A density-sensing factor controls development in Dictyostelium.

Jain, Renu; Yuen, Ita S.; Taphouse, Carl Richard; Gomer, Richard H.

doi:10.1101/gad.6.3.390

Cited by 110 publications

(93 citation statements)

References 60 publications

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“…Ax4 wild-type cells and Ga2 knockout cells (a gift from Dr. Peter Devreotes, Johns Hopkins University, Baltimore, MD) were grown in shaking culture in HL5 medium as previously described [17,21]. Conditioned medium (CM) was prepared by starving Ax4 cells at 5 X10 6 cells/ml in PBM (20 mM KH 2 P0 4 , 10 uM CaCl 2 , 1 mM MgCl 2 , pH 6.1 with KOH) in shaking culture for 20 h, and then clarifying the conditioned medium as described by Gomer et al [16].…”

Section: Cell Culturementioning

confidence: 99%

“…CMF is an 80 kDa glycoprotein with no similarity to any known protein [17]. CMF antisense cells do not aggregate when starved, unless they are allowed to develop in *Corresponding author.…”

Section: Introductionmentioning

confidence: 99%

“…Fax: (1) (713) 285-5154. E-mail: richard@bioc.rice.edu the presence of exogenous CMF or recombinant CMF (rCMF) [17]. We have hypothesized that the function of CMF is to coordinate the development of large fruiting bodies by triggering aggregation only when most of the cells in an area have starved, as signaled by a high level of CMF.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Cell Culturementioning

confidence: 99%

“…CMF is an 80 kDa glycoprotein with no similarity to any known protein [17]. CMF antisense cells do not aggregate when starved, unless they are allowed to develop in *Corresponding author.…”

Section: Introductionmentioning

confidence: 99%

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

1997

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“…Reduction of mRNA levels by the introduction of vectors producing antisense RNA also has proved effective. The Dictyostelium genes whose expression has been blocked by antisense RNA include discoidin I (Crowley et al, 1985), myosin II heavy chain (Knecht and Loomis, 1987) and essential light chain (Pollenz et al, 1992), cAMP receptor (Klein et al, 1988;Sun et al, 1990), D2 esterase (Rubino et al, 1989), gp24 (Loomis and Fuller, 1991), V4 (McPherson and Singleton, 1992), and conditioned medium factor (CMF) (Jain et al, 1992).…”

Section: Introductionmentioning

confidence: 99%

Inducible expression of calmodulin antisense RNA in Dictyostelium cells inhibits the completion of cytokinesis.

Liu

Williams

Clarke

1992

MBoC

100

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The single gene encoding calmodulin in the eukaryotic microorganism Dictyostelium discoideum was cloned and sequenced. The gene was found to contain three introns, one lying immediately after the translation initiation codon. The deduced amino acid sequence indicated that Dictyostelium calmodulin contains 19 amino acid differences from vertebrate calmodulin, including extensions at both termini. Northern blot analysis showed that similar levels of calmodulin mRNA are present throughout growth and development of wild-type cells. A complete copy of the calmodulin cDNA was prepared, and an 87-base pair fragment complementary to the 5'-end of the calmodulin mRNA was subcloned into the Dictyostelium transformation vector pVEII, such that expression of the antisense transcript was driven by the discoidin I gamma promoter. Transformed cells were selected and maintained at low cell density, a condition resulting in minimal activity of the discoidin I promoter. High level expression was induced by allowing the transformants to reach high cell density or by growing them in the presence of medium conditioned by high density cells. Under these conditions, in which calmodulin mRNA and protein levels were reduced about twofold, the calmodulin antisense transformants lost the ability to complete cytokinesis. A contractile ring formed and constricted, but the midbody linking daughter cells failed to break. The resulting cell population contained multinucleated cells and networks of cells connected by cytoplasmic bridges. Normal cell division was restored when the cells were diluted to low density. These observations have identified a new point at which calmodulin may regulate cell cleavage.

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“…1 and 2). The cells eventually overgrow their food supply, and a cell signals that it is starving by secreting a cell density-sensing factor called conditioned medium factor (3)(4)(5).…”

mentioning

confidence: 99%

A Secreted Cell Number Counting Factor Represses Intracellular Glucose Levels to Regulate Group Size in Dictyostelium

Jang

Chiem

Gomer

2002

Journal of Biological Chemistry

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Developing Dictyostelium cells form evenly sized groups of ϳ2 ؋ 10 4 cells. A secreted 450-kDa protein complex called counting factor (CF) regulates group size by repressing cell-cell adhesion and myosin polymerization and by increasing cAMP-stimulated cAMP production, actin polymerization, and cell motility. We find that CF regulates group size in part by repressing internal glucose levels. Transformants lacking bioactive CF and wild-type cells with extracellular CF depleted by antibodies have high glucose levels, whereas transformants oversecreting CF have low glucose levels. A component of CF, countin, affects group size in a manner similar to CF, and a 1-min exposure of cells to countin decreases glucose levels. Adding 1 mM exogenous glucose negates the effect of high levels of extracellular CF on group size and mimics the effect of depleting CF on glucose levels, cell-cell adhesion, cAMP pulse size, actin polymerization, myosin assembly, and motility. These results suggest that glucose is a downstream component in part of the CF signaling pathway and may be relevant to the observed role of the insulin pathway in tissue size regulation in higher eukaryotes.

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A density-sensing factor controls development in Dictyostelium.

Cited by 110 publications

References 60 publications

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

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

Inducible expression of calmodulin antisense RNA in Dictyostelium cells inhibits the completion of cytokinesis.

A Secreted Cell Number Counting Factor Represses Intracellular Glucose Levels to Regulate Group Size in Dictyostelium

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