Division of Translational Cancer Research and Therapy, State Key Laboratory of Molecular Oncology, Cancer Hospital and Institute, Chinese Academy of Medical Sciences, Beijing 100021, China.
Eur J Cell Biol. 2010 Jun;89(6):428-36. doi: 10.1016/j.ejcb.2010.01.002. Epub 2010 Mar 9.
The Bicaudal-C (Bic-C) gene was originally discovered in Drosophila melanogaster. The gene product Bic-C is thought to serve as an RNA-binding molecule targeting diverse proteins at the post-transcriptional level. Recent research has shown this gene to be conserved in many species, from Caenorhabditis elegans to humans. Disruption of this protein can disturb the normal migration direction of the anterior follicle cell of Drosophila oocytes, while mutation of a mouse Bicc1 (a mouse homologue of Bic-C) results in phenotypes mimicking human hereditary polycystic kidney disease (PKD). However, the cellular function of Bicc1 gene products in mammalian systems remains largely unknown. In this study, we established stable IMCD (mouse inner medullary collecting duct) cell lines, in which Bicc1 was silenced by short hairpin RNA inhibition (shRNA). We show that inhibition of Bicc1 disrupted normal tubulomorphogenesis and induced cystogenesis of IMCD cells grown in three dimensional cultures. To determine what factors contributed to the defect, we systematically examined biological changes of Bicc1-silenced IMCD cells. We found that the cells had significant defects in E-cadherin-based cell-cell adhesion, along with abnormalities in actin cytoskeleton organization, cell-extracellular matrix interactions, cell proliferation, and apoptosis. These findings suggest that lack of Bicc1 leads to disruption of normal cell-cell junctions, which in turn impedes establishment of epithelial polarity. These cellular defects may initiate abnormal tubulomorphogenesis and cystogenesis of IMCD cells grown in vitro. The observation of aberrant cellular behaviors in Bicc1-silenced IMCD cells reveal functions for Bicc1 in renal epithelial cells and provides insight into a potential pathogenic mechanism of polycystic kidney disease.
Bicaudal-C (Bic-C) 基因最初在果蝇中发现。该基因产物 Bic-C 被认为是一种 RNA 结合分子，可靶向转录后水平的多种蛋白质。最近的研究表明，该基因在许多物种中都具有保守性，从秀丽隐杆线虫到人类。该蛋白的破坏会干扰果蝇卵母细胞前滤泡细胞的正常迁移方向，而小鼠 Bicc1（Bic-C 的小鼠同源物）的突变会导致类似于人类遗传性多囊肾病 (PKD) 的表型。然而，哺乳动物系统中 Bicc1 基因产物的细胞功能在很大程度上仍然未知。在这项研究中，我们建立了稳定的 IMCD（小鼠内髓集合管）细胞系，其中 Bicc1 通过短发夹 RNA 抑制 (shRNA) 沉默。我们表明，Bicc1 的抑制破坏了 IMCD 细胞在三维培养物中的正常管状形态发生并诱导了囊肿形成。为了确定哪些因素导致了缺陷，我们系统地检查了 Bicc1 沉默的 IMCD 细胞的生物学变化。我们发现，这些细胞在 E-钙粘蛋白为基础的细胞-细胞黏附中存在显著缺陷，同时细胞骨架组织、细胞-细胞外基质相互作用、细胞增殖和细胞凋亡也存在异常。这些发现表明，Bicc1 的缺乏导致正常细胞-细胞连接的破坏，进而阻碍上皮极性的建立。这些细胞缺陷可能引发 IMCD 细胞在体外的异常管状形态发生和囊肿形成。在 Bicc1 沉默的 IMCD 细胞中观察到异常的细胞行为，揭示了 Bicc1 在肾上皮细胞中的功能，并为多囊肾病的潜在致病机制提供了深入了解。
