Fig. 1

Identification of miRNAs expressed in apoptotic cortical neurons and present in corresponding supernatant by miRNA microarray. (a) Representative images of cortical neurons isolated from C57BL/6 mice incubated with either 1 μM staurosporine or DMSO (0.1%) as solvent control for 8 h. Scale bar, 20 μm. Neurons and corresponding supernatant (S/N) were collected separately for small RNA enrichment and subsequent miRNA GeneChip analysis, as indicated by arrows. (b) Immunoblot depicting cleaved caspase-3 in C57BL/6 cortical neurons derived from 5 individual cell cultures after staurosporine (+) or DMSO (−) treatment. β-actin served as loading control. (c) Heat map of significantly differentially expressed miRNAs in apoptotic cortical neurons and corresponding S/N (P < 0.01, Log2 Fold Change > 1) described above. Color scale corresponds to the robust multi-array average-processed miRNA expression values after averaging over replicates. Unstimulated neurons (control, n = 5), staurosporine-treated neurons (n = 5), control S/N (n = 5), apoptotic neuron S/N (n = 4). miRNA IDs are depicted for significantly deregulated miRNAs in the S/N of apoptotic cortical neurons. (d) Volcano plots with significantly differentially expressed miRNA species indicated by black filling in apoptotic neurons and their conditioned S/N (P < 0.01, Log2 Fold Change > 1)