CMT 1A/HNPP research news

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J Neurosci Res. 2005 Feb 18

An 8.5-kb segment of the PMP22 promoter responds to loss of axon signals during

Wallerian degeneration, but does not respond to specific axonal signals during

nerve regeneration.

Orfali W, Nicholson RN, Guiot MC, AC, Snipes GJ.

Department of Pathology, Baylor College of Medicine, Houston, Texas.

Altered expression of the PMP22 gene causes Charcot-Marie-Tooth disease type 1A

(CMT1A) and hereditary neuropathy with liability to pressure palsies (HNPP). We

have examined the promoter activity of 8.5 kb upstream of the first coding exon

of the rat peripheral myelin protein-22 (rPmp22) gene in transgenic mice. We

found that the -8.5 kb rPmp22/chloramphenicol acetyl transferase

(CAT)/beta-galactosidase (lacZ) construct directs reporter gene expression in a

weakly developmental and tissue-specific pattern, consistent with the expression

pattern of the endogenous Pmp22 gene. The -8.5 kb rPmp22/CAT/lacZ transgene

responds to loss of axonal signals during Wallerian degeneration but unlike the

endogenous Pmp22 gene, the transgene fails to respond to axonal signals during

nerve regeneration after a sciatic nerve crush injury. In conclusion, the

function of the -8.5 kb rPmp22/CAT/lacZ transgene suggests that there are

separable regulatory elements in the rPmp22 gene that respond differently to

axonal signals received by Schwann cells during nerve development, and during

remyelination.

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