Collagen, one of the most abundant proteins of the extracellular matrix, plays a dual biological role as a structural protein that provides tensile strength to connective tissues throughout the human body, and as a highly biologically active protein that is responsible for multiple interactions with cells and other matrix molecules to achieve biological functions. Collagen-protein interactions often lead to conformational changes in the protein partners, which in some cases lead to functional states, such as the activation of integrin for platelet adhesion, or may be detrimental and cause protein misfolding diseases, such as dialysis related amyloidosis (DRA) as a result of ?2-microglobulin (?2m) amyloid formation. Many common diseases, such as arthritis, diabetes, and cancer involve abnormal regulation of collagen or collagen interactions. The objectives of this proposal are to understand the role of collagen sequence and architecture in 1) regulation of functional proteins and 2) facilitation of protein misfolding diseases. We propose to use a multifaceted approach integrating NMR, computational methods, microscopy, biological adhesion assays, and other biophysical methods to provide unique structural and dynamic insights into the molecular basis of collagen interactions with the integrin ?2I domain and ?2m.
The specific aims of the proposal include 1) understanding how collagen regulates integrin binding through its unique fibrillar architecture and 2) understanding the role of collagen in the facilitation of the protein misfolding disease DRA. In order to achieve these aims, NMR will be integrated with biophysical methodologies designed to 1) elucidate ?2I domain and ?2m binding sites on collagen monomers and fibrils, 2) probe the role of dynamics on the collagen fibril surface for the accessibility of protein partners to their binding sites using molecular dynamics and computational analyses, and 3) resolve an atomic-level description of the collagen-induced ?2m amyloid precursor on the pathway to DRA. The biomedical significance of collagen and its interactions with partner proteins has led to increasing interest in the mechanisms by which proteins access preferred binding sites and the role of collagen-induced conformational rearrangement in protein functionality. Characterizing how the ?2I domain in its different conformations accesses collagen binding sites in collagen monomer and fibril will provide unprecedented insight into collagen regulation of integrin functionality. Elucidating the mechanisms by which collagen interacts with and induces an amyloidogenic conformation of ?2m will provide critical knowledge to ultimately establish appropriate targets for drug development toward pathological amyloid inhibition.
The tremendous biomedical importance of collagen makes it an important target for understanding the molecular basis of its interactions with receptors that are involved in normal biological processes such as platelet aggregation and cell development, and those that are involved in disease such as arthritis, cancer and heart disease. These studies will set the stage for developing drug targets against debilitating collagen diseases, as well as using collagen as drug delivery systems and new biomaterials.
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