Cardiac-Specific rAAV Expression Cassettes for Low Transgene Output
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Solution Overview
Problem
Existing gene therapy vectors face challenges in achieving high expression of gene products, particularly in cardiac cells, necessitating improved delivery methods for treating heart diseases.
Innovation Solution
The development of recombinant adeno-associated virus (rAAV) virions with optimized expression cassettes containing cardiac-specific promoters, enhancers, and introns, along with codon-optimized transgenes, to enhance gene delivery and expression in cardiomyocytes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional gene therapy vectors are used, then delivery to cardiac cells is achieved, but gene expression levels remain low
Solution Approach 1:
The patent applies parameter changes by optimizing multiple elements of the expression cassette simultaneously: using cardiac-specific promoters (cTnT, MYH6) to change transcriptional regulation, adding enhancers (ACTC1, αMHC) to amplify transcription, incorporating introns to improve mRNA processing and stability, and applying codon optimization to enhance translation efficiency. These parameter changes collectively increase gene expression levels 1.5- to 150-fold in cardiomyocytes.
2Productivity
If standard expression cassettes are used, then vector construction is simple, but transgene expression in cardiac tissue is insufficient
Solution Approach 1:
The patent segments the expression cassette into distinct functional modules: promoter regions (cTnT, MYH6), enhancer elements (ACTC1, αMHC), intron sequences, coding regions with codon optimization, and polyadenylation signals. This segmentation allows each element to be independently optimized for cardiac-specific function while maintaining overall cassette integrity and enabling modular assembly.
Solution Approach 2:
The expression cassette functions as a composite structure combining multiple DNA elements with complementary functions: cardiac-specific promoters provide tissue-selective transcription initiation, enhancers amplify transcriptional output, introns enhance mRNA processing and stability, and codon-optimized coding regions maximize translation efficiency. This composite design achieves synergistic enhancement of gene expression.
3Productivity
If non-specific promoters are used, then broad expression is achieved, but cardiac-specific high-level expression is not obtained
Solution Approach 1:
The patent applies local quality by using cardiac-specific promoters (cTnT for chicken beta-myosin heavy chain, MYH6 for human alpha-myosin heavy chain) and cardiac-specific enhancers (ACTC1 for cardiac muscle, αMHC for alpha-myosin heavy chain) that are locally adapted to cardiac tissue transcriptional machinery. This ensures high-level expression specifically in cardiomyocytes while minimizing expression in other tissues.
Data Source
AI summary
In some aspects, cardiac-specific expression cassettes are provided herein. In some aspects, provided herein is an expression cassette comprising a polynucleotide sequence encoding a gene product for therapy of a heart disease, wherein the polynucleotide sequence is operably linked to promoter (e.g., a cardiac-specific promoter), and optionally an enhancer (e.g., a cardiac-specific enhancer). In some aspects, the disclosure provides recombinant adeno-associated virus (rAAV) virions, comprising a capsid protein and a viral genome comprising an expression cassette comprising a polynucleotide sequence encoding a therapeutic gene product, e.g., dwarf open reading frame (DWORF) polypeptide, operably linked to a promoter, the expression cassette flanked by inverted terminal repeats. The disclosure further provides pharmaceutical compositions and methods of treating or preventing heart disease.