Crystal structure and receptor-interacting residues of MYDGF — a protein mediating ischemic tissue repair

Myeloid-derived growth factor (MYDGF) is a paracrine-acting protein that is produced by bone marrow-derived monocytes and macrophages to protect and repair the heart after myocardial infarction (MI). This effect can be used for the development of protein-based therapies for ischemic tissue repair, also beyond the sole application in heart tissue. Here, we report the X-ray structure of MYDGF and identify its functionally relevant receptor binding epitope. MYDGF consists of a 10-stranded β-sandwich with a folding topology showing no similarities to other cytokines or growth factors. By characterizing the epitope of a neutralizing antibody and utilizing functional assays to study the activity of surface patch-mutations, we were able to localize the receptor interaction interface to a region around two surface tyrosine residues 71 and 73 and an adjacent prominent loop structure of residues 97–101. These findings enable structure-guided protein engineering to develop modified MYDGF variants with potentially improved properties for clinical use. Myeloid-derived growth factor (MYDGF) is an angiogenic growth factor with therapeutic potential for ischemic tissue repair and the receptor is still unknown. Here the authors present the crystal structure of human MYDGF and identify its functional epitope through mutagenesis studies.