title: 8-hydroxyquinoline derivatives as fluorescent sensors for magnesium in living cells.
abstract: Despite the key role of magnesium in many fundamental biological processes, knowledge about its intracellular regulation is still scarce, due to the lack of appropriate detection methods. Here, we report the spectroscopic and photochemical characterization of two diaza-18-crown-6 hydroxyquinoline derivatives (DCHQ) and we propose their application in total Mg(2+) assessment and in confocal imaging as effective Mg(2+) indicators. DCHQ derivatives 1 and 2 bind Mg(2+) with much higher affinity than other available probes (K(d) = 44 and 73 microM, respectively) and show a strong fluorescence increase upon binding. Remarkably, fluorescence output is not significantly affected by other divalent cations, most importantly Ca(2+), or by pH changes within the physiological range. Evidence is provided on the use of fluorometric data to derive total cellular Mg(2+) content, which is consistent with atomic absorption data. Furthermore, we show that DCHQ compounds can be effectively employed to map intracellular ion distribution and movements in live cells by confocal microscopy. A clear staining pattern consistent with known affinities of Mg(2+) for biological ligands is shown; moreover, changes in the fluorescence signal could be tracked following stimuli known to modify intracellular Mg(2+) concentration. These findings suggest that DCHQ derivatives may serve as new tools for the study of Mg(2+) regulation, allowing sensitive and straightforward detection of both static and dynamic signals.
authors.affiliation: Dipartimento di Biochimica G. Moruzzi, Via Irnerio 48, Università degli Studi di Bologna, 40126 Bologna, Italy. giovanna.farruggia@unibo.it
authors.forename: Giovanna
authors.initials: G
authors.lastname: Farruggia
authors.forename: Stefano
authors.initials: S
authors.lastname: Iotti
authors.forename: Luca
authors.initials: L
authors.lastname: Prodi
authors.forename: Marco
authors.initials: M
authors.lastname: Montalti
authors.forename: Nelsi
authors.initials: N
authors.lastname: Zaccheroni
authors.forename: Paul B
authors.initials: PB
authors.lastname: Savage
authors.forename: Valentina
authors.initials: V
authors.lastname: Trapani
authors.forename: Patrizio
authors.initials: P
authors.lastname: Sale
authors.forename: Federica I
authors.initials: FI
authors.lastname: Wolf
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D047248:Crown Compounds / Q000138:chemical synthesis / Q000737:chemistry; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry*; D018922:HL-60 Cells; D006706:Homeostasis; D006801:Humans; D007700:Kinetics; D008274:Magnesium / Q000032:analysis* / Q000378:metabolism; D018613:Microscopy, Confocal; D015125:Oxyquinoline / Q000031:analogs & derivatives* / Q000737:chemistry; D010777:Photochemistry; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence
chemical_list: D047248:Crown Compounds; D005456:Fluorescent Dyes; D015125:Oxyquinoline; D008274:Magnesium