BACKGROUND Damages to subcellular organelles, such as mitochondria and endoplasmic reticulum, are well-recognized in tubular cell injury and death in acute kidney injury (AKI). However, the changes and involvement of Golgi apparatus are much less known. Here, we report the regulation and role of N-acetylgalactosaminyltransferase-3 (GALNT3), a key enzyme for protein glycosylation in Golgi apparatus, in AKI. METHODS AKI was induced in mice by renal ischemia-reperfusion or cisplatin. In vitro, rat kidney proximal tubular cells were subjected to hypoxia/reoxygenation (H/R) injury. To determine the role of GALNT3, its specific inhibitor T3inh-1 was tested in mice, and the effects of GALNT3 overexpression as well as knockdown were examined in the rat renal proximal tubular cells. EGFR activation was induced by recombinant EGF or by overexpressing EGFR. RESULTS GALNT3 was significantly decreased in both in vivo and in vitro models of AKI induced by renal ischemia-reperfusion and cisplatin. T3Inh-1, a specific GALNT3 inhibitor, exacerbated ischemic AKI and suppressed tubular cell proliferation in mice. Moreover, knockdown of GALNT3 increased apoptosis during H/R treatment in rat renal proximal tubular cells, while overexpression of GALNT3 attenuated H/R-induced apoptosis, further supporting a protective role of GALNT3. Mechanistically, GALNT3 contributed to O-glycosylation of epidermal growth factor receptor (EGFR) and associated EGFR signalling. Activation or overexpression of EGFR suppressed the pro-apoptotic effect of GALNT3 knockdown in H/R-treated rat renal proximal tubular cells. CONCLUSIONS GALNT3 protected kidney tubular cells in AKI at least partially through O-glycosylation of EGFR.

中文翻译：

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肾脏缺血再灌注损伤中的 GALNT3。


背景 对亚细胞器的损伤，如线粒体和内质网，在肾小管细胞损伤和急性肾损伤 （AKI） 中的死亡中得到广泛认可。然而，高尔基体的变化和参与鲜为人知。在这里，我们报道了 N-乙酰半乳糖胺基转移酶-3 （GALNT3） 的调节和作用，这是一种高尔基体中蛋白质糖基化的关键酶，在 AKI 中。方法 通过肾缺血再灌注或顺铂诱导小鼠 AKI。在体外，大鼠肾近端肾小管细胞受到缺氧/复氧 （H/R） 损伤。为确定 GALNT3 的作用，在小鼠中测试其特异性抑制剂 T3inh-1，并在大鼠肾近端肾小管细胞中检测 GALNT3 过表达和敲低的影响。EGFR 激活由重组 EGF 或过表达 EGFR 诱导。结果 GALNT3 在肾缺血再灌注和顺铂诱导的 AKI 体内和体外模型中均显著降低。T3Inh-1 是一种特异性 GALNT3 抑制剂，可加剧小鼠缺血性 AKI 并抑制肾小管细胞增殖。此外，在 H/R 处理期间，GALNT3 的敲除增加了大鼠肾近端肾小管细胞的凋亡，而 GALNT3 的过表达减弱了 H/R 诱导的细胞凋亡，进一步支持 GALNT3 的保护作用。从机制上讲，GALNT3 有助于表皮生长因子受体 （EGFR） 的 O 糖基化和相关的 EGFR 信号传导。EGFR 的激活或过表达抑制了 H/R 处理的大鼠肾近端肾小管细胞中 GALNT3 敲低的促凋亡作用。结论 GALNT3 至少部分通过 EGFR 的 O-糖基化保护 AKI 中的肾小管细胞。