Abstract
Purpose :
E50K mutation of autophagy receptor gene Optineurin (OPTN) is known to be associated with normal tension glaucoma (NTG) and cause the damage of retinal ganglion cells (RGCs), but the pathogenesis mechanism remains unknown. Autophagy has been identified to be responsibility as the main pathway that promotes degradation of TAR DNA-binding protein 43 (TDP-43). In this study, we investigated the OPTN(E50K) mutation disrupting autophagy caused the aggregates of TDP-43 in vivo and their involvement in RGCs death.
Methods :
OPTN(E50K) knock-in mice were generated by CRISPR/Cas9 in our laboratory and analyzed for genotype and phenotype. P62 and LC3-II expression in retina of wild type (WT) and OPTN(E50K) mice were measured by Western blotting, respectively. TDP-43 level was evaluated in cytoplasm from retinal tissues. Co-localization and distribution of optineurin and TDP-43 or LC3 were documented by co-Immunoprecipitation and Immunohistochemical analysis. Interaction between TARDBP and Dicer or Drosha was evaluated by the same way.
Results :
Loss of RGCs (p＜0.01) and decreased thickness of retina (p＜0.05) were observed in OPTN(E50K) mice compared with WT mice. Also, we observed visual impairment (p＜0.01) in OPTN(E50K) mice without increased IOP. Meanwhile, increased p62 and LC3-II level(p＜0.05) in OPTN(E50K) mice indicated the inhibition of autophagy. A significantly increased amount of TDP-43 was observed in cytoplasm of retina from OPTN(E50K) mice compared to WT mice (p＜0.05). Although both optineurin colocalized with TDP-43, assessment of the colocalization revealed that TDP-43-immunoreactive areas were more frequently colocalized with E50K optineurin in retinal cytoplasmic granules (p＜0.01). Interestingly, TDP-43-positive granules contained less colocalized signals with both Dicer and Drosha in OPTN(E50K) mice(p＜0.05).
Conclusions :
Glaucoma-associated of E50K-optineurin mutation induced RGCs death and resulted in visual impairment in vivo. The autophagy disrupted by OPTN(E50K) affected the degradation of TDP-43 and may play an important role in E50K-mediated glaucomatous retinal degeneration.
This is a 2020 ARVO Annual Meeting abstract.