Tmprss6, also known as matriptase-2, is a serine protease belonging to the type II transmembrane serine protease family. It is highly expressed in the liver and plays a crucial role in iron homeostasis. Tmprss6 functions as a negative regulator of the systemic iron-regulatory hormone hepcidin [1,3]. Mutations in Tmprss6 disrupt the normal regulation of hepcidin, which is central to the body's iron regulation pathway, controlling serum iron levels by degrading ferroportin in enterocytes and macrophages [4].

In 2008, mutations in Tmprss6 were shown to be the cause of iron-refractory iron deficiency anemia (IRIDA) in both humans and mouse models [1]. This discovery demonstrated that Tmprss6 is essential for normal iron metabolism. Additionally, Tmprss6 is expressed as 4 isoforms in humans. Isoform 2 downregulates hepcidin production by cleaving hemojuvelin and other surface proteins of hepatocytes, while isoforms 3 and 4, although catalytically impaired, can reduce the proteolytic activity of isoform 2 and interact with it. Moreover, 49 potential protein partners common to Tmprss6 isoforms, including TfR1 involved in iron regulation, were identified. TfR1 can be cleaved and shed from the cell surface when co-expressed with Tmprss6 [2].

In conclusion, Tmprss6 is a key regulator of iron homeostasis, mainly through its negative regulation of hepcidin. The identification of Tmprss6 mutations causing IRIDA in mouse models has been instrumental in understanding the role of Tmprss6 in iron-related diseases. These findings provide a basis for developing new therapeutic approaches for disorders of erythropoiesis and iron homeostasis [1].

References:

1. Ganz, Tomas, Nemeth, Elizabeta, Rivella, Stefano, Monia, Brett P, Barrett, Terrance D. 2023. TMPRSS6 as a Therapeutic Target for Disorders of Erythropoiesis and Iron Homeostasis. In Advances in therapy, 40, 1317-1333. doi:10.1007/s12325-022-02421-w. https://pubmed.ncbi.nlm.nih.gov/36690839/

2. Dion, Sébastien P, Désilets, Antoine, Lemieux, Gabriel, Leduc, Richard. 2022. Functionally impaired isoforms regulate TMPRSS6 proteolytic activity. In PloS one, 17, e0273825. doi:10.1371/journal.pone.0273825. https://pubmed.ncbi.nlm.nih.gov/36044454/

3. Wang, Chia-Yu, Meynard, Delphine, Lin, Herbert Y. 2014. The role of TMPRSS6/matriptase-2 in iron regulation and anemia. In Frontiers in pharmacology, 5, 114. doi:10.3389/fphar.2014.00114. https://pubmed.ncbi.nlm.nih.gov/24966834/

4. Camaschella, Clara, Nai, Antonella, Silvestri, Laura. 2020. Iron metabolism and iron disorders revisited in the hepcidin era. In Haematologica, 105, 260-272. doi:10.3324/haematol.2019.232124. https://pubmed.ncbi.nlm.nih.gov/31949017/