Figure 3. Identification of miR-219 and miR-338 as Oligodendrocyte-Specific miRNAs in the Spinal Cord.

A-C) miRNAs isolated from spinal cord and optic nerve tissues from WT, Dicer1CKO or Olig1 null mice were subjected to miRNA microarray analysis. The log₂ transformation of relative fold changes in the miRNA expression level from WT versus Dicer1CKO or Olig1KO mice are indicated.

D) Expression of miR-219 and miR-338 in WT and Olig1 null spinal cord was analyzed by Northern blot. U6 RNA is used as a loading control.

E-F) miR-219 (E) and miR-338 (F) expression was analyzed by qRT-PCR from WT mouse spinal cords at stages indicated. U6 RNA was used as internal control.

G) Expression of miR-219 and miR-338 was examined in the spinal cord of WT and Olig1KO mice at P14 by in situ hybridization as indicated. Arrows indicate the miRNA expressing cells in the white matter region (left part of dashed lines); arrowheads indicate the gray matter. Left panels show at lower magnification, while middle and right panels show at higher magnification.

H-I) Expression of miR-219 and miR-338 was examined in spinal cord of P14 WT mice by in situ hybridization, followed by immunostaining with CC1 and Olig2. Arrows indicate colabeling of miR-219 or miR-338 with oligodendrocyte markers CC1 and Olig2 in the same cells. Scale bars, in G, 100 μm; in H and I, 50 μm.