Fig. 6.

LN potentiates the AChR aggregating activity of agrin via its interaction with α-DG. Cells were treated with 12 nm LN (wide hatched bars), 100 pm agrin (fine hatched bars), or both (filled bars) for 18 hr, and the number of AChR aggregates per myotube segment was quantified as described in Materials and Methods. The concentration of LN used is subthreshold and does not affect the number of AChR aggregates compared with control cultures (open bars) for all cell types. LN enhances the effect of agrin by twofold and 1.7-fold in C2 and 11F cells, respectively. However, in 11E cells, where the α-DG level is only 20% of that in C2 cells, LN does not significantly enhance the effect of agrin. Note that in both DG-antisense clones agrin alone induces AChR aggregation. Values represent means ± SD for two experiments. For each experiment, 15–20 fields from each of two coverslips were quantified. An asterisk indicates a statistically significant difference between agrin and agrin + LN treatment within each cell type (p < 0.05, t test).