Increased global lysine acetylation in diabetic vasculature is associated with downregulation of SIRT‐1 in vascular smooth muscle cells.

Abstract

Vascular complications are the main problems faced by patients with Type 2 Diabetes Mellitus (T2DM). In addition to endothelial dysfunction, vascular smooth muscle cell (VSMC) dysfunction is postulated to play a crucial role in the development of diabetic vascular complications. Recent studies from our laboratory have demonstrated that acetylation of lysine residues, a posttranslational modification, is increased in vascular tissue exposed to metabolic disorders, such as diabetes. We hypothesized that diabetic conditions would dysregulate lysine deacetylases and acetyltransferases in VSMC, consequently leading to increased global lysine acetylation in diabetic blood vessels. Using male adult Goto‐Kakizaki (GK) rats (16‐weeks‐old) as a model of non‐obese type 2 diabetes and their respective Wistar controls, we found that these diabetic rats exhibited high levels of fasting blood glucose (191 ± 12 vs. 98±7 mg/dL vs. controls, p<0.05), as well as hemoglobin A1C (6.82 ± 0.93 vs. 5.2 ±0.2 % controls, p<0.01). Through direct measurement of blood pressure via right carotid catheterization, we also found greater systolic blood pressure in the GK group (166.57 ±24.27 vs. 124.58 ±17.07 controls, p<0.01). This effect was accompanied by high levels of global lysine acetylation in GK blood vessels (3.3 fold of increase vs. control, p<0.001). To test our hypothesis that VSMC is a major cell type in blood vessels contributing to increased vascular lysine acetylation in diabetic conditions, we utilized isolated aortic VSMC from GK rats in primary cultures. After euthanasia with isoflurane (via nasal 5% in 100% O2), thoracic aortas from GK rats were dissected and VSMC were isolated by an enzymatic digestion method. Phenotypically, VSMC from GK rats exhibited an enhanced proliferative phenotype in comparison to VSMC from Wistar control rats (Figure 1). Strikingly, we found that VSMC from GK rats exhibited a marked decrease in SIRT‐1 deacetylase expression (3.5‐fold decrease vs. control, p<0.05). Moreover, expression of the acetyltransferase PCAF was increased in VSMC from GK rats (1.5‐fold increase vs. control, p<0.05). Taken together, our in vitro results suggest that downregulation of SIRT‐1 and upregulation of PCAF may mediate the increased levels of global lysine acetylation in diabetic blood vessels, confirming our hypothesis. To further this investigation, we will identify the proteins that are specifically acetylated in diabetic VSMC through mass spectrometry analysis, as well as the effects on global lysine acetylation when overexpressing SIRT‐1 in VSMC.Support or Funding InformationIn‐House Grant, NYITThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.