Figure 6.

Bcl-w and other retrograde response genes are important for the survival of DRG sensory neurons. A, Representative images of DAPI staining in dorsal root ganglia from cervical and lumbar regions of the spinal cord in bcl-2+/+ and bcl-w−/− mice. Arrows indicate apoptotic cells. Scale bar, 10 μm. B, In vivo analysis of apoptosis. Bcl-w−/− P0 mice show an increase in cell death compared with WT littermates, in both cervical and lumbar DRGs. The percentage of cells in the DRG with condensed nuclei when visualized by DAPI staining are shown. Three animals of each genotype were used, and 3–6 dorsal root ganglia from each lumbar and cervical region were counted. All data show means ± SEM, *p < 0.0001. C, Survival of bclw−/− sensory neurons in compartmented cultures stimulated with neurotrophin applied to the distal axons (DA) or the cell bodies (CB). DRG neurons were dissected at E14 and seeded in compartmented cultures. Bcl-w−/− neurons are more prone to apoptosis in serum free-media compared with bcl-w+/+ and +/− under all conditions tested, *p < 0.05. D, Retrograde response genes: DRG neurons in compartmented cultures were stimulated with NGF and BDNF or vehicle applied either to DA or the cell bodies (CB), for 2 h. RNA was prepared and expression of decorin, alsin, enpeptidase, mef2d, HSF-1, IGF-1, bcl-w, and c-fos were assessed by quantitative RT-PCR and normalized to gapdh in the same sample. Fold induction was measured by comparing normalized level of expression in neurotrophin-treated/vehicle-treated cells for four experiments each involving five cultures for each condition (DA shown first in black). Statistical analysis by z-test, **p ≤ 0.05, *p ≤ 0.10 for a difference from one.