Agrawal Raman, Tran Uyen, Wessely Oliver
Department of Cell Biology and Anatomy, LSU Health Sciences Center, MEB 6A12, 1901 Perdido Street, New Orleans, LA 70112, USA.
Development. 2009 Dec;136(23):3927-36. doi: 10.1242/dev.037432.
MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate gene expression at the post-transcriptional level. They are involved in diverse biological processes, such as development, differentiation, cell proliferation and apoptosis. To study the role of miRNAs during pronephric kidney development of Xenopus, global miRNA biogenesis was eliminated by knockdown of two key components: Dicer and Dgcr8. These embryos developed a range of kidney defects, including edema formation, delayed renal epithelial differentiation and abnormal patterning. To identify a causative miRNA, mouse and frog kidneys were screened for putative candidates. Among these, the miR-30 family showed the most prominent kidney-restricted expression. Moreover, knockdown of miR-30a-5p phenocopied most of the pronephric defects observed upon global inhibition of miRNA biogenesis. Molecular analyses revealed that miR-30 regulates the LIM-class homeobox factor Xlim1/Lhx1, a major transcriptional regulator of kidney development. miR-30 targeted Xlim1/Lhx1 via two previously unrecognized binding sites in its 3'UTR and thereby restricted its activity. During kidney development, Xlim1/Lhx1 is required in the early stages, but is downregulated subsequently. However, in the absence of miR-30 activity, Xlim1/Lhx1 is maintained at high levels and, therefore, may contribute to the delayed terminal differentiation of the amphibian pronephros.
微小RNA（miRNA）是一类小的非编码RNA分子，它们在转录后水平调节基因表达。它们参与多种生物学过程，如发育、分化、细胞增殖和凋亡。为了研究miRNA在非洲爪蟾原肾发育过程中的作用，通过敲低两个关键成分：Dicer和Dgcr8消除了整体miRNA的生物合成。这些胚胎出现了一系列肾脏缺陷，包括水肿形成、肾上皮分化延迟和模式异常。为了鉴定起作用的miRNA，对小鼠和青蛙的肾脏进行筛选以寻找潜在的候选者。其中，miR-30家族表现出最显著的肾脏特异性表达。此外，敲低miR-30a-5p模拟了在整体抑制miRNA生物合成时观察到的大多数原肾缺陷。分子分析表明，miR-30通过其3'非翻译区中两个以前未被识别的结合位点调节LIM类同源框因子Xlim1/Lhx1，而Xlim1/Lhx1是肾脏发育的主要转录调节因子。miR-30通过这些位点靶向Xlim1/Lhx1，从而限制其活性。在肾脏发育过程中，Xlim1/Lhx1在早期阶段是必需的，但随后会下调。然而，在缺乏miR-30活性的情况下，Xlim/lhx1维持在高水平，因此可能导致两栖动物原肾的终末分化延迟。
