Abstract
Purpose: :
Aldehyde dehydrogenase 7A1 (antiquitin) metabolizes many aldehydic substrates produced during oxidative stress including aminoadipic semialdehyde (AASA) and 4-hydroxynonenal (4-HNE). AASA levels in the eye increase significantly during oxidative stress, aging and diabetes. 4-HNE is a highly toxic aldehyde produced during lipid peroxidation and is associated with a number of ocular pathologies including cataracts, macular degeneration and diabetic retinopathy. The metabolism of AASA, 4-HNE and other reactive aldehydes by ALDH7A1 may play an important protective role under highly oxidative conditions. In the current study, we sought to characterize ALDH7A1 expression in the eye and determine its ability to protect cells from toxic aldehydes produced during oxidative stress.
Methods: :
ALDH7A1 localization was determined by immunohistochemistry (IHC) in mouse eye sections. Cell type specific ALDH7A1 expression was assessed by Western blot in retinal pigment epithelial (D407 and ARPE-19), corneal epithelial (hTCEpi) and corneal keratinocyte (HTK) cell lines, as well as, cornea, lens and retina tissue lysates. Cells transfected with human ALDH7A1 and treated with H2O2 and 4-HNE were used to perform cell viability and survival assays.
Results: :
IHC revealed high expression in corneal epithelium and posterior endothelium. ALDH7A1 was also expressed in kerotinocyte nuclei within the stroma. Retinal staining revealed moderate levels within the ganglion cell and inner plexiform layers. High expression was observed in the retinal pigment epithelium. Expression levels were mirrored in D407, AREP-19, hTCEpi and HTK cells via Western analysis. Cells transfected with ALDH7A1 were significantly protected against H2O2- or 4-HNE-induced cytotoxicity.
Conclusions: :
The expression pattern and protective effects of ALDH7A1 in ocular tissue suggests that this protein is a part of the cellular response against oxidative stress.
Keywords: oxidation/oxidative or free radical damage • protein structure/function • protein purification and characterization