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Glycosylation Limits Forward Trafficking of the Tetraspan Membrane Protein PMP22

ABSTRACT: Peripheral myelin protein 22 (PMP22) is a tetraspan integral membrane protein for which mistrafficking-causing mutations are linked to the inherited peripheral neuropathy, Charcot-Marie-Tooth disease (CMTD). Wild type (WT) PMP22 is an inefficient folder with ~20% of the protein trafficking to the plasma membrane. We discovered that N-linked glycosylation significantly limits forward trafficking of WT and disease variants of PMP22. N-glycosylation of WT PMP22 was found to occur primarily post-translationally. Glycosylation inhibition dramatically increased PMP22 trafficking efficiency. Quantitative proteomics identified novel PMP22 interacting proteins that may impact trafficking. Our results suggest that critical quality control decisions for unstable L16P PMP22 occur at earlier stages in the trafficking pathway than for the WT protein. Knock-out cell lines of likely PMP22 interactors led to the discovery that calnexin limits trafficking of stable PMP22 variants, UGGT1 promotes trafficking and RER1 limits trafficking of all PMP22 variants. This work establishes N-glycosylation as a key determinant of PMP22 retention in the ER, ultimately limiting forward surface-trafficking.

INSTRUMENT(S): Orbitrap Exploris 480, Q Exactive HF

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Permanent Cell Line Cell, Kidney

DISEASE(S): Charcot-marie-tooth Disease

SUBMITTER: Madison Wright

LAB HEAD: Charles R. Sanders

PROVIDER: PXD023091 | Pride | 2021-04-27

REPOSITORIES: Pride

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Glycosylation Limits Forward Trafficking of the Tetraspan Membrane Protein PMP22

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