CMT 1B mutation research; DSS and CH too

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(Entire article is available on-line in .pdf format. You will need

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1: BMC Cell Biol 2002 Nov 26;3(1):29 [epub ahead of print]

Tracing Myelin Protein Zero (MPZ, P0) in vivo by construction of P0-GFP

fusion proteins.

Ekici AA, Oezbey SS, Fuchs CC, Nelis EE, Van Broeckhoven CC, Schachner

MM, Rautenstrauss BB.

Background Mutations in P0 (MPZ), the major protein of the myelin sheath

in peripheral nerves, cause the inherited peripheral neuropathies

Charcot-Marie-Tooth disease type 1B (CMT1B), Dejerine-Sottas syndrome

(DSS) and congenital hypomyelination (CH). We reported earlier a de novo

insertional mutation c.662_663GC (Ala221fs) in a DSS patient. The

c.662_663GC insertion results in a frame shift mutation Ala221fs

altering the C-terminal amino acid sequence. The adhesion-relevant

intracellular RSTK domain is replaced by a sequence similar to a Na+/K+

ATPase. To further clarify the molecular disease mechanisms in this

sporadic patient we constructed wild-type MPZ and the c.622_663GC mutant

expression cassettes by site-specific mutagenesis and transfected the

constructs into insect cells (S2, High5). To trace the in vivo effects

green fluorescent protein (GFP) has been added to the carboxyterminus of

the wt and mutated MPZ protein. Results In contrast to the

membrane-localized wtP0-GFP the Ala221fs P0-GFP protein was detectable

almost only in the cytoplasma of the cells, and a complete loss of

adhesion function was observed.

Conclusion: The present study provides evidence that GFP is a versatile

tool to trace in vivo effects of P0 and its mutations. Not only a loss

of adhesion function as a

trafficking indicated by a loss of membrane insertion are possible

consequences of the

Ala221fs mutation.