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IBEC Seminar: Samuel Ojosnegros

Friday, March 11, 2016 @ 10:00 am11:00 am

Imaging Eph/ephrin cell-cell communication through Enhanced Number and Brightness: a novel method for the study of protein aggregation

Dr. Samuel Ojosnegros, Centre de Medicina Regenerativa de Barcelona (CMRB)
Proteins constantly interact with each other assembling a variety of molecular species, including small oligomers, fibers of dynamic polymerization or high-order clusters, among others. However, current methods discriminate poorly the stoichiometry of protein interactions in living cells. To overcome these impediments we developed an enhanced version of Number & Brightness (eN&B), a powerful live imaging technique with capability to investigate multiple domains of information. eN&B determines the distribution of protein aggregates present inside every pixel in an image during time-lapse movies. It can reach unprecedented level of space and time resolution compared to FRET-based or FCS-based methods. When studying EphB2 receptor activation, the eN&B allowed us to resolve simultaneously the aggregation state of 40 different oligomers in 3 dimensions (x, y, t) and pixel depth. We found that Eph oligomerization follows a sophisticated dynamics consistent with a nucleated polymerization process, where activation and clustering are decoupled processes. This decoupling endows the receptor with high sensitivity for low ligand concentrations while at the same time allows to provide a proportional response to a wide range of ligand concentrations. In summary, I will present a novel imaging tool with capability to determine the stoichiometry of receptor-ligand interactions and potentially, many other instances or protein aggregation.


Friday, March 11, 2016
10:00 am–11:00 am
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