Artificial DNA-Binding Proteins for Selective Gene Silencing
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Solution Overview
Problem
Current treatments for autosomal dominant retinitis pigmentosa, particularly those targeting the rhodopsin gene, lack effective solutions and often come with significant side effects, and existing gene therapy approaches face challenges in selectively silencing mutant genes without affecting wild-type alleles or causing off-target effects.
Innovation Solution
Development of a novel artificial DNA-binding domain (ZF6-DBD) that targets a 20-base pair sequence in the human RHODOPSIN promoter, allowing for transcriptional silencing of the rhodopsin gene without an effector domain, using somatic gene transfer to retinal photoreceptors, and potentially incorporating this into a two-step repression-replacement strategy for gene therapy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional gene therapy approaches are used to silence mutant rhodopsin genes, then gene expression can be suppressed, but off-target effects and side effects significantly increase
Solution Approach 1:
The invention divides the gene silencing function into two separate components: a DNA-binding domain (DBD) that specifically recognizes and binds to the mutant rhodopsin gene promoter sequence, and a transcriptional repressor domain that executes the silencing function. This segmentation allows the DBD to be highly specific for the mutant allele while the repressor domain remains confined to the intended target, thereby reducing off-target effects and improving the reliability of gene silencing.
Solution Approach 2:
The fusion protein acts as an intermediary between the specific DNA sequence of the mutant rhodopsin gene and the transcriptional repression machinery. The DNA-binding domain serves as a mediator that recognizes and binds to the specific promoter sequence, while the repressor domain mediates the actual transcriptional silencing. This intermediary structure ensures that repression is directed only at the intended mutant gene, minimizing harmful off-target effects.
2Reliability
If existing treatments for autosomal dominant retinitis pigmentosa are applied, then some therapeutic effect may be achieved, but significant side effects occur
Solution Approach 1:
By segmenting the therapeutic approach into a specific DNA-binding component and a repressor component fused together, the invention achieves targeted suppression of mutant rhodopsin expression. The DBD is engineered to recognize specific sequences in the mutant gene promoter, ensuring therapeutic efficacy is directed only at the pathogenic allele, thereby reducing side effects while maintaining treatment effectiveness.
Solution Approach 2:
The fusion protein exhibits local quality by being specifically designed to bind only to the promoter region of the mutant rhodopsin gene through its DBD. This localized binding ensures that the transcriptional repression effect is confined to the specific mutant gene locus, providing therapeutic benefit without affecting other genes or cellular processes, thus reducing side effects.
3Productivity
If gene therapy approaches target the rhodopsin gene without high specificity, then broader gene suppression may occur, but wild-type alleles are also affected
Solution Approach 1:
The fusion protein structure segments the recognition function (DBD) from the repression function, allowing the DBD to be highly specific for mutant allele sequences. This specificity ensures that only mutant alleles are targeted for silencing, while wild-type alleles remain unaffected, thereby maintaining both selectivity and therapeutic efficiency.
Solution Approach 2:
The DBD is engineered with local quality to recognize and bind specifically to altered promoter sequences present in mutant rhodopsin genes. This localized sequence recognition ensures that the transcriptional repression is selectively applied only to mutant alleles, preserving wild-type allele function while achieving efficient silencing of the pathogenic variant.
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 ZF6-DBD effectively down-regulates rhodopsin transcription in both mouse and pig models, showing higher recovery of retinal function with fewer off-target effects and improved safety compared to traditional approaches, demonstrating potential for treating autosomal dominant retinitis pigmentosa with reduced side effects.
Implementation Method 1
a DNA binding domain (DBD) that specifically binds to a regulatory sequence of the rhodopsin gene
Data Source
AI summary
The present invention relates to proteins consisting of an artificial DNA-binding domain (DBD) and related molecules and uses thereof. In particular, the proteins are ZF-DBD or TALE-DBD and are used for the treatment of eye disorders caused by gain of function mutation. The disorder may be ADRP, in particular ADRP caused by mutation in the rhodopsin gene. The present invention also relates to a method to identify cis-regulatory elements and to modulate them via DBDs.