DIFFERENTIALLY EXPRESSED GENES AFTER PERIPHERAL-NERVE INJURY

In an attempt to identify genes associated with Wallerian degeneration and peripheral nerve regeneration we have performed differential hybr idization screening of a cDNA library from crushed rat sciatic nerve ( 7 days postlesion) using radioactively labeled cDNA prepared from poly (A)(+) RNA of normal vs, crushed nerve, Screening of 5,000 randomly se lected colonies yielded 24 distinct clones that were regulated followi ng nerve injury, Fifteen of the differentially expressed sequences cou ld be classified as induced, whereas 9 sequences appeared to be repres sed at 1 week postcrush, Sequencing and computer-assisted sequence com parison revealed 3 classes of regulated cDNA clones representing 1) no vel gene sequences (8 clones) including 3 transcripts containing a rep etitive ''brain identifier'' (ID) element; 2) identified genes (7 clon es) with previously undetected expression in the peripheral nervous sy stem (PNS), such as apolipoprotein D, peripheral myelin protein 22kD ( PMP22), SPARC (secreted protein, acidic and rich in cysteine), sulfate d glycoprotein SGP-1, apoferritin, decorin, and X16/SRp20; and 3) iden tified genes (9 clones) with known expression in the PNS including, e, g,, the myelin protein P-0, gamma-actin, vimentin, alpha-tubulin, char gerin II, and cytochrome c-oxidase subunit I, Northern blot and polyme rase chain reaction analyses with RNA from crushed and transected nerv e demonstrated that sequences with related function, like the group of myelin genes, cytoskeleton genes, genes involved in RNA processing an d translation, in lipid transport or energy metabolism showed closely related temporal patterns of expression during nerve degeneration and regeneration, Finally, we compared the differentially expressed genes identified at 7 days after crush injury (this investigation) with the regulated sequences isolated previously by De Leon et al, (J Neurosci Res 29:437-488, 1991) from a 3 day postcrush sciatic nerve cDNA librar y. (C) 1995 Wiley-Liss, Inc.