Inducible Anti-sense Repressor Switches for Gene Silencing
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Solution Overview
Problem
Current synthetic regulatory proteins used in gene therapies, such as TALE and CRISPR/dCas9, are immunogenic, large, and pose challenges for delivery due to packaging limits, limiting their widespread adoption.
Innovation Solution
Development of an inducible and reversible synthetic gene circuit using a human genome orthogonal zinc-finger array and a drug-inducible translocation system for precise and temporary repression of target nucleic acids, employing an mRNA anti-sense repressor switch controlled by a synthetic transcription factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TALE and CRISPR/dCas9 synthetic regulatory proteins are used, then transcriptional repression function is achieved, but immunogenicity and delivery difficulty increase
Solution Approach 1:
The patent employs small-molecule inducers (such as tamoxifen or 4-OHT) that are chemically simple, non-immunogenic, and can be easily administered orally or intravenously. These small molecules serve as temporary, disposable triggers that activate the repressor system only when needed, avoiding the immunogenicity issues associated with persistent protein-based systems like TALE and CRISPR/dCas9.
Solution Approach 2:
The patent introduces a synthetic transcription factor (synTF) as an intermediary protein that mediates the effect of the small-molecule inducer on the target gene. The synTF contains a drug-responsive domain that binds the small molecule, causing conformational change and nuclear translocation to activate repression. This intermediary approach allows the use of non-immunogenic small molecules to achieve the function previously requiring immunogenic bacterial proteins.
2Reliability
If TALE and CRISPR/dCas9 proteins are used, then transcriptional repression is achieved, but protein size increases approaching packaging limits
Solution Approach 1:
The patent divides the repression function into separate modular components: (1) a compact synthetic transcription factor (synTF) containing minimal necessary domains for DNA binding and transcriptional activation, (2) a drug-responsive domain that senses the small molecule inducer, and (3) the small-molecule inducer itself. This segmentation allows each component to be optimized for size and delivery, with the synTF being sufficiently small for viral packaging while the small molecule provides the activation trigger.
Solution Approach 2:
The patent changes the functional parameters of the transcriptional repression system by using a synthetic transcription factor with engineered DNA-binding specificity that requires only minimal protein structure. The synTF uses a compact architecture with a small DNA-binding domain, transactivation domain, and drug-responsive domain, reducing the overall protein size compared to natural TALE or CRISPR systems while maintaining repression function through parameter optimization rather than biological complexity.
3Reliability
If existing synthetic repressor systems are used, then gene silencing is achieved, but reversibility and precision are limited
Solution Approach 1:
The patent creates a dynamic, reversible repression system where the synthetic transcription factor transitions between inactive and active states in response to the small-molecule inducer. The drug-responsive domain undergoes conformational change upon binding the inducer, enabling rapid nuclear translocation and activation of repression. Upon inducer removal, the system reverses, allowing precise temporal control over gene silencing that static protein-based systems cannot provide.
Solution Approach 2:
The patent implements a feedback-controlled repression system where the small-molecule inducer serves as an external control signal that can be added or removed at desired time points. The synTF continuously monitors the presence of the inducer through its drug-responsive domain, providing real-time feedback control over repression activation. This allows precise timing and reversibility, as the system responds immediately to inducer presence and can be turned off by simply removing the inducer from the system.
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
Enables robust and transient silencing of transgene expression in mammalian cells, overcoming the limitations of existing systems by providing precise control and reversibility with small molecules, thus advancing the precision and tunability of synthetic gene circuits.
Implementation Method 1
a second promoter in the antisense direction to the first promoter, a DNA binding motif (DBM) orientated in the antisense direction to the GOI, the DBM comprising a target nucleic acid for binding of the at least one DBD of a synTF
Implementation Method 2
encodes at least one antisense nucleic acid sequence directed against at least a portion of the TNA
Data Source
AI summary
The methods and compositions described herein are directed to regulated synthetic gene expression systems. In particular, the technology described herein relates to compositions, systems and methods for inducible and transient (e.g., reversible) transcriptional repression of a target transcript of interest (GOI). The methods, compositions and systems described herein relate to engineered synthetic transcription factors (synTF) that are activated by an inducer molecule, which induces the transcription of a repressor or gene editing molecule from a synthetic inducible repressor constructs where the antisense repressor (or gene editing molecule) mediates reversible repression of a target transcript of interest (GOI) in the presence of the inducer.