title: Calcium microdomains in mitochondria and nucleus.
abstract: Endomembranes modify the progression of the cytosolic Ca(2+) wave and contribute to generate Ca(2+) microdomains, both in the cytosol and inside the own organella. The concentration of Ca(2+) in the cytosol ([Ca(2+)](C)), the mitochondria ([Ca(2+)](M)) and the nucleus ([Ca(2+)](N)) are similar at rest, but may become very different during cell activation. Mitochondria avidly take up Ca(2+) from the high [Ca(2+)](C) microdomains generated during cell activation near Ca(2+) channels of the plasma membrane and/or the endomembranes and prevent propagation of the high Ca(2+) signal to the bulk cytosol. This shaping of [Ca(2+)](C) signaling is essential for independent regulation of compartmentalized cell functions. On the other hand, a high [Ca(2+)](M) signal is generated selectively in the mitochondria close to the active areas, which tunes up respiration to the increased local needs. The progression of the [Ca(2+)](C) signal to the nucleus may be dampened by mitochondria, the nuclear envelope or higher buffering power inside the nucleoplasm. On the other hand, selective [Ca(2+)](N) signals could be generated by direct release of stored Ca(2+) into the nucleoplasm. Ca(2+) release could even be restricted to subnuclear domains. Putative Ca(2+) stores include the nuclear envelope, their invaginations inside the nucleoplasm (nucleoplasmic reticulum) and nuclear microvesicles. Inositol trisphosphate, cyclic ADP-ribose and nicotinic acid adenine dinucleotide phosphate have all been reported to produce release of Ca(2+) into the nucleoplasm, but contribution of these mechanisms under physiological conditions is still uncertain.
authors.affiliation: Instituto de Biología y Genética Molecular (IBGM), Universidad de Valladolid and Consejo Superior de Investigaciones Científicas (CSIC), c/Sanz y Forés s/n, Valladolid, Spain.
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Alonso
authors.forename: Carlos
authors.initials: C
authors.lastname: Villalobos
authors.forename: Pablo
authors.initials: P
authors.lastname: Chamero
authors.forename: Javier
authors.initials: J
authors.lastname: Alvarez
authors.forename: Javier
authors.initials: J
authors.lastname: García-Sancho
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000502:physiology*; D020013:Calcium Signaling / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism*; D017362:Cyclic AMP Response Element-Binding Protein / Q000502:physiology; D005456:Fluorescent Dyes / Q000737:chemistry; D006801:Humans; D051605:Kv Channel-Interacting Proteins / Q000502:physiology; D021962:Membrane Microdomains / Q000502:physiology*; D008928:Mitochondria / Q000378:metabolism*; D013816:Thermodynamics
chemical_list: D015220:Calcium Channels; D017362:Cyclic AMP Response Element-Binding Protein; D005456:Fluorescent Dyes; D051605:Kv Channel-Interacting Proteins; D002118:Calcium