Rational Engineering of a Designed Protein Cage for siRNA Delivery

Area of Science:

• Biotechnology
• Molecular Medicine
• Drug Delivery Systems

Background:

• Oligonucleotide therapeutics offer significant medical promise but require effective delivery systems.
• Current delivery methods face challenges in efficiently transporting nucleic acids into target cells.
• Protein cages present a potential scaffold for creating novel drug delivery vehicles.

Purpose of the Study:

• To engineer a porous protein cage into a functional nucleic acid delivery vehicle.
• To demonstrate the ability of the modified protein cage to encapsulate and deliver oligonucleotides.
• To validate the therapeutic potential of the system through RNA interference (RNAi) in mammalian cells.

Main Methods:

• Designed a porous protein cage with arginine mutations on its lumenal surface to create a positively supercharged interior.
• Encapsidated small interfering RNA (siRNA) within the engineered protein cage in vitro.
• Evaluated cellular uptake of the siRNA-loaded cage in mammalian cells.
• Assessed the release of siRNA cargo and subsequent gene knockdown via RNA interference.

Main Results:

• The modified protein cage effectively encapsulated oligonucleotides with high binding affinity.
• The siRNA-loaded cage demonstrated efficient uptake by mammalian cells.
• Successful release of siRNA cargo led to RNA interference and gene expression knockdown.
• The engineered protein cage functions as a viable nucleic acid delivery system.

Conclusions:

• A simple method was developed to transform a protein cage into a nucleic acid delivery vehicle.
• The positively supercharged protein cage facilitates efficient oligonucleotide encapsulation and cellular delivery.
• This approach shows promise for advancing RNAi-based therapeutics and other nucleic acid delivery applications.