Durbeej M, Söderström S, Ebendal T, Birchmeier C, Ekblom P
Department of Animal Physiology, Uppsala University, Sweden.
Development. 1993 Dec;119(4):977-89. doi: 10.1242/dev.119.4.977.
Early kidney differentiation is driven by local cell-cell interactions. The metanephrogenic mesenchyme stimulates the epithelial ureter bud to grow and branch, whereas the ureter bud stimulates the mesenchyme to convert into a new epithelium. These interactions may be dependent on local growth factors and their receptors. We studied the expression of receptors for nerve growth factors during kidney development. Expression of the low- and high-affinity receptors was cell-type specific. The low-affinity NGF receptor was found in the uninduced mesenchyme at early developmental stages, but in the glomerular podocytes at later developmental stages. In contrast, the high-affinity trkB receptor was found in the cortical mesenchyme cells that will differentiate into stroma. The trkC receptor was found only weakly expressed and in a few parts of the collecting ducts. The role of these receptors and c-ros, a receptor-type kinase expressed on the tip of the ureter bud, was studied by modified antisense oligonucleotides. However, we found that both sense, antisense and nonsense phosphorothioate oligonucleotides inhibited mouse and rat embryonic kidney development in vitro. The oligonucleotides appeared to be toxic for rodent embryonic kidneys in the experimental conditions that we used. Moreover, oligonucleotides did not penetrate well into the epithelial sheets in the organ cultures. We conclude that studies with phosphorothioate antisense oligonucleotides in organ cultures of embryonic kidneys should be interpreted with caution. Our current data do not allow us to not assign a function for the low- or high-affinity NGF receptors or c-ros in kidney development.
早期肾脏分化由局部细胞间相互作用驱动。后肾间充质刺激输尿管芽上皮生长并分支，而输尿管芽则刺激间充质转化为新的上皮。这些相互作用可能依赖于局部生长因子及其受体。我们研究了肾脏发育过程中神经生长因子受体的表达。低亲和力和高亲和力受体的表达具有细胞类型特异性。在发育早期，未诱导的间充质中发现低亲和力NGF受体，但在发育后期的肾小球足细胞中发现。相反，高亲和力trkB受体在将分化为基质的皮质间充质细胞中发现。trkC受体仅在集合管的少数部位有弱表达。通过修饰的反义寡核苷酸研究了这些受体以及在输尿管芽尖端表达的受体型激酶c-ros的作用。然而，我们发现有义、反义和无义硫代磷酸酯寡核苷酸在体外均抑制小鼠和大鼠胚胎肾脏发育。在我们使用的实验条件下，这些寡核苷酸似乎对啮齿动物胚胎肾脏有毒性。此外，寡核苷酸在器官培养物中不能很好地穿透上皮层。我们得出结论，在胚胎肾脏器官培养中使用硫代磷酸酯反义寡核苷酸进行的研究应谨慎解释。我们目前的数据不允许我们确定低亲和力或高亲和力NGF受体或c-ros在肾脏发育中的功能。
