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. 2001 Apr 3;98(8):4722–4727. doi: 10.1073/pnas.081062398

Figure 3.

Figure 3

F-spondin proteins inhibit outgrowth of motor axons. (A) Outgrowth of rat E13 commissural neurons on a substrate of laminin, F-spondin, and TSR. Purified proteins (40 μg/ml) were immobilized on poly(dl-lysine). The neurons were stained with the anti-tubulin III mAb (TUJ-1). For each TUJ-1-positive neuron, the neurite length was measured, or, if no neurite was seen, considered to be zero. The percentage of neurons (ordinate) with neurites longer than a given length (in μm; abscissa) is presented. All of the proteins promote outgrowth to a similar extent. (B) Outgrowth of rat E13 motor neurons on a substrate of laminin F-spondin and TSR. The neurons were stained with the anti-neurofilament mAb 2H3. Laminin promotes outgrowth, whereas F-spondin and the TSR domain protein do not. (C) Outgrowth of rat E13 motor neurons on a substrate of laminin (40 μg), laminin + F-spondin (40 μg), and laminin + TSR domain (40 μg). F-spondin and the TSR domain proteins inhibit the outgrowth of motor axons on laminin. (D) The inhibition of the TSR domain is dose-dependent. Then 40, 20, and 10 μg of the TSR domain protein were added to 40 μg of laminin. The degree of inhibition correlates to the concentration of TSR domain protein because 10 μg of TSR protein is less inhibitory than 20 μg and 40 μg. (E) Outgrowth of rat E13 motor neurons on a substrate of laminin (40 μg) and laminin + reespo (40 μg). The reespo domain protein inhibits the outgrowth of motor axons on laminin. (F) The inhibitory effect of the TSR domain protein is not dependent on the number of TSR repeats. Proteins (40 μg) containing 1 repeat, 2 repeats (1–2), 4 repeats (1–4), or 5 repeats (1–5) were mixed with 40 μg of laminin and immobilized on poly(dl-lysine)-coated plates. The outgrowth of motor neurites on the various mixed substrates is inhibited in a similar manner.