All crawl­ing cells move by first pro­trud­ing a cell front and sub­se­quently retract­ing the cell rear. This sec­tion shows exam­ples of dif­fer­ent cells mov­ing on pla­nar sub­strates.

Video sequences of dif­fer­ent cell types mov­ing in vitro. (Top left) mouse fibrob­lasts mov­ing into an arti­fi­cial wound cre­ated in a petri dish (total video time, 3h). (Bot­tom left) embry­onic chick fibrob­lasts (total video time, 2h). (Top right) mouse melanoma cell (total video time, 20min). (Bot­tom right) trout epi­der­mal ker­a­to­cyte (total video time, 4min). The images were recorded using either phase con­trast optics (chick fibrob­lasts and mouse melanoma cell) or Nomarski inter­fer­ence optics (fish ker­a­to­cyte). The dif­fer­ences in migra­tion speed can be appre­ci­ated from the dif­fer­ent dura­tions of the movie sequences. The rate of motil­ity is highly vari­able with the fish ker­a­to­cyte lead­ing at a speed of around 15µm per minute.

Video sequence of a fish fibrob­last express­ing mCherry-actin (red) and myosin light chain (green). Myosin serves with actin in retrac­tion of the cell body and is mainly excluded from the pro­trud­ing lamel­lipo­dia and filopo­dia. Bar, 10µm.

Rather than reflect­ing dif­fer­ences in the rate of cytoskele­ton turnover, the dif­fer­ent translo­ca­tion speeds stem from dif­fer­ences in the coor­di­na­tion of the sys­tems of motil­ity and anchor­age. In the ker­a­to­cyte, pro­tru­sion and retrac­tion are tightly cou­pled, whereby the body of the ker­a­to­cyte rolls behind the broad lamel­lipodium front.

Another exam­ple of epi­der­mal fish ker­a­to­cytes derived from scales of the alpine trout. Total time for the movie was 3.5 min.

The unique rolling motion of the epi­der­mal ker­a­to­cyte is revealed by plac­ing flu­o­res­cent beads on the sub­strate: as the cell moves it picks up the beads and they are incor­po­rated in the cor­tex of the cell body. Note the move­ment of the two beads in the mid­dle of the ellip­ti­cal cell body. In this video, the cell has been made to “run-on-the-spot” so as to empha­sise the rolling motion. (Ander­son et al., 1996)

Cul­tured HL-60 cells mimic blood neu­trophils dur­ing move­ment towards a chemo-attractant. The movie shows HL-60 cells attracted by a chemo-attractive pep­tide (fMLP) flow­ing from a micro nee­dle. Note the phases of pro­tru­sion at the front and retrac­tion at the rear.

The processes of pro­tru­sion and retrac­tion are both dri­ven by the turnover and reor­gan­i­sa­tion of the actin cytoskele­ton.

Related Pub­li­ca­tions

  • Ander­son, KI., Wang, YL., Small, JV. (1996). Coor­di­na­tion of pro­tru­sion and translo­ca­tion of the ker­a­to­cyte involves rolling of the cell body. J Cell Biol. 134, 12091218. NCBI PubMed

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