Department of Computer Science, Kroto Research Institute, University of Sheffield, Sheffield S3 7HQ, UK.
J R Soc Interface. 2013 Jul 17;10(86):20130487. doi: 10.1098/rsif.2013.0487. Print 2013 Sep 6.
Calcium signalling plays a central role in regulating a wide variety of cell processes. A number of calcium signalling models exist in the literature that are capable of reproducing a variety of experimentally observed calcium transients. These models have been used to examine in more detail the mechanisms underlying calcium transients, but very rarely has a model been directly linked to a particular cell type and experimentally verified. It is important to show that this can be achieved within the general theoretical framework adopted by these models. Here, we develop a framework designed specifically for modelling cytosolic calcium transients in urothelial cells. Where possible, we draw upon existing calcium signalling models, integrating descriptions of components known to be important in this cell type from a number of studies in the literature. We then add descriptions of several additional pathways that play a specific role in urothelial cell signalling, including an explicit ionic influx term and an active pumping mechanism that drives the cytosolic calcium concentration to a target equilibrium. The resulting one-pool model of endoplasmic reticulum (ER)-dependent calcium signalling relates the cytosolic, extracellular and ER calcium concentrations and can generate a wide range of calcium transients, including spikes, bursts, oscillations and sustained elevations in the cytosolic calcium concentration. Using single-variate robustness and multivariate sensitivity analyses, we quantify how varying each of the parameters of the model leads to changes in key features of the calcium transient, such as initial peak amplitude and the frequency of bursting or spiking, and in the transitions between bursting- and plateau-dominated modes. We also show that, novel to our urothelial cell model, the ionic and purinergic P2Y pathways make distinct contributions to the calcium transient. We then validate the model using human bladder epithelial cells grown in monolayer cell culture and show that the model robustly captures the key features of the experimental data in a way that is not possible using more generic calcium models from the literature.
钙信号在调节多种细胞过程中起着核心作用。文献中存在许多能够再现各种实验观测到的钙瞬变的钙信号模型。这些模型被用于更详细地研究钙瞬变的机制,但很少有模型直接与特定的细胞类型相关联并经过实验验证。重要的是要表明,这可以在这些模型采用的一般理论框架内实现。在这里,我们开发了一个专门用于模拟尿路上皮细胞胞质钙瞬变的框架。在可能的情况下,我们借鉴了现有的钙信号模型,整合了文献中多项研究中确定的对该细胞类型重要的组件描述。然后,我们添加了几个额外的通路的描述,这些通路在尿路上皮细胞信号传导中起着特定的作用,包括一个明确的离子流入项和一个主动泵送机制,该机制将胞质钙离子浓度驱动到目标平衡。由此产生的依赖内质网 (ER) 的钙信号的单池模型将胞质、细胞外和 ER 钙浓度联系起来,并可以产生广泛的钙瞬变,包括尖峰、爆发、振荡和胞质钙离子浓度的持续升高。通过单变量稳健性和多变量敏感性分析,我们量化了模型中每个参数的变化如何导致钙瞬变的关键特征发生变化,例如初始峰值幅度和爆发或尖峰的频率,以及爆发主导模式和平台主导模式之间的转变。我们还表明,我们的尿路上皮细胞模型中,离子和嘌呤能 P2Y 通路对钙瞬变有独特的贡献。然后,我们使用单层细胞培养中生长的人膀胱上皮细胞对模型进行验证,并表明模型以文献中更通用的钙模型不可能的方式稳健地捕捉实验数据的关键特征。