The effect of ALS-related mutation on lipid binding of sigma-1 receptor and its relationship with agonist action

Sigma-1 receptor (σ1R) is a chaperone protein localized in ER membrane. Intrinsic molecules like cholesterol and some clinical drugs are known to bind and regulate the receptor. In this decade, twelve mutations of σ1R were discovered in motor neuron diseases like ALS and dHMN. We previously reported that the mutant (E102Q) which was identified in ALS shows abnormal resistant to detergents, intracellular aggregation, and toxicity in NSC-34 cells, a motor neuron-like cultured cells. However, it is fully unknown how the mutation alters the feature of σ1R. We transfected the cells with wildtype and the mutant and performed pulldown assay using cholesterol-beads. Cells were treated with the agonist SA4503 to investigate if the agonist changes the formation of σ1R and lipid complex. Moreover, cells were treated with BODIPY-Cholesterol to analyze cellular distribution of the lipid. As a result, the mutant but not wildtype σ1R binds with cholesterol in NSC-34 cells. SA4503 inhibited the binding of the mutant and cholesterol. BODIPY-Cholesterol was accumulated in the mutant aggregation. These results suggest that ALS-related mutation causes σ1R to bind with cholesterol, leading to aberrant aggregations and toxicity. Moreover, modulations by the agonist can inhibit the binding with the lipid and aggregation. Poster Session