Chimeric Antisense Oligonucleotide Conjugated to α-Tocopherol.

Area of Science:

• Biochemistry
• Molecular Biology
• Drug Delivery Systems

Background:

• Short interfering RNA (siRNA) conjugated with α-tocopherol shows efficient liver delivery and gene silencing.
• Direct α-tocopherol conjugation to locked nucleic acid (LNA)-DNA gapmer antisense oligonucleotides (ASOs) reduced in vivo silencing activity.

Purpose of the Study:

• To enhance the delivery and efficacy of ASOs in the liver.
• To develop a novel ASO structure for improved gene silencing.

Main Methods:

• Conjugation of α-tocopherol to unlocked nucleic acid (UNA) sequences as a "second wing" to LNA-DNA gapmer ASOs.
• Intravenous injection of chimeric ASOs into mice.
• Assessment of gene silencing activity and hepatic tropism in vivo.

Main Results:

• The α-tocopherol-conjugated chimeric ASO demonstrated more potent liver gene silencing compared to ASO alone.
• The UNA wing was cleaved intracellularly, releasing α-tocopherol and activating the ASO.
• The novel ASO structure exhibited high efficacy, hepatic tropism, and safety for in vivo gene silencing.

Conclusions:

• A new, effective LNA-DNA gapmer structure was identified, utilizing drug delivery system (DDS) molecules bound to ASOs via UNA sequences.
• This approach significantly improves ASO delivery and gene silencing efficacy in the liver.
• The developed chimeric ASO is a promising tool for in vivo gene silencing applications.