Mannose-6-phosphate regulates destruction of lipid-linked oligosaccharides.

TitleMannose-6-phosphate regulates destruction of lipid-linked oligosaccharides.
Publication TypeJournal Article
Year of Publication2011
AuthorsGao N, Shang J, Huynh D, Manthati VL, Arias C, Harding HP, Kaufman RJ, Mohr I, Ron D, Falck JR, Lehrman MA
JournalMol Biol Cell
Volume22
Issue17
Pagination2994-3009
Date Published2011 Sep
ISSN1939-4586
KeywordsAmides, Aminoacridines, Animals, CHO Cells, Congenital Disorders of Glycosylation, Cricetinae, Dolichol Phosphates, eIF-2 Kinase, Endoplasmic Reticulum Stress, Fibroblasts, Fluorescent Dyes, Glycogen, Glycogen Phosphorylase, Herpes Simplex, Herpesvirus 1, Human, Host-Pathogen Interactions, Immunity, Cellular, Indoles, Lipopolysaccharides, Mannosephosphates, Mice, Mice, Knockout, Phosphotransferases (Phosphomutases), Polysaccharides, Unfolded Protein Response
Abstract

Mannose-6-phosphate (M6P) is an essential precursor for mannosyl glycoconjugates, including lipid-linked oligosaccharides (LLO; glucose(3)mannose(9)GlcNAc(2)-P-P-dolichol) used for protein N-glycosylation. In permeabilized mammalian cells, M6P also causes specific LLO cleavage. However, the context and purpose of this paradoxical reaction are unknown. In this study, we used intact mouse embryonic fibroblasts to show that endoplasmic reticulum (ER) stress elevates M6P concentrations, leading to cleavage of the LLO pyrophosphate linkage with recovery of its lipid and lumenal glycan components. We demonstrate that this M6P originates from glycogen, with glycogenolysis activated by the kinase domain of the stress sensor IRE1-α. The apparent futility of M6P causing destruction of its LLO product was resolved by experiments with another stress sensor, PKR-like ER kinase (PERK), which attenuates translation. PERK's reduction of N-glycoprotein synthesis (which consumes LLOs) stabilized steady-state LLO levels despite continuous LLO destruction. However, infection with herpes simplex virus 1, an N-glycoprotein-bearing pathogen that impairs PERK signaling, not only caused LLO destruction but depleted LLO levels as well. In conclusion, the common metabolite M6P is also part of a novel mammalian stress-signaling pathway, responding to viral stress by depleting host LLOs required for N-glycosylation of virus-associated polypeptides. Apparently conserved throughout evolution, LLO destruction may be a response to a variety of environmental stresses.

DOI10.1091/mbc.E11-04-0286
Alternate JournalMol. Biol. Cell
PubMed ID21737679
PubMed Central IDPMC3164449
Grant ListHL-052173 / HL / NHLBI NIH HHS / United States
P01 HL057346 / HL / NHLBI NIH HHS / United States
R01 GM056927 / GM / NIGMS NIH HHS / United States
GM-056927 / GM / NIGMS NIH HHS / United States
GM-038545 / GM / NIGMS NIH HHS / United States
GM-031278 / GM / NIGMS NIH HHS / United States
R56 GM038545 / GM / NIGMS NIH HHS / United States
R37 DK042394 / DK / NIDDK NIH HHS / United States
R37 DK047119 / DK / NIDDK NIH HHS / United States
AI-073898 / AI / NIAID NIH HHS / United States
DK-042394 / DK / NIDDK NIH HHS / United States
R01 GM038545 / GM / NIGMS NIH HHS / United States
R-37-DK047119 / DK / NIDDK NIH HHS / United States
R01 DK042394 / DK / NIDDK NIH HHS / United States
R01 HL052173 / HL / NHLBI NIH HHS / United States
R01 GM038545-23 / GM / NIGMS NIH HHS / United States
084812 / / Wellcome Trust / United Kingdom
R01 GM031278 / GM / NIGMS NIH HHS / United States
HL-057346 / HL / NHLBI NIH HHS / United States
R01 AI073898 / AI / NIAID NIH HHS / United States
/ / Wellcome Trust / United Kingdom