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Stuart Kornfeld - One of the best experts on this subject based on the ideXlab platform.
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engineering of glcnac 1 phosphotransferase for production of highly phosphorylated Lysosomal Enzymes for Enzyme replacement therapy
Molecular therapy. Methods & clinical development, 2017Co-Authors: Balraj Doray, Stuart KornfeldAbstract:Several Lysosomal Enzymes currently used for Enzyme replacement therapy in patients with Lysosomal storage diseases contain very low levels of mannose 6-phosphate, limiting their uptake via mannose 6-phosphate receptors on the surface of the deficient cells. These Enzymes are produced at high levels by mammalian cells and depend on endogenous GlcNAc-1-phosphotransferase α/β precursor to phosphorylate the mannose residues on their glycan chains. We show that co-expression of an engineered truncated GlcNAc-1-phosphotransferase α/β precursor and the Lysosomal Enzyme of interest in the producing cells resulted in markedly increased phosphorylation and cellular uptake of the secreted Lysosomal Enzyme. This method also results in the production of highly phosphorylated acid β-glucocerebrosidase, a Lysosomal Enzyme that normally has just trace amounts of this modification.
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the Lysosomal Enzyme receptor protein lerp is not essential but is implicated in Lysosomal function in drosophila melanogaster
Biology Open, 2015Co-Authors: Medina Hasanagic, Stuart Kornfeld, Eline Van Meel, Shan Luan, Rajeev Aurora, Joel C EissenbergAbstract:The Lysosomal Enzyme receptor protein (LERP) of Drosophila melanogaster is the ortholog of the mammalian cation-independent mannose 6-phosphate (Man 6-P) receptor, which mediates trafficking of newly synthesized Lysosomal acid hydrolases to lysosomes. However, flies lack the Enzymes necessary to make the Man 6-P mark, and the amino acids implicated in Man 6-P binding by the mammalian receptor are not conserved in LERP. Thus, the function of LERP in sorting of Lysosomal Enzymes to lysosomes in Drosophila is unclear. Here, we analyze the consequence of LERP depletion in S2 cells and intact flies. RNAi-mediated knockdown of LERP in S2 cells had little or no effect on the cellular content or secretion of several Lysosomal hydrolases. We generated a novel Lerp null mutation, Lerp(F6), which abolishes LERP protein expression. Lerp mutants have normal viability and fertility and display no overt phenotypes other than reduced body weight. Lerp mutant flies exhibit a 30-40% decrease in the level of several Lysosomal hydrolases, and are hypersensitive to dietary chloroquine and starvation, consistent with impaired lysosome function. Loss of LERP also enhances an eye phenotype associated with defective autophagy. Our findings implicate Lerp in lysosome function and autophagy.
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analysis of mucolipidosis ii iii gnptab missense mutations identifies domains of udp glcnac Lysosomal Enzyme glcnac 1 phosphotransferase involved in catalytic function and Lysosomal Enzyme recognition
Journal of Biological Chemistry, 2015Co-Authors: Yi Qian, Eline Van Meel, Heather Flanagansteet, Alexander D Yox, Richard Steet, Stuart KornfeldAbstract:UDP-GlcNAc:Lysosomal Enzyme GlcNAc-1-phosphotransferase tags newly synthesized Lysosomal Enzymes with mannose 6-phosphate recognition markers, which are required for their targeting to the endoLysosomal system. GNPTAB encodes the α and β subunits of GlcNAc-1-phosphotransferase, and mutations in this gene cause the Lysosomal storage disorders mucolipidosis II and III αβ. Prior investigation of missense mutations in GNPTAB uncovered amino acids in the N-terminal region and within the DMAP domain involved in Golgi retention of GlcNAc-1-phosphotransferase and its ability to specifically recognize Lysosomal hydrolases, respectively. Here, we undertook a comprehensive analysis of the remaining missense mutations in GNPTAB reported in mucolipidosis II and III αβ patients using cell- and zebrafish-based approaches. We show that the Stealth domain harbors the catalytic site, as some mutations in these regions greatly impaired the activity of the Enzyme without affecting its Golgi localization and proteolytic processing. We also demonstrate a role for the Notch repeat 1 in Lysosomal hydrolase recognition, as missense mutations in conserved cysteine residues in this domain do not affect the catalytic activity but impair mannose phosphorylation of certain Lysosomal hydrolases. Rescue experiments using mRNA bearing Notch repeat 1 mutations in GNPTAB-deficient zebrafish revealed selective effects on hydrolase recognition that differ from the DMAP mutation. Finally, the mutant R587P, located in the spacer between Notch 2 and DMAP, was partially rescued by overexpression of the γ subunit, suggesting a role for this region in γ subunit binding. These studies provide new insight into the functions of the different domains of the α and β subunits.
