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En Face Detection of Nitric Oxide and Superoxide in Endothelial Layer of Intact Arteries
Published on: February 25, 2016
Nitric oxide differentially affects proteasome activator 28 after arterial injury in type 1 and type 2 diabetic rats
Nick D Tsihlis1, Monica P Rodriguez1, Qun Jiang1
1Division of Vascular Surgery, Northwestern University Feinberg School of Medicine, Northwestern University, Chicago, Illinois; Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, Illinois.
Background:
Diabetic patients display aggressive restenosis after vascular interventions, likely because of proproliferative influences of hyperglycemia and hyperinsulinemia. We have shown that nitric oxide (NO) inhibits neointimal hyperplasia in type 2, but not in type 1, diabetic rats. Here, we examined proteasome activator 28 (PA28) after arterial injury in different diabetic environments, with or without NO. We hypothesize that NO differentially affects PA28 levels based on metabolic environment.
Materials And Methods:
Vascular smooth muscle cell (VSMC) lysates from male, nondiabetic Lean Zucker (LZ) and Zucker Diabetic Fatty (ZDF) rats were assayed for 26S proteasome activity with or without PA28 and S-nitroso-N-acetylpenicillamine. LZ and ZDF VSMCs were treated with (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate for 24 h. Balloon-injured carotid arteries from LZ, streptozotocin-injected LZ (STZ, type 1), and ZDF (type 2) rats treated with disodium 1-[2-(carboxylato)pyrrolidin-1-iyl]diazen-1-ium-1,2-diolate were harvested at 3 or 14 d. PA28α was assessed by Western blotting and immunofluorescent staining.
Results:
S-nitroso-N-acetylpenicillamine reversed PA28-stimulated increases in 26S proteasome activity in LZ and ZDF VSMCs. Increased (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate lowered PA28α in LZ VSMCs but increased PA28α in ZDF VSMCs. At 3 d after injury, disodium 1-[2-(carboxylato)pyrrolidin-1-iyl]diazen-1-ium-1,2-diolate potentiated injury-induced PA28α decreases in LZ, STZ, and ZDF rats, suggesting VSMCs, depleted at this early time point, are major sources of PA28α. At 14 d after injury, total PA28α staining returned to baseline. However, although intimal and medial PA28α staining increased in injured STZ rats, adventitial PA28α staining increased in injured ZDF rats.
Conclusions:
PA28 dysregulation may explain the differential ability of NO to inhibit neointimal hyperplasia in type 1 versus type 2 diabetes.
Insights
Nitric oxide (NO) differentially affects proteasome activator 28 (PA28) levels in type 1 versus type 2 diabetes, influencing neointimal hyperplasia after vascular injury. This dysregulation may explain NO
Area of Science:
- Vascular biology and diabetes research
- Cellular and molecular mechanisms of restenosis
- Proteasome function in diabetic complications
Background:
- Diabetic patients exhibit aggressive restenosis post-vascular interventions, linked to hyperglycemia and hyperinsulinemia.
- Nitric oxide (NO) inhibits neointimal hyperplasia in type 2 diabetic rats but not in type 1.
- Proteasome activator 28 (PA28) role in diabetic vascular environments requires investigation.
Purpose of the Study:
- To examine proteasome activator 28 (PA28) levels after arterial injury in different diabetic models.
- To investigate the differential effects of nitric oxide (NO) on PA28 in type 1 and type 2 diabetes.
- To test the hypothesis that NO differentially affects PA28 levels based on the metabolic environment.
Main Methods:
- Assessed 26S proteasome activity in vascular smooth muscle cells (VSMCs) from Lean Zucker (LZ) and Zucker Diabetic Fatty (ZDF) rats with or without PA28 and NO donors.
- Treated VSMCs with NO donors and measured PA28α levels.
- Analyzed PA28α expression in balloon-injured carotid arteries from nondiabetic, type 1 (STZ-injected), and type 2 (ZDF) diabetic rats at 3 and 14 days post-injury using Western blotting and immunofluorescence.
Main Results:
- NO donors modulated 26S proteasome activity and PA28α levels differently in LZ and ZDF VSMCs.
- NO donors lowered PA28α in LZ VSMCs but increased it in ZDF VSMCs.
- PA28α levels decreased early after injury in all rat models, with distinct intimal/medial (STZ) versus adventitial (ZDF) increases at later time points.
Conclusions:
- PA28 dysregulation in diabetic environments contributes to differential responses to NO.
- Altered PA28 expression patterns in type 1 versus type 2 diabetes may explain the varying efficacy of NO in inhibiting neointimal hyperplasia.
- These findings highlight PA28 as a potential therapeutic target for managing vascular complications in diabetes.
