Silencing thioredoxin1 exacerbates damage of astrocytes exposed to OGD/R by aggravating apoptosis through the Actin–Ras2–cAMP–PKA pathway

Abstract

ABSTRACTPurpose of the study: Induction of endogenous antioxidants is one of the key molecular mechanisms of cell resistance to hypoxia/ischemia. Thioredoxin1 (Trx1) is a small multifunctional ubiquitous antioxidant with redox-active dithiol and plays an important role in cell apoptosis through mitochondrial apoptosis pathways. The specific role of Trx1 in ischemia-reperfusion induced astrocyte apoptosis, however, remains unclear.Materials and methods: In this study, we investigated the effect of Trx1 on apoptosis of astrocyte using an in vitro oxygen-glucose deprivation/reoxygenation (OGD/R) model which mimics ischemic/reperfusion conditions in vivo. The astrocytes prepared from newborn Sprague-Dawley rats were exposed to OGD for 4 h followed by reoxygenation for 24 h. Next, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) was used to assess cell viability while cell damage was assessed by lactate dehydrogenase (LDH).Results: We found that OGD/R increased cell death as well as the expression of Trx1 and that the interference of Trx1 further aggravated astrocyte damage under OGD/R condition. Furthermore, we detected an increase in the intracellular expressions of Ras2, cAMP, and PKA under OGD/R condition, which paralleled cell injury.Conclusions: Notably, the deletion of Trx1 exacerbated astrocyte apoptosis via the Ras2-cAMP-PKA signaling pathway. We concluded that Trx1 protects astrocytes against apoptotic injury induced by OGD/R, and this protective effect may be partly related to the Ras2-cAMP-PKA signaling pathway.