Engineering of a lysosomal-targeted GAA enzyme

Area of Science:

• Biochemistry
• Genetics
• Enzyme Engineering

Background:

• Pompe disease is a genetic disorder resulting in insufficient GAA enzyme activity.
• Current enzyme replacement therapies (ERTs) for Pompe disease face challenges with lysosomal trafficking via the mannose-6-phosphate pathway.
• Inefficient trafficking limits the therapeutic efficacy of recombinant GAA enzyme in Pompe disease treatment.

Purpose of the Study:

• To engineer a novel chimeric GAA enzyme for enhanced lysosomal uptake in Pompe disease.
• To bypass the native mannose-6-phosphate-mediated lysosomal trafficking pathway.
• To improve the cellular delivery and therapeutic potential of GAA enzyme replacement therapy.

Main Methods:

• Rational engineering of a chimeric GAA enzyme.
• Incorporation of a modified Insulin-like Growth Factor II (IGF-II) moiety for receptor-mediated uptake.
• Assessment of cellular uptake, enzymatic activity, and binding to off-target receptors (IGF-I receptor, insulin receptor).

Main Results:

• The engineered chimeric GAA enzyme demonstrated significantly increased cellular uptake.
• The modified IGF-II moiety successfully utilized its native receptor to bypass the mannose-6-phosphate pathway.
• Binding to off-target IGF-I and insulin receptors was ablated, and the enzyme's activity was preserved.

Conclusions:

• A rationally engineered chimeric GAA enzyme offers a promising strategy for improved Pompe disease therapy.
• Bypassing the mannose-6-phosphate pathway via modified IGF-II enhances GAA enzyme cellular delivery.
• This approach holds potential for more effective enzyme replacement therapy in Pompe disease.