CpG-Free Transgenes for Stable Expression in iPSCs
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Solution Overview
Problem
There is an unmet need to identify specific epigenetic mechanisms and methods for altering these mechanisms to prevent variations in gene expression and differentiation performance in induced pluripotent stem cells (iPSCs).
Innovation Solution
The method involves engineering iPSCs to express transgenes with stable expression by optimizing the transgene sequence to remove CpG motifs, using novel promoters (e.g., SEQ ID NOs:1-12 or 17), or by tagging endogenous genes such as HSP90AB1, ACTB, CTNNB1, or MYL6.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transgenes are introduced into iPSCs using conventional methods, then gene expression can be achieved initially, but rapid silencing occurs due to epigenetic modifications and global methylation
Solution Approach 1:
The patent applies parameter changes by modifying the DNA sequence parameters of transgenes - specifically removing CpG motifs and optimizing codon usage - to prevent epigenetic silencing. This sequence optimization changes the chemical composition and structure of the transgene DNA, making it resistant to methylation and maintaining stable expression over time in iPSCs
Solution Approach 2:
The patent employs preliminary action by pre-optimizing transgene sequences before introduction into iPSCs. The sequences are designed in advance with removed CpG motifs and optimized codons to prevent future silencing, rather than attempting to correct silencing after it occurs. This proactive approach ensures stable expression from the moment of transgene introduction
2Manufacturing precision
If standard transgene sequences are used in iPSCs, then initial expression is achieved, but clone-to-clone and batch-to-batch variations occur due to epigenetic modifications
Solution Approach 1:
The patent standardizes transgene expression by changing the sequence parameters - removing CpG motifs and optimizing codon usage - to create uniform transgenes that resist epigenetic silencing. This standardization ensures consistent expression across different clones and batches, eliminating variation caused by differential methylation patterns
Solution Approach 2:
The patent applies homogeneity by creating transgenes with standardized, optimized sequences that behave uniformly across different iPSC clones and batches. The CpG-free, codon-optimized sequences ensure that all transgenes express consistently regardless of the specific clone or batch, achieving homogeneous expression patterns
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
This approach prevents rapid silencing of transgenes due to global methylation or epigenetic dysregulation, ensuring stable and consistent expression of transgenes in iPSCs over extended periods, even during differentiation processes.
Implementation Method 1
This approach prevents rapid silencing of transgenes due to global methylation or epigenetic dysregulation
Data Source
AI summary
Provided herein are methods of producing cell lines with stable expression of a transgene by removal of CpG motifs. In further methods, there are provided methods for cell lines with stable expression of a transgene by driving expression by novel promoters or by tagging endogenous genes.