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analysis of mucolipidosis ii iii gnptab missense mutations identifies domains of udp glcnac Lysosomal Enzyme glcnac 1 phosphotransferase involved in catalytic function and Lysosomal Enzyme recognition
Journal of Biological Chemistry, 2015Co-Authors: Yi Qian, Eline Van Meel, Heather Flanagansteet, Alexander D Yox, Richard Steet, Stuart KornfeldAbstract:UDP-GlcNAc:Lysosomal Enzyme GlcNAc-1-phosphotransferase tags newly synthesized Lysosomal Enzymes with mannose 6-phosphate recognition markers, which are required for their targeting to the endoLysosomal system. GNPTAB encodes the α and β subunits of GlcNAc-1-phosphotransferase, and mutations in this gene cause the Lysosomal storage disorders mucolipidosis II and III αβ. Prior investigation of missense mutations in GNPTAB uncovered amino acids in the N-terminal region and within the DMAP domain involved in Golgi retention of GlcNAc-1-phosphotransferase and its ability to specifically recognize Lysosomal hydrolases, respectively. Here, we undertook a comprehensive analysis of the remaining missense mutations in GNPTAB reported in mucolipidosis II and III αβ patients using cell- and zebrafish-based approaches. We show that the Stealth domain harbors the catalytic site, as some mutations in these regions greatly impaired the activity of the Enzyme without affecting its Golgi localization and proteolytic processing. We also demonstrate a role for the Notch repeat 1 in Lysosomal hydrolase recognition, as missense mutations in conserved cysteine residues in this domain do not affect the catalytic activity but impair mannose phosphorylation of certain Lysosomal hydrolases. Rescue experiments using mRNA bearing Notch repeat 1 mutations in GNPTAB-deficient zebrafish revealed selective effects on hydrolase recognition that differ from the DMAP mutation. Finally, the mutant R587P, located in the spacer between Notch 2 and DMAP, was partially rescued by overexpression of the γ subunit, suggesting a role for this region in γ subunit binding. These studies provide new insight into the functions of the different domains of the α and β subunits. Background: Mutations in GNPTAB cause the Lysosomal disorders mucolipidosis II and III αβ. Results: All reported missense mutations were studied and showed various consequences on its gene product, αβ GlcNAc-1-phosphotransferase. Conclusion: Domains responsible for catalytic activity and Lysosomal hydrolase recognition were identified. Significance: Analysis of patient mutations provided new insight into the functional domains of αβ GlcNAc-1-phosphotransferase.
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binding of gga2 to the Lysosomal Enzyme sorting motif of the mannose 6 phosphate receptor
Science, 2001Co-Authors: Balraj Doray, Anssi Poussu, Velipekka Lehto, Stuart KornfeldAbstract:The GGAs are a multidomain protein family implicated in protein trafficking between the Golgi and endosomes. Here, the VHS domain of GGA2 was shown to bind to the acidic cluster–dileucine motif in the cytoplasmic tail of the cation-independent mannose 6-phosphate receptor (CI-MPR). Receptors with mutations in this motif were defective in Lysosomal Enzyme sorting. The hinge domain of GGA2 bound clathrin, suggesting that GGA2 could be a link between cargo molecules and clathrin-coated vesicle assembly. Thus, GGA2 binding to the CI-MPR is important for Lysosomal Enzyme targeting.
Yi Qian - One of the best experts on this subject based on the ideXlab platform.
