GSE116331
Copper and MTF1: New roles for a classic metal sensing transcription factor in myogenesis
MTF1 is a highly conserved metal-binding transcription factor in eukaryotes. MTF1 binds to DNA sequence motifs, termed metal response elements (MREs) to induce the expression of genes involved in metal and oxidative stress homeostasis. MTF1 is responsive to both metal excess and deprivation, and can also protect cells from oxidative and hypoxic stresses. Disruption of metal homeostasis leads to the development of several pathological states. Despite its roles in these processes , MTF1 has been shown to be required for developmental processes such as embryonic liver formation.  In this study, we used multiple strategies to understand the mechanism by which MTF1 functions in skeletal muscle differentiation and to determine the role cellular copper (Cu) status plays in this process. We provide the functional relationships between MTF1, Cu, myogenic gene promoters, and MyoD, an specific component of the myogenic transcriptional machinery in differentiating primary myoblasts derived from mouse satellite cells. We found that MTF1 is induced and translocated to the nucleus upon initiation of myogenesis. Consistent with previous studies from our laboratory , addition of non-toxic concentrations of Cu promote myogenesis and enhanced MTF1 expression. CRISPR/Cas9-mediated depletion of MTF1 demonstrated that MTF1 is essential for proper development of skeletal muscle, as partial Mtf1 knockdown leads to apoptosis to differentiating myoblasts. MTF1 was also found to bind Cu at a carboxy-terminal tetra-cysteine cluster, which may contribute to the mobilization of Cu to the nucleus during myogenesis. ChIP-seq and ChIP-qPCR analyses showed that MTF1 binds at the promoter regions of myogenic genes as part of a complex with MyoD, the master transcriptional regulator of the myogenic lineage. These results have the potential to initiate a new area of research in MTF1 function and in the regulation of myogenesis. Furthermore, these studies set the basis to understand the role of Cu at the transcriptional level, affects growth and development and will contribute to the largely unexplored are of muscular phenotypes observed in human pathologies associated to Cu misbalance, such as Menkes' and Wilson's diseases. Overall design: ChIP-seq profiling of MTF1 in the presence or absence of CuSO4:  24plusCu is presence of CuSO4.  24noICu and 24plusI are absence of CuSO4.