Dataset Information

Heterodimerization of the sialidase NEU1 with the chaperone protective protein/cathepsin A prevents its premature oligomerization.

ABSTRACT: Lysosomal neuraminidase-1 (NEU1) forms a multienzyme complex with beta-galactosidase and protective protein/cathepsin A (PPCA). Because of its association with PPCA, which acts as a molecular chaperone, NEU1 is transported to the lysosomal compartment, catalytically activated, and stabilized. However, the mode(s) of association between these two proteins both en route to the lysosome and in the multienzyme complex has remained elusive. Here, we have analyzed the hydrodynamic properties of PPCA, NEU1, and a complex of the two proteins and identified multiple binding sites on both proteins. One of these sites on NEU1 that is involved in binding to PPCA can also bind to other NEU1 molecules, albeit with lower affinity. Therefore, in the absence of PPCA, as in the lysosomal storage disease galactosialidosis, NEU1 self-associates into chain-like oligomers. Binding of PPCA can reverse self-association of NEU1 by causing the disassembly of NEU1-oligomers and the formation of a PPCA-NEU1 heterodimeric complex. The identification of binding sites between the two proteins allowed us to create innovative structural models of the NEU1 oligomer and the PPCA-NEU1 heterodimeric complex. The proposed mechanism of interaction between NEU1 and its accessory protein PPCA provides a rationale for the secondary deficiency of NEU1 in galactosialidosis.

SUBMITTER: Bonten EJ

PROVIDER: S-EPMC2788892 | biostudies-literature | 2009 Oct

REPOSITORIES: biostudies-literature

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Heterodimerization of the sialidase NEU1 with the chaperone protective protein/cathepsin A prevents its premature oligomerization.

Bonten Erik J EJ Campos Yvan Y Zaitsev Viateslav V Nourse Amanda A Waddell Brett B Lewis William W Taylor Garry G d'Azzo Alessandra A

The Journal of biological chemistry 20090807 41

Lysosomal neuraminidase-1 (NEU1) forms a multienzyme complex with beta-galactosidase and protective protein/cathepsin A (PPCA). Because of its association with PPCA, which acts as a molecular chaperone, NEU1 is transported to the lysosomal compartment, catalytically activated, and stabilized. However, the mode(s) of association between these two proteins both en route to the lysosome and in the multienzyme complex has remained elusive. Here, we have analyzed the hydrodynamic properties of PPCA, ...[more]

PMID: 19666471

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Project description:Neuraminidase-1 (NEU1) is the predominant sialidase expressed in human airway epithelia and lung microvascular endothelia where it mediates multiple biological processes. We tested whether the NEU1-selective sialidase inhibitor, C9-butyl-amide-2-deoxy-2,3-dehydro-N-acetylneuraminic acid (C9-BA-DANA), inhibits one or more established NEU1-mediated bioactivities in human lung cells. We established the IC50 values of C9-BA-DANA for total sialidase activity in human airway epithelia, lung microvascular endothelia and lung fibroblasts to be 3.74 µM, 13.0 µM and 4.82 µM, respectively. In human airway epithelia, C9-BA-DANA dose-dependently inhibited flagellin-induced, NEU1-mediated mucin-1 ectodomain desialylation, adhesiveness for Pseudomonas aeruginosa and shedding. In lung microvascular endothelia, C9-BA-DANA reversed NEU1-driven restraint of cell migration into a wound and disruption of capillary-like tube formation. NEU1 and its chaperone/transport protein, protective protein/cathepsin A (PPCA), were differentially expressed in these same cells. Normalized NEU1 protein expression correlated with total sialidase activity whereas PPCA expression did not. In contrast to eukaryotic sialidases, C9-BA-DANA exerted far less inhibitory activity for three selected bacterial neuraminidases (IC50 > 800 µM). Structural modeling of the four human sialidases and three bacterial neuraminidases revealed a loop between the seventh and eighth strands of the β-propeller fold, that in NEU1, was substantially shorter than that seen in the six other enzymes. Predicted steric hindrance between this loop and C9-BA-DANA could explain its selectivity for NEU1. Finally, pretreatment of mice with C9-BA-DANA completely protected against flagellin-induced increases in lung sialidase activity. Our combined data indicate that C9-BA-DANA inhibits endogenous and ectopically expressed sialidase activity and established NEU1-mediated bioactivities in human airway epithelia, lung microvascular endothelia, and fibroblasts in vitro and murine lungs in vivo.

Project description:BackgroundMelanoma is a kind of malignant tumor with high mortality originating from melanocytes. It is urgent to find new molecular biomarkers for prognosis and new treatment methods for melanoma. As an important molecule of sialidase family, neuraminidase-1 (NEU1) has been found to play an important role in regulating the occurrence and progression of tumors, but the role of NEU1 in melanoma is not sure.MethodsThe expression level of NEU1 in melanoma and normal tissues was evaluated by analyzing the expression data from ONCOMINE, UALCAN and GEPIA database. The mutation, copy number alteration and gene correlation of NEU1 in melanoma were evaluated by analyzing the melanoma data from cBioPortal database The protein expression levels of NEU1 were further validated by immunohistochemical (IHC) staining data from The Human Protein Atlas database. The melanoma data in TIMER 2.0 database were used to analyze the correlation between NEU1 expression and immune cell infiltration. The proliferative and migratory abilities of melanoma cells were examined by cell proliferation and migration assay in vitro and nude mice.ResultsWe discovered that NEU1 was highly expressed in melanoma samples compared with normal samples. The alteration frequency of NEU1 in melanoma patients reached 18%, and most of them were "mutation" type. The expression of NEU1 was positively correlated with the overall survival of patients with melanoma. The expression of NEU1 was positively correlated with the expression of proliferation marker CDK2 and epithelial-mesenchymal transition marker CD44 and negatively correlated with the expression of apoptosis marker CASP3 and CASP8. Moreover, the expression level of NEU1 was related to the infiltration of immune cells in melanoma. Knockdown of NEU1 attenuated the in vitro proliferative and migratory abilities of melanoma cells, as well as in vivo tumor progression of melanoma cells.ConclusionsThese findings suggest that NEU1 may play a key role in the development of melanoma and may be used as a prognostic target of melanoma.

Dataset Information

Heterodimerization of the sialidase NEU1 with the chaperone protective protein/cathepsin A prevents its premature oligomerization.

Publications

Heterodimerization of the sialidase NEU1 with the chaperone protective protein/cathepsin A prevents its premature oligomerization.

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