@article{10.1371/journal.pcbi.1001040, doi = {10.1371/journal.pcbi.1001040}, author = {Jovic, Andreja AND Howell, Bryan AND Cote, Michelle AND Wade, Susan M. AND Mehta, Khamir AND Miyawaki, Atsushi AND Neubig, Richard R. AND Linderman, Jennifer J. AND Takayama, Shuichi}, journal = {PLOS Computational Biology}, publisher = {Public Library of Science}, title = {Phase-Locked Signals Elucidate Circuit Architecture of an Oscillatory Pathway}, year = {2010}, month = {12}, volume = {6}, url = {https://doi.org/10.1371/journal.pcbi.1001040}, pages = {1-8}, abstract = {This paper introduces the concept of phase-locking analysis of oscillatory cellular signaling systems to elucidate biochemical circuit architecture. Phase-locking is a physical phenomenon that refers to a response mode in which system output is synchronized to a periodic stimulus; in some instances, the number of responses can be fewer than the number of inputs, indicative of skipped beats. While the observation of phase-locking alone is largely independent of detailed mechanism, we find that the properties of phase-locking are useful for discriminating circuit architectures because they reflect not only the activation but also the recovery characteristics of biochemical circuits. Here, this principle is demonstrated for analysis of a G-protein coupled receptor system, the M3 muscarinic receptor-calcium signaling pathway, using microfluidic-mediated periodic chemical stimulation of the M3 receptor with carbachol and real-time imaging of resulting calcium transients. Using this approach we uncovered the potential importance of basal IP3 production, a finding that has important implications on calcium response fidelity to periodic stimulation. Based upon our analysis, we also negated the notion that the Gq-PLC interaction is switch-like, which has a strong influence upon how extracellular signals are filtered and interpreted downstream. Phase-locking analysis is a new and useful tool for model revision and mechanism elucidation; the method complements conventional genetic and chemical tools for analysis of cellular signaling circuitry and should be broadly applicable to other oscillatory pathways.}, number = {12}, }