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analysis of mucolipidosis ii iii gnptab missense mutations identifies domains of udp glcnac Lysosomal Enzyme glcnac 1 phosphotransferase involved in catalytic function and Lysosomal Enzyme recognition
Journal of Biological Chemistry, 2015Co-Authors: Yi Qian, Eline Van Meel, Heather Flanagansteet, Alexander D Yox, Richard Steet, Stuart KornfeldAbstract:UDP-GlcNAc:Lysosomal Enzyme GlcNAc-1-phosphotransferase tags newly synthesized Lysosomal Enzymes with mannose 6-phosphate recognition markers, which are required for their targeting to the endoLysosomal system. GNPTAB encodes the α and β subunits of GlcNAc-1-phosphotransferase, and mutations in this gene cause the Lysosomal storage disorders mucolipidosis II and III αβ. Prior investigation of missense mutations in GNPTAB uncovered amino acids in the N-terminal region and within the DMAP domain involved in Golgi retention of GlcNAc-1-phosphotransferase and its ability to specifically recognize Lysosomal hydrolases, respectively. Here, we undertook a comprehensive analysis of the remaining missense mutations in GNPTAB reported in mucolipidosis II and III αβ patients using cell- and zebrafish-based approaches. We show that the Stealth domain harbors the catalytic site, as some mutations in these regions greatly impaired the activity of the Enzyme without affecting its Golgi localization and proteolytic processing. We also demonstrate a role for the Notch repeat 1 in Lysosomal hydrolase recognition, as missense mutations in conserved cysteine residues in this domain do not affect the catalytic activity but impair mannose phosphorylation of certain Lysosomal hydrolases. Rescue experiments using mRNA bearing Notch repeat 1 mutations in GNPTAB-deficient zebrafish revealed selective effects on hydrolase recognition that differ from the DMAP mutation. Finally, the mutant R587P, located in the spacer between Notch 2 and DMAP, was partially rescued by overexpression of the γ subunit, suggesting a role for this region in γ subunit binding. These studies provide new insight into the functions of the different domains of the α and β subunits.
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analysis of mucolipidosis ii iii gnptab missense mutations identifies domains of udp glcnac Lysosomal Enzyme glcnac 1 phosphotransferase involved in catalytic function and Lysosomal Enzyme recognition
Journal of Biological Chemistry, 2015Co-Authors: Yi Qian, Eline Van Meel, Heather Flanagansteet, Alexander D Yox, Richard Steet, Stuart KornfeldAbstract:UDP-GlcNAc:Lysosomal Enzyme GlcNAc-1-phosphotransferase tags newly synthesized Lysosomal Enzymes with mannose 6-phosphate recognition markers, which are required for their targeting to the endoLysosomal system. GNPTAB encodes the α and β subunits of GlcNAc-1-phosphotransferase, and mutations in this gene cause the Lysosomal storage disorders mucolipidosis II and III αβ. Prior investigation of missense mutations in GNPTAB uncovered amino acids in the N-terminal region and within the DMAP domain involved in Golgi retention of GlcNAc-1-phosphotransferase and its ability to specifically recognize Lysosomal hydrolases, respectively. Here, we undertook a comprehensive analysis of the remaining missense mutations in GNPTAB reported in mucolipidosis II and III αβ patients using cell- and zebrafish-based approaches. We show that the Stealth domain harbors the catalytic site, as some mutations in these regions greatly impaired the activity of the Enzyme without affecting its Golgi localization and proteolytic processing. We also demonstrate a role for the Notch repeat 1 in Lysosomal hydrolase recognition, as missense mutations in conserved cysteine residues in this domain do not affect the catalytic activity but impair mannose phosphorylation of certain Lysosomal hydrolases. Rescue experiments using mRNA bearing Notch repeat 1 mutations in GNPTAB-deficient zebrafish revealed selective effects on hydrolase recognition that differ from the DMAP mutation. Finally, the mutant R587P, located in the spacer between Notch 2 and DMAP, was partially rescued by overexpression of the γ subunit, suggesting a role for this region in γ subunit binding. These studies provide new insight into the functions of the different domains of the α and β subunits. Background: Mutations in GNPTAB cause the Lysosomal disorders mucolipidosis II and III αβ. Results: All reported missense mutations were studied and showed various consequences on its gene product, αβ GlcNAc-1-phosphotransferase. Conclusion: Domains responsible for catalytic activity and Lysosomal hydrolase recognition were identified. Significance: Analysis of patient mutations provided new insight into the functional domains of αβ GlcNAc-1-phosphotransferase.
Richard Steet - One of the best experts on this subject based on the ideXlab platform.
