Department of Physiology and Biophysics, University of California, Irvine, United States
Amit Jairaman
Department of Physiology and Biophysics, University of California, Irvine, United States
Jonathan Skupsky
Department of Physiology and Biophysics, University of California, Irvine, United States; Department of Medicine, University of California, Irvine, United States
Angel Zavala
Department of Physiology and Biophysics, University of California, Irvine, United States
Ian Parker
Department of Physiology and Biophysics, University of California, Irvine, United States; Department of Neurobiology & Behavior, University of California, Irvine, United States
Joseph L Dynes
Department of Physiology and Biophysics, University of California, Irvine, United States
Department of Physiology and Biophysics, University of California, Irvine, United States; Institute for Immunology, University of California, Irvine, United States
Calcium is an essential cellular messenger that regulates numerous functions in living organisms. Here, we describe development and characterization of ‘Salsa6f’, a fusion of GCaMP6f and tdTomato optimized for cell tracking while monitoring cytosolic Ca2+, and a transgenic Ca2+ reporter mouse with Salsa6f targeted to the Rosa26 locus for Cre-dependent expression in specific cell types. The development and function of T cells was unaffected in Cd4-Salsa6f mice. We describe Ca2+ signals reported by Salsa6f during T cell receptor activation in naive T cells, helper Th17 T cells and regulatory T cells, and Ca2+ signals mediated in T cells by an activator of mechanosensitive Piezo1 channels. Transgenic expression of Salsa6f enables ratiometric imaging of Ca2+ signals in complex tissue environments found in vivo. Two-photon imaging of migrating T cells in the steady-state lymph node revealed both cell-wide and localized sub-cellular Ca2+ transients (‘sparkles’) as cells migrate.
