System dynamics of subcellular transport.
In pharmacokinetic experiments, interpretations often hinge on treating cells as a "black box": a single, lumped compartment or boundary. Here, a combinatorial library of fluorescent small molecules was used to visualize subcellular transport pathways in living cells, using a kinetic, high content imaging system to monitor spatiotemporal variations of intracellular probe distribution. Most probes accumulate in cytoplasmic vesicles and probe kinetics conform to a nested, two-compartment dynamical system. At steady state, probes preferentially partition from the extracellular medium to the cytosol, and from the cytosol to cytoplasmic vesicles, with hydrophobic molecules favoring sequestration. Altogether, these results point to a general organizing principle underlying the system dynamics of subcellular, small molecule transport. In addition to plasma membrane permeability, subcellular transport phenomena can determine the active concentration of small molecules in the cytosol and the efflux of small molecules from cells. Fundamentally, direct observation of intracellular probe distribution challenges the simple boundary model of classical pharmacokinetics, which considers cells as static permeability barriers.
Chen
Vivien Y
VY
Department of Pharmaceutical Sciences, University of Michigan College of Pharmacy, Ann Arbor, Michigan 48109, USA.
Khersonsky
Sonya M
SM
Shedden
Kerby
K
Chang
Young Tae
YT
Rosania
Gus R
GR
D009327:4-Chloro-7-nitrobenzofurazan / Q000138:chemical synthesis / Q000737:chemistry; D001692:Biological Transport; D022162:Cytoplasmic Vesicles / Q000187:drug effects; D003600:Cytosol / Q000187:drug effects; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry / Q000493:pharmacokinetics*; D006367:HeLa Cells; D006801:Humans; D015233:Models, Statistical; D015394:Molecular Structure; D014227:Triazines / Q000138:chemical synthesis / Q000737:chemistry / Q000493:pharmacokinetics*
D005456:Fluorescent Dyes; D014227:Triazines; D009327:4-Chloro-7-nitrobenzofurazan