Key Laboratory of Stem Cell Biology and State Key Laboratory of Medical Genomics and Laboratory of Development and Diseases, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine, and Shanghai Institute of Hematology, RuiJin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, People's Republic of China.
Development. 2013 Jul;140(13):2755-64. doi: 10.1242/dev.092825. Epub 2013 May 22.
Multiciliated cells (MCCs) possess multiple motile cilia and are distributed throughout the vertebrate body, performing important physiological functions by regulating fluid movement in the intercellular space. Neither their function during organ development nor the molecular mechanisms underlying multiciliogenesis are well understood. Although dysregulation of members of the miR-34 family plays a key role in the progression of various cancers, the physiological function of miR-34b, especially in regulating organ formation, is largely unknown. Here, we demonstrate that miR-34b expression is enriched in kidney MCCs and the olfactory placode in zebrafish. Inhibiting miR-34b function using morpholino antisense oligonucleotides disrupted kidney proximal tubule convolution and the proper distribution of distal transporting cells and MCCs. Microarray analysis of gene expression, cilia immunostaining and a fluid flow assay revealed that miR-34b is functionally required for the multiciliogenesis of MCCs in the kidney and olfactory placode. We hypothesize that miR-34b regulates kidney morphogenesis by controlling the movement and distribution of kidney MCCs and fluid flow. We found that cmyb was genetically downstream of miR-34b and acted as a key regulator of multiciliogenesis. Elevated expression of cmyb blocked membrane docking of centrioles, whereas loss of cmyb impaired centriole multiplication, both of which resulted in defects in the formation of ciliary bundles. Thus, miR-34b serves as a guardian to maintain the proper level of cmyb expression. In summary, our studies have uncovered an essential role for miR-34b-Cmyb signaling during multiciliogenesis and kidney morphogenesis.
多纤毛细胞 (MCCs) 拥有多个运动纤毛，分布于整个脊椎动物体内，通过调节细胞间空间的液体流动来发挥重要的生理功能。它们在器官发育过程中的功能以及多纤毛发生的分子机制尚不清楚。尽管 miR-34 家族成员的失调在各种癌症的进展中起着关键作用，但 miR-34b 的生理功能，特别是在调节器官形成方面，在很大程度上仍是未知的。在这里，我们证明 miR-34b 在斑马鱼的肾脏 MCCs 和嗅基板中表达丰富。使用形态发生素反义寡核苷酸抑制 miR-34b 的功能会破坏肾脏近端小管卷曲和远端转运细胞和 MCCs 的正确分布。基因表达的微阵列分析、纤毛免疫染色和流体流动测定表明，miR-34b 对于肾脏和嗅基板中的 MCC 多纤毛发生具有功能必要性。我们假设 miR-34b 通过控制肾脏 MCCs 的运动和分布以及流体流动来调节肾脏形态发生。我们发现 cmyb 是 miR-34b 的遗传下游基因，作为多纤毛发生的关键调节因子。cmyb 的高表达阻止了中心粒的膜对接，而 cmyb 的缺失则损害了中心粒的增殖，这两者都会导致纤毛束的形成缺陷。因此，miR-34b 作为守护者来维持 cmyb 表达的适当水平。总之，我们的研究揭示了 miR-34b-Cmyb 信号在多纤毛发生和肾脏形态发生中的重要作用。
