Chimeric GPCR Protein Fusing Melanopsin and mGluR6 for Vision Restoration
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Solution Overview
Problem
Current treatments for retinal photoreceptor degeneration, such as retinitis pigmentosa, face limitations due to immune reactions, toxicity, weak light sensitivity, and insufficient signal amplification from existing light-activatable proteins like channelrhodopsin-2 and melanopsin, which hinder effective restoration of vision.
Innovation Solution
A light-sensitive chimeric GPCR protein is developed by fusing domains from melanopsin and metabotropic glutamate receptor 6 (mGluR6), allowing direct coupling of light signals to the mGluR6 signaling cascade in ON-bipolar cells, enhancing light sensitivity and amplification without relying on functional photoreceptors, and utilizing bi-stable photopigments for improved recovery and reduced immune response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If channelrhodopsin-2 is introduced into inner retinal neurons to restore light sensitivity, then light sensitivity is improved, but immune reactions and calcium toxicity occur
Solution Approach 1:
The invention changes the parameters of the light-sensitive protein by using melanopsin instead of channelrhodopsin-2, which has different biophysical properties including lower calcium permeability and reduced immunogenicity, while maintaining light sensitivity function
Solution Approach 2:
The invention creates a chimeric protein by fusing melanopsin with mGluR6 intracellular domains, combining the light sensitivity of melanopsin with the signaling capabilities of mGluR6 to achieve both functional restoration and reduced side effects
2Illumination intensity
If channelrhodopsin-2 is used for light detection, then light sensitivity is restored, but the response is weak at natural light intensities
Solution Approach 1:
The invention merges melanopsin with the mGluR6 signaling cascade by fusing the intracellular domains, creating a hybrid protein that combines light detection with robust signal transduction capabilities to enhance response strength at natural light intensities
3Power
If melanopsin is expressed in inner retinal neurons to amplify light signals, then signal amplification is improved, but enzymatic partners are insufficiently available
Solution Approach 1:
The invention uses the mGluR6 intracellular domains as an intermediary to bridge melanopsin light activation with the endogenous signaling cascade, allowing signal amplification through the natural mGluR6 pathway without requiring additional enzymatic partners
4Illumination intensity
If foreign proteins are expressed in retinal neurons to compensate for photoreceptor loss, then light sensitivity is restored, but regulatory mechanisms for protein activity are absent
Solution Approach 1:
The invention enables the chimeric protein to utilize the endogenous mGluR6 regulatory mechanisms within retinal neurons, allowing the system to self-regulate protein activity through natural turnover and modulation pathways without requiring external control systems
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 chimeric protein significantly enhances light sensitivity and signal amplification, restoring functional vision in patients with retinal photoreceptor degeneration by directly activating the mGluR6 signaling cascade, even at low light intensities, and maintains high sensitivity and rapid recovery, minimizing immune reactions and enzymatic dependency.
Implementation Method 1
a light-sensitive GPCR chimera capable of coupling a light signal to the signaling cascade of the metabotropic glutamate receptor 6 (mGluR6)
Data Source
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AI summary
A light-sensitive chimeric protein comprising domains from at least two members of the G-protein-coupled-receptor (GPCR) protein super family, which are fused to yield a light-sensitive GPCR chimera capable of coupling a light signal to the signaling cascade of the metabotropic glutamate receptor 6 (mGluR6) is provided for medical therapy and for the manufacture of medicaments for improving vision, in particular for treating loss of vision resulting from retinal photoreceptor degeneration. A first of the at least two GPCR family members contributes domains which mediate the light-sensitivity to the chimeric light-sensitive GPCR protein. This first member belongs to the family of light-sensitive GPCR proteins also called photopigments, and in some embodiments this light-sensitive GPCR protein is melanopsin, in particular human melanopsin. A second of the at least two GPCR family members is mGluR6, which contributes domains for coupling the light signal to the intracellular signalling cascade of mGluR6, which is a native component of the cell membrane of ON-bipolar cells in the inner retina.