Document Detail


Transport of Trembler-J mutant peripheral myelin protein 22 is blocked in the intermediate compartment and affects the transport of the wild-type protein by direct interaction.
MedLine Citation:
PMID:  10066256     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Peripheral myelin protein 22 (PMP22) is an integral membrane protein that is essential for the normal formation and maintenance of peripheral myelin. Duplications, deletions, or mutations in the PMP22 gene account for a set of dominantly inherited peripheral neuropathies. The heterozygous Trembler-J (TrJ) genotype in mice is similar genetically to a Charcot-Marie-Tooth disease type 1A pedigree in humans, whereas the homozygous TrJ condition leads to the most severe form of PMP22-associated neuropathies. To characterize the consequences of the TrJ mutation, we labeled wild-type (wt-) and TrJ-PMP22 in the third loop of the protein with different epitope tags and expressed them separately or together in COS7 cells and primary Schwann cells. Here we show that the transport of the mutant TrJ-PMP22 is interrupted in the intermediate compartment, preventing its insertion into the plasma membrane and affecting the morphology of the endoplasmic reticulum. In addition, TrJ-PMP22 forms a heterodimer with the wt-PMP22. This interaction causes a fraction of the wt-PMP22 to be retained with TrJ-PMP22 in the intermediate compartment of COS7 and Schwann cells. The relative stability of a wt-mutant PMP22 heterodimer as compared with the wt-wt PMP22 homodimer may determine whether a particular mutation is semidominant or dominant. The neuropathy itself appears to result both from decreased trafficking of wt-PMP22 to the plasma membrane and from a toxic gain of function via the accumulation of wt- and TrJ-PMP22 in the intermediate compartment.
Authors:
A R Tobler; L Notterpek; R Naef; V Taylor; U Suter; E M Shooter
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of neuroscience : the official journal of the Society for Neuroscience     Volume:  19     ISSN:  0270-6474     ISO Abbreviation:  J. Neurosci.     Publication Date:  1999 Mar 
Date Detail:
Created Date:  1999-04-13     Completed Date:  1999-04-13     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  8102140     Medline TA:  J Neurosci     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  2027-36     Citation Subset:  IM    
Affiliation:
Department of Neurobiology, Stanford University School of Medicine, Stanford, California 94305-5125, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Biological Transport / physiology
COS Cells
Dimerization
Epitopes / physiology
Mice
Mice, Neurologic Mutants / metabolism*
Mutation / physiology*
Myelin Proteins / chemistry,  genetics,  immunology,  metabolism*
Reference Values
Schwann Cells / metabolism
Grant Support
ID/Acronym/Agency:
NS04270/NS/NINDS NIH HHS; NS09694/NS/NINDS NIH HHS
Chemical
Reg. No./Substance:
0/Epitopes; 0/Myelin Proteins; 0/Pmp22 protein, mouse

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