Manojlovic Zarko, Earwood Ryan, Kato Akiko, Perez Diana, Cabrera Oscar A, Didier Ruth, Megraw Timothy L, Stefanovic Branko, Kato Yoichi
Department of Biomedical Sciences, Florida State University College of Medicine, 1115W. Call Street, Tallahassee, FL 32306-4300 USA.
Department of Translational Genomics, Keck School of Medicine of University of Southern California, Los Angeles, CA 90089-9601 USA.
Cilia. 2017 Mar 23;6:4. doi: 10.1186/s13630-017-0047-7. eCollection 2017.
La-related protein 6 (LARP6) is an evolutionally conserved RNA-binding protein. Vertebrate LARP6 binds the 5' stem-loop found in mRNAs encoding type I collagen to regulate their translation, but other target mRNAs and additional functions for LARP6 are unknown. The aim of this study was to elucidate an additional function of LARP6 and to evaluate the importance of its function during development.
To uncover the role of LARP6 in development, we utilized Morpholino Oligos to deplete LARP6 protein in embryos. Then, embryonic phenotypes and ciliary structures of LAPR6 morphants were examined. To identify the molecular mechanism underlying ciliogenesis regulated by LARP6, we tested the expression level of cilia-related genes, which play important roles in ciliogenesis, by RT-PCR or whole mount in situ hybridization (WISH).
We knocked down LARP6 in embryos and found neural tube closure defects. LARP6 mutant, which compromises the collagen synthesis, could rescue these defects. Neural tube closure defects are coincident with lack of cilia, antenna-like cellular organelles with motility- or sensory-related functions, in the neural tube. The absence of cilia at the epidermis was also observed in LARP6 morphants, and this defect was due to the absence of basal bodies which are formed from centrioles and required for ciliary assembly. In the process of multi-ciliated cell (MCC) differentiation, mcidas, which activates the transcription of genes required for centriole formation during ciliogenesis, could partially restore MCCs in LARP6 morphants. In addition, LARP6 likely controls the expression of in a Notch-independent manner.
La-related protein 6 is involved in ciliated cell differentiation during development by controlling the expression of cilia-related genes including . This LARP6 function involves a mechanism that is distinct from its established role in binding to collagen mRNAs and regulating their translation.
La相关蛋白6（LARP6）是一种进化上保守的RNA结合蛋白。脊椎动物LARP6与编码I型胶原蛋白的mRNA中发现的5'茎环结合，以调节其翻译，但LARP6的其他靶mRNA和额外功能尚不清楚。本研究的目的是阐明LARP6的额外功能，并评估其功能在发育过程中的重要性。
为了揭示LARP6在发育中的作用，我们利用吗啉代寡核苷酸在胚胎中耗尽LARP6蛋白。然后，检查了LAPR6 morphants的胚胎表型和纤毛结构。为了确定LARP6调节纤毛发生的分子机制，我们通过RT-PCR或全胚胎原位杂交（WISH）检测了在纤毛发生中起重要作用的纤毛相关基因的表达水平。
我们在胚胎中敲低了LARP6，发现神经管闭合缺陷。损害胶原蛋白合成的LARP6突变体可以挽救这些缺陷。神经管闭合缺陷与神经管中缺乏纤毛有关，纤毛是具有运动或感觉相关功能的触角状细胞器。在LARP6 morphants中也观察到表皮处缺乏纤毛，这种缺陷是由于缺乏由中心粒形成并用于纤毛组装的基体。在多纤毛细胞（MCC）分化过程中，激活纤毛发生过程中中心粒形成所需基因转录的mcidas可以部分恢复LARP6 morphants中的MCC。此外，LARP6可能以不依赖Notch的方式控制的表达。
La相关蛋白6通过控制包括在内的纤毛相关基因的表达，参与发育过程中的纤毛细胞分化。这种LARP6功能涉及一种与其在结合胶原蛋白mRNA并调节其翻译方面已确立的作用不同的机制。
