Variability in G-protein-coupled signaling studied with microfluidic devices.
Different cells, even those that are genetically identical, can respond differently to identical stimuli, but the precise source of this variability remains obscure. To study this problem, we built a microfluidic experimental system which can track responses of individual cells across multiple stimulations. We used this system to determine that amplitude variation in G-protein-activated calcium release in RAW264.7 macrophages is generally extrinsic, i.e., they arise from long-lived variations between cells and not from stochastic activation of signaling components. In the case of responses linked to P2Y family purine receptors, we estimate that approximately one-third of the observed variability in calcium release is receptor-specific. We further demonstrate that the signaling apparatus downstream of P2Y6 receptor activation is moderately saturable. These observations will be useful in constructing and constraining single-cell models of G protein-coupled calcium dynamics.
Department of Applied Physics, California Institute of Technology, Pasadena, USA. bao@chgr.mgh.harvard.edu
Xiaoyan Robert
XR
Bao
Iain D C
ID
Fraser
Estelle A
EA
Wall
Stephen R
SR
Quake
Melvin I
MI
Simon
D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects; D018929:Cell Culture Techniques; D002460:Cell Line; D003584:Cytological Techniques / Q000295:instrumentation*; D007267:Injections; D007700:Kinetics; D008264:Macrophages / Q000166:cytology / Q000378:metabolism; D051379:Mice; D046210:Microfluidic Analytical Techniques; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D014530:Uridine Diphosphate / Q000494:pharmacology
D043562:Receptors, G-Protein-Coupled; D014530:Uridine Diphosphate