Xiaocheng Weng

Quaternary ammonium zinc phthalocyanine: inhibiting telomerase by stabilizing G quadruplexes and inducing G-quadruplex structure transition and formation.

Water‐soluble, octacationic zinc phthalocyanine (ZnPc) was found to be a very good G‐quadruplex DNA stabilizer by using UV‐melting studies and DNA polymerase stop assays, and a potent telomerase inhibitor by using the telomeric repeat amplification protocol (TRAP) assay. The compound’s DNA‐binding properties were also studied by surface plasmon resonance (SPR). Furthermore, CD experiments demonstrated that ZnPc could induce intramolecular G‐quadruplex structure transition from the antiparallel to parallel form. More importantly, ZnPc was found to induce parallel structure formation in cation‐deficient conditions. The stability of the induced structure was determined with CD melting assays.

Existence of G-quadruplex structures in promoter region of oncogenes confirmed by G-quadruplex DNA cross-linking strategy

Existence of G-quadruplex DNA in vivo always attract widespread interest in the field of biology and biological chemistry. We reported our findings for the existence of G-quadruplex structures in promoter region of oncogenes confirmed by G-quadruplex DNA cross-linking strategy. Probes for selective G-quadruplex cross-linking was designed and synthesized that show high selectivity for G-quadruplex cross-linking. Further biological studies demonstrated its good inhibition activity against murine melanoma cells. To further investigate if G-quadruplex DNA was formed in vivo and as the target, a derivative was synthesized and pull-down process toward chromosome DNAs combined with circular dichroism and high throughput deep sequencing were performed. Several simulated intracellular conditions, including X. laevis oocytes, Ficoll 70 and PEG, was used to investigate the compounds pure cross-linking ability upon preformed G-quadruplex. Thus, as a potent G-quadruplex cross-linking agent, our strategy provided both valuable evidence of G-quadruplex structures in vivo and intense potential in anti-cancer therapy.

Cationic Metal–Corrole Complexes: Design, Synthesis, and Properties of Guanine‐Quadruplex Stabilizers

A series of pyridinium and quaternary ammonium copper corroles has been designed and synthesized. All new compounds have been fully characterized by NMR spectroscopy, high-resolution mass spectrometry, UV/Vis spectrscopy, and elemental analysis. Biochemical studies have indicated that all of these corrole derivatives can stabilize G-quadruplex structures, with corrole 4 being the most effective according to the results of circular dichroism (CD) melting experiments, polymerase chain reaction (PCR) stop assays, and surface plasmon resonance (SPR) experiments. Moreover, both corroles 3 and 4 tend to induce the human telomeric sequence to form hybrid G-quadruplex structures, whereas corroles 8 and 9 are more inclined to induce the human telomeric sequence to form antiparallel G-quadruplex structures.

Conformational Switching of G‐Quadruplex DNA by Photoregulation

Native, self-assembling nucleic acid nanomachines that can walk, move, or rotate have been developed. Owing to their ability to form diverse secondary structures, for example, by the highly sequence-specific hybridization of complementary sequences, the hybridization of DNA and RNA through Watson–Crick H bonds, and the assembly of triplexes through Hoogsteen bonds, nucleic acids are ideal building blocks for the construction of nanodevices. Quadruplex architecture is a nucleic acid secondary structure that plays an important role in nanomachine research, particularly in the control of reversible folding and extension of the G quadruplex of DNA in the presence of external stimuli. Mergny and coworkers reported that a copper(II)-mediated structural switch with a flexible ligand could regulate the conformation of the G quadruplex. Nanodevices based on a quadruplex-toduplex-transition that rely on the use of single-stranded DNA as fuels have been shown to perform rotary movements. Among external stimuli, such as temperature, pH value, electrical-field strength, and molecular recognition, photoregulation is particularly advantageous for controlling movement and conformation. For example, photoregulation does not require any additional components and does not cause undesirable side reactions. Irradiation is an accurate and simple method, and the timing, location, and strength of light can be controlled readily. Moreover, photoregulation provides a clean source of energy and can be repeated many times without loss of efficiency. The introduction of a photochromic group into biomolecules, such as peptides, oligonucleotides, sugar scaffolds, and phospholipids, can cause conformational changes that alter the photochemical properties of the biomolecule. Accordingly, various biological processes involving modified biomolecules can be regulated in a straightforward manner by irradiation. Recently, Ogasawara and Maeda demonstrated the successful photoregulation of G-quadruplex formation through isomerization of a photochromic nucleobase, G, incorporated in aptamers. Spada and co-workers introduced a photoactive moiety at the C8 position of a lipophilic guanosine derivative to regulate the existence of G quartets. However, all these photocontrollers are photochromic modified nucleobases. Specific molecules have not been shown to function as G-quadruplex photocontrollers; thus, we became interested in designing a photoswitch to regulate the formation of G-quadruplex DNA. The azobenzene moiety is widely used as a photoresponsive molecular tool because it possesses excellent photochemical characteristics. Specifically, azobenzene isomerizes to predominantly trans and cis forms under visible (Vis) and ultraviolet (UV) light, respectively. In this study, we synthesized the azobenzene derivative 1 (Scheme 1) to control the movement and conformation of a G quadruplex by irradiation. Our results suggest that the formation and dissociation of G-quadruplex DNAwas induced by interconversion of the trans and cis forms of compound 1. Compound 1 was synthesized by treating 4,4’-dihydroxyazobenzene with 1-(2-chloroethyl)piperidine hydrochloride

