Truncated GDE Polypeptide for AAV Packaging in Glycogen Storage Disease III
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Solution Overview
Problem
Current treatments for glycogen storage disease III (GSDIII) are symptomatic and lack an effective long-term therapy, with gene therapy hindered by the large size of the GDE transgene that exceeds the packaging limit of most gene therapy vectors.
Innovation Solution
A functional truncated GDE polypeptide with a C-terminal deletion, small enough to be packaged into a single AAV vector, retains enzymatic activities for glycogen degradation and muscle strength rescue, allowing for efficient gene therapy delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the full-length GDE transgene is used for gene therapy, then complete enzymatic activity is achieved, but the transgene size exceeds the packaging limit of AAV vectors
Solution Approach 1:
The patent extracts and removes the C-terminal region (amino acids 1421-1532) of the GDE protein from the full-length transgene. This deletion reduces the coding sequence length from 4596 bp to approximately 4000 bp, making it compatible with AAV vector packaging limits while preserving the essential catalytic domains and enzymatic functions required for glycogen degradation.
Solution Approach 2:
The GDE protein is segmented into functional domains, with the invention retaining the N-terminal catalytic regions (4-alpha-glucotransferase and amylo-1,6-glucosidase activities) while removing the C-terminal region. This segmentation allows the essential functional portions to be packaged into the viral vector while excluding non-essential portions.
2Length of moving object
If dual AAV vectors are used to deliver the GDE transgene, then the size limitation is overcome, but the complexity of the gene therapy strategy increases
Solution Approach 1:
By extracting and removing the C-terminal region of the GDE protein, the invention creates a truncated version that fits within the packaging capacity of a single AAV vector. This eliminates the need for dual vector systems and associated complexities in vector production, transduction efficiency matching, and potential recombination issues.
3Ease of operation
If symptomatic treatment is provided, then immediate symptom relief is achieved, but long-term disease progression is not altered
Solution Approach 1:
The patent implements preliminary action by delivering a functional GDE transgene via AAV vector that will continuously express the enzyme throughout the patient's life. This gene therapy approach addresses the root cause of the disease by establishing permanent enzymatic function, thereby preventing long-term disease progression and morbidity rather than merely managing symptoms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The truncated GDE polypeptide effectively rescues muscle strength and glycogen accumulation in GSDIII mice, demonstrating potential for long-term treatment of the disease.
Implementation Method 1
GDE has two independent catalytic activities which occur at different sites on the protein: a 4-alpha-glucotransferase activity and an amylo-1,6-glucosidase activity
Data Source
AI summary
The present invention relates to a functional C-terminal truncated GDE polypeptide for the treatment of glycogen storage disease III.