Dimerizable Caspase-3 Transgenic Mice for Tissue-Specific Apoptosis
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Solution Overview
Problem
Current models for degenerative human diseases lack a system to induce apoptosis in a time- and tissue-specific manner, limiting the creation of animal models for these diseases.
Innovation Solution
Development of transgenic mice with an inducible caspase-3 gene, where a bioengineered dimerizable caspase-3 gene is controlled by a Cre-recombinase system and a dimerizing agent, allowing for targeted cell ablation in specific tissues and at specific times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single promoter is placed upstream of the caspase sequence, then the cell death timing is determined by promoter expression, but the tissue specificity is limited to what the promoter naturally provides
Solution Approach 1:
The patent creates a universal transgenic mouse system where a single caspase construct with floxed STOP sequence can be combined with any Cre-expressing mouse line to achieve tissue-specific cell death. This multi-functional approach allows the same basic construct to work across numerous different tissue types by simply changing the Cre driver, rather than creating separate constructs for each tissue type.
Solution Approach 2:
The system separates the tissue-specificity function (handled by various Cre mouse lines with different promoters) from the cell death execution function (handled by the caspase construct). This segmentation allows independent optimization and combination of different Cre drivers with the caspase system to target specific tissues.
2Loss of time
If the STOP sequence is removed by Cre recombinase, then the caspase gene is expressed, but cell death occurs immediately without temporal control
Solution Approach 1:
The system performs preliminary action by having Cre recombinase remove the STOP sequence and activate caspase expression in advance, but the actual cell death is delayed until chemical induction. The caspase is expressed as an inactive monomer that requires dimerization by a chemical inducer (rapamycin or FK506) to become active and execute cell death, providing temporal control after the preliminary genetic activation.
Solution Approach 2:
A chemical inducer (rapamycin or FK506) acts as an intermediary between the activated caspase gene and the execution of cell death. The chemical binds to FKBP12-dimerizable caspase fusion protein to induce dimerization and activation, providing a controllable intermediate step that separates gene activation from death execution.
3Adaptability or versatility
If apoptosis is induced in adult tissues, then disease models can be created, but existing systems lack the ability to induce apoptosis in a time- and tissue-specific manner
Solution Approach 1:
The patent creates a universal transgenic mouse system where a single caspase construct with floxed STOP sequence can be combined with any Cre-expressing mouse line to achieve tissue-specific cell death. This multi-functional approach allows the same basic construct to work across numerous different tissue types by simply changing the Cre driver, rather than creating separate constructs for each tissue type.
4Adaptability or versatility
If tissue-specific markers are used for targeting, then specific cell types can be targeted, but many markers are only expressed during development and not in adult tissues
Solution Approach 1:
The system performs preliminary action by having Cre recombinase remove the STOP sequence and activate caspase expression in advance, but the actual cell death is delayed until chemical induction. The caspase is expressed as an inactive monomer that requires dimerization by a chemical inducer (rapamycin or FK506) to become active and execute cell death, providing temporal control after the preliminary genetic activation.
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 tissue-specific and time-controlled cell death, expanding the range of tissues that can be targeted and allowing for the creation of more accurate disease models and cancer models, as well as the study of physiological processes.
Implementation Method 1
a bioengineered dimerizable caspase-3 gene under a stop-flox sequence
Implementation Method 2
administration of a dimerizer which specifically binds to a dimerizing sequence, e.g., the Fv sequence
Implementation Method 3
caspase-3 is rapidly activated after it is dimerized, targeted cells are rapidly ablated through apoptosis
Data Source
AI summary
Described are transgenic animals for conditional and inducible cell targeting, that express a dimerizable conditional-STOP caspase 3 transgene.