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Keratocytes pull with similar forces on their dorsal and ventral surfaces.

Galbraith CG, Sheetz MP - J. Cell Biol. (1999)

Bottom Line: Borisy. 1997.Cell Biol. 139:397-415).Similar forces were generated on both the ventral (0.2 nN/microm(2)) and the dorsal (0.4 nN/microm(2)) surfaces of the lamella, suggesting that dorsal matrix contacts are as effectively linked to the force-generating cytoskeleton as ventral contacts.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.

ABSTRACT
As cells move forward, they pull rearward against extracellular matrices (ECMs), exerting traction forces. However, no rearward forces have been seen in the fish keratocyte. To address this discrepancy, we have measured the propulsive forces generated by the keratocyte lamella on both the ventral and the dorsal surfaces. On the ventral surface, a micromachined device revealed that traction forces were small and rearward directed under the lamella, changed direction in front of the nucleus, and became larger under the cell body. On the dorsal surface of the lamella, an optical gradient trap measured rearward forces generated against fibronectin-coated beads. The retrograde force exerted by the cell on the bead increased in the thickened region of the lamella where myosin condensation has been observed (Svitkina, T.M., A.B. Verkhovsky, K.M. McQuade, and G. G. Borisy. 1997. J. Cell Biol. 139:397-415). Similar forces were generated on both the ventral (0.2 nN/microm(2)) and the dorsal (0.4 nN/microm(2)) surfaces of the lamella, suggesting that dorsal matrix contacts are as effectively linked to the force-generating cytoskeleton as ventral contacts. The correlation between the level of traction force and the density of myosin suggests a model for keratocyte movement in which myosin condensation in the perinuclear region generates rearward forces in the lamella and forward forces in the cell rear.

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Traction forces on either side of the keratocyte nucleus measured with the micromachined substratum. Traction forces measured on either side of the nucleus are large and orthogonal to the direction of motion, ∼12 nN. Bar, 5 μm.
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Figure 2: Traction forces on either side of the keratocyte nucleus measured with the micromachined substratum. Traction forces measured on either side of the nucleus are large and orthogonal to the direction of motion, ∼12 nN. Bar, 5 μm.

Mentions: We measured the predominant traction force generated on either side of the nucleus (Fig. 2) to compare the magnitude of the force determined by our device with the force determined by other substrata. As the force vs. time trace in Fig. 2 illustrates, the maximum force that is generated by the pincer region on either side of the nucleus is ∼13 nN. Measurements made of the same region with other substratum report values as high as 11 nN (Oliver et al. 1999). Thus, both substrata measure forces of very similar magnitude in the pincer region of the cell.


Keratocytes pull with similar forces on their dorsal and ventral surfaces.

Galbraith CG, Sheetz MP - J. Cell Biol. (1999)

Traction forces on either side of the keratocyte nucleus measured with the micromachined substratum. Traction forces measured on either side of the nucleus are large and orthogonal to the direction of motion, ∼12 nN. Bar, 5 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2168090&req=5

Figure 2: Traction forces on either side of the keratocyte nucleus measured with the micromachined substratum. Traction forces measured on either side of the nucleus are large and orthogonal to the direction of motion, ∼12 nN. Bar, 5 μm.
Mentions: We measured the predominant traction force generated on either side of the nucleus (Fig. 2) to compare the magnitude of the force determined by our device with the force determined by other substrata. As the force vs. time trace in Fig. 2 illustrates, the maximum force that is generated by the pincer region on either side of the nucleus is ∼13 nN. Measurements made of the same region with other substratum report values as high as 11 nN (Oliver et al. 1999). Thus, both substrata measure forces of very similar magnitude in the pincer region of the cell.

Bottom Line: Borisy. 1997.Cell Biol. 139:397-415).Similar forces were generated on both the ventral (0.2 nN/microm(2)) and the dorsal (0.4 nN/microm(2)) surfaces of the lamella, suggesting that dorsal matrix contacts are as effectively linked to the force-generating cytoskeleton as ventral contacts.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.

ABSTRACT
As cells move forward, they pull rearward against extracellular matrices (ECMs), exerting traction forces. However, no rearward forces have been seen in the fish keratocyte. To address this discrepancy, we have measured the propulsive forces generated by the keratocyte lamella on both the ventral and the dorsal surfaces. On the ventral surface, a micromachined device revealed that traction forces were small and rearward directed under the lamella, changed direction in front of the nucleus, and became larger under the cell body. On the dorsal surface of the lamella, an optical gradient trap measured rearward forces generated against fibronectin-coated beads. The retrograde force exerted by the cell on the bead increased in the thickened region of the lamella where myosin condensation has been observed (Svitkina, T.M., A.B. Verkhovsky, K.M. McQuade, and G. G. Borisy. 1997. J. Cell Biol. 139:397-415). Similar forces were generated on both the ventral (0.2 nN/microm(2)) and the dorsal (0.4 nN/microm(2)) surfaces of the lamella, suggesting that dorsal matrix contacts are as effectively linked to the force-generating cytoskeleton as ventral contacts. The correlation between the level of traction force and the density of myosin suggests a model for keratocyte movement in which myosin condensation in the perinuclear region generates rearward forces in the lamella and forward forces in the cell rear.

Show MeSH
Related in: MedlinePlus