The role of cytoplasmic nanospaces in smooth muscle cell Ca2+ signalling
We address the importance of cytoplasmic nanospaces in Ca2 + transport and signalling in smooth muscle cells and how quantitative modelling can shed significant light on the understanding of signalling mechanisms. Increasingly more convincing evidence supports the view that these nanospaces—nanometre-scale spaces between organellar membranes, hosting cell signalling machinery—are key to Ca2 + signalling as much as Ca2 + transporters and Ca2 + storing organelles. Our research suggests that the origin of certain diseases is to be sought in the disruption of the proper functioning of cytoplasmic nanospaces. We begin with a historical perspective on the study of smooth muscle cell plasma membrane–sarcoplasmic reticulum nanospaces, including experimental evidence of their role in the generation of asynchronous Ca2 + waves. We then summarize how stochastic modelling approaches have aided and guided our understanding of two basic functional steps leading to healthy smooth muscle cell contraction. We furthermore outline how more sophisticated and realistic quantitative stochastic modelling is now being employed not only to deepen our understanding but also to aid in the hypothesis generation for further experimental investigation.
KeywordsCytoplasmic nanospaces Calcium signalling Vascular smooth muscle Sarcoplasmic reticulum Stochastic computational model Random walk
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