Selective chemical labelling of 5-formylcytosine in DNA by fluorescent dyes.

Direct labelling: 5-Formylcytosine in DNA can be selectively labelled by fluorescent dyes containing an active amino group. The labelled DNA shows strong fluorescence and can be detected by polyacrylamide gel electrophoresis (PAGE) and fluorescence measurements (see scheme). This method can distinguish 5-formylcytosine from other methylation forms of cytosine in DNA.

Selective detection of 5-formyl-2'-deoxycytidine in DNA using a fluorogenic hydroxylamine reagent.

Fluorogenic hydroxylamine reagents were used for detecting 5-fC through a labeling pathway. Chemical synthesis, HPLC, denaturing PAGE, and DNA MS were applied to testify that the probe reacted with 5-fC with oligodeoxynucleotide selectivity to achieve 5-fC detection conveniently and quantificationally with the method of fluorescence. The feasibility of fluorescently detecting 5-fC in a genome was also investigated.

A turn-on fluorescent probe for detection of tyrosinase activity

We have presented a fluorescent probe that exhibits a fluorescence turn-on signal upon reaction with tyrosinase, and we show that it can be readily employed for the assessment of tyrosinase activity and tyrosinase inhibitor activities in buffered aqueous solution.

Visual observation of G-quadruplex DNA with the label-free fluorescent probe silole with aggregation-induced emission

AIE molecule silole 1 could be used to detect G-quadruplex formation using an exonuclease I hydrolysis assay. This visual observation of G-quadruplexes has been successfully used in investigating multiple G-quadruplexes, including the one-stranded telomeric, c-myc, c-kit, VEGF G-quadruplexes, and a d(G(4)T(4)G(4)) inter-molecular G-quadruplex. The detection of G-quadruplex can be also applied to G-quadruplex isomers induced by small molecules.

A specific probe for two-photon fluorescence lysosomal imaging.

Lysosomes are vital organelles in physiological processes, as they receive and degrade macromolecules from the secretory and endocytic procedures. Evidences have shown that lysosomes were related to oncogenic activation and cancer progression, so lysosomes targeting and imaging probes make them convenient to be observed. In this study, a lysosome specific probe W-7 was designed and synthesized via convenient one-pot reaction and Heck reaction. This probe was derived from Trögers base with a dimethylaminomethyl end group. The optical properties of this compound were measured. W-7 also showed two-photon absorption (TPA) effect by using laser excitation at the wavelength of infrared light. In vivo experiment, W-7 showed high specificity and selectivity for lysosomes in living cells (HeLa cells, MRC-5 cells and NRK cells), compared with LT Red, GT Red and MT Red (R=0.96). Two-photon fluorescence images of HeLa cells stained by W-7 were obtained. And high resolution 3D reconstruction of lysosomes in one HeLa cell was provided by using two-photon confocal microscopy. The anantioseparation of racemic W-7 was carried out by chiral-HPLC, and the two enantiomers showed no significant difference in lysosomes imaging.

Pyridyl-substituted corrole isomers: synthesis and their regulation to G-quadruplex structures.

G-quadruplex DNA plays an important role in the potential therapeutic target for the design and development of anticancer drugs. As various G-quadruplex sequences in the promoter regions or telomeres can form different secondary structural modes and display a diversity of biology functions, variant G-quadruplex interactive agents may be necessary to cure different disease by differentiating variant types of G-quadruplexes. We synthesize five cationic methylpyridylium corroles and compare the interactions of corroles with different types of G-quadruplexes such as cmyc, htelo, and bcl2 by using surface plasmon resonance. Because of the importance of human telomere G-quadruplex DNA, we focus on the biological properties of the interactions between human telomere G-quadruplex DNA and corrole isomers using CD, T(m), PCR-stop (PCR= polymerase chain reaction), and polymerase-stop assay, which demonstrate the excellent ability of the corrole to induce and stabilize the G-quadruplex. This study provides the first experimental insight into how selectivity might be achieved for different G-quadruplexes by a single group of methylpyridylium corrole isomers that may be optimized for potential selective cancer therapy.