Angiotensin AT1 receptor antagonism ameliorates murine retinal proteome changes induced by diabetes

Abstract

Diabetic retinopathy is the most common microvascular complication caused by diabetes mellitus and is a leading cause of vision loss among working-age adults in developed countries. Understanding the effects of diabetes on the retinal proteome may provide insights into factors and mechanisms responsible for this disease. We have performed a comprehensive proteomic analysis and comparison of retina from C57BL/6 mice with 2 months of streptozotocin-induced diabetes and age-matched nondiabetic control mice. To explore the role of the angiotensin AT1 receptor in the retinal proteome in diabetes, a subgroup of mice were treated with the AT1 antagonist candesartan. We identified 1792 proteins from retinal lysates, of which 65 proteins were differentially changed more than 2-fold in diabetic mice compared with nondiabetic mice. A majority (72%) of these protein changes were normalized by candesartan treatment. Most of the significantly changed proteins were associated with metabolism, oxidative phosphorylation, and apoptotic pathways. An analysis of the proteomics data revealed metabolic and apoptotic abnormalities in the retina from diabetic mice that were ameliorated with candesartan treatment. These results provide insight into the effects of diabetes on the retina and the role of the AT1 receptor in modulating this response.

Figure 1. Characteristics of diabetic mice (DM) and nondiabetic mice (NDM)

Blood glucose (a) body weight (b) systolic blood pressure (c) diastolic blood pressure (d) NDM, DM, and diabetic mice treated with candesartan (DMC). ** P < 0.01 and *** P < 0.001 compared with NDM, ## P < 0.01 compared with DM. Error bars represent standard error of the mean (S.E.M). n = 6–11.

Figure 2. Extracted spectral counting of Hspa12a and Rdh12 from retina of diabetic mice (DM), nondiabetic mice (NDM), and diabetic mice treated with candesartan (DMC) displayed as grayscale digital image

The spectral counting from each slice was converted to 256 intensities (i.e., shades of gray). The black represents the strongest intensity and the white represents the weakest intensity.

Figure 3. The selection of peptide count (a) and fold change (b) affected the false discovery rate

The false significant rate was calculated by dividing the significantly changed protein number of a random group by the experiment group and multiplying by 100.

Figure 4. Effect of candesartan on proteins in diabetic mouse retina

Diabetic mice (DM), nondiabetic mice (NDM), and diabetic mice treated with candesartan (DMC). 24 proteins were normalized by the treatment of candesartan (a) (P < 0.05, NDM vs. DM and DM vs. DMC) and 6 proteins were not reversed by the treatment of candesartan (b) (P < 0.05, NDM vs. DM and NDM vs. DMC). Error bars represent standard error of the mean (S.E.M). n = 5 mice.