Figure 4.

Mef2D and p38 regulate Pol II recruitment and progression. (A) MDER cells were transduced with control (GFP), MKK6E (K6), and/or Mef2D (2D) retroviruses, induced to differentiate 12 h and ChIP for Pol II, or P-CTD Pol II performed. The combination of Mef2D and p38 is associated with Pol II recruitment and phosphorylation. (B) MDER cells were transduced with the indicated retroviruses and induced to differentiate for 16 h. At this later time point when endogenous Mef2D and other muscle-specific Mef2 isoforms are accumulating, p38 activation induces polymerase progression and accumularion of P-CTD Pol II in the 3′ end of the gene. ChIP performed for Pol II and Ser 5-phosphorylated Pol II (P-CTD Pol II). Amplification of the gene promoter and a region in the 3′-transcribed regions of the gene (exon 7 of desmin, 6.5 kb from the promoter, and exon 27 of MHC, 19 kb from the promoter) was performed. Titrations, internal control, and graphs are as previously indicated.