Migration and chemotaxis of anucleate cytoplasmic leukocyte fragments

Keller, H. U.; Bessis, M

doi:10.1038/258723a0

Cited by 68 publications

(34 citation statements)

References 4 publications

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“…I B and 2 B) is of particular interest in this regard, when one considers how little they have retained of the parent cell's structure. These anucleate fragments contain few or no granules; they are derived from the microfilamentrich, organelle-excluding cortical cytoplasm (hyaloplasm) that is prominent in the leading front (protopod, lamellipodium) of intact, migrating PMN (1)(2)(3)17). This general lack ofintracellular organelles in cytokineplasts, combined with their retained ability to store calcium internally and to mobilize it on appropriate stimulation, points to the plasmalemma as a likely calcium depot.…”

Section: Discussionmentioning

confidence: 99%

“…Cytokineplasts ("kine," to emphasize their motile capacities), induced by the briefapplication ofheat to adherent PMN, are capable ofrandom locomotion, chemotaxis, capping, and other motile functions, but lack respiratory burst oxidase activity (1)(2)(3)(4)(5). Other anucleate fragments (herein called cytochalasin B [CB]-cytoplasts), which are produced by the high-speed centrifugation of CB-treated PMN in discontinuous gradients of Ficoll (6), have defective motile function (4,6), the basis of which is not known, but 1.…”

Section: Introductionmentioning

confidence: 99%

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Stimulated cytokineplasts from human polymorphonuclear leukocytes mobilize calcium and polymerize actin. Cytoplasts made in cytochalasin B retain a defect in actin polymerization.

Dyett¹,

Malawista²,

Naccache³

et al. 1986

J. Clin. Invest.

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Biologically active fragments from polymorphonuclear leukocytes (PMN) are simplified systems that can be used to elucidate specific pathways by which cell function is altered. In the current study we have found that cytokineplasts, which are motile fragments derived from the leading front (protopod, lamellipodium) of human PMN, rapidly increase their intracellular free calcium concentration when stimulated by chemotactic formyl peptide or by leukotriene B4, as measured by Quin-2 acetoxymethyl ester fluorescence. As in the parent cell, extracellular EGTA blunts this response only partially. Hence, cytokineplasts retain a mobilizable internal calcium pool, despite a general lack of intracellular organelles. In addition, formyl peptide more than doubles the amount of cytoskeleton-associated (polymerized) actin. In contrast, cytoplasts made by high-speed, discontinuous gradient centrifugation of cytochalasin B-treated leukocytes also increase their intracellular free calcium on stimulation, but cytoskeletonassociated actin increases by only 14%. Thus, defective motile function in the latter cytoplast is associated with compromised effector function (actin polymerization).

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stimulated cytokineplasts from human polymorphonuclear leukocytes mobilize calcium and polymerize actin. Cytoplasts made in cytochalasin B retain a defect in actin polymerization.

Dyett¹,

Malawista²,

Naccache³

et al. 1986

J. Clin. Invest.

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“…This attractive hypothesis has subsequently been reinforced by studies in other cell types (5,9,10). However, microtubules may not always be essential for cell polarization (11) or movement (12)(13)(14), and the centrosome may also occupy a position other than behind the leading edge in certain locomoting cells (15)(16)(17). All these studies, however, are based on an analysis of cells fixed for immunofluorescence or electron microscopy to determine centrosome position.…”

Section: Introductionmentioning

confidence: 99%

Centrosome positioning and directionality of cell movements

Ueda¹,

Gräf²,

MacWilliams³

et al. 1997

Proc. Natl. Acad. Sci. U.S.A.

