UC San Diego

Regulated differences between cells fundamentally endows multicellular organisms with the huge diversity of complex functions and behaviors we observe in nature. Recent advances in single-cell technology such as droplet-based RNA-Seq are revealing at an unprecedented rate different cellular states and their dynamics. However, not all differences at the gene expression level are necessarily related to cell states. Differences between cells can arise from noisy effects such as transcriptional bursting. Similarly, not all phenotypic variability necessarily arises from systematic differences in gene expression. For example, variability can be explained by post transcriptional regulation and/or intrinsic fluctuations in components of the calcium signaling network. In order to clarify the sources of variability in calcium signaling, we sought to use in situ sequential hybridization smFISH in order to obtain highly accurate single-cell expression counts paired to measurement of a complex phenotype, calcium signaling dynamics, which is an emergent property of gene expression plus post-transcriptional regulation. In this work, we identify an upper bound for how much gene expression variability could arise from allele specific transcriptional bursting, and then investigate how much of calcium signaling variability is explained by gene expression differences related to different cell states.