Abstract
Purpose :
The purpose of this study is to sequence and analyze the expression of bovine and mouse retina-specific tau isoforms.
Methods :
Total RNA extracted from bovine or mouse brain and retinal tissues were used to amplify and sequence tau isoforms. Quantitative polymerase chain reaction (qPCR) and western blotting were used to examine tau mRNA and protein expression, respectively.
Results :
Tau protein, a microtubule-associated protein is critical to neuron structure and function. Tau-associated disorders appear to display biochemical signatures consisting of specific phosphorylation sites, and distinct kinases and phosphatases, suggesting specific tau isoforms with unique biochemical patterns (e.g., phosphorylation) provide definitive biomarkers for tau-associated disorders including glaucoma. Although abnormal tau aggregates are present in retinal neurons in glaucoma and in brain neurons in Alzheimer’s disease, it is not clear whether the same tau isoforms are involved since tau isoforms in the retina remain to be identified. Our study examines whether there is a correlation between the expression of the different tau isoforms in the brain and retina and whether these tau isoforms display similar biochemical signatures. Our data indicate that both brain and retina contain the same set of major tau isoforms and they are present in almost equal proportional quantities. However, both bovine and mouse retinas contain additional novel tau isoforms that were not detected in the brain tissues. Tau distribution in the retina examined by immunohistochemistry showed its presence in outer nuclear layer.
Conclusions :
Based on our observations, we propose that mammalian retina contain specific tau isoforms that are different from brain isoforms. Taking into account retinal tau sequencing data and previously published studies we speculate that these retina-specific isoforms could be associated with photoreceptor function.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.