Bbs8, together with the planar cell polarity protein Vangl2, is required to establish left-right asymmetry in zebrafish

Laterality defects such as situs inversus are not uncommonly encountered in humans, either in isolation or as part of another syndrome, but can have devastating developmental consequences. The events that break symmetry during early embryogenesis are highly conserved amongst vertebrates and involve the establishment of unidirectional flow by cilia within an organising centre such as the node in mammals or Kupffer's vesicle (KV) in teleosts. Disruption of this flow can lead to the failure to successfully establish left-right asymmetry. The correct apical-posterior cellular position of each node/KV cilium is critical for its optimal radial movement which serves to sweep fluid (and morphogens) in the same direction as its neighbours. Planar cell polarity (PCP) is an important conserved process that governs ciliary position and posterior tilt; however the underlying mechanism by which this occurs remains unclear. Here we show that Bbs8, a ciliary/basal body protein important for intraciliary/flagellar transport and the core PCP protein Vangl2 interact and are required for establishment and maintenance of left-right asymmetry during early embryogenesis in zebrafish. We discovered that loss of bbs8 and vangl2 results in laterality defects due to cilia disruption at the KV. We showed that perturbation of cell polarity following abrogation of vangl2 causes nuclear mislocalisation, implying defective centrosome/basal body migration and apical docking. Moreover, upon loss of bbs8 and vangl2, we observed defective actin organisation. These data suggest that bbs8 and vangl2 act synergistically on cell polarization to establish and maintain the appropriate length and number of cilia in the KV and thereby facilitate correct LR asymmetry.     

Evidence for an early role for BMP4 signaling in thymus and parathyroid morphogenesis

The thymus and parathyroids are pharyngeal endoderm-derived organs that develop from common organ primordia, which undergo a series of morphological events resulting in separate organs in distinct locations in the embryo. Previous gene expression and functional analyses have suggested a role for BMP4 signaling in early thymus organogenesis. We have used conditional deletion of Bmp4 or Alk3 from the pharyngeal endoderm and/or the surrounding mesenchyme using Foxg1-Cre, Wnt1-Cre or Foxn1-Cre. Deleting Bmp4 from both neural crest cells (NCC) and early endoderm-derived epithelial cells in Foxg1-Cre;Bmp4 conditional mutants resulted in defects in thymus-parathyroid morphogenesis. Defects included reduced condensation of mesenchymal cells around the epithelium, partial absence of the thymic capsule, a delay in thymus and parathyroid separation, and failed or dramatically reduced organ migration. Patterning of the primordia and initial organ differentiation were not affected in any of the mutants. Deleting Bmp4 from NCC-derived mesenchyme or differentiating thymic epithelial cells (TECs) had no effects on thymus-parathyroid development, while loss of Alk3 from either neural crest cells or TECs resulted in only a mild thymic hypoplasia. these results show that the processes of cell specification and morphogenesis during thymus-parathyroid development are independently controlled, and suggest a specific temporal and spatial role for BMP4-mediated epithelial-mesenchymal interactions during early thymus and parathyroid morphogenesis.     

两种Wnt 通路抑制剂对牙周膜干细胞作用的比较研究

目的:本实验主要探讨Wnt通路抑制剂XAV-939相比DKK1在牙周膜干细胞增殖及矿化中的作用差异。方法:酶消化法培养牙周膜干细胞,鉴定后,用CCK8试剂盒检测XAV-939和DKK1对牙周膜干细胞增殖能力的影响,茜素红染色及定量检测XAV-939和DKK1对牙周膜干细胞成骨分化能力的影响,q RT-PCR检测DKK1和XAV-939对牙周膜干细胞Wnt通路相关基因GSK-3β和β-catenin及成骨分化相关基因ALP,DSPP,BSP,OCN,RUNX-2的影响。结果:XAV-939和DKK1都可以通过抑制Wnt通路来抑制牙周膜干细胞的增殖及成骨分化。当没有外源性Wnt蛋白刺激时,XAV-939作为Wnt通路抑制剂的抑制作用要强于DKK1,而加入外源性Wnt蛋白后,XAV-939与DKK1的作用效果相当。结论:XAV-939对比DKK1,具有更为广泛而稳定的抑制效果。XAV-939可以作为高效的Wnt通路抑制剂应用于未来关于牙周膜干细胞和Wnt通路相关实验研究中。     

