Direct visualization of nucleolar G-quadruplexes in live cells by using a fluorescent light-up probe.
Biochim Biophys Acta Gen Subj 2018;
1862:1101-1106. [PMID:
29410183 DOI:
10.1016/j.bbagen.2018.01.022]
[Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 01/23/2018] [Accepted: 01/31/2018] [Indexed: 11/24/2022]
Abstract
BACKGROUND
Direct detection of G-quadruplexes in human cells has become an important issue due to the vital role of G-quadruplex related to biological functions. Despite several probes have been developed for detection of the G-quadruplexes in cytoplasm or whole cells, the probe being used to monitor the nucleolar G-quadruplexes is still lacking.
METHODS
Formation of the nucleolar G-quadruplex structures was confirmed by using circular dichroism (CD) spectroscopy. The binding affinity and selectivity of Thioflavin T (ThT) towards various DNA/RNA motifs in solution and gel system were measured by using fluorescence spectroscopy and polyacrylamide gel electrophoresis (PAGE), respectively. G-quadruplex imaging in live cells was directly captured by using confocal laser scanning microscopy (CLSM).
RESULTS
Formation of the rDNA and rRNA G-quadruplex structures is demonstrated in vitro. ThT is found to show much higher affinity and selectivity towards these G-quadruplex structures versus other nucleic acid motifs either in solution or in gel system. The nucleolar G-quadruplexes in living cells are visualized by using ThT as a fluorescent probe. G-quadruplex-ligand treatments in live cells lead to sharp decrease of ThT signal.
CONCLUSIONS
The natural existence of the G-quadruplexes structure in the nucleoli of living cells is directly visualized by using ThT as an indicator.
GENERAL SIGNIFICANCE
The research provides substantive evidence for formation of the rRNA G-quadruplex structures, and also offers an effective probe for direct visualization of the nucleolar G-quadruplexes in living cells.
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