title: Mitochondrial [Ca(2+)] oscillations driven by local high [Ca(2+)] domains generated by spontaneous electric activity.
abstract: Mitochondria take up calcium during cell activation thus shaping Ca(2+) signaling and exocytosis. In turn, Ca(2+) uptake by mitochondria increases respiration and ATP synthesis. Targeted aequorins are excellent Ca(2+) probes for subcellular analysis, but single-cell imaging has proven difficult. Here we combine virus-based expression of targeted aequorins with photon-counting imaging to resolve dynamics of the cytosolic, mitochondrial, and nuclear Ca(2+) signals at the single-cell level in anterior pituitary cells. These cells exhibit spontaneous electric activity and cytosolic Ca(2+) oscillations that are responsible for basal secretion of pituitary hormones and are modulated by hypophysiotrophic factors. Aequorin reported spontaneous [Ca(2+)] oscillations in all the three compartments, bulk cytosol, nucleus, and mitochondria. Interestingly, a fraction of mitochondria underwent much larger [Ca(2+)] oscillations, which were driven by local high [Ca(2+)] domains generated by the spontaneous electric activity. These oscillations were large enough to stimulate respiration, providing the basis for local tune-up of mitochondrial function by the Ca(2+) signal.
authors.affiliation: Instituto de Biologia y Genética Molecular (IBGM), Universidad de Valladolid and Consejo Superior de Investigaciones Cientificas, Departamento de Fisiologia y Bioquimica, Facultad de Medicina, E-47005 Valladolid, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Villalobos
authors.forename: L
authors.initials: L
authors.lastname: Núñez
authors.forename: P
authors.initials: P
authors.lastname: Chamero
authors.forename: M T
authors.initials: MT
authors.lastname: Alonso
authors.forename: J
authors.initials: J
authors.lastname: García-Sancho
mesh_terms: D000331:Aequorin / Q000096:biosynthesis / Q000235:genetics; D000818:Animals; D020013:Calcium Signaling; D004594:Electrophysiology; D007091:Image Processing, Computer-Assisted; D008163:Luminescent Measurements; D008928:Mitochondria / Q000378:metabolism*; D010101:Oxygen Consumption; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000378:metabolism*; D010907:Pituitary Hormones / Q000378:metabolism; D051381:Rats
chemical_list: D010907:Pituitary Hormones; D000331:Aequorin