Distinct cellular states determine calcium signaling response

Abstract

The heterogeneity in mammalian cells signaling response is largely a result of pre‐existing cell‐to‐cell variability. It is unknown whether cell‐to‐cell variability rises from biochemical stochastic fluctuations or distinct cellular states. Here, we utilize calcium response to adenosine trisphosphate as a model for investigating the structure of heterogeneity within a population of cells and analyze whether distinct cellular response states coexist. We use a functional definition of cellular state that is based on a mechanistic dynamical systems model of calcium signaling. Using Bayesian parameter inference, we obtain high confidence parameter value distributions for several hundred cells, each fitted individually. Clustering the inferred parameter distributions revealed three major distinct cellular states within the population. The existence of distinct cellular states raises the possibility that the observed variability in response is a result of structured heterogeneity between cells. The inferred parameter distribution predicts, and experiments confirm that variability in IP 3R response explains the majority of calcium heterogeneity. Our work shows how mechanistic models and single‐cell parameter fitting can uncover hidden population structure and demonstrate the need for parameter inference at the single‐cell level. image Single‐cell measurements of calcium responses to ATP , in combination with analyses of the full distribution of kinetic parameters, reveal the existence of three major distinct cellular states within the population. Calcium signaling response to ATP is used as a model to analyze whether distinct cellular response states coexist. Single‐cell parameter fitting of a differential equations model of calcium response to ATP identifies a unique kinetic signature for each single cell. Cells can be classified into three distinct cell states. Each of the three states has a distinct feedback motif that connects calcium concentration to IP 3R activity.