Cardiac Hamp mRNA Is Predominantly Expressed in the Right Atrium and Does Not Respond to Iron

Hepcidin is a liver-derived hormone that controls systemic iron traffic. It is also expressed in the heart, where it acts locally. We utilized cell and mouse models to study the regulation, expression, and function of cardiac hepcidin. Hepcidin-encoding mRNA was induced upon differentiation of C2C12 cells to a cardiomyocyte-like phenotype and was not further stimulated by BMP6, BMP2, or IL-6, the major inducers of hepatic hepcidin. The mRNAs encoding hepcidin and its upstream regulator hemojuvelin (Hjv) are primarily expressed in the atria of the heart, with ~20-fold higher mRNA levels in the right vs. left atrium and negligible expression in the ventricles and apex. Hjv mice, a model of hemochromatosis due to suppression of liver hepcidin, exhibit only modest cardiac deficiency and minor cardiac dysfunction. Dietary iron manipulations did not significantly affect cardiac mRNA in the atria of wild-type or Hjv mice. Two weeks following myocardial infarction, was robustly induced in the liver and heart apex but not atria, possibly in response to inflammation. We conclude that cardiac is predominantly expressed in the right atrium and is partially regulated by Hjv; however, it does not respond to iron and other inducers of hepatic hepcidin.