Periostin Is a Disulfide-Bonded Homodimer and Forms\na Complex with Fibronectin in the Human Skin

The protein periostin is a matricellular\nprotein that is expressed\nin connective tissue. It is composed of five globular domains arranged\nin an elongated structure with an extensive disordered C-terminal\ntail. Periostin contains 11 cysteine residues, of which one is unpaired\nand the rest form five intramolecular disulfide bonds. Periostin plays\nan important role during wound healing and is also involved in driving\nthe inflammatory state in atopic diseases. This study provides a comprehensive\nbiochemical characterization of periostin in human skin and in dermal\nand pulmonary fibroblasts <i>in vitro</i>. Through the application\nof Western blotting, co-immunoprecipitation, and LC-MS/MS, we show\nfor the first time that periostin is a disulfide-bonded homodimer\nand engages in a novel disulfide-bonded complex with fibronectin both <i>in vivo</i> and <i>in vitro</i>. This inherent characteristic\nof periostin holds the potential to redefine our approach to exploring\nand understanding its functional role in future research endeavors.