Ye Huang

Systematic review with meta‐analysis: the diagnostic accuracy of transient elastography for the staging of liver fibrosis in patients with chronic hepatitis B

Transient elastography is a non‐invasive method for staging liver fibrosis. The meta‐analysis using the hierarchical models to evaluate the diagnostic accuracy of transient elastography for the staging of liver fibrosis in patients with chronic hepatitis B was rarely reported.

Synthesis and biological evaluation of peptide-siRNA conjugates with phosphodiester unit as linker

In this paper, a series of peptide-siRNA conjugates with phosphodiester unit as the linker targeting to Cdc2 gene were synthesized by solid phase stepwise strategy. The conjugation of peptides at either 3′-terminus of siCdc2 bring no change to the classical A-form of RNA duplex, but slightly compromise the thermodynamic stability. Peptide conjugation at the 3′-terminus of sense strand could improve the serum stability obviously, however, the opposite peptide conjugation at the 3′-terminus of antisense strand shows no such influence. According to the results of artificial silencing activity assay system, peptide conjugation at 3′-terminus of antisense strand slightly weakens the silencing activity of siCdc2. But sense strand peptide conjugation exhibits similar silencing activity as native siCdc2, meanwhile, it could mitigate the unwanted off-target effect of sense strand targeting to its own mRNA.

Exploring Directional Invasion of Serum Nuclease into siRNA Duplexes by Asymmetrical Terminal Modifications

In this study we demonstrated that ribonuclease A (RNase A) can recognize the thermodynamic asymmetry of siRNA duplexes, similar to other proteins involved in siRNA function such as argonaute 2. RNase A preferentially invades the siRNA duplex through the less stable terminus, i.e., the 3′ terminus of the sense strand. As evidence, only phosphorothioate (PS) modification at the sense strand overhang improved serum stability, whereas PS modification at the antisense strand overhang did not affect stability. Moreover, the improvement in stability caused by modification at the sense strand overhang was found to correlate with the terminal base pair composition of the siRNA. Gel electrophoresis and MALDI‐TOF MS analysis indicated that modifications at the sense strand overhang improved the serum stability of siRNAs by inhibiting the directional invasion of RNase A. The blocking effect was not brought about by stabilization of the siRNA duplexes because there was no clear difference between the melting temperatures of siRNAs with PS modifications at each 3′ overhang.

Loss of silencing activity caused by 5′-terminal modification with d-/l-isonucleotide (isoNA) or locked nucleic acid (LNA) could not be restored by 5′-terminal phosphorylation

In this study, a series of 5′-phosphorylated siRNAs with d-/l-isonucleotide (isoNA) or locked nucleic acid (LNA) incorporated at the 5′-terminus were synthesized. It was found that after incorporating either isoNA or LNA at the 5′-terminus of the antisense strand or sense strand, the silencing activity of modified strands has been inhibited, which cannot be recovered by phosphorylation at the 5′-terminus; however, the silencing activity of unmodified strand to its own target was increased. This work indicates that the isoNA and LNA modification at 5′-terminus can interfere with the strand selection during the RISC assembling process, and the disturbance of the 5′-phosporylation should not be the only viable mechanism.

Synthesis, physicochemical and biological properties of oligonucleotides incorporated with amino-isonucleosides

Antisense oligonucleotides (ASONs) and siRNAs have been applied extensively for the regulation of cellular and viral gene expression, and RNAi is currently one of the most promising new approaches for anti-tumor and anti-viral therapy. In order to improve bioactivity properties and physicochemical properties of siRNA, we synthesized a novel class of ASONs II–VII incorporated with amino-isonucleoside (isoA1 and isoA2) for investigation on basic physicochemical properties. Then we designed amino-isonucleoside (isoA1, isoA2 and isoT1) incorporated siRNA 2–7. Some meaningful results have been obtained from the physicochemical property experiments in ASONs. In RNAi potency experiments, we investigated RNAi potency of each strand of the siRNA. These amino-isonucleosides incorporated siRNAs showed promising bioactivity properties and had position specificity. Reduced off target effect from sense strand loading in siRNA application was observed.