Glycosaminoglycans (GAGs) and AMP-activated Protein Kinase (AMPK) are two critical molecular players involved in cellular homeostasis. Both of them are altered due to hyperglycemia in the kidney, leading to the pathogenesis of diabetic nephropathy. Here, we have looked into the effect of AMPK modulation on sulfated GAG (sGAG) levels of tubular cells of proximal and distal origin to understand the mechanism of hyperglycemia-mediated pathogenesis of the diabetic nephropathy. In MDCK cells (Distal tubular cell) and NRK-52E (Proximal tubular cell), AMPK inhibition resulted in increased sGAG levels under normal glucose conditions characteristically of heparan sulfate class, whereas AMPK activation did not have any effect. High glucose (HG) condition did not alter sGAG levels in MDCK cell despite a decrease in AMPK phosphorylation. Subjecting NRK-52E cells to HG milieu significantly decreased sGAG levels more so of chondroitin/dermatan sulfate, which is significantly prevented when HG is co-treated with AMPK activator. Interestingly, knockdown of AMPK by AMPK α 1/α 2 siRNA showed increased sGAG levels in NRK-52E. Our results suggest that changes in sGAG level, in particular, as a result of AMPK modulation is differentially regulated and is dependent on cell type as well as its physiological status. Furthermore, activation of AMPK is beneficial in preventing the HG-mediated decrease in sGAGs in proximal tubular cells.

中文翻译：

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在正常和高葡萄糖环境下，AMPK在近端肾小管细胞中差异地改变硫酸化的糖胺聚糖。

糖胺聚糖（GAG）和AMP激活的蛋白激酶（AMPK）是参与细胞稳态的两个关键分子。两者均由于肾脏中的高血糖而改变，从而导致糖尿病性肾病的发病机理。在这里，我们研究了AMPK调节对近端和远端起源的肾小管细胞硫酸盐GAG（sGAG）水平的影响，以了解高血糖介导的糖尿病性肾病发病机理。在MDCK细胞（远端肾小管细胞）和NRK-52E（近端肾小管细胞）中，AMPK抑制作用导致在正常葡萄糖条件下具有硫酸乙酰肝素类特征的sGAG水平升高，而AMPK激活没有任何作用。尽管AMPK磷酸化降低，但高葡萄糖（HG）条件并未改变MDCK细胞中的sGAG水平。使NRK-52E细胞受到HG环境的影响，使软骨素/硫酸皮肤素的sGAG水平显着降低，而当HG与AMPK激活剂共同处理时，sGAG的水平会大大降低。有趣的是，AMPKα1 /α2 siRNA敲低AMPK显示NRK-52E中sGAG水平升高。我们的结果表明，特别是由于AMPK调节而导致的sGAG水平变化受到差异调节，并且取决于细胞类型及其生理状态。此外，AMPK的激活有利于防止HG介导的近端小管细胞中sGAG的减少。AMPKα1 /α2 siRNA敲低AMPK显示NRK-52E中sGAG水平升高。我们的结果表明，特别是由于AMPK调节而导致的sGAG水平变化受到差异调节，并且取决于细胞类型及其生理状态。此外，AMPK的激活有利于防止HG介导的近端小管细胞中sGAG的减少。AMPKα1 /α2 siRNA敲低AMPK显示NRK-52E中sGAG水平升高。我们的结果表明，特别是由于AMPK调节而导致的sGAG水平变化受到差异调节，并且取决于细胞类型及其生理状态。此外，AMPK的激活有利于防止HG介导的近端小管细胞中sGAG的减少。