Mechanisms and optimization of in vivo delivery of lipophilic siRNAs.
Cholesterol-conjugated siRNAs can silence gene expression in vivo. Here we synthesize a variety of lipophilic siRNAs and use them to elucidate the requirements for siRNA delivery in vivo. We show that conjugation to bile acids and long-chain fatty acids, in addition to cholesterol, mediates siRNA uptake into cells and gene silencing in vivo. Efficient and selective uptake of these siRNA conjugates depends on interactions with lipoprotein particles, lipoprotein receptors and transmembrane proteins. High-density lipoprotein (HDL) directs siRNA delivery into liver, gut, kidney and steroidogenic organs, whereas low-density lipoprotein (LDL) targets siRNA primarily to the liver. LDL-receptor expression is essential for siRNA delivery by LDL particles, and SR-BI receptor expression is required for uptake of HDL-bound siRNAs. Cellular uptake also requires the mammalian homolog of the Caenorhabditis elegans transmembrane protein Sid1. Our results demonstrate that conjugation to lipophilic molecules enables effective siRNA uptake through a common mechanism that can be exploited to optimize therapeutic siRNA delivery.
Wolfrum
Christian
C
Institute of Molecular Systems Biology, Swiss Federal Institute of Technology, ETH Zürich, HPT E73.
Shi
Shuanping
S
Jayaprakash
K Narayanannair
KN
Jayaraman
Muthusamy
M
Wang
Gang
G
Pandey
Rajendra K
RK
Rajeev
Kallanthottathil G
KG
Nakayama
Tomoko
T
Charrise
Klaus
K
Ndungo
Esther M
EM
Zimmermann
Tracy
T
Koteliansky
Victor
V
Manoharan
Muthiah
M
Stoffel
Markus
M
D000818:Animals; D001055:Apolipoproteins B / Q000235:genetics / Q000378:metabolism; D002784:Cholesterol; D006224:Cricetinae; D018014:Gene Transfer Techniques; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL / Q000235:genetics / Q000378:metabolism; D008647:Mesocricetus; D051379:Mice; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics*; D018110:Receptors, Lipoprotein / Q000378:metabolism
D001055:Apolipoproteins B; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D034741:RNA, Small Interfering; D018110:Receptors, Lipoprotein; D002784:Cholesterol