In bloodhounds and neutrophils, getting the scent is not enough. Dogs and immune cells have to remember the chemoattractant they are pursuing, even when it momentarily fades out or threatens to overwhelm. On the cellular scale, the process of following a signal toward or away from its source is called chemotaxis. While we've learned a great deal about how cells orient themselves on a chemotactic grade, the precise quantitative and molecular details of how they remember where they are going have been fuzzy.
Marshaling a diverse team of collaborators from University College London, Harvard University, and Florida State University, researchers Harrison V. Prentice-Mott and ASCB member Jagesh V. Shah in Systems Biology at Harvard Medical School report in a new PNAS paper that they have identified key elements of the basic mechanism in "directional memory."
By precisely controlling attractant concentrations flowing to chemotactic neutrophil-like cells in a 1D microfluidic channel, the researchers can now say that moesin, an ERM-family protein, working with other polarized cytoskeletal structures including actomyosin and microtubules themselves are the molecular basis for longer-lived directional memory. This mechanism, say Prentice-Mott et al., allows neutrophils and other chemotactic cells to keep their bearings in low signal or even uniform environments while still being able to respond to short-term cycles.
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