Invited Paper TR-ThA3
Molecular Mechanisms of Aqueous Boundary Lubrication by Mucinous Glycoproteins

Thursday, November 13, 2014, 3:00 pm, Room 303

In this talk I will focus on lubricin and surface zone protein, secreted, cytoprotective glycoproteins, encoded by the gene PRG4, that are essential to maintaining joint function and long-term integrity of synovial joints by providing boundary lubrication, preventing cartilage-cartilage adhesion, and mediating adsorption of cells and proteins. Specifically I will report on our results from nanotribo-mechanical measurements on model surfaces and cartilage, combined with other surface specific, physicochemical measurements that shed new light on the mechanisms by which Prg4 provides lubrication and wear protection in diarthrodial joints. Furthermore, I will report on the interaction of PRG4 with collagenous model surfaces. taken together, our results suggest that the role of effective boundary lubricants in mediating friction in articular joints is largely one of wear protection of surface asperities, by maintaining the surfaces in a nonadhesive mode and causing shear dissipation in the biopolymeric boundary lubricant layer, even at the cost of attaining “high” coefficients of friction (COF ~ 0.15). Our results also contribute to the understanding of the conformation and physico-chemical function of mucinous glycoproteins on biological interfaces.