NFATc1 activates the acetylcholinesterase promoter in rat muscle

Nuclear factor of activated T-cells (NFAT) plays a role in the response of muscle to chronic contractile activity that can result in fiber type switching and hypertrophy. These effects are due in part to activation of target genes following Ca2+-mediated nuclear translocation of NFAT. Acetylcholinesterase (AChE), a component of the neuromuscular junction, is regulated by chronic muscle and nerve activity through changes in intracellular Ca2+, suggesting that the Ache gene may be a potential downstream target of NFAT signaling. To determine whether elements of the Ache promoter are modulated by NFAT, we transiently co-expressed reporter constructs driven by fragments of the Ache promoter with an NFATc1 that is constitutively translocated to the nucleus [NFATc1(S --> A)] in rat muscle cultures. NFATc1 potentiated reporter activity when co-transfected with constructs containing Ache genomic elements from -1280 to -490 bp upstream of transcription initiation. Electrophoretic mobility shift assays demonstrated strong binding to a potential NFAT element at -793 bp and weaker binding to one at -678 bp. Co-transfection of promoter fragments, containing the binding sites at -793 and at -678 bp, with NFATc1(S --> A) potentiated reporter activity, supporting sites of interaction with NFAT. Our data suggests a role for NFAT as a modulator of Ache gene transcription.