Uromodulin p.Cys147Trp mutation drives kidney disease by activating ER stress and apoptosis
Uromodulin p.Cys147Trp mutation drives kidney disease by activating ER stress and apoptosis
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DOI：
10.1172/jci93817
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发表时间：
2017-11-01
影响因子：
15.9
通讯作者：
Duffield, Jeremy S.
中科院分区：
文献类型：
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作者：
Johnson, Bryce G.;Dang, Lan T.;Duffield, Jeremy S.
尿调蛋白相关性肾病（UAKD）是由尿调蛋白（UMOD）基因突变引起的，该突变导致UMOD蛋白的错误折叠形式，该蛋白通常由肾单位分泌。在UAKD患者中，突变型UMOD分泌不良，并在远端肾上皮的ER中积累，但其在疾病进展中的作用在很大程度上尚不清楚。在此，我们通过表达人UMOD p.Cys148Trp点突变的鼠等效物（Umod（C147 W/+）小鼠）来模拟小鼠中的UMOD蓄积。与受影响的人类一样，这些Umod（C147 W/+）小鼠在24周内发生了自发性和进行性肾脏疾病，伴有器官衰竭。对患病肾脏和纯化的UMOD产生细胞的分析揭示了PKR样ER激酶/活化转录因子4（PERK/ATF 4）ER应激途径的早期活化、先天免疫介质和增加的凋亡信号传导，包括半胱天冬酶-3活化。出乎意料的是，我们也检测到了自噬缺陷。表达UMOD p.Cys147Trp的人细胞重现了Umod（C147 W/+）小鼠中的发现，并且mTOR抑制剂的自噬激活刺激了聚集的突变体UMOD的细胞内去除。由于ER应激介质tribbles-3的表达增加，产生突变UMOD的人细胞对TNF-α和TRAIL介导的细胞凋亡敏感。用可溶性重组融合蛋白TNFR：Fc在体内阻断TNF-α通过减少活性半胱天冬酶-3来减缓UmodC 147 W/+小鼠的疾病进展，从而防止肾小管细胞死亡和上皮功能丧失。这些发现揭示了UAKD所涉及的疾病过程的靶向机制。
Uromodulin-associated kidney disease (UAKD) is caused by mutations in the uromodulin (UMOD) gene that result in a misfolded form of UMOD protein, which is normally secreted by nephrons. In UAKD patients, mutant UMOD is poorly secreted and accumulates in the ER of distal kidney epithelium, but its role in disease progression is largely unknown. Here, we modeled UMOD accumulation in mice by expressing the murine equivalent of the human UMOD p.Cys148Trp point mutation (Umod(C147W/+) mice). Like affected humans, these Umod(C147W/+) mice developed spontaneous and progressive kidney disease with organ failure over 24 weeks. Analysis of diseased kidneys and purified UMOD-producing cells revealed early activation of the PKR-like ER kinase/activating transcription factor 4 (PERK/ATF4) ER stress pathway, innate immune mediators, and increased apoptotic signaling, including caspase-3 activation. Unexpectedly, we also detected autophagy deficiency. Human cells expressing UMOD p. Cys147Trp recapitulated the findings in Umod(C147W/+) mice, and autophagy activation with mTOR inhibitors stimulated the intracellular removal of aggregated mutant UMOD. Human cells producing mutant UMOD were susceptible to TNF-alpha-and TRAIL-mediated apoptosis due to increased expression of the ER stress mediator tribbles-3. Blocking TNF-alpha in vivo with the soluble recombinant fusion protein TNFR: Fc slowed disease progression in UmodC147W/+ mice by reducing active caspase-3, thereby preventing tubule cell death and loss of epithelial function. These findings reveal a targetable mechanism for disease processes involved in UAKD.