Navas-Navarro, P., Rojo-Ruiz, J., Rodriguez-Prados, M., Ganfornina, M.D., Looger, L.L., Alonso, M.T., García-Sancho, J. (2016). GFP-Aequorin Protein Sensor for Ex Vivo and In Vivo Imaging of Ca[2+] Dynamics in High-Ca[2+] Organelles.  Cell Chem. Biol. 23(6): 738--745.

FBrf0241114

Research paper

Proper functioning of organelles such as the ER or the Golgi apparatus requires luminal accumulation of Ca(2+) at high concentrations. Here we describe a ratiometric low-affinity Ca(2+) sensor of the GFP-aequorin protein (GAP) family optimized for measurements in high-Ca(2+) concentration environments. Transgenic animals expressing the ER-targeted sensor allowed monitoring of Ca(2+) signals inside the organelle. The use of the sensor was demonstrated under three experimental paradigms: (1) ER Ca(2+) oscillations in cultured astrocytes, (2) ex vivo functional mapping of cholinergic receptors triggering ER Ca(2+) release in acute hippocampal slices from transgenic mice, and (3) in vivo sarcoplasmic reticulum Ca(2+) dynamics in the muscle of transgenic flies. Our results provide proof of the suitability of the new biosensors to monitor Ca(2+) dynamics inside intracellular organelles under physiological conditions and open an avenue to explore complex Ca(2+) signaling in animal models of health and disease.