RT Journal Article
SR Electronic
T1 Nanog fluctuations in ES cells highlight the problem of measurement in cell biology
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 060558
DO 10.1101/060558
A1 Rosanna C G Smith
A1 Patrick S Stumpf
A1 Sonya J Ridden
A1 Aaron Sim
A1 Sarah Filippi
A1 Heather Harrington
A1 Ben D MacArthur
YR 2016
UL http://biorxiv.org/content/early/2016/06/27/060558.abstract
AB A number of important pluripotency regulators, including the transcription factor Nanog, are observed to fluctuate stochastically in individual embryonic stem (ES) cells. By transiently priming cells for commitment to different lineages, these fluctuations are thought to be important to the maintenance of, and exit from, pluripotency. However, since temporal changes in intracellular protein abundances cannot be measured directly in live cells, these fluctuations are typically assessed using genetically engineered reporter cell lines that produce a fluorescent signal as a proxy for protein expression. Here, using a combination of mathematical modeling and experiment, we show that there are unforeseen ways in which widely used reporter strategies can systemically disturb the dynamics they are intended to monitor, sometimes giving profoundly misleading results. In the case of Nanog we show how genetic reporters can compromise the behavior of important pluripotency-sustaining positive feedback loops, and induce a bifurcation in the underlying dynamics that gives rise to heterogeneous Nanog expression patterns in reporter cell lines that are not representative of the wild-type. These findings help explain the range of published observations of Nanog variability and highlight a fundamental measurement problem in cell biology.