Regeneration of renal epithelial cells from metanephric mesenchymal cells

大鼠后肾间充质细胞与碱性成纤维细胞生长因子和激光诱导因子孵育诱导上皮细胞标记物E-钙粘附素的表达。E-钙粘蛋白的表达不受ERK阻断的影响，但受p38阻断的抑制。为了确定介导p38效应的基因，我们使用CDNA微阵列分析了p38抑制剂培养的后肾细胞中的基因表达模式。在p38抑制剂下调的基因中，我们发现了信号分子受体样蛋白酪氨酸磷酸酶k(rptpκ)。Rptpκ属于受体样酪氨酸磷酸酶家族，与细胞黏附和增殖有关。在肾脏发育过程中，rptpκ的蛋白表达与p38相同，并被p38抑制剂抑制。接下来，我们研究了多囊肾病pcy小鼠模型中MAP激酶的表达。胚胎14~25周龄囊上皮内可见增殖细胞核抗原阳性细胞。而ERK是在…中表达的对照组和pcy组小鼠肾小管较多，囊上皮细胞免疫染色较强。磷酸化ERK仅在pcy小鼠中检测到，主要定位于囊肿内。对照组出生后不再表达p38，但在所有发育阶段的pcy小鼠的囊上皮细胞中均可检测到p38的表达。出生后7天，对照组肾小管段均有JNK的表达，而肾小管和肾囊肿中JNK的表达较少。给6周龄的pcy小鼠腹腔注射MEK抑制剂PD98059 4周后，显著减少了水的摄入量，增加了尿液渗透压，并抑制了包囊的形成。结论：pcy小鼠囊性上皮细胞ERK、磷酸化ERK和p38表达上调，JNK表达下调。ERK的抑制抑制了囊性病变的形成，减轻了尿液浓缩缺陷。这些结果提示，MAPKs，尤其是ERK的异常调节可能在多囊肾病的病理生理过程中起重要作用，并可能成为一个新的治疗靶点。较少

Incubation of rat metanephric mesenchymal cells with bFGF and LIF induced expression of an epithelial cell marker E-cadherin. The expression of E-cadherin was not affected by the blockade of ERK, but was suppressed by the blockade of p38. To identify genes that mediate the effect of p38, we analyzed patterns of gene expression in metanephroi cultured under a p38 inhibitor using CDNA microarray. Among downregulated genes by a p38 inhibitor, we found a signaling molecule receptor-like protein tyrosine phosphatase k (RPTPκ). RPTPκ belongs to the family of receptor-like tyrosine phosphatases and is implicated in cell adhesion and proliferation. The protein expression of RPTPκ during kidney development was identical to that of p38, and suppressed by a p38 inhibitor.We next investigated the expression of MAP kinases in a murine model of polycystic kidney disease pcy mice. PCNA-positive cells were recognized in cyst epithelia from embryonic day 14 to 25 weeks of age. While ERK was expressed i … More n tubules of kidneys from control and pcy mice, stronger immunostaining was observed in cyst epithelia. Phosphorylated ERK was detected only in pcy mice localizing predominantly in cysts. p38 was no longer expressed after birth in controls, but was detected in cyst epithelia of pcy mice at all stages examined. JNK was expressed in all tubular segments of controls after neonatal day 7. In contrast, tubules and cysts of pcy kidneys expressed little JNK. Administration of a MEK inhibitor PD98059 to 6-week old pcy mice intraperitoneally for 4 weeks significantly decreased water intake, increased urine osmolality, and suppressed cyst formation. In conclusion, the expression of ERK, phosphorylated ERK, and p38 were upregulated, and that of JNK was downregulated in cyst epithelia of pcy mice. The inhibition of ERK suppressed cyst formation and alleviated the urinary concentrating defect. These resuks suggest that dysregulation of MAPKs, especially that of ERK, may play an important role in the pathophysiology of polycystic kidney disease and could be a novel therapeutic target. Less