Figure 2.

c-Jun-Dependent Regulation of Schwann Cell Genes and Proteins

(A) In purified Schwann cell cultures, c-Jun suppresses myelin genes but activates genes of denervated cells. Graphs show RT-QPCR measurements of six differentially regulated genes in cells from control mice with physiological levels of c-Jun (WT), in cells from mutants lacking c-Jun (cKO), and in mutant cells infected with c-Jun adenovirus to re-express c-Jun (cKO + c-Jun). The y axis shows fold difference in expression levels. Error bars: ± SEM; ^∗p < 0.05, n = 4.

(B and C) Posttranscriptional control of protein expression by c-Jun. (B) Immunolabeling of Schwann cell cultures (5 days in vitro) from p8 WT and mutant nerves. Three proteins characteristically expressed by denervated Schwann cells are shown. Note suppression of N-cadherin (N-cad) and p75NTR but overexpression of NCAM in mutant cells. (Bar: 50 μm). (C) Western blots of distal stump nerve extracts from WT and mutants (cKO) 7 days after cut show a similar expression pattern. Lower panel: quantitation. Error bars: ± SEM; ^∗p < 0.05; ^∗∗∗p < 0.001, n = 3.

(D and E) Immature and denervated cells differ in gene expression. (D) In situ hybridization using probes against Olig1 (left panel), Shh (middle panel), and GDNF (right panel). mRNAs of these are virtually absent from uninjured newborn and adult sciatic nerve but highly upregulated in distal stumps of adult nerve 3 days after transection. Numerous positive cells display the half moon shape typical of Schwann cells (insets in bottom panels). (Bar: 25μm). (E) Agarose gel electrophoresis of GDNF, Olig1, Shh, and GAPDH products amplified by RT-QPCR from cDNA extracted from WT sciatic nerves of E18 and adult mice and from distal stumps of adult mice 7 days postcut.

See also Tables S4 and S5.