|
|
|
|
|
|
|
||
Max-Planck-Institut für Biochemie, D-82152 Martinsried, Germany
Myosin II is not essential for cytokinesis in
cells of Dictyostelium discoideum that are anchored on
a substrate (Neujahr, R., C. Heizer, and G. Gerisch.
1997. J. Cell Sci. 110:123-137), in contrast to its importance for cell division in suspension (DeLozanne, A.,
and J.A. Spudich. 1987. Science. 236:1086-1091; Knecht, D.A., and W.F. Loomis. 1987. Science. 236:
1081-1085.). These differences have prompted us to
investigate the three-dimensional distribution of myosin
II in cells dividing under one of three conditions: (a)
in shaken suspension, (b) in a fluid layer on a solid substrate surface, and (c) under mechanical stress applied by compressing the cells. Under the first and second
conditions outlined above, myosin II does not form patterns that suggest a contractile ring is established in the
furrow. Most of the myosin II is concentrated in the regions that flank the furrow on both sides towards the
poles of the dividing cell. It is only when cells are compressed that myosin II extensively accumulates in the
cleavage furrow, as has been previously described
(Fukui, Y., T.J. Lynch, H. Brzeska, and E.D. Korn.
1989. Nature. 341:328-331), i.e., this massive accumulation is a response to the mechanical stress. Evidence is
provided that the stress-associated translocation of myosin II to the cell cortex is a result of the dephosphorylation of its heavy chains. F-actin is localized in the dividing cells in a distinctly different pattern from that of
myosin II. The F-actin is shown to accumulate primarily
in protrusions at the two poles that ultimately form the
leading edges of the daughter cells. This distribution
changes dynamically as visualized in living cells with a
green fluorescent protein-actin fusion.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
