title: Stable interactions between mitochondria and endoplasmic reticulum allow rapid accumulation of calcium in a subpopulation of mitochondria.
abstract: To better understand the functional role of the mitochondrial network in shaping the Ca2+ signals in living cells, we took advantage both of the newest genetically engineered green fluorescent protein-based Ca2+ sensors ("Cameleons," "Camgaroos," and "Pericams") and of the classical Ca(2+)-sensitive photoprotein aequorin, all targeted to the mitochondrial matrix. The properties of the green fluorescent protein-based probes in terms of subcellular localization, photosensitivity, and Ca2+ affinity have been analyzed in detail. It is concluded that the ratiometric pericam is, at present, the most reliable mitochondrial Ca2+ probe for single cell studies, although this probe too is not devoid of problems. The results obtained with ratiometric pericam in single cells, combined with those obtained at the population level with aequorin, provide strong evidence demonstrating that the close vicinity of mitochondria to the Ca2+ release channels (and thus responsible for the fast uptake of Ca2+ by mitochondria upon receptor activation) are highly stable in time, suggesting the existence of specific interactions between mitochondria and the endoplasmic reticulum.
authors.affiliation: Department of Biomedical Sciences and CNR Institute of Neuroscience, University of Padua, Viale G. Colombo 3, 35121 Padua, Italy. luisa.filippin@unipd.it
authors.forename: Luisa
authors.initials: L
authors.lastname: Filippin
authors.forename: Paulo J
authors.initials: PJ
authors.lastname: Magalhães
authors.forename: Giulietta
authors.initials: G
authors.lastname: Di Benedetto
authors.forename: Matilde
authors.initials: M
authors.lastname: Colella
authors.forename: Tullio
authors.initials: T
authors.lastname: Pozzan
mesh_terms: D000331:Aequorin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D008027:Light; D008164:Luminescent Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000378:metabolism*; D013997:Time Factors
chemical_list: D018076:DNA, Complementary; D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins; D000331:Aequorin; D002118:Calcium