Cell Biology & Genetics Research Center

endothelial cells A revised model for the secretion of tPA and cytokines from cultured http://bloodjournal.hematologylibrary.org/content/116/12/2183.full.html Updated information and services can be found at: (249 articles) Vascular Biology Articles on similar topics can be found in the following Blood collections http://bloodjournal.hematologylibrary.org/site/misc/rights.xhtml#repub_requests

protein Von Willebrand factor (VWF), however, under specific conditions WPBs also contain a cocktail of small pro-inflammatory cytokines. WPB exocytosis is driven by an increase in intracellular free calcium ion concentration ([Ca 2þ ] i ); the majority of WPB fusion events result in complete discharge of cargo components, however, in a small fraction of cases cytokines are selectively released indicating that the fusion pore may act as a molecular size filter. Carbon fibre amperometry has been used to characterize fusion pore behavior in a number of cell types, but to date this approach has not been applied to WPBs. Therefore, we used this technique in combination with simultaneous optical imaging of fluorescent WPB exocytosis and changes in [Ca 2þ ] i and can report, for the first time, the kinetic properties of WPB fusion pore formation and expansion in human cultured endothelial cells. A clear delay (mean~50 ms) is seen between the onset of the current spike and the increase in intra-WPB EGFP fluorescence indicating that WPB alkalinsation is delayed by the strong proton buffering capacity of the WPB lumen (55 mM/pH unit). Analysis of current spike parameters reveal a mean 25-75% rise time, peak amplitude and decay time of 1.63 ms, 50 pA and 6.63 ms respectively. Approximately 50% of current spikes were preceded by a foot signal of mean duration 6.34 ms. Occasional low amplitude, prolonged current increases, reminiscent of stand alone foot signals, were observed in conjunction with morphological rounding of WPBs, possibly reflecting kiss-and-run or lingering kiss fusion events. Following characterization of the WPB fusion pore under control conditions the impact of changing cellular parameters, including cholesterol levels, was also assessed.

interaction with the Rab27A effector Slp4-a STXBP1 promotes Weibel-Palade body exocytosis through its http://bloodjournal.hematologylibrary.org/content/123/20/3185.full.html Updated information and services can be found at: (450 articles) Vascular Biology (702 articles) Thrombosis and Hemostasis Articles on similar topics can be found in the following Blood collections http://bloodjournal.hematologylibrary.

The antigen-specific binding of T cells to antigen presenting cells results in recruitment of signalling proteins to microclusters at the cellcell interface known as the immunological synapse (IS). The Vav1 guanine nucleotide exchange factor plays a critical role in T cell antigen receptor (TCR) signalling, leading to the activation of multiple pathways. We now show that it is recruited to microclusters and to the IS in primary CD4 + and CD8 + T cells. Furthermore, we show that this recruitment depends on the SH2 and C-terminal SH3 (SH3 B ) domains of Vav1, and on phosphotyrosines 112 and 128 of the SLP76 adaptor protein. Biophysical measurements show that Vav1 binds directly to these residues on SLP76 and that efficient binding depends on the SH2 and SH3 B domains of Vav1. Finally, we show that the same two domains are critical for the phosphorylation of Vav1 and its signalling function in TCR-induced calcium flux. We propose that Vav1 is recruited to the IS by binding to SLP76 and that this interaction is critical for the transduction of signals leading to calcium flux.