132

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In several cell types, an intriguing correlation exists between the position of the centrosome and the direction of cell movement: the centrosome is located behind the leading edge, suggesting that it serves as a steering device for directional movement. A logical extension of this suggestion is that a change in the direction of cell movement is preceded by a reorientation, or shift, of the centrosome in the intended direction of movement. We have used a fusion protein of green f luorescent protein (GFP) and ␥-tubulin to label the centrosome in migrating amoebae of Dictyostelium discoideum, allowing us to determine the relationship of centrosome positioning and the direction of cell movement with high spatial and temporal resolution in living cells. We find that the extension of a new pseudopod in a migrating cell precedes centrosome repositioning. An average of 12 sec elapses between the initiation of pseudopod extension and reorientation of the centrosome. If no reorientation occurs within approximately 30 sec, the pseudopod is retracted. Thus the centrosome does not direct a cell's migration. However, its repositioning stabilizes a chosen direction of movement, most probably by means of the microtubule system.

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“…Keratocytes, as well as other motile cell types (11), can spontaneously detach cytoplasmic fragments which move with speed and persistence similar to whole-cells (12)(13)(14). These lamellipodial fragments, which lack nuclei, microtubules, and most organelles, are likely the simplest natural model system for studying actin-based cell motility.…”

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confidence: 99%

Actin disassembly clock determines shape and speed of lamellipodial fragments

Ofer

Mogilner

Keren

2011

Proc. Natl. Acad. Sci. U.S.A.

113

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A central challenge in motility research is to quantitatively understand how numerous molecular building blocks self-organize to achieve coherent shape and movement on cellular scales. A classic example of such self-organization is lamellipodial motility in which forward translocation is driven by a treadmilling actin network. Actin polymerization has been shown to be mechanically restrained by membrane tension in the lamellipodium. However, it remains unclear how membrane tension is determined, what is responsible for retraction and shaping of the rear boundary, and overall how actin-driven protrusion at the front is coordinated with retraction at the rear. To answer these questions, we utilize lamellipodial fragments from fish epithelial keratocytes which lack a cell body but retain the ability to crawl. The absence of the voluminous cell body in fragments simplifies the relation between lamellipodial geometry and cytoskeletal dynamics. We find that shape and speed are highly correlated over time within individual fragments, whereby faster crawling is accompanied by larger front-to-rear lamellipodial length. Furthermore, we find that the actin network density decays exponentially from front-to-rear indicating a constant net disassembly rate. These findings lead us to a simple hypothesis of a disassembly clock mechanism in which rear position is determined by where the actin network has disassembled enough for membrane tension to crush it and haul it forward. This model allows us to directly relate membrane tension with actin assembly and disassembly dynamics and elucidate the role of the cell membrane as a global mechanical regulator which coordinates protrusion and retraction.cell motility | keratocyte fragments U nderstanding the large-scale coordination of molecular processes into coherent behavior at the cellular level is one of the central challenges in cell biology. Actin-based motility involves numerous molecular players with complex interactions (1) that span a wide-range of scales from the molecular level to the cellular one. Despite substantial progress in characterizing the molecular details involved (2), we still do not understand the remarkable self-organization of these molecular components into a moving cell. The complex interplay between biochemical reactions and biophysical forces plays a central role in this selforganization. In particular, the mechanical feedback between the cell membrane and the dynamic actin network has been shown to have a substantial effect on cell protrusion (3, 4), and a significant role in coordinating protrusion over cellular scales (5, 6). However, quantitative understanding of the coupling between the cell membrane and the motility machinery is still lacking; it is unknown what determines membrane tension and how membrane tension is related to the protrusion and retraction dynamics. Elucidating this dynamic interplay is essential for understanding how overall cell morphology and movement emerge from the underlying molecular processes.Fish epithelial keratocytes are...

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Migration and chemotaxis of anucleate cytoplasmic leukocyte fragments

Cited by 68 publications

References 4 publications

Stimulated cytokineplasts from human polymorphonuclear leukocytes mobilize calcium and polymerize actin. Cytoplasts made in cytochalasin B retain a defect in actin polymerization.

Stimulated cytokineplasts from human polymorphonuclear leukocytes mobilize calcium and polymerize actin. Cytoplasts made in cytochalasin B retain a defect in actin polymerization.

Centrosome positioning and directionality of cell movements

Actin disassembly clock determines shape and speed of lamellipodial fragments

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