Aβ upregulates and colocalizes with LGI3 in cultured rat astrocytes

1. The leucine-rich glioma inactivated (LGI) family of genes encodes a leucine-rich repeat (LRR) protein, proteins that are thought to be specifically involved in protein-protein and protein-matrix interactions. Since amyloid beta peptide (A beta) has been previously shown to induce the expression of another LRR-encoding gene in neural cells, we assessed how A beta affects LGI gene expression in rat primary cerebral cortical cultures and astrocyte cultures. Both RT-PCR and Western Blotting analyses revealed that A beta robustly induced the expression of LGI3 in rat astrocyte cultures. 2. Western Blotting analyses also showed that both glial fibrillary acidic protein (GFAP) and apolipoprotein E (ApoE) significantly increased coincidentally with the A beta-induced upregulation of LGI3. Immunocytochemistry showed that LGI3 colocalized with A beta at plasma membranes and also with internalized A beta in astrocytes. These findings suggest that activated LGI3 may be involved in the astroglial response against A beta.