SRF-UCOE Chromatin Element for Stable Long-Term Transgene Expression
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Solution Overview
Problem
Long-term stable expression of transgenes in mammalian cells is challenging due to transgene silencing effects such as position effects, heterochromatin spreading, and de novo methylation, which are not effectively addressed by existing passive and active chromatin remodelling elements.
Innovation Solution
A novel ubiquitous chromatin opening element (UCOE) named SRF-UCOE, derived from the human Surfeit locus, which is modular, smaller in size, and not inherently transcriptionally active, is used to operably link with heterologous promoters to maintain chromatin in an open state and resist silencing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional passive boundary elements like cHS4 are used to counteract position effects, then some stability is conferred to transgenes, but the elements are cumbersome and highly host cell dependent with limited utility in non-blood cell lineages
Solution Approach 1:
The patent extracts the essential chromatin-opening function from the complex cHS4 insulator element, isolating only the necessary UCNE sequences that provide anti-silencing activity. This extracted UCOE element maintains transgene stability while eliminating the cumbersome features and host cell limitations of the original cHS4 element.
Solution Approach 2:
The patent applies local quality by creating a simplified UCOE element that concentrates the essential anti-silencing function in a specific localized sequence (UCNE), rather than requiring the entire complex cHS4 insulator structure. This localized element provides the necessary stability function with reduced complexity and broader host cell applicability.
2Reliability
If the A2UCOE element is used to resist silencing, then long-term stable expression is achieved, but the element size is large and it has synthetic promoter activity that may cause safety concerns
Solution Approach 1:
The patent extracts only the essential UCNE sequences from the A2UCOE element that are responsible for chromatin opening and anti-silencing activity, while excluding the synthetic promoter regions. This creates a safer SRF-UCOE element that maintains long-term stable expression without the harmful synthetic promoter activity.
Solution Approach 2:
The patent changes the size parameter of the UCOE element by truncating and optimizing the sequence to create a more compact SRF-UCOE element. This size reduction and removal of synthetic promoter sequences eliminates safety concerns while preserving the essential long-term stable expression function.
3Reliability
If transgenes are integrated into the host cell genome, then stable expression is achieved, but position effects cause varying expression levels when integrated into different regions
Solution Approach 1:
The patent introduces the UCOE element as an intermediary between the transgene and the host cell genome integration site. This UCOE mediator creates a controlled chromatin environment that shields the transgene from position effects, ensuring consistent expression regardless of the integration location in the genome.
Solution Approach 2:
The patent changes the chromatin state parameter in the region surrounding the transgene by introducing the UCOE element. This creates a stable, open chromatin configuration that maintains consistent transgene expression levels across different genomic integration sites, overcoming the variability caused by position effects.
4Device complexity
If no insulator element is used, then the construct is simple, but heterochromatin spreading represses neighboring DNA and causes transgene silencing
Solution Approach 1:
The patent extracts the essential heterochromatin-blocking function from complex insulator elements, creating a minimal UCOE sequence that provides just enough protection against heterochromatin spreading. This extracted element maintains transgene expression stability with minimal added complexity to the construct.
Data Source
AI summary
A novel ubiquitous chromatin opening element (UCOE) named SRF-UCOE and methods for its use are provided. Compositions including recombinant and synthetic SRF-UCOE nucleic acid molecules, DNA constructs and vectors comprising the SRF-UCOE nucleic acid molecules, host cells comprising the DNA constructs or vectors, and cell culture systems comprising such host cells. SRF-UCOE polynucleotide sequences can be used in DNA constructs or expression cassettes for transformation and expression in cells or organisms of interest. The compositions and methods provided are useful for increasing and/or maintaining expression of a gene of interest. Transgenic cells, tissues, and animals comprising a SRF-UCOE nucleotide sequence are also provided. Methods are provided for increasing and/or maintaining expression of a gene of interest and for treating a subject via gene therapy.