In an upcoming issue of G&D, Drs. Maria Divina Deato and Robert Tjian (HHMI, UC Berkeley) reveal that the formation of an alternative transcriptional core promoter complex directs cell-type specific differentiation during myogenesis. The article uncovers a whole new level of transcriptional control of terminal cell differentiation, and will be published online ahead of its September 1 print date at www.genesdev.org.
"For nearly 30 years, we have assumed that the basal transcription machinery, particularly the highly conserved TBP and TFIID complex, would be invariant and universal for all cell types in eukaryotes. It seems that this simplistic model will need to be revised with significant implications for mechanisms controlling multi-cellular differentiation," explains Dr. Tjian.
Skeletal muscle differentiation, or myogenesis, involves a multi-step transition from muscle precursor cells (myoblasts) to myotubes that ultimately comprise the contractile myofibers of the muscle tissue. Drs. Deato and Tjian show that during myogenesis, a component of the canonical transcription initiation machinery - a multi-subunit transcription factor called TFIID - is disassembled and replaced with an alternative core promoter recognition complex. The researchers determined that this alternative complex contains both TAF3 and TRF3, and is required for successful myogenesis.