Bone morphogenetic protein-2 (BMP2) enhances osteogenic differentiation of bone progenitor cells.  However, BMP-2 treatment has not been utilized extensively for bone repair and regeneration due to severe side effects caused by the large dosage of the protein required. Cartilage oligomeric matrix protein (COMP) is a non-collagenous homopentameric protein found in the extracellular matrix of cartilage, ligaments, and tendons. Prior studies have reported that stimulating progenitor cells with COMP and BMP2 mixture greatly enhanced osteogenesis. This presentation aims at providing structural evidence at the molecular level that COMP binds BMP2 molecules via multivalent interactions.  High resolution atomic force microscopy (AFM) enables visualization of the conformation of COMP, mostly in a pentameric form.  In addition, AFM topographic images reveal the number and location of BMP-2 bound on a COMP molecule.  This is the first direct and label-free evidence that BMP2 bound to the C-terminal domains of COMP. These findings, in conjunction with cellular osteogenesis assays, provide new insights on how molecular level presentation of growth factors impacts the downstream cellular signaling processes to enhance cellular differentiation for bone growth and regeneration.

Label-free direct visualization of multivalent binding of cartilage oligomeric matrix protein and bone morphogenetic protein-2

256th National Meeting (2018)

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