Special Seminar Tuesday, December 15

Speaker:
Ben Ovryn, Ph.D.
Associate Professor
Department of Anatomy and Structural Biology
Gruss-Lipper Biophotonics Center
Albert Einstein College of Medicine

 

Title:
Modeling and single molecule tracking of glycoprotein motility in the vicinity of integrin adhesions and on membrane connections between cells.

 

Location:
Fenster Hall Room 698

 

Time:
10:00 -- 11:00 AM

 

Abstract:
  The surface of all eukaryotic cells is covered with a dense layer of glycans. Although cell surface glycoproteins affect numerous physiological processes and aberrant cell-surface glycosylation has been implicated in cancer, inflammation and other diseases, the functions of glycans remain poorly understood. Using a combination of bioorthogonal click reactions, super-resolution imaging, interference microscopy and single molecule tracking, we are able to observe the dynamics of cell-surface glycans on live cells with high spatial and temporal resolution. With these tools, we seek to unravel the mechanisms that govern the interactions of glycoproteins with integrins at cell-matrix adhesions and the role of glycoproteins in cell-cell interactions.

     Because glycoproteins are considerably longer than integrins, they should locally inhibit integrins from binding to ligands on the extracellular matrix. We have developed a model which incorporates the energetics that govern the nucleation, growth and disassembly of early integrin adhesions in the presence of these long repeller molecules and we seek experimental verification of several of our model predictions. Among the glycoproteins that diffuse on the cell surface with extensions into the extracellular space, we are particularly interested in imaging heparan sulfate proteoglycans; these molecules are known to play a role in adhesion and mechanotransduction, but their interactions with integrins are not yet understood.

     Our experimental approach has also enabled us to visualize the dynamic nature of tunneling nanotubes connections between cells and to track the movement of glycosylated receptors along the surface of these membranes with single molecule resolution. We are exploring the implications of the observed viscoelastic behavior associated with these nanotubes.