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Di Wu, Kousuke Noda, Miyuki Murata, Ye Liu, Atsuhiro Kanda, Susumu Ishida; Modulation of Spermine Oxidation in Müller Glial Cells under Hypoxic Condition. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5199. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Spermine is one of the naturally occurring polyamines and its oxidation catalyzed by spermine oxidase (SMOX) results in the generation of hydrogen peroxide (H2O2), 3-aminopropanal and spermidine. Previously, it was reported that vitreous level of spermine is approximately 15-times higher in patients with proliferative diabetic retinopathy (PDR) than those without diabetes, and an important role of oxidative stress caused by reactive oxygen species such as H2O2 in diabetic retinopathy (DR) has been well studied. The purpose of this study was to determine whether hypoxia modulates spermine oxidation by SMOX and increases the generation of its reaction product, H2O2, in Müller glial cells.
Rat Müller glial cells (TR-MUL5) were cultured under hypoxic (1% O2) or normoxic (20% O2) conditions for 6 h and 24 h. Expression levels of polyamine catabolic enzymes including Smox, spermidine/spermine N1-acetyltransferase (Ssat) and N1-acetylpolyamine oxidase (Apao), were quantified by real-time PCR. Protein level of Smox was measured by enzyme-linked immunosorbent assay. Generation of H2O2 in TR-MUL5 cells treated with spermine and/or MDL72527 (SMOX inhibitor) was evaluated using H2O2 detection kit.
The mRNA expression level of Smox was significantly upregulated at 6h (2.3-fold, p<0.01) and 24h (1.5-fold, p<0.05) under hypoxic condition, whereas the expression of Ssat and Apao remained unchanged. Hypoxia increased Smox protein level by 1.5-fold (p<0.05) compared with normoxia control. Furthermore, H2O2 concentration increased by 1.7-fold (p<0.01) in TR-MUL5 cells treated with spermine under hypoxic condition, and the increase was significantly inhibited by MDL72527.
The current data indicate that hypoxia induces spermine oxidation and increases H2O2 generation in Müller glial cells under hypoxic condition.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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