SORT1-Mediated Lysosomal Enzyme Targeting
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Solution Overview
Problem
Current enzyme replacement therapies for lysosomal storage diseases, such as Sanfilippo syndrome, face challenges in effectively targeting lysosomes due to low levels or absence of mannose-6-phosphate phosphorylation in recombinantly produced enzymes, limiting their therapeutic efficacy.
Innovation Solution
The use of the sortilin-1 receptor (SORT1) for lysosomal targeting of enzymes, allowing for delivery without the need for glycosylation and/or mannose-6-phosphate phosphorylation, and the development of fusion proteins combining lysosomal enzymes with SORT1-targeting moieties like SORT1 propeptide, progranulin peptide, or prosaposin peptide for enhanced delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cation-independent mannose-6-phosphate receptor (CI-MPR) is used for lysosomal targeting, then proper lysosomal targeting can be achieved, but the manufacturing process becomes complex and unreliable due to dependence on glycosylation and M6P phosphorylation
Solution Approach 1:
The patent introduces SORT1 as an intermediary receptor to replace the conventional CI-MPR pathway. Instead of relying on the complex glycosylation-M6P phosphorylation-receptor binding cascade, the invention uses SORT1-binding peptides (such as progranulin peptide, prosaposin peptide, or SORT1 propeptide) as direct mediators that bind to SORT1 receptor, which then mediates lysosomal targeting. This intermediary approach simplifies the manufacturing process while maintaining reliable lysosomal delivery.
Solution Approach 2:
The patent fundamentally changes the targeting parameter from M6P phosphorylation-dependent binding to SORT1 receptor binding. By using peptides that naturally bind to SORT1 (such as the progranulin C-terminal peptide, prosaposin DC peptide, or SORT1 propeptide), the system achieves lysosomal targeting through a different molecular parameter—SORT1 affinity—thereby eliminating the need for complex glycosylation and M6P phosphorylation steps in the manufacturing process.
2Ease of manufacture
If recombinant Naglu protein is produced without glycosylation and M6P phosphorylation, then manufacturing is simplified, but lysosomal targeting becomes difficult or impossible
Solution Approach 1:
The patent uses SORT1-binding peptides as intermediaries to bridge the gap between simplified recombinant enzyme production and effective lysosomal targeting. These peptides (progranulin peptide, prosaposin peptide, or SORT1 propeptide) serve as delivery vehicles that can bind to SORT1 receptor and facilitate the uptake of non-glycosylated, non-M6P phosphorylated enzymes into lysosomes, thus maintaining targeting efficiency without compromising manufacturing simplicity.
Solution Approach 2:
The patent creates a composite therapeutic system consisting of the recombinant lysosomal enzyme (without glycosylation or M6P phosphorylation) conjugated or complexed with a SORT1-binding peptide. This composite structure combines the enzymatic activity of the recombinant protein with the targeting capability of the SORT1-binding peptide, enabling both simplified manufacturing and reliable lysosomal delivery.
3Adaptability or versatility
If conventional ERT is used for CNS manifestations, then peripheral tissues can be treated, but CNS delivery is limited due to blood-brain barrier and lack of SORT1-based targeting
Solution Approach 1:
The patent applies local quality by utilizing the specific enrichment of SORT1 receptor in the central nervous system (CNS). While conventional ERT using CI-MPR can deliver enzymes to peripheral tissues, the SORT1-based approach exploits the high expression of SORT1 in neurons and glial cells to achieve preferential and efficient delivery to the CNS. The SORT1-binding peptide therapeutics are designed to leverage this local receptor distribution pattern to overcome the blood-brain barrier and target brain tissues specifically.
Solution Approach 2:
The patent introduces SORT1 as a CNS-specific intermediary receptor that facilitates blood-brain barrier penetration and neuronal uptake. The SORT1-binding peptides act as mediators that exploit the unique SORT1 enrichment in the CNS to achieve targeted delivery to brain tissues, thereby extending the adaptability of ERT to treat CNS manifestations of lysosomal storage diseases that were previously inaccessible to conventional CI-MPR-based therapies.
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
This approach enables efficient and reliable lysosomal targeting of enzymes, simplifying the manufacturing process and improving therapeutic outcomes for lysosomal storage diseases with CNS manifestations by ensuring effective enzyme delivery to neurons and other tissues.
Implementation Method 1
binding of the M6P moiety to the cation-independent mannose-6-phosphate receptor (CI-MPR)
Implementation Method 2
replacement enzymes can be effectively delivered to lysosomes via a receptor other than the cation-independent mannose-6-phosphate receptor, i.e., the sortilin-1 receptor (SORT1)
Data Source
AI summary
The invention provides compositions and methods for effective lysosomal targeting mediated by SORT1. In particular, the compositions and methods provided by the invention may be used to treat lysosomal storage diseases such as Sanfilippo syndrome type B.