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analysis of mucolipidosis ii iii gnptab missense mutations identifies domains of udp glcnac Lysosomal Enzyme glcnac 1 phosphotransferase involved in catalytic function and Lysosomal Enzyme recognition
Journal of Biological Chemistry, 2015Co-Authors: Yi Qian, Eline Van Meel, Heather Flanagansteet, Alexander D Yox, Richard Steet, Stuart KornfeldAbstract:UDP-GlcNAc:Lysosomal Enzyme GlcNAc-1-phosphotransferase tags newly synthesized Lysosomal Enzymes with mannose 6-phosphate recognition markers, which are required for their targeting to the endoLysosomal system. GNPTAB encodes the α and β subunits of GlcNAc-1-phosphotransferase, and mutations in this gene cause the Lysosomal storage disorders mucolipidosis II and III αβ. Prior investigation of missense mutations in GNPTAB uncovered amino acids in the N-terminal region and within the DMAP domain involved in Golgi retention of GlcNAc-1-phosphotransferase and its ability to specifically recognize Lysosomal hydrolases, respectively. Here, we undertook a comprehensive analysis of the remaining missense mutations in GNPTAB reported in mucolipidosis II and III αβ patients using cell- and zebrafish-based approaches. We show that the Stealth domain harbors the catalytic site, as some mutations in these regions greatly impaired the activity of the Enzyme without affecting its Golgi localization and proteolytic processing. We also demonstrate a role for the Notch repeat 1 in Lysosomal hydrolase recognition, as missense mutations in conserved cysteine residues in this domain do not affect the catalytic activity but impair mannose phosphorylation of certain Lysosomal hydrolases. Rescue experiments using mRNA bearing Notch repeat 1 mutations in GNPTAB-deficient zebrafish revealed selective effects on hydrolase recognition that differ from the DMAP mutation. Finally, the mutant R587P, located in the spacer between Notch 2 and DMAP, was partially rescued by overexpression of the γ subunit, suggesting a role for this region in γ subunit binding. These studies provide new insight into the functions of the different domains of the α and β subunits.
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analysis of mucolipidosis ii iii gnptab missense mutations identifies domains of udp glcnac Lysosomal Enzyme glcnac 1 phosphotransferase involved in catalytic function and Lysosomal Enzyme recognition
Journal of Biological Chemistry, 2015Co-Authors: Yi Qian, Eline Van Meel, Heather Flanagansteet, Alexander D Yox, Richard Steet, Stuart KornfeldAbstract:UDP-GlcNAc:Lysosomal Enzyme GlcNAc-1-phosphotransferase tags newly synthesized Lysosomal Enzymes with mannose 6-phosphate recognition markers, which are required for their targeting to the endoLysosomal system. GNPTAB encodes the α and β subunits of GlcNAc-1-phosphotransferase, and mutations in this gene cause the Lysosomal storage disorders mucolipidosis II and III αβ. Prior investigation of missense mutations in GNPTAB uncovered amino acids in the N-terminal region and within the DMAP domain involved in Golgi retention of GlcNAc-1-phosphotransferase and its ability to specifically recognize Lysosomal hydrolases, respectively. Here, we undertook a comprehensive analysis of the remaining missense mutations in GNPTAB reported in mucolipidosis II and III αβ patients using cell- and zebrafish-based approaches. We show that the Stealth domain harbors the catalytic site, as some mutations in these regions greatly impaired the activity of the Enzyme without affecting its Golgi localization and proteolytic processing. We also demonstrate a role for the Notch repeat 1 in Lysosomal hydrolase recognition, as missense mutations in conserved cysteine residues in this domain do not affect the catalytic activity but impair mannose phosphorylation of certain Lysosomal hydrolases. Rescue experiments using mRNA bearing Notch repeat 1 mutations in GNPTAB-deficient zebrafish revealed selective effects on hydrolase recognition that differ from the DMAP mutation. Finally, the mutant R587P, located in the spacer between Notch 2 and DMAP, was partially rescued by overexpression of the γ subunit, suggesting a role for this region in γ subunit binding. These studies provide new insight into the functions of the different domains of the α and β subunits. Background: Mutations in GNPTAB cause the Lysosomal disorders mucolipidosis II and III αβ. Results: All reported missense mutations were studied and showed various consequences on its gene product, αβ GlcNAc-1-phosphotransferase. Conclusion: Domains responsible for catalytic activity and Lysosomal hydrolase recognition were identified. Significance: Analysis of patient mutations provided new insight into the functional domains of αβ GlcNAc-1-phosphotransferase.
Alexander D Yox - One of the best experts on this subject based on the ideXlab platform.
