Polo-Like Kinase 1 Directs Assembly of the HsCyk-4 RhoGAP/Ect2 RhoGEF Complex to Initiate Cleavage Furrow Formation

We have cloned a full-length cDNA encoding a novel myosin II heavy chain kinase (mhckC) from Dictyostelium. Like other members of the myosin heavy chain kinase family, themhckC gene product, MHCK C, has a kinase domain in its N-terminal half and six WD repeats in the C-terminal half. GFP-MHCK C fusion protein localized to the cortex of interphase cells, to the cleavage furrow of mitotic cells, and to the posterior of migrating cells. These distributions of GFP-MHCK C always corresponded with that of myosin II filaments and were not observed in myosin II-null cells, where GFP-MHCK C was diffusely distributed in the cytoplasm. Thus, localization of MHCK C seems to be myosin II-dependent. Cells lacking the mhckC gene exhibited excessive aggregation of myosin II filaments in the cleavage furrows and in the posteriors of the daughter cells once cleavage was complete. The cleavage process of these cells took longer than that of wild-type cells. Taken together, these findings suggest MHCK C drives the disassembly of myosin II filaments for efficient cytokinesis and recycling of myosin II that occurs during cytokinesis.

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PtdIns(4,5)P2 Functions at the Cleavage Furrow during Cytokinesis

Current Biology ◽

10.1016/j.cub.2005.06.059 ◽

2005 ◽

Vol 15 (15) ◽

pp. 1407-1412 ◽

Cited By ~ 121

Author(s):

Seth J. Field ◽

Nikki Madson ◽

Monica L. Kerr ◽

Kenneth A.A. Galbraith ◽

Caitlin E. Kennedy ◽

...

Keyword(s):

Cleavage Furrow

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Actin-like filaments in the cleavage furrow of newt egg*

Experimental Cell Research ◽

10.1016/s0014-4827(71)80075-7 ◽

1971 ◽

Vol 65 (1) ◽

pp. 249-253 ◽

Cited By ~ 86

Author(s):

M PERRY ◽

H JOHN ◽

N THOMAS

Keyword(s):

Cleavage Furrow

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The permeability to cytochalasin B of the new unpigmented surface in the first cleavage furrow of the newt's egg

Development ◽

10.1242/dev.36.2.321 ◽

1976 ◽

Vol 36 (2) ◽

pp. 321-341

Author(s):

G. G. Selman ◽

J. Jacob ◽

M. M. Perry

Keyword(s):

Osmium Tetroxide ◽

Cytochalasin B ◽

Specific Activity ◽

High Specific Activity ◽

Scintillation Counting ◽

Cleavage Furrow ◽

Limited Extent ◽

Normal Medium ◽

Cleavage Initiation ◽

Whole Egg

Two to 10 µg/ml cytochalasin B (CB) caused retraction of the first cleavage furrow in Triturus eggs, a spreading of the unpigmented surface from the furrow region and a flattening of the whole egg. CB appears to act against the contractility of the microfilamentous band at mid-cleavage so as to relax the furrow and also to weaken unpigmented surface to allow the egg to flatten. Uncleaved eggs and the initial formation of the cleavage groove were unaffected by CB. A fully-retracted first cleavage furrow reformed itself on transfer of the egg to normal medium but only at the time of second cleavage. Initiation of second cleavage depended upon there being sufficient of the original pigmented surface on the animal hemisphere. Tritium-labelled CB of high specific activity was prepared and used to study its ability to penetrate the surface of newt eggs during cleavage. Scintillation counting of whole eggs showed that CB was not taken into the newt egg until mid-cleavage (about 17 min after the double stripe stage) when new surface began to spread in the cleavage furrow. Fixation in glutaraldehyde and osmium tetroxide retained radioactivity in the egg, but more CB was retained after fixation in osmium tetroxide alone than after double fixation. Most of the retained radioactivity was in yolk platelets. Autoradiographs were prepared of sectioned eggs whichad been fixed at late cleavage after [3H]CB had flattened the furrow. These showed that CBentered the egg through the unpigmented surface which formed in the furrow but it could not enter through the pigmented surface. The impermeability of the pigmented surface explains the observations that CB does not prevent initial furrowing at cleavage. Once inside the egg CB is transported slowly. CB penetrates to a limited extent beneath the pigmented surface from its border with the unpigmented surface in the first cleavage furrow and this seems insufficient in some circumstances to suppress the contractile phase of second cleavage.

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Spatiotemporal dynamics of actin concentration during cytokinesis and locomotion in Dictyostelium

Journal of Cell Science ◽

10.1242/jcs.111.15.2097 ◽

1998 ◽

Vol 111 (15) ◽

pp. 2097-2108 ◽

Cited By ~ 3

Author(s):

S. Yumura ◽

Y. Fukui

Keyword(s):

Relative Concentration ◽

Leading Edge ◽

Live Cells ◽

Cell Behavior ◽

Cleavage Furrow ◽

Two Dimensional ◽

Dynamic Changes ◽

Temporal Regulation ◽

Ph Dependent ◽

Actin Concentration

To study the spatial and temporal regulation of the actin cytoskeleton, we have analyzed the actin concentration dynamics in live Dictyostelium. The relative actin concentration was analyzed with respect to cell behavior by fluorescence morphometry. We electroporated rhodamine-actin into Dictyostelium cells and acquired images with 200–300 millisecond temporal and approximately 250 nm spatial resolutions. To convert fluorescence intensity into actin concentration, the observation was made on nearly two-dimensional cells, and the actin signal was ratioed over a volume marker (FITC-BSA or GFP). Since the emission of FITC and GFP is pH-dependent, we first measured the cytoplasmic pH in live cells and determined that the pHi in pseudopods is same as that of general cytoplasm. During cytokinesis, the relative concentration of actin in the cleavage furrow was significantly higher than in the general cytoplasm. In migrating cells, actin was recruited surprisingly rapidly, particularly in the pseudopod. We found that the region of high actin concentration moves relative to the leading edge when a pseudopod projects or retracts. When the pseudopod retracts, the actin density dissipates within 5 seconds. We have also found that actin accumulates in developing pseudopods in an oscillatory manner, and this timing coordinates with advancement of the centroid. This is the first study to reveal the dynamic changes in relative concentration of actin in live cells and to quantitatively correlate these changes with the locomotive behavior of the amoeba.

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