Human neutrophil motility: Time‐dependent three‐dimensional shape and granule diffusion

Felder, S; Kam, Zvi

doi:10.1002/cm.970280403

Cited by 32 publications

(25 citation statements)

References 38 publications

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“…This value is consistent with previous microrheological measurements of the diffusion coefficient within chemotaxing PMN cells (28). In general, lysosome size varies widely, with a typical diameter of about 0.5 mm (29).…”

Section: Application To Organelle Movement In Motile Cellssupporting

confidence: 92%

Disentangling Random Motion and Flow in a Complex Medium

Koslover¹,

Chan²,

Theriot³

2017

Biophysical Journal

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We describe a technique for deconvolving the stochastic motion of particles from large-scale fluid flow in a dynamic environment such as that found in living cells. The method leverages the separation of timescales to subtract out the persistent component of motion from single-particle trajectories. The mean-squared displacement of the resulting trajectories is rescaled so as to enable robust extraction of the diffusion coefficient and subdiffusive scaling exponent of the stochastic motion. We demonstrate the applicability of the method for characterizing both diffusive and fractional Brownian motion overlaid by flow and analytically calculate the accuracy of the method in different parameter regimes. This technique is employed to analyze the motion of lysosomes in motile neutrophil-like cells, showing that the cytoplasm of these cells behaves as a viscous fluid at the timescales examined.

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Section: Application To Organelle Movement In Motile Cellssupporting

confidence: 92%

Disentangling Random Motion and Flow in a Complex Medium

Koslover¹,

Chan²,

Theriot³

2017

Biophysical Journal

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“…PBs moved in channel-like areas in between mitochondria and when the microtubule network was disrupted, the areas of movement and diffusion were greatly reduced. Other studies have also found that depolymerization of actin or microtubules did not increase the diffusion of vesicles/granules (Felder and Kam, 1994;Jones Ϫ4 m 2 /s) (Salmeen et al, 1985), neutrophilic vesicles (2.5 ϫ 10 Ϫ2 m 2 /s) (Felder and Kam, 1994), secretory vesicles (3.9 ϫ 10 Ϫ4 -7.4 ϫ 10 Ϫ3 m 2 /s) (Burke et al, 1997), and chromaffin granules (3 ϫ 10 Ϫ3 m 2 /s) (Steyer et al, 1997). Slow diffusion and restricted movements of cytoplasmic organelles are attributed to the nonhomogeneity of the cytoplasm and to the effects that crowding, obstruction and exclusion have on transport (Luby-Phelps, 2000), meaning that long-range delivery within the cytoplasm has to rely on mechanisms of active transport.…”

Section: Dynamics Of P Bodies In Living Cellsmentioning

confidence: 86%

The Dynamics of Mammalian P Body Transport, Assembly, and Disassembly In Vivo

Aizer

Brody

Ler

et al. 2008

MBoC

218

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Exported mRNAs are targeted for translation or can undergo degradation by several decay mechanisms. The 533 degradation machinery localizes to cytoplasmic P bodies (PBs). We followed the dynamic properties of PBs in vivo and investigated the mechanism by which PBs scan the cytoplasm. Using proteins of the decapping machinery, we asked whether PBs actively scan the cytoplasm or whether a diffusion-based mechanism is sufficient. Live-cell imaging showed that PBs were anchored mainly to microtubules. Quantitative single-particle tracking demonstrated that most PBs exhibited spatially confined motion dependent on microtubule motion, whereas stationary PB pairs were identified at the centrosome. Some PBs translocated in long-range movements on microtubules. PB mobility was compared with mitochondria, endoplasmic reticulum, peroxisomes, SMN bodies, and stress granules, and diffusion coefficients were calculated. Disruption of the microtubule network caused a significant reduction in PB mobility together with an induction of PB assembly. However, FRAP measurements showed that the dynamic flux of assembled PB components was not affected by such treatments. FRAP analysis showed that the decapping enzyme Dcp2 is a nondynamic PB core protein, whereas Dcp1 proteins continuously exchanged with the cytoplasm. This study reveals the mechanism of PB transport, and it demonstrates how PB assembly and disassembly integrate with the presence of an intact cytoskeleton. INTRODUCTIONGene expression begins with the synthesis of mRNA molecules in the nucleus. After processing events, transcripts are exported to the cytoplasm where they can face several posttranscriptional fates, elicited by a balance between cytoplasmic translation and mRNA degradation pathways. Quality control pathways regulate the degradation of mRNAs and facilitate their sequestration or translational repression (Meyer et al., 2004). In eukaryotes, mRNA degradation typically begins with deadenylation, and then either of two major pathways is used. The exosome protein complex degrades mRNAs in the 3Ј35Ј direction, whereas the 5Ј33Ј direction involves other factors, including a decapping enzyme followed by the Xrn1 exonuclease (Parker and Song, 2004).The removal of the cap structure irreversibly marks the mRNA for degradation. The decapping process is tightly regulated biochemically and spatially. It was first discovered that the Xrn1 nuclease localizes in discrete cytoplasmic foci in eukaryotic cells (Bashkirov et al., 1997). Some years later, a decapping protein termed Dcp2 was found to colocalize in Xrn1-foci (Ingelfinger et al., 2002;Lykke-Andersen, 2002;van Dijk et al., 2002), finally leading to the understanding that both yeast (Sheth and Parker, 2003) and mammalian cells (Cougot et al., 2004) contain discrete areas in which mRNA decapping and 5Ј33Ј degradation can occur (Sheth and Parker, 2006). These cytoplasmic foci are now widely known as P bodies (PBs), and they have been referred to as Dcpbodies, processing bodies, mRNA-decay foci, and GW182 bodies. Since ...

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“…Diffusion coefficients, which are values that describe the relative speed at which a particle moves within a defined area, were in a range that is similar to other cytoplasmic organelles (10 -3 to 10 -2 μm 2 / sec). For instance: mitochondria (5 x 10 -4 μm 2 /sec), 22 neutrophilic vesicles (2.5 x 10 -2 μm 2 /sec), 23 secretory vesicles (3.9 x 10 -4 to 7.4 x 10 -3 μm 2 /sec), 24 chromaffin granules (3 x 10 -3 μm 2 /sec). 25 Slow diffusion and restricted movements of cytoplasmic organelles are known phenomena and are attributed to the non-homogeneity of the cytoplasm and to the effects that crowding, obstruction and exclusion have on cytoplasmic transport.…”

mentioning

confidence: 99%