Figure 3.

Chromatin remodelling factor-mediated regulation of cardiac transcription factors. (A) In the absence of Baf60c, the cardiac transcription factors Gata4, Mef2c, and Tbx5 may not have access to their target genes. The highly condensed euchromatin in which the DNA is tightly wrapped around histones makes transcription factors inaccessible to regulatory DNA, thereby represses transcription. (B) Chromatin remodelling factors modify chromatin organization by unwinding DNA from the histones, making target sequences accessible for transcription factors. Baf60c acts as a bridge to bring the Brg1 complex together with the transcription factors Tbx5 and Gata4 in a tissue-specific manner. (C) Heart-restricted expression of Baf60c and Brg1 shown by immunostaining. (D) Expression of Smarcd3 (encoding Baf60c) restricted to cardiogenic mesoderm and the developing heart shown by in situ hybridization (adapted from Lickert et al.⁵⁶).