Functional analysis of matriptase-2 mutations and domains: insights into the molecular basis of iron-refractory iron deficiency anemia

matriptase-2 mutations and domains: insights into the molecular basis of iron-refractory iron deficiency anemia. Am J Physiol Cell Physiol 308: C539 –C547, 2015. First published January 14, 2015; doi:10.1152/ajpcell.00264.2014.—Mutations in the TMPRSS6 gene are associated with severe iron-refractory iron deficiency anemia resulting from an overexpression of hepcidin, the key regulator of iron homeostasis. The matriptase (MT)-2 protein (encoded by the TMPRSS6 gene) regulates hepcidin expression by cleaving hemoju-velin [HJV/hemochromatosis type 2 (HFE2)], a bone morphogenetic protein (BMP) coreceptor in the hepcidin regulatory pathway. We investigated the functional consequences of five clinically associated TMPRSS6 variants and the role of MT-2 protein domains by gener-ating epitope-tagged mutant and domain-swapped MT-2-MT-1 (en-coded by the ST14 gene) chimeric constructs and expressing them in HepG2/C3A cells. We developed a novel cell culture immunofluo