member of the ZYXIN family of LIM domain-containing proteins, WTIP. ASXL2 and WTIP genetically interact in yeast, co-immunoprecipitate in mammalian cells and show direct interaction in vitro. Furthermore, we have discovered that a C-terminal region of ASXL2 functions as a transcriptional co-activator for retinoic acid (RA)-dependent luciferase activity and that WTIP blocks that effect. LIM domains 2 and 3 of WTIP were necessary and sufficient for repression of RA-dependent transcription. Additionally, WTIP is expressed in mouse primary epicardial cells and E18.5 mouse heart sections. Asxl2 was also shown to be expressed in a mouse epicardial cell line. These results suggest that ASXL2 and WTIP may play an important role in the regulation of RA signaling in the developing mouse heart.