The cytoplasmic tail of FPC antagonizes the full-length protein in the regulation of mTOR pathway.
The cytoplasmic tail of FPC antagonizes the full-length protein in the regulation of mTOR pathway.
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DOI：
10.1371/journal.pone.0095630
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发表时间：
2014
期刊：
影响因子：
3.7
通讯作者：
Zhou J
中科院分区：
文献类型：
--
作者：
Wang S;Wu M;Yao G;Zhang J;Zhou J
FPC（纤维囊肿蛋白或多囊蛋白）是一种单跨膜受体样蛋白，导致人类常染色体隐性多囊肾病 (ARPKD)。最近有人提出，FPC 会经历类似 Notch 的裂解，随后裂解的羧基 (C) 末端片段易位至细胞核。为了研究分离的 C 尾的功能，我们在肾上皮细胞中表达了人 FPC (hICD) 的胞内结构域。通过 3 维 (3D) 肾小管发生测定，我们发现与对照细胞形成的肾小管样结构相比，表达 hICD 的细胞专门形成囊肿样结构。通过蛋白质印迹，我们发现 Akt/mTOR 通路（通过 Akt 在丝氨酸 473 处和 S6 激酶 1 在苏氨酸 389 处的磷酸化增加表明）在 hICD 表达细胞中被组成型激活，类似于 FPC 敲低细胞和 ARPKD 肾脏中的激活。此外，mTOR抑制剂雷帕霉素的应用减小了hICD表达细胞形成的囊肿样结构的大小。应用 LY294002 或渥曼青霉素均抑制 S6K1 和 Akt 的激活。全长FPC的表达抑制S6和S6激酶的激活，而hICD与全长FPC的共表达拮抗全长FPC对mTOR的抑制作用。综上所述，我们认为 FPC 调节 PI3K/Akt/mTOR 通路，而切割的 C 尾调节全长蛋白的功能。
FPC (fibrocystin or polyductin) is a single transmembrane receptor-like protein, responsible for the human autosomal recessive polycystic kidney disease (ARPKD). It was recently proposed that FPC undergoes a Notch-like cleavage and subsequently the cleaved carboxy(C)-terminal fragment translocates to the nucleus. To study the functions of the isolated C-tail, we expressed the intracellular domain of human FPC (hICD) in renal epithelial cells. By 3-dimensional (3D) tubulogenesis assay, we found that in contrast to tubule-like structures formed from control cells, hICD-expressing cells exclusively formed cyst-like structures. By western blotting, we showed that the Akt/mTOR pathway, indicated by increased phosphorylation of Akt at serine 473 and S6 kinase 1 at threonine 389, was constitutively activated in hICD-expressing cells, similar to that in FPC knockdown cells and ARPKD kidneys. Moreover, application of mTOR inhibitor rapamycin reduced the size of the cyst-like structures formed by hICD-expressing cells. Application of either LY294002 or wortmannin inhibited the activation of both S6K1 and Akt. Expression of full-length FPC inhibited the activation of S6 and S6 kinase whereas co-expression of hICD with full-length FPC antagonized the inhibitory effect of full-length FPC on mTOR. Taken together, we propose that FPC modulates the PI3K/Akt/mTOR pathway and the cleaved C-tail regulates the function of the full-length protein.
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影响因子：
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作者：
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DOI：
10.1097/01.asn.0000029587.47950.25
发表时间：
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影响因子：
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作者：
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通讯作者：
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