Modified MBNL Polypeptide for CUG Repeat Displacement in DM1
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Solution Overview
Problem
Current treatments for myotonic dystrophy, particularly DM1, fail to effectively reverse splicing misregulations and counteract clinical symptoms such as myotonia due to the sequestration of MBNL proteins by CUGexp-RNAs, necessitating an alternate and efficient means to restore MBNL function.
Innovation Solution
A modified MBNL polypeptide with reduced splicing activity is ectopically expressed using viral vectors to bind pathological CUG repeats, displacing sequestered endogenous MBNL proteins and restoring their function, thereby reversing splicing misregulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If functional MBNL proteins are overexpressed to compensate for MBNL loss, then splicing misregulation is corrected, but the therapeutic approach is insufficient to reverse clinical symptoms
Solution Approach 1:
The invention extracts and removes the harmful CUGexp-RNA sequences from the system using antisense oligonucleotides that bind to and degrade the expanded repeats. This eliminates the toxic RNA that causes MBNL sequestration, allowing endogenous MBNL proteins to function normally without competition from the pathogenic RNA.
Solution Approach 2:
The invention introduces modified MBNL proteins as intermediary therapeutic agents that can bind to CUG repeats and displace sequestered endogenous MBNL proteins. These modified MBNL proteins act as mediators that restore normal splicing function without requiring complete elimination of the pathogenic RNA.
2Reliability
If CUGexp-RNAs are degraded to release sequestered MBNL proteins, then splicing function is restored, but the approach fails to sufficiently counteract clinical symptoms
Solution Approach 1:
The invention modifies the MBNL proteins by altering their physical or chemical parameters - specifically creating MBNL proteins with modified binding affinities or steric properties that enable them to more effectively compete with CUGexp-RNAs for MBNL protein binding sites, thereby enhancing the release of sequestered MBNL and improving clinical outcomes.
3Reliability
If modified MBNL polypeptide is ectopically expressed to bind CUG repeats, then splicing defects are normalized, but the mechanism of action requires reduced splicing activity
Solution Approach 1:
The invention segments the MBNL protein function by creating truncated or modified versions of the protein that retain only the essential RNA-binding domain while removing or reducing the splicing regulatory domains. This segmentation allows the protein to bind CUG repeats effectively without exerting strong splicing activity, thereby correcting splicing defects through competition rather than direct regulation.
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 modified MBNL polypeptide effectively normalizes splicing defects and alleviates myotonia in myotonic dystrophy models both in vitro and in vivo, demonstrating potential therapeutic benefits.
Implementation Method 1
MBNL1 like the other MBNL protein paralogues binds to expanded CUG repeats with high affinity
Data Source
AI summary
The present invention relates to compositions and methods for treating myotonic dystrophy.