Aberrant Smad3 phosphoisoforms in cyst-lining epithelial cells in the cpk mouse, a model of autosomal recessive polycystic kidney disease
Aberrant Smad3 phosphoisoforms in cyst-lining epithelial cells in the cpk mouse, a model of autosomal recessive polycystic kidney disease
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DOI：
10.1152/ajprenal.00697.2016
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发表时间：
2017-12-01
影响因子：
4.2
通讯作者：
Suzuki, Hiroyuki
中科院分区：
文献类型：
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作者：
Hama, Taketsugu;Nakanishi, Koichi;Suzuki, Hiroyuki
多囊肾病（PKD）的囊性上皮获得间充质样特征。在这种表型改变中，众所周知，转化生长因子（TGF）-β/Smad 3信号转导参与其中;然而，出现了Smad 3磷酸化亚型的新数据：Smad 3在连接区（pSmad 3L），COOH末端区（pSmad 3C）和两者（pSmad 3L/C）磷酸化。pSmad 3L/C在结直肠癌中具有病理学作用。TGF-β/Smad 3通路中的间充质表型特异性细胞反应与癌有关在这项研究中，我们证实了间充质的功能，并检查Smad 3磷酸异构体在cpk小鼠，常染色体隐性PKD模型。肾切片用抗间充质标志物和结构域特异性磷酸化Smad 3的抗体染色。通过蛋白质印迹法评估TGF-β、pSmad 3L、pSmad 3C、JNK、细胞周期蛋白依赖性激酶（CDK）4和c-Myc。通过免疫沉淀法评估pSmad 3L/C的共磷酸化。表明间充质特征的α-平滑肌肌动蛋白在cpk小鼠中表达更高。pSmad 3L的表达在cpk小鼠中增加，并且主要定位于囊肿中的肾小管上皮细胞的细胞核中;然而，pSmad 3C在cpk和对照小鼠中同样表达。cpk小鼠细胞核中pSmad 3L、JNK、CDK 4和c-Myc蛋白的水平显著高于对照组。免疫沉淀结果显示，Smad 3在cpk小鼠体内存在共磷酸化（pSmad 3L/C）。smad 3基因敲除/cpk双突变小鼠显示cpk异常的改善。这些发现表明，通过JNK/CDK 4依赖性pSmad 3L途径上调c-Myc可能是cpk小鼠病理生理学的关键。总之，TGF-β/Smad 3通路的定性而非定量异常参与PKD，可能是疾病特异性干预的靶点。
Cystic epithelia acquire mesenchymal-like features in polycystic kidney disease (PKD). In this phenotypic alteration, it is well known that transforming growth factor (TGF)-beta/Smad3 signaling is involved; however, there is emerging new data on Smad3 phosphoisoforms: Smad3 phosphorylated at linker regions (pSmad3L), COOH-terminal regions (pSmad3C), and both (pSmad3L/C). pSmad3L/C has a pathological role in colorectal cancer. Mesenchymal phenotype-specific cell responses in the TGF-beta/Smad3 pathway are implicated in carcinomas. In this study, we confirmed mesenchymal features and examined Smad3 phosphoisoforms in the cpk mouse, a model of autosomal recessive PKD. Kidney sections were stained with antibodies against mesenchymal markers and domain-specific phospho-Smad3. TGF-beta, pSmad3L, pSmad3C, JNK, cyclin-dependent kinase (CDK) 4, and c-Myc were evaluated by Western blotting. Cophosphorylation of pSmad3L/C was assessed by immunoprecipitation. alpha-Smooth muscle actin, which indicates mesenchymal features, was expressed higher in cpk mice. pSmad3L expression was increased in cpk mice and was predominantly localized in the nuclei of tubular epithelial cells in cysts; however, pSmad3C was equally expressed in both cpk and control mice. Levels of pSmad3L, JNK, CDK4, and c-Myc protein in nuclei were significantly higher in cpk mice than in controls. Immunoprecipitation showed that Smad3 was cophosphorylated (pSmad3L/C) in cpk mice. Smad3 knockout/cpk double-mutant mice revealed amelioration of cpk abnormalities. These findings suggest that upregulating c-Myc through the JNK/CDK4-dependent pSmad3L pathway may be key to the pathophysiology in cpk mice. In conclusion, a qualitative rather than a quantitative abnormality of the TGF-beta/Smad3 pathway is involved in PKD and may be a target for disease-specific intervention.