New Modified Deoxythymine with Dibranched Tetraethylene Glycol Stabilizes G-Quadruplex Structures

Zeptoliter DNA Origami Reactor to Reveal Cosolute Effects on Nanoconfined G-Quadruplexes

Cellular environments such as nanoconfinement and molecular crowding can change biomolecular properties. However, in nanoconfinement, it is extremely challenging to investigate effects of crowding cosolutes on macromolecules. By using optical tweezers, here, we elucidated the effects of hexaethylene glycol (HEG) on the mechanical stability of a telomeric G-quadruplex (GQ) in a zeptoliter DNA origami reactor (zepto-reactor). When HEG molecules were introduced in the GQ-containing zepto-reactor at different positions, we found that the GQ species split into two equilibrated populations, reflecting diverse effects of the oligoethylene glycol on the GQ via either a long-range dehydration effect or direct interactions. When the number of HEG molecules was increased, the stability of the GQ unexpectedly decreased, suggesting that the direct destabilizing interaction between the GQ and HEG is dominating over the long-range stabilizing dehydration effects of the HEG in hydrophilic nanocavities. These findings indicate that a nanoconfined environment can alter regular effects of cosolutes on biomacromolecules.

Characterization of 2-Fluoro-2'-deoxyadenosine in Duplex, G-quadruplex and I-motif

Among various kinds of fluorine-substituted biomolecules, 2-fluoroadenine (2FA) and its derivatives have been actively investigated as therapeutic reagents, radio-sensitizers, and 19F-NMR probe. In spite of their excellent properties, DNA containing 2FA has not been studied well. Toward fundamental understanding and future applications to the development of functional nucleic acids, we characterized 2FA-containing oligonucleotides for canonical right-handed DNA duplex, G-quadruplex, and i-motif structures. Properties of 2FA were similar to native adenine due to the small size of fluorine atom, but it showed unique features caused by high electronegativity. This work provides useful information for future application of 2FA-modified DNA.

Ginsenoside Compound K Assisted G-Quadruplex Folding and Regulated G-Quadruplex-Containing Transcription

Ginsenoside compound K (CK) is one of the major metabolites of the bioactive ingredients in Panax ginseng, which presents excellent bioactivity and regulates the expression of important proteins. In this work, the effects of CK on G-quadruplexes (G4s) were quantitatively analyzed in the presence and absence of their complementary sequences. CK was demonstrated to facilitate the formation of G4s, and increase the quantity of G4s in the competition with duplex. Thermodynamic experiments suggested that the electrostatic interactions were important for G4 stabilization by CK. CK was further found to regulate the transcription of G4-containing templates, reduce full-length transcripts, and decrease the transcription efficiency. Our results provide new evidence for the pharmacological study of ginsenosides at the gene level.

Enhancing anti-PD-1 Immunotherapy by Nanomicelles Self-Assembled from Multivalent Aptamer Drug Conjugates

A tumor-targeting enhanced chemotherapy, enabled by aptamer-drug conjugate nanomicelles, is reported that boosts antitumor immune responses. Multivalent aptamer drug conjugate (ApMDC), an amphiphilic telodendrimer consisting of a hydrophilic aptamer and a hydrophobic monodendron anchored with four anticancer drugs by acid-labile linkers, was designed and synthesized. By co-self-assembly with an ApMDC analogue, in which aptamer is replaced with polyethylene glycol, the surface aptamer density of these nanomicelles can be screened to reach an optimal complementation between blood circulation and tumor-targeting ability. Optimized nanomicelles can enhance immunogenic cell death of tumor cells, which strikingly augments the tumor-specific immune responses of the checkpoint blockade in immunocompetent tumor-bearing mice. ApMDC nanomicelles represent a robust platform for structure-function optimization of drug conjugates and nanomedicines.