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. 2007 Jun 6;27(23):6185–6196. doi: 10.1523/JNEUROSCI.0628-07.2007

Figure 1.

Figure 1.

Regulation of p57Kip2 expression. p57Kip2 is expressed in differentiating OLs. A, p57Kip2 is induced in differentiating OLs in vitro. Expression levels of p57Kip2 (black circles, rc_AA998565_at probe set), early induced myelin genes CNP (gray triangles, L16532_at) and MBP (gray squares, average K00512_at, rc_AI044093_at, rc_AI145512_at), and late induced myelin gene MOG (gray dashed X, M99485_at) as assayed on Affymetrix U34A-C gene chips (Dugas et al., 2006). OPC, Purified OPCs; d1–d9, days after induction of OL differentiation in vitro by mitogen withdrawal and T3 exposure; AcOL, acutely purified P12 OLs. All expression values are normalized to OPC expression level and expressed on a log2 scale. B, In situ expression of p57Kip2 in sagittal sections of P7 (B1) and P42 (B2) mouse brain, obtained from St. Jude's BGEM website (www.stjudebgem.org). C–F, Immunostaining of P7 (C, D) and P24 (E, F) optic nerve sections. Sections were costained for CC-1 (red) and p57Kip2 (white) expression (C, E) or NG2 (red) and p57Kip2 (white) expression (D, F). Blue, DAPI nuclear stain. Green arrows indicate cells expressing only p57Kip2; red arrows indicate cells only expressing CC-1 (C, E) or NG2 (D, F); and yellow arrows indicate cells coexpressing p57Kip2 and either CC-1 or NG2. White boxes indicate regions of higher magnification shown in the lower left corners of C1–F1. G, Proportion of NG2+ OPCs (gray bars) and CC-1+ OLs (black bars) that were positive for p57Kip2 expression in the optic nerve at various developmental ages, as assayed by immunostaining. H, Proportion of p57Kip2-positive cells that were NG2+ OPCs (gray bars) or CC-1+ OLs (black bars) in the optic nerve at various developmental ages. At P2, the >100% sum of NG2+ and CC-1+ cells may reflect the presence of a small population of cells that coexpress NG2 and CC-1. In G and H, for each age-staining (p57Kip2 + NG2 and p57Kip2 + CC-1), >100 cells were scored from two distinct optic nerves, except P24-NG2 and P40-NG2 (48 and 23 cells, respectively) because of paucity of NG2+ and p57Kip2+ cells at those ages. All data presented are ± SE of the proportion. I, RT-PCR to assay p57Kip2 (23 and 25 cycles) and β-actin (control, 23 cycles) expression levels in purified P8 OPCs incubated for 6 DIV in medium containing or lacking PDGF/NT3 (± P), containing or lacking T3 (± T).