Mobilization of Ca2+ in response to IgE receptor-mediated signaling is a key process in many aspects of mast cell function. Here we summarize our current understanding of the molecular bases for this process and the roles that it plays in physiologically relevant mast cell biology. Activation of IgE receptor signaling by antigen that crosslinks these complexes initiates Ca2+ mobilization as a fast wave that is frequently followed by a series of Ca2+ oscillations which are dependent on Ca2+ influx-mediated by coupling of the endoplasmic reticulum luminal Ca2+ sensor STIM1 to the calcium release activated calcium channel protein Orai1. Granule exocytosis depends on this process, together with the activation of protein kinase C isoforms, and specific roles for these signaling steps are beginning to be understood. Ca2+ mobilization also plays important roles in stimulated exocytosis of recycling endosomes and newly synthesized cytokines, as well as in antigen-mediated chemotaxis of rat mucosal mast cells. Phosphoinositide metabolism plays key roles in all of these processes, and we highlight these roles in several cases.
In resting and activated B-cells, IgM and IgG B-cell receptors (BCRs) reside in highly heterogeneous protein islands that vary in size and number of BCRs but intrinsically maintain a high frequency of BCR monomers. IgG BCRs are more clustered than IgM BCRs on resting cells and form larger protein islands after antigen activation.
The 5th Scientific Conference of the International Pemphigus and Pemphigoid Foundation (IPPF), “Pemphigus and Pemphigoid: A New Era of Clinical and Translational Science” was held in Orlando, Florida, on May 15–16, 2018. Scientific sessions covered recent, ongoing, and future clinical trials in pemphigus and bullous pemphigoid, disease activity and quality of life instruments, and the IPPF Natural History Study. Furthermore, the meeting provided an opportunity to hear firsthand from patients, investigators, and industry about their experience enrolling for clinical trials.
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