Simple sensing in fibroblasts

Fibroblasts are like the dumb cousins of neutrophils when it comes to gradient sensing. On page 883, Schneider and Haugh show that fibroblasts need stricter instructions and apparently lack the sophisticated signaling loops that are found in neutrophils.

Neutrophils take small differences in chemoattractant levels at the front and back of the cell and amplify them, via GTPase-driven positive feedback loops, into large differences in 3′ phosphoinositide (PI) production that drive the polarization of cytoskeletal changes. Neutrophils also adapt quickly to uniform chemoattractant levels by returning 3′ PI to near basal levels (possibly through global inhibition of 3′ PI production, as seen in Dictyostelium).

PDGF-stimulated fibroblasts, by contrast, do not adapt, prompting the authors to wonder how this sensing mechanism works. The team formulated a mathematical model to describe...