Department of Pediatrics, College of Medicine, Chungbuk National University, Cheongju, Korea.
Department of Food Science and Technology, College of Natural Resources, Yeungnam University, Gyeongsan, Korea.
Kidney Res Clin Pract. 2014 Mar;33(1):26-32. doi: 10.1016/j.krcp.2014.02.001. Epub 2014 Mar 17.
Adenosine monophosphate-activated protein kinases (AMPKs), as a sensor of cellular energy status, have been known to play an important role in the pathophysiology of diabetes and its complications. Because AMPKs are known to be expressed in podocytes, it is possible that podocyte AMPKs could be an important contributing factor in the development of diabetic proteinuria. We investigated the roles of AMPKs in the pathological changes in podocytes induced by high-glucose (HG) and advanced glycosylation end products (AGEs) in diabetic proteinuria.
We prepared streptozotocin-induced diabetic renal tissues and cultured rat and mouse podocytes under diabetic conditions with AMPK-modulating agents. The changes in AMPKα were analyzed with confocal imaging and Western blotting under the following conditions: (1) normal glucose (5mM, =control); (2) HG (30mM); (3) AGE-added; or (4) HG plus AGE-added.
The density of glomerularphospho-AMPKα in experimental diabetic nephropathy decreased as a function of the diabetic duration. Diabetic conditions including HG and AGE changed the localization of phospho-AMPKα from peripheral cytoplasm to internal cytoplasm and peri- and intranuclear areas in podocytes. HG reduced the AMPKα (Thr172) phosphorylation of rat podocytes, and similarly, AGEs reduced the AMPKα (Thr172) phosphorylation of mouse podocytes. The distributional and quantitative changes in phospho-AMPKα caused by diabetic conditions were preventable using AMPK activators, metformin, and 5-aminoimidazole-4-carboxamide-1β-riboside.
We suggest that diabetic conditions induce the relocation and suppression of podocyte AMPKα, which would be a suggestive mechanism in diabetic podocyte injury.
腺苷单磷酸激活的蛋白激酶（AMPK）作为细胞能量状态的传感器，在糖尿病及其并发症的病理生理学中起着重要作用。因为 AMPK 已知在足细胞中表达，所以足细胞 AMPK 可能是糖尿病蛋白尿发展的一个重要因素。我们研究了 AMPK 在高糖（HG）和糖基化终产物（AGEs）诱导的糖尿病蛋白尿足细胞病理变化中的作用。
我们制备链脲佐菌素诱导的糖尿病肾组织，并在 AMPK 调节剂存在下用糖尿病条件培养大鼠和小鼠足细胞。在以下条件下用共聚焦成像和 Western blot 分析 AMPKα 的变化：（1）正常葡萄糖（5mM，=对照）；（2）HG（30mM）；（3）添加 AGE；或（4）HG 加 AGE 添加。
实验性糖尿病肾病肾小球磷酸化 AMPKα 的密度随糖尿病病程的延长而降低。包括 HG 和 AGE 在内的糖尿病条件改变了足细胞中磷酸化 AMPKα 的定位，从外周细胞质到内部细胞质以及核周和核内区域。HG 降低了大鼠足细胞中 AMPKα（Thr172）的磷酸化，类似地，AGEs 降低了小鼠足细胞中 AMPKα（Thr172）的磷酸化。AMPK 激活剂二甲双胍和 5-氨基咪唑-4-甲酰胺-1β-核糖苷可预防糖尿病条件引起的磷酸化 AMPKα 的分布和定量变化。
我们认为，糖尿病条件诱导足细胞 AMPKα 的重定位和抑制，这可能是糖尿病足细胞损伤的一种提示性机制。
