Super Resolution and Receptor Clustering!

Post lunch session – on super resolution microscopy and receptor clustering.  I am really looking forward to this.

First talk by Katharina Gaus from UNSW. She studies clustering of T cell receptors. The punch line of the talk is dense T cell receptor (TCR) clusters are signaling active. In an elaborate study where they use two color super resolution imaging they quantify both the TCRs and phosphorylation events. After looking at many parameters, they find that what matters to TCR signaling is the density of TCR clusters. Signaling clusters have a higher molecular density whereas non-signaling clusters had a lower density. To establish causality, they analyzed where would the information flow from – higher density clusters to signaling or signaling to increase in cluster density. Using correlation analyses they observe that information flows from cluster density to signaling. How is the density of clusters regulated, still needs to be established.

This was followed by a talk by Gregory Giannone from CNRS, Bordeaux. Using single particle tracking in PALM they have shown that integrins are present in immobile and confined diffusion states in the focal adhesions. Further, in collaboration with Val Weavers laboratory they showed that glycocalyx, mucin would create potential wells that would promote integrin clustering in locations where integrins bind ligand. In some recent studies they show that, Kindlin is required for the motility of integrins. They generate kindlin PH deletion mutants that can’t bind to PIP3 lipids. They propose a model where kindlin brings the integrins to the adhesions sites, which could be followed by replacement of kindlin by Talin.

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