AAV Capsid-Promoter Interactions Determine CNS Cell-Selective Gene Expression In Vivo

Area of Science:

• Neuroscience
• Molecular Biology
• Gene Therapy

Background:

• Cell-selective gene expression is crucial for adeno-associated virus (AAV) vector gene therapies.
• Current strategies rely on AAV capsid engineering, cell-specific promoters, or enhancers.

Purpose of the Study:

• To investigate the influence of AAV9 capsid on constitutive promoters for cell-selective gene expression in the rat central nervous system (CNS).
• To explore novel AAV capsid-promoter interactions for enhanced gene therapy targeting.

Main Methods:

• Utilized AAV9 and AAV2 vectors with chicken β-actin (CBA) and truncated CBA hybrid (CBh) promoters in rat striatum.
• Engineered AAV9 capsid by inserting glutamate or alanine residues to assess effects on gene expression.
• Analyzed cell-specific gene expression patterns in neurons and oligodendrocytes.

Main Results:

• AAV9 vectors with the CBA promoter drove dominant neuronal gene expression.
• AAV9 vectors with the CBh promoter shifted gene expression to striatal oligodendrocytes.
• AAV2 vectors showed neuron-specific expression regardless of the promoter.
• AAV9 capsid modifications (glutamate/alanine insertions) altered cell-type specificity of gene expression.

Conclusions:

• AAV9 capsid significantly influences constitutive promoter activity, altering cell-type gene expression in the CNS.
• Specific capsid modifications can redirect AAV-mediated gene expression between neurons and oligodendrocytes.
• This capsid-promoter interaction represents a novel mechanism for achieving cell-selective AAV gene expression.