论文标题

鞭毛长度控制真核生物:飞行时间,共享游泳池,火车交通和合作现象

Flagellar length control in biflagellate eukaryotes: time-of-flight, shared pool, train traffic and cooperative phenomena

论文作者

Patra, Swayamshree, Jülicher, Frank, Chowdhury, Debashish

论文摘要

真核细胞的鞭毛是短暂的长圆柱突起。形成和维持鞭毛所需的蛋白质在细胞体中合成并运输到远端尖端。 “统治者”或“计时器”是一种特定类型的单元,用于在材料的向外和内部运输之间取得平衡,以维持其在稳态状态下的特定长度,这是细胞自组织中的开放问题之一。更加奇怪的是,biflagellates的两个鞭毛(例如Chlamydomonas renhardtii)如何通过其基础进行交流以协调其长度。在本文中,我们开发了一个基于飞行时间(TOF)机制的鞭毛长度控制的随机模型。这种TOF机制决定是否将结构蛋白加载到flagellar的运输(IFT)火车上,然后才开始其从底座到鞭毛尖端的机动旅行。由于持续的营业额,从鞭毛尖端释放的结构蛋白也通过IFT火车运回细胞体。我们将IFT火车的流量表示为完全不对称的简单排除过程(TASEP)。每个鞭毛的TOF机制,以及基于TASEP的IFT列车的描述,结合了双鞭毛蛋白酶中常见的鞭毛结构蛋白的共享场景,可以说明实验已知现象的所有关键特征。这些包括纤毛生成,吸收,缩水和再生两种鞭毛之一后。我们还表明,如果考虑到TASEP捕获的IFT列车的相互排除的影响,Ishikawa和Marshall的实验观察结果与长度控制的TOF机制是一致的。此外,我们对鞭毛长度波动和公共池的作用做出了新的预测。

Flagella of eukaryotic cells are transient long cylindrical protrusions. The proteins needed to form and maintain flagella are synthesized in the cell body and transported to the distal tips. What `rulers' or `timers' a specific type of cells use to strike a balance between the outward and inward transport of materials so as to maintain a particular length of its flagella in the steady state is one of the open questions in cellular self-organization. Even more curious is how the two flagella of biflagellates, like Chlamydomonas Reinhardtii, communicate through their base to coordinate their lengths. In this paper we develop a stochastic model for flagellar length control based on a time-of-flight (ToF) mechanism. This ToF mechanism decides whether or not structural proteins are to be loaded onto an intraflagellar transport (IFT) train just before it begins its motorized journey from the base to the tip of the flagellum. Because of the ongoing turnover, the structural proteins released from the flagellar tip are transported back to the cell body also by IFT trains. We represent the traffic of IFT trains as a totally asymmetric simple exclusion process (TASEP). The ToF mechanism for each flagellum, together with the TASEP-based description of the IFT trains, combined with a scenario of sharing of a common pool of flagellar structural proteins in biflagellates, can account for all key features of experimentally known phenomena. These include ciliogenesis, resorption, deflagellation as well as regeneration after selective amputation of one of the two flagella. We also show that the experimental observations of Ishikawa and Marshall are consistent with the ToF mechanism of length control if the effects of the mutual exclusion of the IFT trains captured by the TASEP are taken into account. Moreover, we make new predictions on the flagellar length fluctuations and the role of the common pool.

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