Epithelial cell fate in the nephron tubule is mediated by the ETS transcription factors etv5a and etv4 during zebrafish kidney development.
Epithelial cell fate in the nephron tubule is mediated by the ETS transcription factors etv5a and etv4 during zebrafish kidney development.
复制标题
DOI：
10.1016/j.ydbio.2016.01.035
复制
发表时间：
2016-03-15
影响因子：
2.7
通讯作者：
Wingert RA
中科院分区：
文献类型：
--
作者：
Marra AN;Wingert RA
肾脏的发育需要离散的肾单位上皮细胞系的分化和组织，然而参与这些事件的遗传和分子通路仍然知之甚少。斑马鱼胚胎肾脏，或称前肾，为研究肾脏发生提供了一个简单而有用的模型。原肾主要由两类上皮细胞组成：运输细胞和多纤毛细胞(MCC)。运输细胞占据不同的小管段，以各种溶质转运蛋白的表达为特征，而单核细胞在流体推进中发挥作用，并以盐和胡椒的方式分散在小管中。上皮细胞的识别依赖于Notch信号通路和维甲酸(RA)信号之间的相互作用，其中RA通过抑制肾前体细胞中的Notch活性来促进MCC的命运，而Notch则在下游作用以触发转运细胞的形成并阻止MCC身份的采用。先前的研究表明，转录因子ETS变异体5a(Etv5a)及其密切相关的ETS家族成员在其他斑马鱼组织的纤毛发生中是必需的。在这里，我们将etv5a的表达映射到占据MCC后来出现的区域的肾脏前体细胞。因此，我们推测etv5a是肾单位MCC正常发育所必需的。Etv5a功能丧失导致MCC数量下降，这表明表达MCC特异性标记的细胞频率降低，精子尾巴外致密纤维3b(Odf3b)和中心蛋白4(Cetn4)，其中救援实验部分恢复了MCC的发生率。有趣的是，ETS变体4(Etv4)的缺失也导致了MCC数量的减少，而etv5a/4的双重缺失又进一步减少了MCC的数量，这表明这两个ETS因子对MCC的形成是必不可少的，它们也可能具有多余的活性。在上位性研究中，外源性RA治疗扩大了肾脏祖细胞领域中的etv5a结构域，RA抑制阻断了这一人群中的etv5a，表明etv5a作用于RA的下游。此外，外源RA处理部分挽救了etv5a丢失后减少的MCC表型。此外，用小分子抑制剂DAPT去除Notch可以增加etv5a缺陷胚胎中肾祖细胞etv5a的表达结构域和MCC密度，提示Notch作用于上游抑制etv5a。相反，肾祖细胞中的ETV4水平不受RA或Notch信号水平变化的影响，这表明在原肾形成过程中可能有非细胞自主作用。综上所述，这些发现揭示了关于肾脏发生过程中上皮细胞发育的遗传机制的新见解。
Kidney development requires the differentiation and organization of discrete nephron epithelial lineages, yet the genetic and molecular pathways involved in these events remain poorly understood. The embryonic zebrafish kidney, or pronephros, provides a simple and useful model to study nephrogenesis. The pronephros is primarily comprised of two types of epithelial cells: transportive and multiciliated cells (MCCs). Transportive cells occupy distinct tubule segments and are characterized by the expression of various solute transporters, while MCCs function in fluid propulsion and are dispersed in a “salt-and-pepper” fashion within the tubule. Epithelial cell identity is reliant on interplay between the Notch signaling pathway and retinoic acid (RA) signaling, where RA promotes MCC fate by inhibiting Notch activity in renal progenitors, while Notch acts downstream to trigger transportive cell formation and block adoption of an MCC identity. Previous research has shown that the transcription factor ets variant 5a (etv5a), and its closely related ETS family members, are required for ciliogenesis in other zebrafish tissues. Here, we mapped etv5a expression to renal progenitors that occupy domains where MCCs later emerge. Thus, we hypothesized that etv5a is required for normal development of MCCs in the nephron. etv5a loss of function caused a decline of MCC number as indicated by the reduced frequency of cells that expressed the MCC-specific markers outer dense fiber of sperm tails 3b (odf3b) and centrin 4 (cetn4), where rescue experiments partially restored MCC incidence. Interestingly, deficiency of ets variant 4 (etv4), a related gene that is broadly expressed in the posterior mesoderm during somitogenesis stages, also led to reduced MCC numbers, which were further reduced by dual etv5a/4 deficiency, suggesting that both of these ETS factors are essential for MCC formation and that they also might have redundant activities. In epistatic studies, exogenous RA treatment expanded the etv5a domain within the renal progenitor field and RA inhibition blocked etv5a in this populace, indicating that etv5a acts downstream of RA. Additionally, treatment with exogenous RA partially rescued the reduced MCC phenotype after loss of etv5a. Further, abrogation of Notch with the small molecule inhibitor DAPT increased the renal progenitor etv5a expression domain as well as MCC density in etv5a deficient embryos, suggesting Notch acts upstream to inhibit etv5a. In contrast, etv4 levels in renal progenitors were unaffected by changes in RA or Notch signaling levels, suggesting a possible non-cell autonomous role during pronephros formation. Taken together, these findings have revealed new insights about the genetic mechanisms of epithelial cell development during nephrogenesis.