title: Fluorescent probe for visualizing guanine-quadruplex DNA by fluorescence lifetime imaging microscopy.
abstract: The importance of guanine-quadruplex (G4) is not only in protecting the ends of chromosomes for human telomeres but also in regulating gene expression for several gene promoters. However, the existence of G4 structures in living cells is still in debate. A fluorescent probe, 3,6-bis(1-methyl-2-vinylpyridinium) carbazole diiodide (o-BMVC), for differentiating G4 structures from duplexes is characterized. o-BMVC has a large contrast in fluorescence decay time, binding affinity, and fluorescent intensity between G4 structures and duplexes, which makes it a good candidate for probing G4 DNA structures. The fluorescence decay time of o-BMVC upon interaction with G4 structures of telomeric G-rich sequences is ∼2.8  ns and that of interaction with the duplex structure of a calf thymus is ∼1.2  ns. By analyzing its fluorescence decay time and histogram, we were able to detect one G4 out of 1000 duplexes in vitro. Furthermore, by using fluorescence lifetime imaging microscopy, we demonstrated an innovative methodology for visualizing the localization of G4 structures as well as mapping the localization of different G4 structures in living cells.
authors.affiliation: National Yang-Ming University, Institute of Biophotonics, Taipei 11221, Taiwan.
authors.forename: Ting-Yuan
authors.initials: TY
authors.lastname: Tseng
authors.forename: Cheng-Hao
authors.initials: CH
authors.lastname: Chien
authors.forename: Jen-Fei
authors.initials: JF
authors.lastname: Chu
authors.forename: Wei-Chun
authors.initials: WC
authors.lastname: Huang
authors.forename: Mei-Ying
authors.initials: MY
authors.lastname: Lin
authors.forename: Cheng-Chung
authors.initials: CC
authors.lastname: Chang
authors.forename: Ta-Chau
authors.initials: TC
authors.lastname: Chang
mesh_terms: D000818:Animals; D002227:Carbazoles / Q000032:analysis / Q000737:chemistry; D002417:Cattle; D045744:Cell Line, Tumor; D004247:DNA / Q000032:analysis / Q000737:chemistry; D005456:Fluorescent Dyes / Q000032:analysis / Q000737:chemistry*; D054856:G-Quadruplexes; D006147:Guanine / Q000032:analysis / Q000737:chemistry*; D006801:Humans; D008856:Microscopy, Fluorescence / Q000379:methods*; D011726:Pyridinium Compounds / Q000032:analysis / Q000737:chemistry; D013050:Spectrometry, Fluorescence
chemical_list: C486012:3,6-bis(1-methyl-4-vinylpyridium)carbazole diiodide; D002227:Carbazoles; D005456:Fluorescent Dyes; D011726:Pyridinium Compounds; D006147:Guanine; D004247:DNA; C427203:calf thymus DNA