Matriptase-2 (TMPRSS6) is directly up-regulated by hypoxia inducible factor-1: identification of a hypoxia-responsive element in the TMPRSS6 promoter region

The type II transmembrane serine protease matriptase-2 (TMPRSS6) down-regulates the expression of hepcidin, the main regulator of systemic iron homeostasis, and increases in this way iron plasma levels. Matriptase-2 is up-regulated under hypoxic conditions, providing a new link between hypoxia signaling and iron homeostasis. In this study, we have characterized the TMPRSS6 promoter region and identified a functional hypoxia-responsive element (HRE). Mutations of the hypoxia inducible factor (HIF)-binding site located within the HRE abrogate HIF-1α-dependent induction of TMPRSS6 expression. The action of HIF-1α on TMPRSS6 promoter activity reveals a new regulative element for the suppression of hepcidin synthesis.