Glycosylation limits forward trafficking of the tetraspan membrane protein PMP22.

Autor:	Marinko JT; Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA; Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA., Wright MT; Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA., Schlebach JP; Department of Chemistry, Indiana University, Bloomington, Indiana, USA., Clowes KR; Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA; Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA., Heintzman DR; Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, Tennessee, USA., Plate L; Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA; Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA., Sanders CR; Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA; Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA. Electronic address: chuck.sanders@vanderbilt.edu.
Jazyk:	angličtina
Zdroj:	The Journal of biological chemistry [J Biol Chem] 2021 Jan-Jun; Vol. 296, pp. 100719. Date of Electronic Publication: 2021 Apr 30.
DOI:	10.1016/j.jbc.2021.100719
Abstrakt:	Peripheral myelin protein 22 (PMP22) folds and trafficks inefficiently, with only 20% of newly expressed protein trafficking to the cell surface. This behavior is exacerbated in many of the mutants associated with Charcot-Marie-Tooth disease, motivating further study. Here we characterized the role of N-glycosylation in limiting PMP22 trafficking. We first eliminated N-glycosylation using an N41Q mutation, which resulted in an almost 3-fold increase in trafficking efficiency of wildtype (WT) PMP22 and a 10-fold increase for the severely unstable L16P disease mutant in HEK293 cells, with similar results in Schwann cells. Total cellular levels were also much higher for the WT/N41Q mutant, although not for the L16P/N41Q form. Depletion of oligosaccharyltransferase OST-A and OST-B subunits revealed that WT PMP22 is N-glycosylated posttranslationally by OST-B, whereas L16P is cotranslationally glycosylated by OST-A. Quantitative proteomic screens revealed similarities and differences in the interactome for WT, glycosylation-deficient, and unstable mutant forms of PMP22 and also suggested that L16P is sequestered at earlier stages of endoplasmic reticulum quality control. CRISPR knockout studies revealed a role for retention in endoplasmic reticulum sorting receptor 1 (RER1) in limiting the trafficking of all three forms, for UDP-glucose glycoprotein glucosyltransferase 1 (UGGT1) in limiting the trafficking of WT and L16P but not N41Q, and calnexin (CNX) in limiting the trafficking of WT and N41Q but not L16P. This work shows that N-glycosylation is a limiting factor to forward trafficking PMP22 and sheds light on the proteins involved in its quality control. Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article. (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)
Databáze:	MEDLINE
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