Bio-compatible gene-delivery systems with transcriptional-enhancing function

点击翻译按钮获取中文摘要

In eukaryotic nuclei, DNA forms highly folded chromatin which is not actively transcribed. High mobility group (HMG) proteins, having characteristic structures comprising both cationic DNA-binding domains and an anionic region, are known to loosen the chromatin structure to facilitate the transcription. Amphoteric structure is necessary to activate the transcription, though its mechanism is still not clear.The amphoteric HMG protein binds to DNA, simultaneously interacting with histones, and the strong binding between DNA and histones would be relaxed. Highly compacted chromatin would then be loosened to reduce the distortion, presumably to promote the approach of transcription factors.To prove the hypothesis, we synthesized water-soluble polyampholytes, a poly(ethylene glycol) (PEG) derivative bearing both amino- and carboxylic acid-pendants (PEG-AC), and a hyaluronic acid (HA) having spermine side chains (Spn-HA), and their transcription-stimulating effect on the chromatin was examined.Incubation of chromatin with these polyampholytes evidently enhanced the transcriptional efficiency, and 9-17 times higher transcriptional rate than the original chromatin was observed. Transcription efficiency of DNA/polycation complexes was also obviously improved by these polyampholyte. Loosening of the DNA complexes by these polyampholytes was confirmed by the fluorescent restoration and anisotropy measurements.These results would show a novel physiological mechanism of HMG protein-induced transcriptional activation. These synthetic polyampholytes are expected as an artificial HMG protein model, and also a gene transfection improver.