Modified Fibronectin Fragments for Selective Integrin Antagonism
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Solution Overview
Problem
Current integrin antagonists, such as disintegrins and Yersinia pseudotuberculosis protein invasin, are either non-specific, highly immunogenic, or unstable, posing challenges for therapeutic use due to their inability to selectively inhibit integrins α5β1 and αvβ3 without affecting αIIbβ3, leading to potential hemorrhage risks and stability issues.
Innovation Solution
Modified human fibronectin fragments with engineered disulfide bonds in the FNIII 10 and FNIII 9-10 domains, specifically Cys substitutions to form intradomain or interdomain bonds, enhance stability and solubility while maintaining or improving antagonist activity against integrins α5β1 and αvβ3, reducing the risk of affecting αIIbβ3 activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If disintegrin is used as integrin antagonist, then platelet aggregation is inhibited, but hemorrhage risk increases due to non-specific inhibition of αIIbβ3 integrin
Solution Approach 1:
The patent applies local quality by designing fibronectin fragments with specific structural modifications (deletion of type I and II domains, retention of type III domains with RGD motif) that confer selective binding affinity. The modified fragments maintain high affinity for α5β1 and αvβ3 integrins through the RGD motif while lacking the ability to bind αIIbβ3, thus achieving local specificity in the protein structure to prevent harmful off-target effects.
Solution Approach 2:
The patent segments the full-length fibronectin protein into specific domains (retaining only type III domains 9 and 10 containing the RGD motif) to create a minimal functional unit. This segmentation allows the fragment to maintain integrin antagonistic activity while reducing molecular weight and eliminating domains that might contribute to non-specific binding, thereby achieving selective inhibition without hemorrhage risk.
2Reliability
If truncated fibronectin (FNIII 9-10) is used as integrin antagonist, then specificity for α5β1 and αvβ3 is improved, but solubility and stability decrease
Solution Approach 1:
The patent applies parameter changes by systematically varying the amino acid sequence of the FNIII 9-10 fragment through site-directed mutagenesis. Specific residues are modified to enhance solubility and stability while preserving the RGD motif's integrin-binding function. These parameter changes in the protein sequence allow the fragment to maintain high specificity for α5β1 and αvβ3 integrins while improving its biophysical properties for therapeutic use.
3Reliability
If full-length fibronectin is used as integrin antagonist, then integrin binding activity is maintained, but immunogenicity increases
Solution Approach 1:
The patent extracts only the essential functional domains (type III domains 9 and 10 containing the RGD motif) from the full-length fibronectin protein. This extraction removes immunogenic regions present in the complete protein while retaining the minimal sequence required for integrin binding and antagonistic activity. The resulting fragment has reduced molecular weight and lower immunogenicity while maintaining therapeutic efficacy.
Data Source
AI summary
The present invention provides isolated polypeptides comprising a modified fibronectin fragment that comprises FNIII 10 and optionally further comprising FNIII 9. Also provided are pharmaceutical compositions comprising the polypeptides and methods of making and using the polypeptides.