Mannose-6-phosphate glycan for lysosomal targeting: various applications from enzyme replacement therapy to lysosome-targeting chimeras

Abstract

A lysosome, an acidic membrane-bound organelle, contains hydrolytic enzymes to digest macromolecules for recycling. Many lysosomal enzymes (LEs) traffic to the lysosome through the mannose-6-phosphate (M6P)-dependent pathway. Some mannose residues of high-mannose type N -glycans on LEs can be phosphorylated in the Golgi apparatus through two-step enzyme reactions. The consequent M6P moiety is recognized by M6P receptors (MPRs) on the trans -Golgi network membrane and delivered through the endo-lysosomal pathway. On the other hand, secreted LEs containing M6P glycans can be recaptured by MPRs on the plasma membrane and targeted to the lysosome. Enzyme replacement therapy (ERT) for lysosomal storage diseases exploits this M6P-MPR-dependent endocytosis to deliver recombinant enzymes to lysosomes. This review discusses various engineering and application technologies using M6P’s lysosomal targeting. Glyco-engineering for increasing M6P contents developed ‘Bio-better’ ERT enzymes with enhanced therapeutic efficacy. M6P-decorated peptides, proteins, liposomes, and nanoparticles have been developed for drug delivery and subcellular imaging. A recently developed lysosome-targeting chimera uses an M6P-based bifunctional binder to degrade specific extracellular and membrane proteins. The success and efficiency of M6P-based lysosomal targeting will boost further technological developments with new applications in the biomedical field.

Comparative site-specific N-glycoproteome analysis reveals aberrant N-glycosylation and gives insights into mannose-6-phosphate pathway in cancer

“…The first step is transferring GlcNAc-1-phosphate from UDP-GlcNAc to high-mannose N-glycans, which is mediated by GlcNAc-phosphotransferase. In the second step, N-acetylglucosamine-1-phosphodiester α-N-acetyl-glucosaminidase removes the GlcNAc portion from GlcNAc-1-phosphate-high mannose N-glycan and thereby forms M6P 9 . In the sorting process, two M6P receptors, CI-MPR and 46 kDa cation-dependent M6P receptor (CD-MPR, P20645|MPRD) recognize and bind to M6P N-glycans on the lysosomal hydrolases and capture these hydrolases into endosomes.…”

Glycosylation Shapes the Efficacy and Safety of Diverse Protein, Gene and Cell Therapies

“…Trafficking and uptake of these lysosomal enzymes are mediated largely by the mannose-6-phosphate dependent pathway, which involves recognition and binding by mannose-6-phosphate receptors (MPRs) (Sly, 1985, Parenti et al, 2013, Varki and Kornfeld, 1980, Achord et al, 1978) (Figure 2B). Like ASGPRs and MRs, MPRs are lectins that recognize and bind specific glycosylation features on glycoproteins, particularly those that bear mannose-6-phosphate residues (Kaplan et al, 1977, Seo andOh, 2022). Glycan manipulation ERT enzymes for better lysosomal targeting has improved cellular uptake and increase therapeutic efficacy.…”

Glycoengineering for the Production of Lysosomal Enzymes

“…To improve the uptake of the enzymes into cells, avalglucosidase alfa-ngpt has increased Man-6-P levels by approximately 15-fold compared with aglucosidase alfa (34). A chemically synthesized P 2 -Man 6 GlcNAc 2 glycan structure, which can be efficiently bound to the CI-MPR, is conjugated to the sialic acid on the glycans of recombinant acid α-glucosidase by a chemical reaction (43).…”