Komers Radko, Schutzer William E, Reed John F, Lindsley Jessie N, Oyama Terry T, Buck David C, Mader Scott L, Anderson Sharon
Division of NephrologyHypertension PP262, Oregon Health and Science University, 3314 SW US Veterans Hospital Rd., Portland, OR 97239, USA.
Diabetes. 2006 Jun;55(6):1651-9. doi: 10.2337/db05-1595.
Experimental diabetes is associated with complex changes in renal nitric oxide (NO) bioavailability. We explored the effect of diabetes on renal cortical protein expression of endothelial NO synthase (eNOS) with respect to several determinants of its enzymatic function, such as eNOS expression, membrane localization, phosphorylation, and dimerization, in moderately hyperglycemic streptozotocin-induced diabetic rats compared with nondiabetic control rats and diabetic rats with intensive insulin treatment to achieve near-normal metabolic control. We studied renal cortical expression and localization of caveolin-1 (CAV-1), an endogenous modulator of eNOS function. Despite similar whole-cell eNOS expression in all groups, eNOS monomer and dimer in membrane fractions were reduced in moderately hyperglycemic diabetic rats compared with control rats; the opposite trend was apparent in the cytosol. Stimulatory phosphorylation of eNOS (Ser1177) was also reduced in moderately hyperglycemic diabetic rats. eNOS colocalized and interacted with CAV-1 in endothelial cells throughout the renal vascular tree both in control and moderately hyperglycemic diabetic rats. However, the abundance of membrane-localized CAV-1 was decreased in diabetic kidneys. Intensive insulin treatment reversed the effects of diabetes on each of these parameters. In summary, we observed diabetes-mediated alterations in eNOS and CAV-1 expression that are consistent with the view of decreased bioavailability of renal eNOS-derived NO.
实验性糖尿病与肾脏一氧化氮（NO）生物利用度的复杂变化有关。我们研究了糖尿病对中度高血糖链脲佐菌素诱导的糖尿病大鼠肾皮质内皮型一氧化氮合酶（eNOS）蛋白表达的影响，涉及该酶功能的几个决定因素，如eNOS表达、膜定位、磷酸化和二聚化，并与非糖尿病对照大鼠以及接受强化胰岛素治疗以实现接近正常代谢控制的糖尿病大鼠进行了比较。我们研究了小窝蛋白-1（CAV-1）的肾皮质表达和定位，CAV-1是eNOS功能的内源性调节剂。尽管所有组的全细胞eNOS表达相似，但与对照大鼠相比，中度高血糖糖尿病大鼠膜组分中的eNOS单体和二聚体减少；在细胞质中则出现相反的趋势。中度高血糖糖尿病大鼠中eNOS（Ser1177）的刺激性磷酸化也减少。在对照大鼠和中度高血糖糖尿病大鼠的整个肾血管树的内皮细胞中，eNOS与CAV-1共定位并相互作用。然而，糖尿病肾脏中膜定位的CAV-1丰度降低。强化胰岛素治疗逆转了糖尿病对这些参数的影响。总之，我们观察到糖尿病介导的eNOS和CAV-1表达改变，这与肾eNOS衍生的NO生物利用度降低的观点一致。
