A novel EID-1 family member, EID-2, associates with histone deacetylases and inhibits muscle differentiation.

An EID-1 (E1A-like inhibitor of differentiation-1) inhibits differentiation by blocking the histone acetyltransferase activity of p300. Here we report a novel inhibitor of differentiation exhibiting homology to EID-1, termed EID-2 (EID-1-like inhibitor of differentiation-2). EID-2 inhibited MyoD-dependent transcription and muscle differentiation. Unlike EID-1, EID-2 did not block p300 activity. Interestingly, EID-2 associated with class I histone deacetylases (HDACs). The N-terminal portion of EID-2 was required for the binding to HDACs. This region was also involved in the transcriptional repression and nuclear localization, suggesting the importance of the involvement of HDACs in the EID-2 function. These results indicate a new family of differentiation inhibitors, although there are several differences in the biochemical mechanisms between EID-2 and EID-1.