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Show 90 outlined in the next section. It is worth noting that, although initially characterized in astrocytes, microglia and neurons, the PC::G5-tdT line should not be restricted for use in neuroscience research. In fact, the some of the most "calcium active" cells in the body are muscle cells (Vergara and DiFranco, 1992). Bone, kidney and pancreatic cells all exhibit significant calcium activity (Lu et al., 2012; Marciniak et al., 2014). Dynamical calcium imaging via GECIs has been underutilized in these fields and could provide significant insight into organ-specific physiology, especially if applied in vivo. The nephrology field has already recognized the utility of GECI reporter lines, including the PC::G5-tdT mouse (Peti-Peterdi et al., 2015). Possible roles of astrocyte calcium signaling There are many types of cytosolic calcium signals in astrocytes. In general, these can be categorized by origin- calcium may either enter the cytosol from extracellular space or via highly concentrated intracellular stores such as endoplasmic reticula (ER) or mitochondria. The type of signal can further be categorized by route of entry such as the type of channel or exchanger which is used for transmembrane transport or by a receptor in the upstream signaling pathway such as metabotropic membrane receptors. The type of information which is transmitted via calcium is likely dependent on more complex spatial and temporal dynamics and localization of receptors relative to the cell and to nearby intracellular structures. Astrocytes express a large array of neurotransmitter receptors, many of which are GPCRs (Porter and McCarthy, 1997). Gq-GPCRs signal through IP3- dependent release of calcium from ER stores. Because Gq-GPCR cascades are similar between receptor types, the high number of ligands which act through Gq-GPCRs must transmit information through localization and association with specific intracellular |
