Protective effect of thioredoxins 1 and 2 in retinal ganglion cells after optic nerve transection and oxidative stress.

Abstract

PURPOSE: Oxidative stress has been implicated in retinal ganglion cell (RGC) death pathways after optic nerve transection (ONT) and during glaucomatous neuropathy. The authors investigated the expression and cell-protective roles of thioredoxins (cytosolic Trx1 and mitochondrial Trx2), important regulators of the cellular redox state, on RGCs after ONT and pharmacologic oxidative stress induction.

METHODS: ONT was performed on adult Wistar rats. Trx1 and Trx2 quantitative and spatial expression were examined with Western blot and immunohistochemistry, respectively. Electroporation and calcium phosphate-mediated procedures were used to deliver Trx1 and Trx2 expression constructs to RGCs in vivo and to cultured RGC-5 cells, respectively. Cell-protective effects of Trx1 and Trx2 overexpression on RGCs after ONT and on RGC-5 cells treated with glutamate/buthionine sulfoximine (BSO) were determined by RGC density analysis and cell viability assay, respectively.

RESULTS: Upregulation of Trx1 and Trx2 was observed in RGCs at different times after ONT and in RGC-5 cells after glutamate/BSO treatment. Trx1 and Trx2 overexpression in RGC-5 cells increased their survival rate by approximately twofold and threefold 24 and 48 hours after glutamate/BSO treatment, respectively. A neuroprotective effect of Trx1 and Trx2 overexpression on RGCs was also observed in vivo; the survival rate of RGCs was increased by 35% and 135%, respectively, 1 and 2 weeks after ONT.

CONCLUSIONS: These findings provide evidence for in vitro and in vivo cell-protective effects of Trx1 and Trx2 on RGCs against oxidative stress-induced neurodegeneration.