Analysis of Wdr68 function during cellular differentiation in mouse myoblast C2C12 Cells

Skeletal muscle development requires activation of myogenic regulatory factors including MEF2. In C2C12 cells the Dyrk1b-Wdr68 complex is important for myog expression during differentiation. Therefore we hypothesized that wdr68 is able to modulate reporter activity in differentiating C2C12 cells. Wdr68 enhancement of myog-luciferase activity was blocked by a Nuclear Export Signal or transcriptional repression domain. Physical complexes of MEKK1-Wdr68-Dyrk1b have been reported. Therefore we tested whether interference with MEKK1 would alter myog-luciferase activity. Although the dnMEKK1 construct enhanced myog-luciferase activity by itself, neither it nor MEKK1 alter the Wdr68-mediated increase in myog-luciferase activity. Recent findings in plants suggest Wdr68 orthologs may tether to promoter regions of target genes. Therefore, we hypothesized that Gal4Wdr68 would modulate GAL4/UAS reporter in C2C12 cells. We found that Gal4Wdr68 increased reporter activity 3-fold above Gal4DBD alone during cellular differentiation. Thus Wdr68 functions in the cell nucleus to enhance transcription of downstream target genes independent of MEKK1 activity