Function of methyltransferase-deficient ASH1.

(A) Effect of ASH1 and its mutants on endogenous HoxC8 (closed bars) and HoxB6 (open bars) genes in K562 cells. Catalytically inactive ASH1H2113K augments endogenous Hox genes. Data represent triplicate K562 samples and error bars indicate standard deviation. Endogenous HoxC8 activation by ASH1H2113K is statistically significant (*: p-value < 0.05). (B) Top: a reporter construct harbouring GAL4 binding sequences (x4) and c-fos promoter. Bottom: Expression vectors carrying GAL4-DNA binding domain (DBD), DBD fused to wild type ASH1 SET domain (DBD-ASH1), or DBD fused to catalytically inactive ASH1 SET domain (DBD-H2113K) were co-transfected with the reporter into HeLa cells. Wild type ASH1 SET domain is approximately 3-fold less efficient than catalytically inactive ASH1 SET domain, suggesting that K36 methylation attenuates transcription. Data represent triplicate HeLa samples and error bars indicate standard deviation. Differences between DBD and DBD-ASH1 and between DBD-ASH1 and DBD-H2113K were statistically significant (*: p-value < 0.01).