A glaucoma‐ and ALS‐associated mutant of OPTN induces neuronal cell death dependent on Tbk1 activity, autophagy and ER stress

Mutations in OPTN are associated with glaucoma, an eye disease, and also amyotrophic lateral sclerosis (ALS), a motor neuron disease. A 2-bp insertion (691_692insAG or 2bpIns-OPTN) is both glaucoma ALS. This mutation results frame shift after 127 amino acids, giving rise to protein C-terminal aberrant sequence. We have explored the mechanism of induction cell death by this mutant line, NSC-34, retinal 661W. Compared wild-type OPTN, induced more NSC-34 661W cells. localizes predominantly nucleus whereas normal cytoplasm. Deletion analysis 2bpIns-OPTN showed that sequence was not essential for induction. interacts TANK-binding kinase 1 (Tbk1) but activates Tbk1. ER stress cells as seen C/EBP homologous (CHOP) some other genes. Induction CHOP, autophagosomal LC3-II were abrogated Tbk1 knockdown 4-phenylbutyric acid, inhibits stress. CHOP autophagy dependent shown effect Atg5 knockdown. caused increased formation LC3-positive aggregates. Treatment inducer rapamycin reduced aggregates, 2bpIns-OPTN. These suggest constitutive activation leads impaired death.