Cell Density-sensing in Dictyostelium by Means of the Accumulation Rate, Diffusion Coefficient and Activity Threshold of a Protein Secreted by Starved Cells

Yuen, Ita S.; Gomer, Richard H.

doi:10.1006/jtbi.1994.1069

Cited by 40 publications

(43 citation statements)

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“…Furthermore, we obtained similar findings when cells were plated on agar of varying thickness, where the dense agar gel effectively prevents convective flows (supplementary material Fig. S1) without reducing diffusion (Yuen and Gomer, 1994). However, cAMP dynamics are complex, so we cannot exclude the possibility that cAMP has a role in regulating the dependence of streaming on fluid height.…”

Section: Short Cell-cell Distances and Small Fluid Heights Are Necesssupporting

confidence: 62%

Cell speed, persistence and information transmission during signal relay and collective migration

McCann

Kriebel

Parent

et al. 2010

Journal of Cell Science

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SummaryCollective migration is a key feature of the social amoebae Dictyostelium discoideum, where the binding of chemoattractants leads to the production and secretion of additional chemoattractant and the relay of the signal to neighboring cells. This then guides cells to migrate collectively in a head-to-tail fashion. We used mutants that were defective in signal relay to elucidate which quantitative metrics of cell migration are most strongly affected by signal relay and collective motion. We show that neither signal relay nor collective motion markedly impact the speed of cell migration. Cells maintained a preferred overall direction of motion for several minutes with similar persistence, regardless of whether or not they were attracted to moving neighbors, moving collectively in contact with their neighbors, or simply following a fixed exogenous signal. We quantitatively establish that signal relay not only increases the number of cells that respond to a chemotactic signal, but most remarkably, also transmits information about the location of the source accurately over large distances, independently of the strength of the exogenous signal. We envision that signal relay has a similar key role in the migration of a variety of chemotaxing mammalian cells that can relay chemoattractant signals.

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Section: Short Cell-cell Distances and Small Fluid Heights Are Necesssupporting

confidence: 62%

Cell speed, persistence and information transmission during signal relay and collective migration

McCann

Kriebel

Parent

et al. 2010

Journal of Cell Science

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“…Previously, we used calculations to show that a secreted factor that diffuses away from a group of cells can be used as part of a mechanism to sense the number of cells in a group (Yuen and Gomer 1994;Clarke and Gomer 1995). We used 450 kD as the molecular mass of counting factor to calculate a diffusion coefficient of 3.4 × 10 −7 cm 2 /sec.…”

Section: Discussionmentioning

confidence: 99%

“…Dictyostelium normally exists as a single cell that eats bacteria on soil surfaces and increases in number by fission. When a cell starves, it signals that it is starving by slowly secreting a cell-density sensing factor, the glycoprotein CMF (Mehdy et al 1985;Gomer et al 1991;Jain et al 1992;Jain and Gomer 1994;Yuen and Gomer 1994;Yuen et al 1995). As more and more cells in a 1 to 10 mm diameter area of soil starve, the concentration of CMF increases.…”

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confidence: 99%

A cell-counting factor regulating structure size in Dictyostelium

Brock¹,

Gomer²

1999

Genes & Development

125

187

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Developing Dictyostelium cells form large aggregation streams that break up into groups of 0.2 × 10 5 to 1 × 10 5 cells. Each group then becomes a fruiting body. smlA cells oversecrete an unknown factor that causes aggregation streams to break up into groups of ∼5 × 10 3 cells and thus form very small fruiting bodies. We have purified the counting factor and find that it behaves as a complex of polypeptides with an effective molecular mass of 450 kD. One of the polypeptides is a 40-kD hydrophilic protein we have named countin. In transformants with a disrupted countin gene, there is no detectable secretion of counting factor, and the aggregation streams do not break up, resulting in huge (up to 2 × 10 5 cell) fruiting bodies.

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“…The predicted diffusion of CMF indicates that CMF might be able to mediate density sensing in the wild [18]. CMF is secreted by starved cells at a rate of 12 molecules/cell per min, and the theoretical diffusion from a cell on a soil surface or submerged in water predicts that the concentration of CMF in the immediate vicinity of an isolated starved cell remains below 0.3 ng/ml, the half-maximal activity of CMF, by a factor of at least 10 even after 10 h of continuous secretion.…”

Section: Introductionmentioning

confidence: 99%

A cell‐density sensing factor regulates the lifetime of a chemoattractant‐induced Gα‐GTP conformation

1997

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Starving Dictyostelium discoideum cells monitor the local density of other starving cells by simultaneously secreting and sensing CMF. CMF regulates signal transduction through the chemoattractant cAMP receptor, cARl. cARl activates a heterotrimeric G protein by stimulating Goc2 to release GDP and bind GTP. We show here that the rate of cAMP-stimulated GTP hydrolysis in membranes from cells exposed to CMF is roughly 4 times slower than in membranes from untreated cells, even though the rate of GTP binding is the same. This hydrolysis is abolished in cells lacking Goc2. Our data thus suggest that CMF regulates cAMP signal transduction in part by prolonging the lifetime of the Ga2-GTP complex.

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Cell Density-sensing in Dictyostelium by Means of the Accumulation Rate, Diffusion Coefficient and Activity Threshold of a Protein Secreted by Starved Cells

Cited by 40 publications

References 0 publications

Cell speed, persistence and information transmission during signal relay and collective migration

Cell speed, persistence and information transmission during signal relay and collective migration

A cell-counting factor regulating structure size in Dictyostelium

A cell‐density sensing factor regulates the lifetime of a chemoattractant‐induced Gα‐GTP conformation

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