scholarly journals Chemoenzymatic glycan-selective remodeling of a therapeutic lysosomal enzyme with high-affinity M6P-glycan ligands. Enzyme substrate specificity is the name of the game

2021 ◽  
Author(s):  
Xiao Zhang ◽  
Huiying Liu ◽  
Naresh Meena ◽  
Chao Li ◽  
Guanghui Zong ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Cellular Uptake ◽  
Lysosomal Enzyme ◽  
Therapeutic Efficacy ◽  
Lysosomal Enzymes ◽  
High Affinity ◽  
Enzyme Substrate ◽  
Mannose 6 Phosphate

Functionalization of therapeutic lysosomal enzymes with mannose-6-phosphate (M6P) glycan ligands represents a major strategy for enhancing the cation-independent M6P receptor (CI-MPR)-mediated cellular uptake, thus improving the overall therapeutic efficacy of...

scholarly journals Specific alterations in levels of mannose 6-phosphorylated glycoproteins in different neuronal ceroid lipofuscinoses

1998 ◽  
Vol 334 (3) ◽  
pp. 547-551 ◽  
Author(s):  
David E. SLEAT ◽  
Istvan SOHAR ◽  
Premila S. PULLARKAT ◽  
Peter LOBEL ◽  
Raju K. PULLARKAT
Keyword(s):  
Lysosomal Enzyme ◽  
Neurodegenerative Disorders ◽  
Enzyme Activities ◽  
Lysosomal Enzymes ◽  
Vesicular Transport ◽  
Cell Types ◽  
Neuronal Ceroid Lipofuscinoses ◽  
Mannose 6 Phosphate ◽  
Normal Controls ◽  
Lysosomal Proteins

Mannose 6-phosphate (Man-6-P) is a carbohydrate modification that is generated on newly synthesized lysosomal proteins. This modification is specifically recognized by two Man-6-P receptors that direct the vesicular transport of the lysosomal enzymes from the Golgi to a prelysosomal compartment. The Man-6-P is rapidly removed in the lysosome of most cell types; however, in neurons the Man-6-P modification persists. In this study we have examined the spectrum of Man-6-P-containing glycoproteins in brain specimens from patients with different neuronal ceroid lipofuscinoses (NCLs), which are progressive neurodegenerative disorders with established links to defects in lysosomal catabolism. We find characteristic alterations in the Man-6-P glycoproteins in specimens from late-infantile (LINCL), juvenile (JNCL) and adult (ANCL) patients. Man-6-P glycoproteins in LINCL patients were similar to controls, with the exception that the band corresponding to CLN2, a recently identified lysosomal enzyme whose deficiency results in this disease, was absent. In an ANCL patient, two Man-6-P glycoproteins were elevated in comparison with normal controls, suggesting that this disease also results from a perturbation in lysosomal hydrolysis. In JNCL, total levels of Man-6-P glycoproteins were 7-fold those of controls. In general this was reflected by increased lysosomal enzyme activities in JNCL but three Man-6-P glycoproteins were elevated to an even greater degree. These are CLN2 and the unidentified proteins that are also highly elevated in the ANCL.

scholarly journals An alternative hypothesis of cellular transport of lysosomal enzymes in fibroblasts. Effect of inhibitors of lysosomal enzyme endocytosis on intra- and extra-cellular lysosomal enzyme activities

1978 ◽  
Vol 176 (3) ◽  
pp. 943-950 ◽  
Author(s):  
Kurt Von Figura ◽  
Ernst Weber
Keyword(s):  
Cell Surface ◽  
Lysosomal Enzyme ◽  
Lysosomal Enzymes ◽  
Alternative Hypothesis ◽  
Fold Increase ◽  
Cellular Transport ◽  
Intracellular Enzyme ◽  
Surface Receptors ◽  
Mannose 6 Phosphate ◽  
A Minor

