CRISPR Logic Circuits with Ribozyme Safety Switches
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Solution Overview
Problem
Current gene therapy techniques face challenges such as incorrect cell targeting, gene silencing over time, difficulty in delivering large genes, high manufacturing costs, and the risk of permanently altering a patient's germline DNA, limiting the translation of genetic therapies into clinical use.
Innovation Solution
The development of synthetic CRISPR-based genetic circuits that utilize a multifunctional Cas nuclease and guide RNAs of varying lengths, along with ligand-responsive ribozymes, to provide spatial and temporal control over gene expression, allowing for safe and predictable modulation of endogenous gene expression in mammalian cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CRISPR-based gene therapy is used to modify gene expression, then therapeutic efficacy is improved, but the risk of off-target effects and germline mutations increases
Solution Approach 1:
The patent applies cell-type-specific promoters to ensure that CRISPR components are expressed only in specific cell types where therapeutic effect is needed. This localized expression approach prevents off-target effects in other cell types and avoids germline mutation risks by restricting activity to somatic cells only.
Solution Approach 2:
The patent employs inducible promoters that can be activated or deactivated in response to specific signals. This dynamic control allows temporal regulation of CRISPR activity, enabling therapeutic intervention at optimal times while preventing premature or sustained activity that could cause off-target effects.
2Productivity
If CRISPR components are expressed universally to maximize therapeutic effect, then treatment effectiveness is improved, but the risk of germline DNA alteration increases
Solution Approach 1:
The patent uses tissue-specific or cell-type-specific promoters to restrict CRISPR expression to particular locations within the body. This ensures therapeutic effectiveness in target tissues while preventing system-wide expression that could lead to germline DNA alteration.
3Duration of action of stationary object
If CRISPR activity is sustained continuously to maintain gene modulation, then therapeutic duration is improved, but the risk of gene silencing over time increases
Solution Approach 1:
The patent employs inducible promoters that can be activated periodically or in response to specific signals rather than continuous expression. This periodic activation maintains therapeutic duration through repeated dosing while allowing periods of non-expression that prevent adaptive silencing mechanisms from developing.
Solution Approach 2:
The patent incorporates regulatory elements that provide feedback control over CRISPR expression. This feedback mechanism monitors therapeutic response and adjusts promoter activity accordingly, maintaining effective gene modulation while preventing sustained expression that could trigger silencing.
4Object-affected harmful factors
If precise control over CRISPR expression is implemented to reduce off-target effects, then safety is improved, but the complexity of the regulatory system increases
Solution Approach 1:
The patent divides the regulatory control into separate modular components: cell-type-specific promoters, inducible promoters, and CRISPR activity. This segmentation allows independent optimization of each component and simplifies the overall system by using well-characterized, independently controllable elements rather than a single complex regulatory mechanism.
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
These circuits enable precise and controlled genome editing and transcriptional modulation, reducing the risk of off-target effects and germline mutations, while allowing for targeted activation or repression of specific genes, thereby enhancing the safety and efficacy of gene therapies.
Implementation Method 1
The regulatory control element can comprise a ligand-responsive ribozyme comprising a sensor component capable of detecting the presence of a germ cell-specific signal and an actuator component configured for inducible expression of the second gRNA
Implementation Method 2
Streptococcus pyogenes Cas9 protein can be targeted to any DNA sequence of interest by means of a small RNA (gRNA) that can be engineered to carry complementary sequences to target DNA. Once at the target, Cas9 protein can either cleave or bind DNA
Implementation Method 3
a first gRNA of 15 or less nucleotides (nt) in length that is complementary to at least a portion of a gene targeted for activation or repression
Data Source
AI summary
Aspects of the disclosure relate to synthetic regulatory systems composed of a multifunctional Cas nuclease, at least two guide RNAs (gRNAs) configured to target distinct nucleotide sequences, and a multilayered regulatory control element comprising ribozyme-based safety switches providing spatial and temporal control over the synthetic circuit in vivo.