title: In chemotaxing fibroblasts, both high-fidelity and weakly biased cell movements track the localization of PI3K signaling.
abstract: Cell movement biased by a chemical gradient, or chemotaxis, coordinates the recruitment of cells and collective migration of cell populations. During wound healing, chemotaxis of fibroblasts is stimulated by platelet-derived growth factor (PDGF) and certain other chemoattractants. Whereas the immediate PDGF gradient sensing response has been characterized previously at the level of phosphoinositide 3-kinase (PI3K) signaling, the sensitivity of the response at the level of cell migration bias has not yet been studied quantitatively. In this work, we used live-cell total internal reflection fluorescence microscopy to monitor PI3K signaling dynamics and cell movements for extended periods. We show that persistent and properly aligned (i.e., high-fidelity) fibroblast migration does indeed correlate with polarized PI3K signaling; accordingly, this behavior is seen only under conditions of high gradient steepness (>10% across a typical cell length of 50 μm) and a certain range of PDGF concentrations. Under suboptimal conditions, cells execute a random or biased random walk, but nonetheless move in a predictable fashion according to the changing pattern of PI3K signaling. Inhibition of PI3K during chemotaxis is accompanied by loss of both cell-substratum contact and morphological polarity, but after a recovery period, PI3K-inhibited fibroblasts often regain the ability to orient toward the PDGF gradient.
authors.affiliation: Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA.
authors.forename: Adam T
authors.initials: AT
authors.lastname: Melvin
authors.forename: Erik S
authors.initials: ES
authors.lastname: Welf
authors.forename: Yana
authors.initials: Y
authors.lastname: Wang
authors.forename: Darrell J
authors.initials: DJ
authors.lastname: Irvine
authors.forename: Jason M
authors.initials: JM
authors.lastname: Haugh
mesh_terms: D000464:Alginates / Q000737:chemistry; D000818:Animals; D022081:Cell Surface Extensions / Q000187:drug effects / Q000378:metabolism; D002633:Chemotaxis / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D051379:Mice; D008863:Microspheres; D041681:NIH 3T3 Cells; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000737:chemistry / Q000494:pharmacology; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013269:Stochastic Processes
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D010982:Platelet-Derived Growth Factor; D020723:Glucuronic Acid; D019869:Phosphatidylinositol 3-Kinases; D017479:Receptors, Platelet-Derived Growth Factor