Figure 3.

Histone H2A.Z accumulates at the myogenin promoter early during muscle differentiation in a p18^Hamlet-dependent manner. (A) ChIP analysis of histones H2A.Z and H3 binding to the TATA box-containing region of the myogenin promoter in proliferating C2C12 myoblasts (GM) and at early times during muscle differentiation (DM) either in the presence or absence of SB203580 (SB). qPCR data are shown as means±s.d. of two independent experiments performed in triplicates. Histone-binding values are normalized to the respective input DNA and are referred to the binding of each histone under GM conditions, which is given the value of 1. (B) C2C12 myoblasts were cultured as indicated in (A), and the binding of H2A.Z, and H3 to the myogenin TATA box was analysed by ChIP followed by semiquantitative PCR. (C) Mouse wt and p38α−/− (KO) primary myoblasts were grown in GM or DM in the presence or absence of SB203580 (SB) for the indicated times. H2A.Z binding to the myogenin TATA box-containing region was analysed by ChIP and qPCR. Relative-binding values are referred to the binding in wt myoblasts under GM conditions, which is given the value of 1. (D) C2C12 myoblasts were incubated with either p18^Hamlet or H2A.Z siRNAs and then cultured in GM or incubated in DM for 14 h. MyoD binding to the myogenin TATA box region was analysed by ChIP followed by semiquantitative PCR. Analysis by qPCR of the same samples is shown in Supplementary Figure S3.