Abstract
Purpose :
Tumour necrosis factor alpha (TNF-α) is recognised to be responsible for inflammatory responses during retinal degeneration. Müller glia are known to produce neuroprotective molecules such as antioxidants that protect retinal neurons against oxidative stress and glutamate induced toxicity associated with degeneration. Many studies have suggested that TNF-α could induce either degeneration or neuroprotection, however its downstream effect on the change of antioxidants released by Müller glia has not been explored. This study investigated the transcriptomic changes of antioxidants induced by TNF-α in the human Müller glial stem cell line MIO-M1 by transcriptome sequencing.
Methods :
MIO-M1 cells were cultured with TNF-α at 50ng/mL for 24 hours. Total RNA was extracted, and a cDNA library was prepared using the NEB Next mRNA Ultra II kit, followed by 75 bp pair-end sequencing on an Illumina NextSeq 500 platform with 26 million reads per sample. Sequencing data was analysed using the established bioinformatics pipeline. The transcriptional and translational expression of the antioxidants SOD2 and PRDX6, and the main gliotic marker intermediate filament glial fibrillary acidic protein (GFAP) were examined by both RT-PCR and Western blotting, respectively.
Results :
The analysis identified 1708 upregulated genes and 1527 downregulated genes in the transcriptomics of MIO-M1 cells. Gene enrichment analysis revealed that five antioxidation enzymes including glutathione S-transferase omega-1, peroxiredoxin 6 (PRDX6), superoxide dismutatse 2 (SOD2), glutathione peroxidase 1 (GPX1) and peroxidasin homolog (PXDN) were significantly upregulated. RT-PCR and Western blotting analysis confirmed the increased expression of PRDX6 and SOD2. Interestingly, the results showed that TNF-α also induced downregulation of the gliosis associated marker GFAP.
Conclusions :
This study reports the anti-oxidant transcriptomic analysis of the MIO-M1 cells in response to TNF-α treatment. Müller glia could respond to TNF-α signalling pathway by elevating antioxidant release and reducing the expression of gliosis associated proteins such as GFAP. These findings suggest that TNF-α may possibly promote Müller glia-dependent neuroprotection and this merits further investigations.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.