Neuraminidase 1 secondary deficiency contributes to CNS pathology in neurological mucopolysaccharidoses via brain protein hypersialylation
TianMeng Xu, Rachel Heon-Roberts, Travis Moore, Patricia Dubot, Xuefang Pan, Tianlin Guo, Christopher W. Cairo, Rebecca J. Holley, Brian Bigger, Thomas M. Durcan, Thierry Levade, Jerôme Ausseil, Bénédicte Amilhon, Alexei Gorelik, Bhushan Nagar, Shaukat Khan, Shunji Tomatsu, Luisa Sturiale, Angelo Palmigiano, Iris Röckle, Hauke Thiesler, Herbert Hildebrandt, Domenico Garozzo, Alexey V. Pshezhetsky
TianMeng Xu, Rachel Heon-Roberts, Travis Moore, Patricia Dubot, Xuefang Pan, Tianlin Guo, Christopher W. Cairo, Rebecca J. Holley, Brian Bigger, Thomas M. Durcan, Thierry Levade, Jerôme Ausseil, Bénédicte Amilhon, Alexei Gorelik, Bhushan Nagar, Shaukat Khan, Shunji Tomatsu, Luisa Sturiale, Angelo Palmigiano, Iris Röckle, Hauke Thiesler, Herbert Hildebrandt, Domenico Garozzo, Alexey V. Pshezhetsky
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Research Article Genetics Neuroscience

Neuraminidase 1 secondary deficiency contributes to CNS pathology in neurological mucopolysaccharidoses via brain protein hypersialylation

Abstract

Mucopolysaccharidoses (MPS) are lysosomal storage diseases caused by defects in catabolism of glycosaminoglycans. MPS I, II, III, and VII, which are associated with lysosomal accumulation of heparan sulphate (HS), manifest with neurological deterioration and currently lack effective treatments. We report that neuraminidase 1 (NEU1) activity is drastically reduced in brain tissues of patients with neurological MPS and mouse models but not in neurological lysosomal disorders without HS storage. Accumulated HS disrupts the lysosomal multienzyme complex of NEU1 with cathepsin A, β-galactosidase (GLB1), and glucosamine-6-sulfate sulfatase (GALNS), leading to NEU1 deficiency and partial GLB1 and GALNS deficiencies in cortical tissues and induced pluripotent stem cell–derived (iPSC-derived) cortical neurons of patients with neurological MPS. Increased sialylation of N-linked glycans in brains of patients with MPS and mice implicated insufficient processing of sialylated glycans, except for polysialic acid. Correction of NEU1 activity in MPS IIIC mice by lentiviral (LV) gene transfer ameliorated previously identified hallmarks of the disease, including memory impairment, behavioral traits, and reduced levels of excitatory synapse markers VGLUT1 and PSD95. Overexpression of NEU1 also restored levels of VGLUT1/PSD95–positive puncta in cortical iPSC-derived MPS IIIA neurons. Our results demonstrate that HS-induced secondary NEU1 deficiency and aberrant sialylation of brain glycoproteins constitute what we believe is a novel pathological pathway in the neurological MPS spectrum crucially contributing to CNS pathology.

Authors

TianMeng Xu, Rachel Heon-Roberts, Travis Moore, Patricia Dubot, Xuefang Pan, Tianlin Guo, Christopher W. Cairo, Rebecca J. Holley, Brian Bigger, Thomas M. Durcan, Thierry Levade, Jerôme Ausseil, Bénédicte Amilhon, Alexei Gorelik, Bhushan Nagar, Shaukat Khan, Shunji Tomatsu, Luisa Sturiale, Angelo Palmigiano, Iris Röckle, Hauke Thiesler, Herbert Hildebrandt, Domenico Garozzo, Alexey V. Pshezhetsky

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Figure 5

NEU1 deficiency in tissues and cells with lysosomal storage of HS is associated with the disruption of the LMC.

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NEU1 deficiency in tissues and cells with lysosomal storage of HS is ass...
(A) Neu1 mRNA measured by quantitative RT-PCR and normalized for Rpl32 expression. (B) Neu1, Neu3, and Neu4 (relative to WT mice) expression measured in the hippocampi by total mRNA sequencing (14). (C) GLB1 activity is reduced in cortical tissues from patients with MPS I (561), MPS II (902), MPS IIIA (3617 and 563), MPS IIIC (6194), and MPS IIID (5411 and 5424), compared with corresponding controls; numbers in parentheses refer to identity of neurological MPS patients in Supplemental Table 1. (D) GALNS activity is reduced in samples from patients with MPS compared with control samples. (E) GALNS activity is reduced in brains of MPS IIIC mice compared with WT mice. (F) NEU1, but not GLB1 or GALNS, is deficient in the brains of galactosialidosis CathAS190A-neo mice. (G and H) CTSA activity in brain samples of patients with MPS (G) and MPS IIIC mice (H) is similar or higher than that of controls. (I) Reduced NEU1 and unchanged CTSA protein levels in MPS IIIA-IIIC mouse brains compared with WT. (J) The gel-filtration profiles of total protein extracts from brain tissues of MPS IIIC HgsnatP304L, WT, and CathAS190A-Neo mice and GLB1 and NEU1 activities in the eluted fractions. (K) HS inhibits NEU1 activity in vitro. Purified recombinant NEU1 was incubated with or without CTSA and HS, followed by NEU1 enzymatic activity (moles of substrate/moles of NEU1/sec) measurement. Insert shows expanded view of the results obtained with the NEU1 apo form. (L) Docked pose of an HS tetramer in the active site of NEU1 (8DU5). The arginine triad of NEU1 is able to engage sulfate and carboxylate groups of the ligand. All graphs show individual results and means ± SD; n = 3–5 (mice) or 3 independent measurements (human samples or recombinant enzymes). *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, determined by ANOVA with Tukey’s (A, B, E, and H) or Šídák’s (C, D, and G) post hoc tests or t test (F).