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analysis of mucolipidosis ii iii gnptab missense mutations identifies domains of udp glcnac Lysosomal Enzyme glcnac 1 phosphotransferase involved in catalytic function and Lysosomal Enzyme recognition
Journal of Biological Chemistry, 2015Co-Authors: Yi Qian, Eline Van Meel, Heather Flanagansteet, Alexander D Yox, Richard Steet, Stuart KornfeldAbstract:UDP-GlcNAc:Lysosomal Enzyme GlcNAc-1-phosphotransferase tags newly synthesized Lysosomal Enzymes with mannose 6-phosphate recognition markers, which are required for their targeting to the endoLysosomal system. GNPTAB encodes the α and β subunits of GlcNAc-1-phosphotransferase, and mutations in this gene cause the Lysosomal storage disorders mucolipidosis II and III αβ. Prior investigation of missense mutations in GNPTAB uncovered amino acids in the N-terminal region and within the DMAP domain involved in Golgi retention of GlcNAc-1-phosphotransferase and its ability to specifically recognize Lysosomal hydrolases, respectively. Here, we undertook a comprehensive analysis of the remaining missense mutations in GNPTAB reported in mucolipidosis II and III αβ patients using cell- and zebrafish-based approaches. We show that the Stealth domain harbors the catalytic site, as some mutations in these regions greatly impaired the activity of the Enzyme without affecting its Golgi localization and proteolytic processing. We also demonstrate a role for the Notch repeat 1 in Lysosomal hydrolase recognition, as missense mutations in conserved cysteine residues in this domain do not affect the catalytic activity but impair mannose phosphorylation of certain Lysosomal hydrolases. Rescue experiments using mRNA bearing Notch repeat 1 mutations in GNPTAB-deficient zebrafish revealed selective effects on hydrolase recognition that differ from the DMAP mutation. Finally, the mutant R587P, located in the spacer between Notch 2 and DMAP, was partially rescued by overexpression of the γ subunit, suggesting a role for this region in γ subunit binding. These studies provide new insight into the functions of the different domains of the α and β subunits.
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analysis of mucolipidosis ii iii gnptab missense mutations identifies domains of udp glcnac Lysosomal Enzyme glcnac 1 phosphotransferase involved in catalytic function and Lysosomal Enzyme recognition
Journal of Biological Chemistry, 2015Co-Authors: Yi Qian, Eline Van Meel, Heather Flanagansteet, Alexander D Yox, Richard Steet, Stuart KornfeldAbstract:UDP-GlcNAc:Lysosomal Enzyme GlcNAc-1-phosphotransferase tags newly synthesized Lysosomal Enzymes with mannose 6-phosphate recognition markers, which are required for their targeting to the endoLysosomal system. GNPTAB encodes the α and β subunits of GlcNAc-1-phosphotransferase, and mutations in this gene cause the Lysosomal storage disorders mucolipidosis II and III αβ. Prior investigation of missense mutations in GNPTAB uncovered amino acids in the N-terminal region and within the DMAP domain involved in Golgi retention of GlcNAc-1-phosphotransferase and its ability to specifically recognize Lysosomal hydrolases, respectively. Here, we undertook a comprehensive analysis of the remaining missense mutations in GNPTAB reported in mucolipidosis II and III αβ patients using cell- and zebrafish-based approaches. We show that the Stealth domain harbors the catalytic site, as some mutations in these regions greatly impaired the activity of the Enzyme without affecting its Golgi localization and proteolytic processing. We also demonstrate a role for the Notch repeat 1 in Lysosomal hydrolase recognition, as missense mutations in conserved cysteine residues in this domain do not affect the catalytic activity but impair mannose phosphorylation of certain Lysosomal hydrolases. Rescue experiments using mRNA bearing Notch repeat 1 mutations in GNPTAB-deficient zebrafish revealed selective effects on hydrolase recognition that differ from the DMAP mutation. Finally, the mutant R587P, located in the spacer between Notch 2 and DMAP, was partially rescued by overexpression of the γ subunit, suggesting a role for this region in γ subunit binding. These studies provide new insight into the functions of the different domains of the α and β subunits. Background: Mutations in GNPTAB cause the Lysosomal disorders mucolipidosis II and III αβ. Results: All reported missense mutations were studied and showed various consequences on its gene product, αβ GlcNAc-1-phosphotransferase. Conclusion: Domains responsible for catalytic activity and Lysosomal hydrolase recognition were identified. Significance: Analysis of patient mutations provided new insight into the functional domains of αβ GlcNAc-1-phosphotransferase.
Heather Flanagansteet - One of the best experts on this subject based on the ideXlab platform.
