Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri; and.
Renal Division, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts.
J Am Soc Nephrol. 2019 Dec;30(12):2370-2383. doi: 10.1681/ASN.2019030321. Epub 2019 Nov 1.
Sustained activation of EGF receptor (EGFR) in proximal tubule cells is a hallmark of progressive kidney fibrosis after AKI and in CKD. However, the molecular mechanisms and particular EGFR ligands involved are unknown.
We studied EGFR activation in proximal tubule cells and primary tubular cells isolated from injured kidneys . To determine the role of amphiregulin, a low-affinity EGFR ligand that is highly upregulated with injury, we used ischemia-reperfusion injury or unilateral ureteral obstruction in mice with proximal tubule cell-specific knockout of amphiregulin. We also injected soluble amphiregulin into knockout mice with proximal tubule cell-specific deletion of amphiregulin's releasing enzyme, the transmembrane cell-surface metalloprotease, a disintegrin and metalloprotease-17 (ADAM17), and into ADAM17 hypomorphic mice.
Yes-associated protein 1 (YAP1)-dependent upregulation of amphiregulin transcript and protein amplifies amphiregulin signaling in a positive feedback loop. YAP1 also integrates signals of other moderately injury-upregulated, low-affinity EGFR ligands (epiregulin, epigen, TGF), which also require soluble amphiregulin and YAP1 to induce sustained EGFR activation in proximal tubule cells . , soluble amphiregulin injection sufficed to reverse protection from fibrosis after ischemia-reperfusion injury in ADAM17 hypomorphic mice; injected soluble amphiregulin also reversed the corresponding protective proximal tubule cell phenotype in injured proximal tubule cell-specific ADAM17 knockout mice. Moreover, the finding that proximal tubule cell-specific amphiregulin knockout mice were protected from fibrosis after ischemia-reperfusion injury or unilateral ureteral obstruction demonstrates that amphiregulin was necessary for the development of fibrosis.
Our results identify amphiregulin as a key player in injury-induced kidney fibrosis and suggest therapeutic or diagnostic applications of soluble amphiregulin in kidney disease.
急性肾损伤（AKI）和慢性肾脏病（CKD）后，近端肾小管细胞中表皮生长因子受体（EGFR）的持续激活是进行性肾纤维化的标志。然而，其涉及的分子机制和特定的 EGFR 配体尚不清楚。
我们研究了损伤肾脏中近端肾小管细胞和原代肾小管细胞中 EGFR 的激活。为了确定低亲和力 EGFR 配体 amphiregulin 的作用，该配体在损伤时高度上调，我们使用缺血再灌注损伤或单侧输尿管梗阻，在近端肾小管细胞特异性缺失 amphiregulin 的小鼠中进行研究。我们还将可溶性 amphiregulin 注射到近端肾小管细胞特异性缺失 amphiregulin 释放酶、跨膜细胞表面金属蛋白酶、解整合素金属蛋白酶 17（ADAM17）的小鼠，以及 ADAM17 低功能小鼠中。
Yes 相关蛋白 1（YAP1）依赖性 amphiregulin 转录本和蛋白的上调放大了正反馈环中的 amphiregulin 信号。YAP1 还整合了其他中度损伤上调的、低亲和力 EGFR 配体（epiregulin、epigen、TGF）的信号，这些配体也需要可溶性 amphiregulin 和 YAP1 诱导近端肾小管细胞中持续的 EGFR 激活。在 ADAM17 低功能小鼠中，注射可溶性 amphiregulin 足以逆转缺血再灌注损伤后的纤维化保护作用；注射可溶性 amphiregulin 也逆转了损伤后近端肾小管细胞特异性 ADAM17 敲除小鼠中相应的保护性近端肾小管细胞表型。此外，近端肾小管细胞特异性 amphiregulin 敲除小鼠在缺血再灌注损伤或单侧输尿管梗阻后免受纤维化的发现表明，amphiregulin 是纤维化发展所必需的。
我们的研究结果确定 amphiregulin 是损伤诱导的肾脏纤维化的关键因素，并提示可溶性 amphiregulin 在肾脏疾病中的治疗或诊断应用。
