The effect of SUMOylated peroxisome proliferator-activated receptor γ in the regulation of diabetes mellitus accelerated atherosclerosis / 中国医师进修杂志

ABSTRACT

Objective:To explore the role of SUMOylaiton of peroxisome proliferator-activated receptor γ (PPARγ) in diabetes mellitus prompted inflammation and atherosclerosis in vascular and endothelial cells.Methods:From September 2014 to January 2017, 32 Sprague-Dawley rats in 14 weeks-old were divided into sham operated group, artery injured without diabetes group, artery injured with diabetes group and ubiquitin-conjugating enzyme 9 (UBC9) transfection group (Group D) by random digits table method with 8 rats each. Model of type 1 diabetes mellitus (T1DM) and rat carotid artery balloon injury was made in the assigned group. One rat was excluded because of model failure in each group. Systolic and diastolic common carotid artery diameter and intimal thickness of injured and healthy common carotid artery were evaluated by vascular ultrasound, and the standardized common carotid artery diastolic diameter (sCADD) was calculated. Histological tests and immunohistochemical staining were performed to evaluate intimal hyperplasia, and the ratio of intimal area to media area was calculated when the media area was equal. Human umbilical vein endothelial cells (HUVEC) were cultured 24 h in high glucose medium with different duration and concentration, and the expression levels of interleukin (IL)-8 and IL-1β mRNA were determined by real time reverse transcription polymerase chain reaction (RT-PCR), the expression level of UBC9 was determined by Western blot method, SUMOylation assay kit was used to evaluate SUMOylation of PPARγ. HUVEC was cultured in vitro and PPAR was stimulated by high glucose at different concentrations and different times PPARγ SUMOylation level. UBC9 was overexpressed by lentivirus in vivo and in vitro, and the PPARγ SUMOylation level was detected.Results:The intimal thickness, intimal area and ratio of intimal area to media area 8 weeks after carotid artery injuring in sham operated group, artery injured without diabetes group and artery injured with diabetes group were increased respectively (0.026 ± 0.018), (0.084 ± 0.007) and (0.264 ± 0.022) mm; (0.18 ± 0.09) × 10 6, (0.32 ± 0.06) × 10 6 and (1.64 ± 0.22)×10 6 μm 2; 0.345 ± 0.073, 0.570 ± 0.080 and 2.710 ± 0.220, the sCADD was decreased respectively 0.903 ± 0.084, 0.800 ± 0.071 and 0.330 ± 0.036, and there were statistical differences ( F = 10.40, 9.40, 8.20 and 8.60; P<0.05). After HUVEC was cultured in high glucose for 24 h, the IL-8 mRNA at sugar concentrations of 10, 20 and 40 mmol/L was 1.00 ± 0.11, 3.57 ± 0.22 and 4.07 ± 0.40, the IL-1β mRNA was 1.00 ± 0.07, 3.32 ± 0.29 and 5.13 ± 0.19, and there were statistical differences ( F = 73.05 and 205.80, P<0.05). The level of PPARγ SUMOylation and UBC9 in artery injured with diabetes group were significantly lower than those in artery injured without diabetes group (0.46 ± 0.25 vs. 1.00 ± 0.21 and 0.45 ± 0.02 vs. 1.00 ± 0.07), and there were statistical differences ( P<0.05); there was no statistical difference in PPARγ between 2 groups (0.94 ± 0.07 vs. 1.00 ± 0.04, P>0.05). The UBC9 and PPARγ SUMOylation at sugar concentrations of 0, 10, 20 and 40 mmol/L were decreased respectively (0.99 ± 0.05, 0.80 ± 0.06 and 0.62 ± 0.05; 1.00 ± 0.05, 0.57 ± 0.13 and 0.55 ± 0.08), and there were statistical differences ( F = 21.02 and 14.31, P<0.05); there was no statistical difference in PPARγ (1.00 ± 0.03, 0.90 ± 0.04 and 0.91 ± 0.05; F = 3.11, P>0.05). In HUVEC cultured in high glucose medium (20 mmol/L) for 6, 12, 24 and 48 h, the UBC9 and PPARγ SUMOylation were downregulated progressively (1.00 ± 0.09, 0.75 ± 0.05, 0.70 ± 0.08, 0.38 ± 0.04 and 0.35 ± 0.03; 1.00 ± 0.03, 0.86 ± 0.01, 0.59 ± 0.01, 0.51 ± 0.11 and 0.35 ± 0.08), and there were statistical differences ( F = 36.06 and 33.13, P<0.05); but there was no statistical difference in PPARγ (1.00 ± 0.03, 1.14 ± 0.02, 1.18 ± 0.17, 0.98 ± 0.01 and 1.04 ± 0.05; F = 1.90, P>0.05). After overexpression of UBC9 in rats with diabetes, histological analysis showed that UBC9 in artery injured without diabetes group, artery injured with diabetes group and UBC9 transfection group was 1.53 ± 0.18, 1.00 ± 0.22 and 3.62 ± 0.35, there was statistical difference ( F = 5.64, P<0.05). Ultrasonic test results show that in artery injured without diabetes group, artery injured with diabetes group and UBC9 transfection group intimal thickness was increased respectively (0.077 ± 0.015), (0.216 ± 0.007) and (0.125 ± 0.014) mm, and there was statistical difference ( F = 27.18, P<0.05). Histological analysis showed that intimal area in artery injured without diabetes group, artery injured with diabetes group and UBC9 transfection group was (0.335 ± 0.066) ×10 6, (1.053 ± 0.103) ×10 6 and (0.544 ± 0.040) ×10 6 μm 2, the ratio of intimal area to media area was 0.63 ± 0.063, 2.03 ± 0.052 and 0.93 ± 0.100, there were statistical differences ( F = 13.58 and 53.96, P<0.05). Conclusions:Diabetes mellitus could inhibit the PPARγ SUMOylaiton and prompt inflammation and atherosclerosis in vascular and endothelial cells. Upregulation of PPARγ SUMOylaiton though UBC9 overexpressioncould play a protecting role in diabetes mellitus prompted atherosclerosis.