Yuan Huifang, Wang Wei, Hu Bin, Pan Changkun, Chen Mingliang, Ke Linlin, Yang Lirong, Chen Jianming
Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, State Oceanic Administration, Xiamen, Fujian Province, China.
School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, China.
PLoS One. 2016 Dec 22;11(12):e0168579. doi: 10.1371/journal.pone.0168579. eCollection 2016.
The paired box 6 (Pax6) gene encodes a transcription factor essential for eye development in a wide range of animal lineages. Here we describe the cloning and characterization of Pax6 gene from the blind hydrothermal vent tubeworm Ridgeia piscesae (RpPax6). The deduced RpPax6 protein shares extensive sequence identity with Pax6 proteins from other species and contains both the paired domain and a complete homeodomain. Phylogenetic analysis indicates that it clusters with the corresponding sequence from the closely related species Platynereis dumerilii (P. dumerilii) of Annelida. Luciferase reporter assay indicate that RpPax6 protein suppresses the transcription of sine oculis (so) in D. melanogaster, interfering with the C-terminal of RpPax6. Taking advantage of Drosophila model, we show that RpPax6 expression is not able to rescue small eye phenotype of ey2 mutant, only to cause a more severe headless phenotype. In addition, RpPax6 expression induced apoptosis and inhibition of apoptosis can partially rescue RpPax6-induced headless phenotype. We provide evidence RpPax6 plays at least two roles: it blocks the expression of later-acting transcription factors in the eye development cascade, and it promotes cell apoptosis. Our results indicate alternation of the Pax6 function may be one of the possible causes that lead the eye absence in vestimentiferan tubeworms.
配对盒6（Pax6）基因编码一种转录因子，在广泛的动物谱系中，该转录因子对眼睛发育至关重要。在此，我们描述了来自盲的热液喷口管虫多毛纲蠕虫（RpPax6）的Pax6基因的克隆与特性分析。推导的RpPax6蛋白与其他物种的Pax6蛋白具有广泛的序列同一性，并且包含配对结构域和完整的同源结构域。系统发育分析表明，它与来自环节动物门近缘物种杜氏阔沙蚕（P. dumerilii）的相应序列聚类。荧光素酶报告基因检测表明，RpPax6蛋白抑制黑腹果蝇中无眼（so）的转录，干扰RpPax6的C末端。利用果蝇模型，我们发现RpPax6的表达无法挽救ey2突变体的小眼表型，反而只会导致更严重的无头表型。此外，RpPax6的表达诱导细胞凋亡，而抑制细胞凋亡可部分挽救RpPax6诱导的无头表型。我们提供的证据表明，RpPax6至少发挥两种作用：它在眼睛发育级联反应中阻断后期作用的转录因子的表达，并促进细胞凋亡。我们的结果表明，Pax6功能的改变可能是导致巨型管虫眼睛缺失的可能原因之一。