Recapture of lysosomal enzymes secreted by fibroblasts was inhibited by growing the cells in the presence of either free or immobilized antibodies against lysosomal enzymes or in the presence of phosphorylated carbohydrates known to interact with the cell-surface receptors for lysosomal enzymes. The following results were obtained. 1. Conditions that prevent recapture of released lysosomal enzymes increase the rate of extracellular accumulation of these enzymes up to twice that of controls. 2. Growing cells for 12 days in the presence of 0.5mm-mannose 6-phosphate, which decreases β-N-acetylglucosaminidase endocytosis to less than 10% of that of controls, has no effect on the intracellular activity of this and four other lysosomal enzymes. 3. Growing cells for 4 days in the presence of 50mm-mannose 6-phosphate, which is a 1000-fold higher concentration than that required for 50% inhibition of lysosomal enzyme endocytosis, leads to a 4-fold increase in extracellular β-N-acetylglucosaminidase accumulation and a decrease in intracellular enzyme. These results give evidence that, in fibroblasts, transfer of lysosomal enzymes into lysosomes does not require secretion before a receptor-mediated recapture [Hickman & Neufeld (1972) Biochem. Biophys. Res. Commun.49, 992–999]. We propose that (a) lysosomal enzymes are present in a receptor-bound form in those vesicles that fuse with the cell membrane, (b) the major part of the lysosomal enzyme cycles via the cell surface in a receptor-bound form and (c) only a minor part of the lysosomal enzyme is released into the extracellular space during its life cycle.

A bacterial glycosidase enables mannose-6-phosphate modification and improved cellular uptake of yeast-produced recombinant human lysosomal enzymes

2012 ◽  
Vol 30 (12) ◽  
pp. 1225-1231 ◽  
Author(s):  
Petra Tiels ◽  
Ekaterina Baranova ◽  
Kathleen Piens ◽  
Charlotte De Visscher ◽  
Gwenda Pynaert ◽  
...  
Keyword(s):  
Cellular Uptake ◽  
Lysosomal Enzymes ◽  
Mannose 6 Phosphate

scholarly journals Mouse mutants lacking the cation-independent mannose 6-phosphate/insulin-like growth factor II receptor are impaired in lysosomal enzyme transport: comparison of cation-independent and cation-dependent mannose 6-phosphate receptor-deficient mice

1998 ◽  
Vol 330 (2) ◽  
pp. 903-908 ◽  
Author(s):  
Istvan SOHAR ◽  
David SLEAT ◽  
Chang-Gong LIU ◽  
Thomas LUDWIG ◽  
Peter LOBEL
Keyword(s):  
Growth Factor ◽  
Lysosomal Enzyme ◽  
Enzyme Activities ◽  
Lysosomal Enzymes ◽  
Insulin Like Growth Factor ◽  
Factor Ii ◽  
Solid Tissues ◽  
Mannose 6 Phosphate ◽  
Deficient Mice

Two proteins have been implicated in the mannose 6-phosphate-dependent transport of lysosomal enzymes to lysosomes: the 300 kDa cation-independent and the 46 kDa cation-dependent mannose 6-phosphate receptors (CI- and CD-MPRs). The mammalian CI-MPR also mediates endocytosis and clearance of insulin-like growth factor II (IGF-II). Mutant mice that lack the CD-MPR are viable, mice that lack the CI-MPR accumulate high levels of IGF-II and usually die perinatally, whereas mice that lack both IGF-II and CI-MPR are viable. To investigate the relative roles of the MPRs in the targeting of lysosomal enzymes in vivo, we analysed the effect of a deficiency of either MPR on lysosomal enzyme activities in animals lacking IGF-II. In CD-MPR-deficient mice, most activities were relatively normal in solid tissues and some were marginally elevated in serum. In CI-MPR-deficient mice, some enzyme activities were moderately decreased in solid tissues and multiple enzymes were markedly elevated in serum. Finally, total levels of serum mannose 6-phosphorylated glycoproteins were ~ 45-fold and ~ 15-fold higher than wild type in CI- and CD-MPR-deficient mice respectively, and there were specific differences in the pattern of these proteins when comparing CI- and CD-MPR deficient animals. These results indicate that while lack of the CI-MPR appears to perturb lysosome function to a greater degree than lack of the CD-MPR, each MPR has distinct functions for the targeting of lysosomal enzymes in vivo.

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