SGSH Variant M6P Mutation Enhances Enzyme Secretion

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Solution Overview

Problem

Current treatments for Mucopolysaccharidosis type IIIA (MPS IIIA) are limited by the inefficient secretion and uptake of sulfamidase (SGSH) enzymes, leading to inadequate cross-correction and therapeutic benefits.

Innovation Solution

A modified sulfamidase (SGSH) variant with improved secretion and uptake properties is developed by mutating specific mannose-6-phosphorylation (M6P) sites, particularly the N264Q modification, which enhances enzyme secretion and uptake without requiring the mannose-6-phosphate receptor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If wild-type SGSH is used for gene therapy, then the enzyme can be produced in transduced cells, but secretion efficiency is insufficient leading to inadequate cross-correction

Engineering Contradiction:

Improveenzyme secretion efficiencyVSAvoidtherapeutic benefit

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies parameter changes by mutating specific amino acid residues at mannose-6-phosphate (M6P) recognition sites on the SGSH enzyme. The N264Q mutation changes the chemical properties of the enzyme surface, preventing abnormal binding to M6P receptors and thereby improving secretion efficiency from transduced cells into the CNS environment where it can be taken up by non-transduced cells.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If M6P site modification is made to improve secretion, then enzyme secretion increases, but enzyme uptake by cells may be affected

Engineering Contradiction:

Improveenzyme secretionVSAvoidenzyme uptake

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

The patent applies local quality by making targeted modifications only at specific M6P recognition sites (residues 264 and/or 268) on the enzyme surface, while leaving the rest of the enzyme structure and its cellular uptake mechanisms unchanged. This localized modification approach improves secretion without compromising uptake capability.

Inventive Principle:

Principle #3Local quality

3Productivity

If enzyme is secreted efficiently, then cross-correction can occur, but enzyme buildup in cells causes secondary lysosomal dysfunction

Engineering Contradiction:

Improveenzyme secretionVSAvoidsecondary lysosomal dysfunction

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful effect of abnormal M6P receptor binding (which causes enzyme buildup and lysosomal dysfunction) into a beneficial effect by mutating the M6P sites. This prevents the harmful abnormal binding while maintaining or improving secretion, thereby eliminating the source of secondary lysosomal dysfunction.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS12221635B2Sulfamidase (SGSH) variants, vectors, compositions and methods and uses for treating mucopolysaccharidosis type IIIA (MPS IIIA)

Publication Date: 2025.02.11 THE CHILDRENS HOSPITAL OF PHILADELPHIA

AI summary

The invention relates to sulfamidase (SGSH) and SGSH variants. SGSH and SGSH variants can be delivered by way of a recombinant adeno-associated virus (rAAV) particle to a mammal's central nervous system (CNS) to transduce CNS cells that contact cerebrospinal fluid (CSF). Target mammals for SGSH and SGSH variant administration include mammals with a deficiency or defect in SGSH expression or function.