Grant: CIHR Fellowship

Iron is an essential nutrient for all living organisms: it is necessary for oxygen transport using the carrier protein hemoglobin and in metabolic reactions. Iron deficiency can lead to several severe pathologies such as anemia, while in excess it is toxic. Globally, anemia affects 1.62 billion people worldwide and half of which are preschool-age children. Matriptase-2 is a recently identified member of the type II transmembrane serine protease (TTSP) family. It is an enzyme predominantly located at the surface of liver cells and is capable of cutting other proteins to generate peptide fragments. Recent studies suggest that these peptide fragments are able to modulate iron balance and in an overactive state can lead to anemia. My working hypothesis is that Matriptase-2 is an essential regulator of iron homeostasis through its generation of novel signaling peptides. To confirm this hypothesis, Matriptase-2 targets in an anemia mouse model will be identified. Genetically modified mice that do not produce Matriptase-2, and their wild-type counterparts (control) will be employed. A comparison between the proteins contained in the outside environment of liver cells from each mouse strain will identify differences specific to the presence of Matriptase-2. To enrich for peptide fragments, a technique developed in our laboratory known as TAILS (Terminal Amine Isotopic Labeling of Substrate) will be applied. TAILS utilizes an in-house developed polymer to specifically select isotopically labeled N-termini. This enrichment will allow a better and specific identification of cleaved neo N-termini of natural protease substrates by mass spectrometry. Potential substrates will be identified and the direct action of the protease will be confirmed using standard biochemical techniques. The identification of the mechanisms by which Matriptase-2 influences the regulation of iron homeostasis will inform the rational development new drugs for iron deficiency and toxicity treatment.