Matriptase-2- and proprotein convertase-cleaved forms of hemojuvelin have different roles in the down-regulation of hepcidin expression

J Biol Chem. 2010 Dec 10;285(50):39021-8. doi: 10.1074/jbc.M110.183160. Epub 2010 Oct 11.

Abstract

Hemojuvelin (HJV) is an important regulator of iron metabolism. Membrane-anchored HJV up-regulates expression of the iron regulatory hormone, hepcidin, through the bone morphogenic protein (BMP) signaling pathway by acting as a BMP co-receptor. HJV can be cleaved by the furin family of proprotein convertases, which releases a soluble form of HJV that suppresses BMP signaling and hepcidin expression by acting as a decoy that competes with membrane HJV for BMP ligands. Recent studies indicate that matriptase-2 binds and degrades HJV, leading to a decrease in cell surface HJV. In the present work, we show that matriptase-2 cleaves HJV at Arg(288), which produces one major soluble form of HJV. This shed form of HJV has decreased ability to bind BMP6 and does not suppress BMP6-induced hepcidin expression. These results suggest that the matriptase-2 and proprotein convertase-cleavage products have different roles in the regulation of hepcidin expression.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antimicrobial Cationic Peptides / biosynthesis*
  • Arginine / chemistry
  • GPI-Linked Proteins / chemistry*
  • Gene Expression Regulation, Enzymologic*
  • Hemochromatosis / genetics*
  • Hemochromatosis / metabolism
  • Hemochromatosis Protein
  • Hepcidins
  • Humans
  • Iron / metabolism
  • Membrane Proteins / metabolism*
  • Mutation
  • Proprotein Convertases / metabolism*
  • Protein Binding
  • RNA, Small Interfering / metabolism
  • Rats
  • Serine Endopeptidases / metabolism*
  • Tissue Distribution

Substances

  • Antimicrobial Cationic Peptides
  • GPI-Linked Proteins
  • HAMP protein, human
  • HJV protein, human
  • Hamp protein, rat
  • Hemochromatosis Protein
  • Hepcidins
  • Membrane Proteins
  • RNA, Small Interfering
  • Arginine
  • Iron
  • Proprotein Convertases
  • Serine Endopeptidases
  • matriptase 2