Figure 7.

hnRNP-K knockdown inhibits MBP synthesis during myelination. (A) Western blot for hnRNP-K in oligodendrocytes after knockdown with three different hnRNP-K–specific target sequences or combinations thereof and a nontargeting control miR RNA. (B) OPCs were infected with lentivirus miR RNA against hnRNP-K or the nontargeting control as indicated. These cells were then added to DRG neurons and myelination by the oligodendrocytes they generate was quantified after staining for GFP (green), NG2 (purple), MBP (red), and NF (blue). Note the reduction in MBP expression in the cells infected with the hnRNP-K miR RNA. Quantification of this experiment is shown in the next three panels, with means ±SD shown from at least 10 pictures from each of two coverslips in three independent experiments. (C) Number of GFP+ cells/40x field. (D) MBP+ cells/40x field. (E) Percentage of the MBP+ cells forming internodes and therefore scored as myelinating. Statistical significance was tested by one-way ANOVA followed by a Tukey’s multiple comparison test. ***, P < 0.001. Note that although the number of cells expressing MBP is significantly reduced, the percentage of myelinating cells among those that do express MBP is unaffected.