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Discovery of a pathway for endogenous mucin glycodomain catabolism in mammals

ABSTRACT: Mucins are functionally implicated in a range of human pathologies, including cystic fibrosis, influenza, bacterial endocarditis, gut dysbiosis, and cancer. These observations have motivated the study of mucin biosynthesis as well as development of strategies for inhibition of mucin glycosylation. Mammalian pathways for mucin catabolism, however, have remained underexplored. The canonical view, derived from analysis of N-glycoconjugates in human lysosomal storage disorders, is that proteolysis and glycan degradation occur largely independently. Here, we challenge this view by providing genetic and biochemical evidence supporting mammalian proteolysis of heavily O-glycosylated mucin domains, without prior deglycosylation. Using activity screening coupled with mass spectrometry we ascribed mucin-degrading activity in murine liver to the lysosomal protease cathepsin D. Knockout of cathepsin D in a murine model of the human lysosomal storage disorder neuronal ceroid lipofuscinosis resulted in accumulation of mucins in liver-resident macrophages. Our findings suggest that mucin-degrading activity is not limited to the bacterial kingdom and is a component of glycoprotein catabolism in mammalian tissues.

INSTRUMENT(S): Orbitrap Fusion

ORGANISM(S): Homo Sapiens (human) Mus Musculus (mouse)

TISSUE(S): Brain, Liver

SUBMITTER: Nicholas Riley

LAB HEAD: Carolyn Bertozzi

PROVIDER: PXD027616 | Pride | 2022-09-03

REPOSITORIES: Pride

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			Action	DRS
	2020_05_16_KP_BC1.raw	Raw
	2020_05_16_KP_BC10.raw	Raw
	2020_05_16_KP_BC11.raw	Raw
	2020_05_16_KP_BC12.raw	Raw
	2020_05_16_KP_BC2.raw	Raw

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