Identification of novel bone morphogenetic protein- responsive elements in a hepcidin promoter.

Hepcidin plays a central role in systemic iron metabolism. The bone morphogenetic protein (BMP) pathway regulates expression of hepcidin through transcriptional activation via BMP-responsive elements (REs) 1 and 2 on the promoter. Previous studies also revealed that the BMP pathway stimulates transcription of its target genes via GC-rich sequences on the promoter. A search for GC-rich sequences on the hepcidin promoter indicated 13 regions across the distal (A to F), middle (G to I), and proximal (J to M) areas; among them, mutations of the GC-rich element found in regions B to D exhibited decreased responsiveness to ALK3(QD) expression in the presence of BMP-RE1 mutations, indicating necessity of the elements for full expression of hepcidin by the BMP pathway.