FIG. 1.

Identification of a CRE-like element in the MuSK promoter. (A) Schematic diagram of M715-Luc. The CRE-like element, located between −648 and −641, has the consensus sequence of the CRE element (24). (B) Interaction of the CRE-like element with CREB1 in ChIP assays. Chromatin preparations of C2C12 myotubes were incubated without (No Ab) or with antibodies against CREB1 or p300. Immunopurified DNA was used as the template for PCR amplification using primers against the indicated products. (C) Binding of the CRE-like element to purified CREB1. A 50-bp DNA fragment flanking the CRE-like element of the MuSK promoter was labeled with [γ-³²P]ATP by PNK. The labeled probe was incubated with various amounts of purified His-CREB1 without or with excess wild-type unlabeled probes. The reaction mixture was resolved on a nondenaturing polyacrylamide gel. (D) Supershift of the CRE probe-CREB1 complex in the presence of anti-CREB1 antibodies.