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Shiming Luo, Jack S Crabb, Mariya Ali, Alyson Wolk, Geeng-Fu Jang, Belinda Willard, John W Crabb, Bela Anand-Apte; Elucidating sexual dimorphism in the retina of mice with type 1 diabetes. Invest. Ophthalmol. Vis. Sci. 2019;60(9):2717.
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© ARVO (1962-2015); The Authors (2016-present)
There is increasing evidence that sex differences are important in the epidemiology, pathophysiology, responses to treatments, and outcomes in a number of diseases. Reported sex differences in the prevalence of diabetic retinopathy have shown controversial results in humans and mice. The purpose of this study was to evaluate differences in the retina proteome of male and female diabetic mice. This analysis will provide insights into the sexual dimorphism of mechanisms and biomarkers of diabetic eye disease.
Four 7-8 week old mice (eight enucleated eyes) were harvested for each group: 1) male diabetic (induced by streptozotocin), 2) female diabetic, 3) male control, and 4) female control. Tryptic peptides were labeled with unique iTRAQ tag, combined and fractionated by RP-HPLC at pH 10. Chromatography fractions were selectively pooled, analyzed by LC MS/MS with LUMOS mass spectrometry. Protein identification used Mascot engine and the Mus musculus Uni-Prot/Swiss-Protein sequence database. ≥2 unique peptides per protein were required for protein identification. Database search was restricted to a false discovery rate of ≤ 1%. iTRAQ tags were quantified by the equal weights method. Differential protein expression between experimental condition versus control for each sex was quantitated. Pathways were analyzed with Ingenuity Pathway Analysis software. Western Blot validation studies were conducted.
Expression of crystallin αA and αB was significantly higher in the retinas of wild type female mice compared to their male counterparts. Of >3000 proteins quantified, crystallin proteins were significantly elevated in the retinas of diabetic male mice and significantly decreased in the retinas of diabetic female mice (p ≤ 0.05, t-test). Specifically, crystallins αα/αα2, αβ, ββ1, ββ2, ββ3, and γS were significantly elevated in male diabetics versus male controls, and reduced in female diabetics compared to female controls. Crystallins protect the retina during hypoxia and inflammation. Hyperglycemia impairs crystallin chaperone function; diabetes potentially impairs neuroprotective properties of crystallins.
Proteomics and Western Blot approaches have for the first time identified a sexual dimorphism in the retina. Further investigation into the divergent response of male and female retinas to diabetes will yield an improved understanding of the pathogenesis of diabetic retinopathy.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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