Primary cilia dynamics in pancreatic duct network development

胰腺囊肿在纤毛病的一个子集中已有报道，但对胰腺中初级纤毛的功能知之甚少，特别是在胎儿中，当囊性表型开始时。在发育过程中，外分泌和内分泌细胞的纤毛祖细胞形成胰管网的壁。这个网络从一个网格重新构建为一个树，优化了流体传输，大概是为了响应流动。通过与其他系统的类比，我们假设，在祖细胞和纤毛流动传感的初级纤毛在发育过程中的胰管的形态发生中起着至关重要的作用。利用胰腺发育（Grapin-Botton）和生物流体力学和信号传导（Friedrich）的数学建模的互补专业知识，我们建议使用胰腺作为一个新的模型来了解初级纤毛动力学在跨时间尺度的管状网络形成中的作用。在（分）秒的时间尺度上，我们将测试纤毛是否是胰管中的流量传感器，并根据定量输入-输出关系来表征纤毛流量传感，该定量输入-输出关系将稳定和振荡的外部流体流量的大小与动态纤毛信号联系起来，主要关注钙。我们进一步假设，流量可能会导致纤毛蛋白质组的变化，观察到的化学信号，但迄今尚未探索的流量传感。为了获得对胰腺祖细胞中纤毛蛋白质组和刺激后纤毛内蛋白质组成变化的机制见解，我们将使用NPHP 3作为诱饵使用邻近标记。在几天的时间尺度上，我们将系统地研究纤毛细胞的比例，它们的长度和方向，并将这些形态学数据映射到细胞化的导管网络结构上。这将使我们能够确定纤毛的存在和长度是否随发育时间、导管直径和在胰腺导管网络中的位置而变化。最后，我们将在（亚）秒尺度上将胰腺中纤毛机械感测的见解与胚胎发育期间胰腺导管网络重塑的生理相关过程联系起来，这需要几天的时间。为了做到这一点，我们将监测体内的流动，并将其施加在灌注的胰腺类器官中，研究它是否会引发重塑。两者合计，我们的工作将提供机械的见解，通过初级纤毛在胰腺的机械传感。此外，我们的研究结果将奠定基础，以解开受损的胰腺纤毛信号在纤毛病变的影响。

Pancreatic cysts have been reported in a subset of ciliopathies, but the function of primary cilia in the pancreas is poorly understood, particularly in the fetus, when the cystic phenotypes are initiated. During development, ciliated progenitors of the exocrine and endocrine cells form the walls of the pancreatic duct network. This network remodels from a mesh to a tree optimized for fluid transport, presumably in response to flow. By analogy with other systems, we hypothesize that the primary cilia on the progenitors and cilia flow sensing play an essential role in the morphogenesis of the pancreatic ducts during development. Using complementary expertise in pancreas development (Grapin-Botton) and mathematical modeling of biological hydrodynamics and signaling (Friedrich), we propose to use the pancreas as a new model to understand the role of primary cilia dynamics in tubular network formation across time-scales. At the (sub)second time scale, we will test whether cilia are flow sensors in pancreatic ducts and characterize cilia flow sensing in terms of a quantitative input-output relationships that link the magnitudes of both steady and oscillatory external fluid flow to dynamic cilia signaling, focusing primarily on calcium. We further hypothesize that flow may lead to changes in the cilia proteome, as observed for chemical signaling but so far unexplored for flow sensing. To gain mechanistic insights into the cilia proteome in pancreatic progenitors and changes in the intracilliary protein composition upon stimulation, we will use proximity labelling using NPHP3 as a bait. At the time scale of days, we will systematically investigate the proportion of cells with cilia, their length and orientation and map this morphometric data on skeletonized ductal network structures. This will enable us to establish whether cilia presence and length change with developmental time, duct diameter, and position in the pancreas duct network. Finally, we will connect the insight on ciliary mechanical sensing in the pancreas at the (sub)second scale to the physiologically relevant process of pancreas duct network remodeling during embryonic development, which takes place over days. To do so, we will monitor the flow in vivo and impose it in perfused pancreas organoids, investigating whether it triggers remodeling. Taken together, our work will offer mechanistic insights into mechanical sensing by primary cilia in the pancreas. In addition, our results will lay the foundation to unravel the implications of impaired pancreatic cilia signaling in ciliopathies.