Truncated SMN1 Promoters for AAV CNS Gene Packaging
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Solution Overview
Problem
The packaging capacity of recombinant adeno-associated viral (rAAV) vectors is limited to less than 5 kb, preventing the delivery of larger therapeutic genes, such as those encoding proteins like Survival Motor Neuron (SMN) or interfering nucleic acids, which are essential for treating central nervous system (CNS) diseases.
Innovation Solution
Utilization of truncated human SMN1 promoters, which are at least 60% identical to native SMN1 promoters, to drive efficient expression of larger transgenes in CNS cells, such as spinal cord neurons, within recombinant AAV vectors, allowing for reduced promoter size and increased packaging capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional rAAV vectors are used, then packaging capacity is limited to less than 5 kb, but this prevents delivery of larger therapeutic genes encoding proteins like SMN or interfering nucleic acids
Solution Approach 1:
The patent extracts and removes the native SMN1 promoter sequence from the therapeutic construct, replacing it with a truncated version. This extraction of the full promoter element allows significant reduction in overall construct size, enabling packaging within the rAAV capacity limit while preserving essential promoter function for driving therapeutic gene expression.
Solution Approach 2:
The patent changes the size parameter of the promoter element by creating truncated versions of the native SMN1 promoter. By reducing the promoter length from its full sequence to a shortened functional version, the overall therapeutic construct size is reduced below 5 kb, enabling successful packaging in rAAV vectors while maintaining gene expression capability.
2Quantity of substance
If truncated SMN1 promoters are used, then promoter size is reduced and packaging capacity is increased, but promoter functionality must be maintained
Solution Approach 1:
The patent extracts only the essential functional elements of the SMN1 promoter, removing non-essential sequences. This extraction process creates a truncated promoter that retains core transcriptional activation capability while reducing overall size, thus maintaining reliability for driving therapeutic gene expression in CNS cells.
Solution Approach 2:
The patent applies local quality by preserving the critical functional regions of the promoter while removing less important sequences. The truncated promoter maintains essential transcription factor binding sites and regulatory elements in specific locations, ensuring reliable gene expression while achieving size reduction for rAAV packaging.
Data Source
AI summary
Aspects of the disclosure relate to compositions and methods for delivery of certain gene products (e.g., proteins, nucleic acids, etc.) to a subject, e.g., to the central nervous system (CNS) of a subject. The disclosure is based, in part, on expression cassettes (e.g., isolated nucleic acids) comprising a nucleic acid sequence operably linked to a human SMN1 promoter or a variant of a human SMN1 promoter, for example variants that are truncated relative to native SMN1 promoters.