Poster abstracts

Poster number 30 submitted by Yufeng Liang

Melamine functionalized lipid particles for selective siRNA loading and delivery

Yufeng Liang (Department of Chemistry and Biochemistry), Zhun Zhou (Department of Chemistry and Biochemistry), Sarah Rundell (Department of Chemistry and Biochemistry)

Abstract:
We’ve developed a bifacial polymer nucleic acid (bPoNA) binding pattern through uridine-melamine-uridine base tripling recognition. bPoNA has been demonstrated to deliver uridine-rich siRNA into HELA and HepG2 cells through receptor-mediated endocytosis. 40% of luciferase in HELA cells is knocked down by 100 nM of siRNA with bPoNA and the IC50 is 5 nM for the siRNA-bPoNA complex which targets the ApoB gene in HepG2 cells. Since melamine-uridine binding pattern shows great potential in siRNA delivery, herein we propose another siRNA delivery approach—melamine functionalized lipid particle for uridine-rich siRNA delivery. Compared to stable nucleic acid lipid particle (SNALP), which contains considerable cationic lipid for electrostatic interaction towards RNA phosphate backbone, the melamine functionalized lipid particle might selectively bind to unpaired uridines in siRNA sequence. We’ve synthesized melamine functionalized phosphatidylethanolamine (PE) lipids and tested their encapsulation efficiency towards uridine-rich RNA by measuring the concentration of the remaining RNA in the supernatant after a lipid pulldown assay. The preliminary data shows that melamine modified lipids selectively encapsulate about 30% of uridine modified RNAs from the surrounding buffers, while no unmodified RNA is bound. To further investigate the binding property of melamine lipid, we propose to test lipid particle assembly under various pHs and with rational lipid compositions. If the melamine lipids show significant encapsulation of uridine-rich RNA, the lipid can be further modified with ligands for cell surface receptor. The neutral or zwitterionic lipid particles without intense positive charges can be specifically targeted to cells through ligand-receptor recognition. Therefore, the target gene in a specific cell might be silenced by this melamine lipid approach.

References:
Zhou, Z., Xia, X., and Bong, D. (2015) Synthetic Polymer Hybridization with DNA and RNA Directs Nanoparticle Loading, Silencing Delivery, and Aptamer Function. J. Am. Chem. Soc. 137, 8920–8923.

Keywords: siRNA delivery, lipid particle, uridine-melamine-uridine base tripling recognition