146 bp DNA Insulator for Stable Mammalian Expression
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Solution Overview
Problem
Current expression vectors in mammalian cells face challenges with random and unstable integration of genes, leading to variable expression due to local environmental effects, such as enhancers or silencers, which can result in gene silencing and reduced stability.
Innovation Solution
A 146 bp DNA element with specific sequence (SEQ ID No: 1) acts as a chromatin insulator when duplicated and inserted upstream and downstream of an expression unit, enhancing the number of expressing clones and stability of long-term expression by preventing chromatin position effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If genes are introduced into mammalian cells by transfection, then gene integration into the genome occurs, but the integration is random and unstable leading to variable expression
Solution Approach 1:
The patent introduces insulator DNA sequences as intermediary elements flanking the transgene expression unit. These insulator sequences act as protective barriers that mediate between the transgene and the surrounding genomic environment, shielding the transgene from position effects such as enhancers and silencers. This intermediary protection stabilizes transgene expression by preventing unwanted interactions with host chromatin structures.
2Reliability
If large DNA fragments are used as insulators, then chromatin position effects are prevented, but vector size increases reducing stability and accommodating capacity
Solution Approach 1:
The patent extracts and utilizes only the essential insulator sequences (such as the 250 bp core region of the chicken beta-globin insulator or the 146 bp element of SEQ ID NO: 1) that contain the critical CTCF binding sites and functional domains. By taking out only the necessary protective elements rather than using entire large insulator regions, the patent achieves chromatin protection while minimizing vector size increase.
Solution Approach 2:
The patent applies insulator sequences locally at the boundaries of the transgene expression unit, specifically positioning them upstream and downstream of the expression cassette. This localized application of protective elements provides targeted protection against position effects only where needed, rather than requiring large widespread insulator regions throughout the vector.
3Duration of action of stationary object
If insulator sequences are added to expression vectors, then long-term stable expression is achieved, but the complexity of vector construction increases
Solution Approach 1:
The patent incorporates insulator sequences into the expression vector design during the initial construction phase, positioning them flanking the expression unit before transfection. This preliminary inclusion of protective elements ensures that stable expression is established from the outset, preventing later expression degradation without requiring complex post-transfection modifications or selection procedures.
Data Source
AI summary
The invention relates to expression vectors comprising a DNA sequence of 146 bp capable of acting as chromatin insulator, to host cells containing such vectors, to a method of producing a desired polypeptide by using vectors containing said sequence and to the use of said DNA sequence.