Modified binary hammerhead ribozymes with high catalytic activity

Area of Science:

• Biochemistry
• Molecular Biology
• RNA Therapeutics

Background:

• Hammerhead ribozymes are catalytic RNA molecules with therapeutic potential.
• Improving ribozyme stability against nucleases is crucial for in vivo applications.
• MDR1 mRNA is a target for overcoming multidrug resistance in cancer.

Purpose of the Study:

• To design and evaluate binary hammerhead ribozymes with enhanced nuclease resistance and catalytic activity.
• To investigate the impact of Z-modified nucleotides and a 3'-3-linked thymidine cap on ribozyme performance.
• To assess the cleavage efficiency of modified ribozymes against a specific MDR1 mRNA fragment.

Main Methods:

• Design and synthesis of binary hammerhead ribozymes incorporating Z-modified nucleotides.
• Chemical modification of ribozymes with a 3'-3-linked thymidine cap.
• In vitro cleavage assays using a 190-nucleotide MDR1 mRNA fragment.
• Comparison of catalytic activity and nuclease resistance with unmodified analogs.

Main Results:

• Incorporation of Z-modified nucleotides and a thymidine cap significantly enhanced nuclease resistance.
• Modified binary ribozymes demonstrated efficient cleavage of the target MDR1 mRNA fragment.
• Catalytic activity of the modified ribozymes was substantially higher than their full-length counterparts.

Conclusions:

• Z-modified binary hammerhead ribozymes with a thymidine cap represent a promising strategy for improved RNA-based therapeutics.
• These modifications overcome key limitations of ribozymes, enhancing their stability and catalytic efficiency.
• The developed ribozymes show potential for targeting MDR1 mRNA in therapeutic contexts.