Wnt与MAPK信号通路在肿瘤发生中的串话

Wnt和MAPK信号通路在生物进化过程中高度保守,参与调控胚胎发育和细胞增殖、分化及凋亡等。Wnt和MAPK信号通路调控失常可导致胚胎发育异常和肿瘤形成。近年来发现这两条信号通路在肿瘤发生发展中存在着大量串话（crosstalk）,彼此之间相互调节,共同发挥促癌或抑癌作用,因此,更好地了解两条通路是如何在肿瘤形成中发生交叉对话对于将来肿瘤治疗非常有价值。     

A Protein Disulfide Isomerase Controls Neuronal Migration through Regulation of Wnt Secretion

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Wnt信号通路与皮肤创面愈合的关系

创面愈合是由炎性细胞、细胞因子等多种因素共同参与,涉及组织修复、再生、重建的一个复杂有序的病理生理过程。皮肤慢性创面的愈合仍然是临床研究的重点与热点,随着分子生物学的发展,对皮肤创面愈合机制的认识也逐渐深入。Wnt信号通路是一条由Wnt蛋白及其受体、调节蛋白等组成的高度保守的信号通路,参与细胞增殖、凋亡、分化等多种生物学过程。Wnt信号通路作为参与皮肤愈合的信号通路之一,被认为具有调控皮肤及其附属器的发育、诱导皮肤附件的形态发生、调节毛囊的周期生长、促进创面血管新生及上皮重塑等多方面的功能。因此本文试从炎性细胞、成纤维细胞、干细胞、血管新生、表皮新生与毛囊新生等方面对Wnt信号通路与皮肤创面愈合的关系作一综述。     

FrzA基因转导干预缺血性心力衰竭小鼠心肌Wnt信号通路的研究

目的:研究重组9型腺相关病毒(recombinant adeno-associated virus serotype 9,rAAV9)携带FrzA基因转导干预缺血性心衰小鼠心肌Wnt信号通路的可行性,为基因治疗心力衰竭提供新的思路.方法:选择3月龄雄性C57BL/6J小鼠共130只,随机分为空白组(n=10),心衰组(n=40),心衰+空病毒(rAAV9-GFP)注射组(n=40),心衰+rAAV9-FrzA组(n=40),采用结扎左冠状动脉定量控制心梗面积,于术后2周行心脏超声评各组心功能变化,再经尾静脉注射已稀释好的病毒,28d后处死小鼠取心脏标本,RT-PCR检测心肌目的基因FrzA以及Dvl-1,β-catenin的表达;Western blot检测心肌Wnt信号通路关键分子Dvl-1,GSK3β,p-GSK3β,β-catenin的表达.结果:与空白组相比,成功建立心衰模型后小鼠心功能均不同程度降低(P＜0.05);FrzA组与心衰组相比,心功能明显改善(P＜0.05);经尾静脉注射可成功将rAAV9-FrzA导入小鼠体内,并且目的基因FrzA在心肌组织中高表达(P＜0.05);心衰小鼠心肌中Wnt信号通路关键分子Dvl-1,p-GSK3β,β-catenin的表达显著升高(P＜0.05),FrzA转导后小鼠心肌中Wnt信号通路中关键分子Dvl-1,p-GSK3β,β-catenin表达均降低(P＜0.05)结论:利用rAAV9-FrzA转导缺血性心衰小鼠可以有效的干预心肌Wnt信号通路,抑制其活性,为基因治疗缺血性心衰提供了新的思路.