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analysis of mucolipidosis ii iii gnptab missense mutations identifies domains of udp glcnac Lysosomal Enzyme glcnac 1 phosphotransferase involved in catalytic function and Lysosomal Enzyme recognition
Journal of Biological Chemistry, 2015Co-Authors: Yi Qian, Eline Van Meel, Heather Flanagansteet, Alexander D Yox, Richard Steet, Stuart KornfeldAbstract:UDP-GlcNAc:Lysosomal Enzyme GlcNAc-1-phosphotransferase tags newly synthesized Lysosomal Enzymes with mannose 6-phosphate recognition markers, which are required for their targeting to the endoLysosomal system. GNPTAB encodes the α and β subunits of GlcNAc-1-phosphotransferase, and mutations in this gene cause the Lysosomal storage disorders mucolipidosis II and III αβ. Prior investigation of missense mutations in GNPTAB uncovered amino acids in the N-terminal region and within the DMAP domain involved in Golgi retention of GlcNAc-1-phosphotransferase and its ability to specifically recognize Lysosomal hydrolases, respectively. Here, we undertook a comprehensive analysis of the remaining missense mutations in GNPTAB reported in mucolipidosis II and III αβ patients using cell- and zebrafish-based approaches. We show that the Stealth domain harbors the catalytic site, as some mutations in these regions greatly impaired the activity of the Enzyme without affecting its Golgi localization and proteolytic processing. We also demonstrate a role for the Notch repeat 1 in Lysosomal hydrolase recognition, as missense mutations in conserved cysteine residues in this domain do not affect the catalytic activity but impair mannose phosphorylation of certain Lysosomal hydrolases. Rescue experiments using mRNA bearing Notch repeat 1 mutations in GNPTAB-deficient zebrafish revealed selective effects on hydrolase recognition that differ from the DMAP mutation. Finally, the mutant R587P, located in the spacer between Notch 2 and DMAP, was partially rescued by overexpression of the γ subunit, suggesting a role for this region in γ subunit binding. These studies provide new insight into the functions of the different domains of the α and β subunits.
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analysis of mucolipidosis ii iii gnptab missense mutations identifies domains of udp glcnac Lysosomal Enzyme glcnac 1 phosphotransferase involved in catalytic function and Lysosomal Enzyme recognition
Journal of Biological Chemistry, 2015Co-Authors: Yi Qian, Eline Van Meel, Heather Flanagansteet, Alexander D Yox, Richard Steet, Stuart KornfeldAbstract:UDP-GlcNAc:Lysosomal Enzyme GlcNAc-1-phosphotransferase tags newly synthesized Lysosomal Enzymes with mannose 6-phosphate recognition markers, which are required for their targeting to the endoLysosomal system. GNPTAB encodes the α and β subunits of GlcNAc-1-phosphotransferase, and mutations in this gene cause the Lysosomal storage disorders mucolipidosis II and III αβ. Prior investigation of missense mutations in GNPTAB uncovered amino acids in the N-terminal region and within the DMAP domain involved in Golgi retention of GlcNAc-1-phosphotransferase and its ability to specifically recognize Lysosomal hydrolases, respectively. Here, we undertook a comprehensive analysis of the remaining missense mutations in GNPTAB reported in mucolipidosis II and III αβ patients using cell- and zebrafish-based approaches. We show that the Stealth domain harbors the catalytic site, as some mutations in these regions greatly impaired the activity of the Enzyme without affecting its Golgi localization and proteolytic processing. We also demonstrate a role for the Notch repeat 1 in Lysosomal hydrolase recognition, as missense mutations in conserved cysteine residues in this domain do not affect the catalytic activity but impair mannose phosphorylation of certain Lysosomal hydrolases. Rescue experiments using mRNA bearing Notch repeat 1 mutations in GNPTAB-deficient zebrafish revealed selective effects on hydrolase recognition that differ from the DMAP mutation. Finally, the mutant R587P, located in the spacer between Notch 2 and DMAP, was partially rescued by overexpression of the γ subunit, suggesting a role for this region in γ subunit binding. These studies provide new insight into the functions of the different domains of the α and β subunits. Background: Mutations in GNPTAB cause the Lysosomal disorders mucolipidosis II and III αβ. Results: All reported missense mutations were studied and showed various consequences on its gene product, αβ GlcNAc-1-phosphotransferase. Conclusion: Domains responsible for catalytic activity and Lysosomal hydrolase recognition were identified. Significance: Analysis of patient mutations provided new insight into the functional domains of αβ GlcNAc-1-phosphotransferase.
