Department of Internal Medicine III, Jena University Hospital, Erlanger Allee, Jena, Germany.
Nephrol Dial Transplant. 2017 Apr 1;32(4):641-653. doi: 10.1093/ndt/gfw313.
Growth arrest specific 2-like protein 1 (GAS2L1) protein is a member of the GAS2 family of proteins, known to regulate apoptosis and cellular cytoskeleton reorganization in different cells. Recently we identified that Gas2l1 gene expression in podocytes is influenced by advanced glycation end product-bovine serum albumin(AGE-BSA).
The study was performed employing cultured podocytes and diabetic ( db/db ) mice, a model of type 2 diabetes. Akbuminuria as wellas urinary neutrophil gelatinase-associated lipocalin (NGAL) excretion as measured with specific ELISAs. Gene expression was analysed via semiquantitative and real-time polymerase chain reaction. The protein levels were determined by western blotting and immunostaining.
We found that the Gas2l1 α isoform is expressed in podocytes. Treatment with AGE-BSA induced Gas2l1 α and Gas2 mRNA levels compared with controls incubated with non-glycated control BSA (Co-BSA). Moreover, application of the recombinant soluble receptor of AGEs (sRAGE), a competitor of cellular RAGE, reversed the AGE-BSA effect. Interestingly, AGE-BSA also increased the protein levels of GAS2L1α in a RAGE-dependent manner, but did not affect the GAS2 expression. Periodic acid-Schiff staining and albuminuria as well as urinary NGAL excretion revealed that db/db mice progressively developed diabetic nephropathy with renal accumulation of N ε -carboxy-methyl-lysine (immunohistochemistry, western blots). Analyses of GAS2L1α and GAS2 proteins in diabetic mice revealed that both were significantly elevated relative to their non-diabetic littermates. In addition, GAS2L1α and GAS2 proteins positively correlated with the accumulation of AGEs in the blood plasma of diabetic mice and the administration of sRAGE in diabetic mice reduced the glomerular expression of both proteins.
We show for the first time that the protein expression of GAS2L1α in vitro and in vivo is regulated by the AGE-RAGE axis. The suppression of AGE ligation with their RAGE in diabetic mice with progressive nephropathy reversed the GAS2L1α expression, thus suggesting a role of GAS2L1α in the development of diabetic disease, which needs to be further elucidated.
生长停滞特异性蛋白 2 样蛋白 1（GAS2L1）蛋白是 GAS2 蛋白家族的一员，已知其在不同细胞中调节细胞凋亡和细胞细胞骨架重组。最近我们发现，足细胞中 Gas2l1 基因的表达受晚期糖基化终产物-牛血清白蛋白（AGE-BSA）的影响。
本研究采用培养的足细胞和糖尿病（db/db）小鼠（2 型糖尿病模型）进行。采用特定的 ELISA 法检测白蛋白尿和尿中性粒细胞明胶酶相关脂质运载蛋白（NGAL）的排泄。通过半定量和实时聚合酶链反应分析基因表达。通过 Western blot 和免疫染色测定蛋白水平。
我们发现 Gas2l1α 异构体在足细胞中表达。与用非糖化对照 BSA（Co-BSA）孵育的对照组相比，用 AGE-BSA 处理诱导 Gas2l1α 和 Gas2 mRNA 水平升高。此外，应用 AGEs 的重组可溶性受体（sRAGE），一种细胞 RAGE 的竞争物，逆转了 AGE-BSA 的作用。有趣的是，AGE-BSA 还以 RAGE 依赖的方式增加 GAS2L1α 的蛋白水平，但不影响 GAS2 的表达。过碘酸-Schiff 染色、白蛋白尿和尿 NGAL 排泄显示，db/db 小鼠逐渐发展为糖尿病肾病，肾内积累 Nε-羧甲基赖氨酸（免疫组织化学、Western blot）。对糖尿病小鼠的 GAS2L1α 和 GAS2 蛋白分析表明，与非糖尿病同窝小鼠相比，这两种蛋白均显著升高。此外，GAS2L1α 和 GAS2 蛋白与糖尿病小鼠血浆中 AGEs 的积累呈正相关，糖尿病小鼠中 sRAGE 的给药降低了这两种蛋白的肾小球表达。
我们首次表明，体外和体内 GAS2L1α 的蛋白表达受 AGE-RAGE 轴的调节。在进展性肾病的糖尿病小鼠中，用其 RAGE 抑制 AGE 结合可逆转 GAS2L1α 的表达，因此提示 GAS2L1α 在糖尿病疾病的发展中起作用，这需要进一步阐明。
