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dc.contributor.authorHyun, Sang W
dc.contributor.authorImamura, Akihiro
dc.contributor.authorIshida, Hideharu
dc.contributor.authorPiepenbrink, Kurt H
dc.contributor.authorGoldblum, Simeon E
dc.contributor.authorLillehoj, Erik P
dc.date.accessioned2021-11-05T15:42:25Z
dc.date.available2021-11-05T15:42:25Z
dc.date.issued2021-10-22
dc.identifier.urihttp://hdl.handle.net/10713/17060
dc.description.abstractThe extracellular domain (ED) of the membrane-spanning sialoglycoprotein, mucin-1 (MUC1), is an in vivo substrate for the lysosomal sialidase, neuraminidase-1 (NEU1). Engagement of the MUC1-ED by its cognate ligand, Pseudomonas aeruginosa-expressed flagellin, increases NEU1-MUC1 association and NEU1-mediated MUC1-ED desialylation to unmask cryptic binding sites for its ligand. However, the mechanism(s) through which intracellular NEU1 might physically interact with its surface-expressed MUC1-ED substrate are unclear. Using reciprocal co-immunoprecipitation and in vitro binding assays in a human airway epithelial cell system, we show here that NEU1 associates with the MUC1-cytoplasmic domain (CD), but not with the MUC1-ED. Prior pharmacologic inhibition of NEU1 catalytic activity using the NEU1-selective sialidase inhibitor, C9-BA-DANA, did not diminish NEU1-MUC1-CD association. In addition, glutathione S-transferase (GST) pull-down assays utilizing deletion mutants of the MUC1-CD mapped the NEU1-binding site to the membrane-proximal 36 amino acids of the MUC1-CD. In a cell-free system, we found that purified NEU1 interacted with immobilized GST-MUC1-CD, and purified MUC1-CD associated with immobilized 6XHis-NEU1, indicating that the NEU1-MUC1-CD interaction was direct and independent of its chaperone protein, protective protein/cathepsin A. However, the NEU1-MUC1-CD interaction was not required for NEU1-mediated MUC1-ED desialylation. Finally, we demonstrated that overexpression of either wild-type NEU1 or a catalytically-dead NEU1 G68V mutant diminished association of the established MUC1-CD binding partner, phosphoinositide 3-kinase (PI3K), to MUC1-CD and reduced downstream Akt kinase phosphorylation. These results indicate that NEU1 associates with the juxtamembranous region of the MUC1-CD to inhibit PI3K-Akt signaling independent of NEU1 catalytic activity.en_US
dc.description.urihttps://doi.org/10.1016/j.jbc.2021.101337en_US
dc.language.isoenen_US
dc.publisherElsevier Inc.en_US
dc.relation.ispartofJournal of Biological Chemistryen_US
dc.rightsCopyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.en_US
dc.subjectAkt PBKen_US
dc.subjectcell surface associated (MUC1)en_US
dc.subjectmucin 1en_US
dc.subjectneuraminidase-1en_US
dc.subjectphosphatidylinositide 3‐kinase (PI 3‐kinase)en_US
dc.subjectsialic aciden_US
dc.subjectsialidaseen_US
dc.titleThe sialidase NEU1 directly interacts with the juxtamembranous segment of the cytoplasmic domain of mucin-1 to inhibit downstream PI3K-Akt signalingen_US
dc.typeArticleen_US
dc.identifier.doi10.1016/j.jbc.2021.101337
dc.identifier.pmid34688655
dc.source.beginpage101337
dc.source.endpage
dc.source.countryUnited States


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