Photoactivatable Tet-ON System for Spatial Gene Control
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Solution Overview
Problem
The conventional Tet-OFF/ON system lacks the temporal and spatial control required for precise gene expression, particularly in studies involving dynamic gene expression in stem cells or progenitor cells.
Innovation Solution
Incorporating a photoactivatable binding switch, such as the Cry2/CIB1-PA or BphP1/Q-PAS1-PA binding switch, into the Tet-OFF/ON system allows for control of target gene expression using light irradiation in addition to Tet-based compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a chemically controlled gene expression system (Tet-OFF/ON) is used, then gene expression can be regulated by treating cells with Tet or doxycycline, but it is difficult to induce target gene expression in a limited time frame or in cells within a limited space
Solution Approach 1:
The patent introduces a photoactivatable binding switch consisting of two proteins (e.g., CRY2 and CIB1, or BphP1 and Q-PAS1) that act as intermediaries between light irradiation and gene expression control. When irradiated with light of a specific wavelength, these proteins bind to each other to form a heterodimer, which then interacts with the Tet repressor or reverse Tet repressor to control target gene expression. This intermediary mechanism enables precise temporal and spatial control of gene expression by converting optical energy into biochemical signaling, thereby achieving both ease of operation and high temporal-spatial resolution simultaneously
2Manufacturing precision
If a photoactivatable expression system using light irradiation is used, then temporal and spatial control of gene expression can be achieved, but the system complexity increases due to the need for light irradiation apparatus and photoactivatable components
Solution Approach 1:
The patent combines the Tet-OFF/ON system with a photoactivatable binding switch to create a dual-controlled gene expression system that can respond to both chemical inducers (Tet/doxycycline) and light irradiation. This multi-functional design allows the same system to provide both chemical control (for general regulation) and optical control (for precise temporal-spatial resolution), thereby achieving high manufacturing precision without requiring completely separate systems, thus moderating the increase in device complexity
Solution Approach 2:
The photoactivatable binding switch components (CRY2/CIB1 or BphP1/Q-PAS1) are designed to automatically bind to each other upon light irradiation without requiring additional cellular machinery or complex signaling pathways. The proteins self-assemble into heterodimers that directly interact with the Tet repressor system, enabling the system to perform the photoactivation function autonomously once the light stimulus is provided, thereby reducing the overall system complexity
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
The PA-Tet-OFF/ON system achieves precise temporal and spatial control of gene expression, enabling rapid activation or inactivation of target genes with high spatial specificity.
Implementation Method 1
Cry2 can bind to the bHLH transcription factor CIB1 in a blue light-specific manner
Implementation Method 2
In a case where BphP1 and Q-PAS1 are irradiated with near-infrared light at 740 to 780 nm, the proteins bind to each other and form a heterodimer
Data Source
AI summary
The present invention provides a photoactivatable Tet-OFF/ON system that can precisely control temporal and spatial gene expression. The present invention is a PA-Tet-OFF/ON system that includes a target gene expression cassette including a TRE having a TetO sequence, a promoter which is controlled by the TRE, and a target gene whose expression is controlled by the promoter; a first fusion protein expression cassette containing a gene which encodes a first fusion protein containing TetR or rTetR and a first protein; and a second fusion protein expression cassette containing a gene which encodes a second fusion protein containing p65AD and a second protein, in which the first protein and the second protein bind to each other to form a heterodimer only in a state of being irradiated with light at a specific wavelength.