Figure 5.
Effects of NF-M deletion on transport rates and levels of α-internexin, NF-L, and NF-H in optic axons. A, B, Mouse genomic DNA was screened for targeted disruption of NF-M homozygous mice through genotyping the NF-M loci by hybridizing with a sequence from NF-M. C–F, On immunoblots of 10–20 μg of total optic nerve protein extract from 3- to 4-month-old mice, α-internexin and neurofilament triplet subunits were identified with mAbs to α-internexin, NF-M, NF-H, and NF-L (C, D, E, and F, respectively), relative levels of each protein were determined by NIH imaging. Measurements are mean ± SD from four animals for each group. In the absence of NF-M protein (D), the levels of α-internexin, NF-H, and NF-L proteins were 54 ± 8% (C), 33 ± 8% (E), and 22 ± 3% (F) of the wild-type level, respectively. G–I, Slow axonal transport analyses, after intravitreal injection of 35S-methionine in control (G) and mko mice (H), demonstrate increased velocities of α-internexin, NF-H, and NF-L and unchanged rates of Triton-insoluble tubulin and actin in mko mice (I). J, Distribution of α-internexin, NF-H, and NF-L in mko along optic pathway compared with that in wild-type mice. The squares represent wild-type control, and diamonds represent knock-out mice.