BioTech IP Review

1. RNA Editing (ADAR-based systems)

RNA editing changes the sequence of an RNA molecule after it is transcribed—without altering DNA.

Most therapeutic systems are based on ADAR (adenosine deaminase acting on RNA) enzymes.

Core mechanism

• ADAR converts adenosine (A) → inosine (I) in double-stranded RNA
• Inosine is read as guanosine (G) by the ribosome

Functional outcome

RNA sequence change → altered codon → altered protein

How therapeutic ADAR systems work

1. A guide RNA binds target mRNA near the edit site
2. Creates a short dsRNA structure
3. Recruits:
   • Endogenous ADAR
   • Or an engineered ADAR fusion protein
4. Site-specific A→I editing occurs

What RNA editing can do

• Correct point mutations
• Restore protein function
• Modify splicing
• Alter protein isoforms

Key feature

• Reversible and transient
• No permanent genomic change

Limitations

• Only A→I edits (G in practice)
• Editing efficiency varies
• Off-target editing risk
• Repeat dosing required

IP focus

• Guide RNA design
• ADAR recruitment domains
• Editing specificity
• Delivery systems

2. RNA Regulation (Broad Category)

RNA regulation changes how much RNA or protein is made, without changing RNA sequence.

Core mechanisms

RNA regulation affects:

• RNA stability
• Translation efficiency
• Splicing patterns
• Localization

But not nucleotide identity.

Major RNA regulation modalities

A. siRNA

• Degrades target mRNA
• Lowers protein levels

B. Antisense oligonucleotides

• Modulate splicing
• Block translation
• Trigger RNase H

C. miRNA modulation

• Fine-tunes gene expression
• Partial repression

D. RNA-binding protein control

• Stabilize or destabilize transcripts

What RNA regulation can do

• Turn genes down or off
• Adjust isoform ratios
• Temporarily tune pathways

Limitations

• Cannot fix mutated codons
• Effects are quantitative, not qualitative
• Often incomplete suppression

IP focus

• Target RNA selection
• Chemical modifications
• Delivery and dosing
• Functional outcomes

Summary

• RNA editing = rewrite the message
• RNA regulation = control the volume

RNA editing changes what a protein is; RNA regulation changes how much of it exists.

• Use RNA editing when:
  • Disease caused by point mutation
  • Protein function must be restored
• Use RNA regulation when:
  • Disease caused by over/under-expression
  • Pathway modulation is sufficient

ADAR-based RNA editing rewrites RNA sequences to correct function, while RNA regulation tunes expression without altering the message—two distinct strategies operating at the same biological layer.