Role fo AMP-activated protein kinase (AMPK) in diabetic nephropathy: change of tubuloglomerular feeedback and salt transport

AMP活化蛋白激酶（AMPK）是一种丝氨酸-苏氨酸激酶，在心脏和骨骼肌中调节多种代谢途径，包括脂肪酸β-氧化、胆固醇合成、糖酵解和葡萄糖转运。AMPK被认为是能量传感器激酶，因为它以非常敏感的方式被消耗ATP或增加AMP/ATP比率的细胞应激激活。AMPK在哺乳动物肾脏中的作用尚不清楚。免疫组织化学和免疫荧光染色证实，激活AMPK的强表达在皮质厚acending肢和致密斑细胞的顶膜以及集合管细胞的基底外侧表面。此外，AMPK活性增加了25%，在高盐饮食治疗的大鼠中，观察到致密斑细胞系中AMPK的瞬时激活，以响应渗透压摩尔浓度的变化，这表明该激酶在控制肾小管盐重吸收和肾小管肾小球反馈反应中的作用。本研究的目的是阐明AMPK在肾脏血流动力学、肾小管盐转运和肾小管-肾小球反馈中的作用。为此，我们将在大鼠和转基因小鼠体内的清除和微穿刺实验中结合肾脏AMPK表达的分析来进行AMPK的药理学抑制或激活。

AMP-activated protein kinase (AMPK) is a serine-threonine kinase that regulates many metabolic pathways including fatty acid ß-oxidation, cholesterol synthesis, glycolysis and glucose transport in heart and skeletal muscle. AMPK is considered as a energy sensor kinase since it is activated in a very sensitive manner by cellular stress that depletes ATP or increases AMP/ATP ratio. The role of AMPK in mamalian kidney is unknown. Immunohistochemical and immunofluorescence staining confirmed strong expression of activated AMPK in the apical membrance of cortical thick acending limb and macula densa cells as well as basolateral surface of the collecting duct cells of rat kidney. Furthermore, AMPK activity was increased by 25% in rats treated with high salt diet and a transient activation of AMPK was observed in a macula densa cell line in response to changes in osmolality suggesting a role for this kinase in the control of tubular salt reabsorption and tubuloglomerular feedback response. The aim of this project is to clarify the role of AMPK in control of renal hemodynamics, tubular salt transport and tubuloglomerular feedback. To this end, we will perform pharmacological inhibition or activation of AMPK in clearance and micropuncture experiments in rats and transgenic mice in vivo combined with analysis of renal AMPK expression.