Biomedical Engineering Reference
In-Depth Information
Figure 2.1.
Keratocyte cells and lamellipodial fragments exhibit similar persistent
motility. (a-c) Time-lapse phase contrast image sequence of a keratocyte cell and a
lamellipodial fragment. (d) The cell outlines from the images were overlaid on top
of each other. Image sequence courtesy of Greg Allen.
merize [30, 36, 37, 38]. The precise balance between protrusion at the leading
edge and inward contraction at the rear enables smooth continuous movement
of the cells such that they appear to glide forward without changing shape
[39, 40, 41].
Although individual cells in a keratocyte population may move over a
broad range of net speeds [43] and take on variable shapes [24, 43, 44], the
processes contributing to motility are precisely balanced within each cell such
that fast-moving cells and slow-moving cells are both able to maintain persis-
tent shape and behavior. In this chapter, we describe progress toward under-
standing the mechanisms of this large-scale coordination, using the geomet-
rically simple, rapidly moving keratocytes as a model system. We emphasize
the role of mechanical processes and their interplay with biochemical pro-
cesses in this coordination. For example, global biophysical parameters such
as the membrane tension and traction forces introduce effective coupling be-
tween biochemical processes occurring at different regions within the cell. We
