Folate responsiveness during growth and development of <i>Dictyostelium:</i> separate but related pathways control chemotaxis and gene regulation

Blusch, Jürgen; Nellen, Wolfgang

doi:10.1111/j.1365-2958.1994.tb00313.x

Cited by 20 publications

(23 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Bacteria secrete folic acid, and this molecule chemotactically attracts vegetative amoebae, resulting in successful predation and feeding (1). The role of RasG and RasC in folate chemotaxis was determined by measuring the movement of cells toward a folate filled micropipette.…”

Section: Resultsmentioning

confidence: 99%

Ras Proteins Have Multiple Functions in Vegetative Cells of Dictyostelium

Bolourani

Spiegelman

2010

Eukaryot Cell

View full text Add to dashboard Cite

show abstract

Section: Resultsmentioning

confidence: 99%

Ras Proteins Have Multiple Functions in Vegetative Cells of Dictyostelium

Bolourani

Spiegelman

2010

Eukaryot Cell

View full text Add to dashboard Cite

show abstract

“…To understand its possible role in these processes, attempts were made to overexpress the gene. Since preliminary experiments, using a constitutive actin 15 promoter, indicated that overexpression of the rasG gene might be toxic to the cell, the gene was cloned downstream of the folate-repressible discoidin (dis1␥) promoter in the vector pVEII (4,5), and the resulting construct, pVEII-rasG, was used to transform Ax-2 cells. Transformants were selected in the presence of 1 mM folate to repress the discoidin promoter.…”

Section: Resultsmentioning

confidence: 99%

“…This low level expression of rasG-G12T had no effect on growth but caused impaired aggregation under certain developmental conditions (40). In the study reported here, we have successfully overexpressed the rasG gene by using the folate-repressible discoidin promoter (4,5) and have determined the effects of overexpression on growth and differentiation.…”

mentioning

confidence: 99%

Overexpression of an Activated rasG Gene during Growth Blocks the Initiation of Dictyostelium Development

Khosla

Spiegelman

Weeks

1996

Molecular and Cellular Biology

View full text Add to dashboard Cite

Transformants that expressed either the wild-type rasG gene, an activated rasG-G12T gene, or a dominant negative rasG-S17N gene, all under the control of the folate-repressible discoidin (dis1␥) promoter, were isolated. All three transformants expressed high levels of Ras protein which were reduced by growth in the presence of folate. All three transformants grew slowly, and the reduction in growth rate correlated with the amount of RasG protein produced, suggesting that RasG is important in regulating cell growth. The pVEIIrasG transformant containing the wild-type rasG gene developed normally despite the presence of high levels of RasG throughout development. This result indicates that the down regulation of rasG that normally occurs during aggregation of wild-type strains is not essential for the differentiation process. Dictyostelium transformants expressing the dominant negative rasG-S17N gene also differentiated normally. Dictyostelium transformants that overexpressed the activated rasG-G12T gene did not aggregate. The defect occurred very early in development, since the expression of car1 and pde, genes that are normally induced soon after the initiation of development, was repressed. However, when the transformant cells were pulsed with cyclic AMP, expression of both genes returned to wild-type levels. The transformants exhibited chemotaxis to cyclic AMP, and development was synergized by mixing with wild-type cells. Furthermore, cells that were pulsed with cyclic AMP for 4 h before being induced to differentiate by plating on filters produced small, but otherwise normal, fruiting bodies. These results suggest that the rasG-G12T transformants are defective in cyclic AMP production and that RasG ⅐ GTP blocks development by interfering with the initial generation of cyclic AMP pulses.

show abstract

“…Above a threshold level of the PSF:bacteria ratio (approximately three generations before the onset of starvation), low-level discoidin expression is initiated (Rathi et al, 1991). Folate represses discoidin expression when added to axenically growing cells (Blusch and Nellen, 1994). Similarly, autoclaved bacteria can repress discoidin (Burdine and Clarke, 1995).…”

Section: Introductionmentioning

confidence: 99%

gdt1, a New Signal Transduction Component for Negative Regulation of the Growth–Differentiation Transition inDictyostelium discoideum

Zeng

Anjard

Riemann

et al. 2000

MBoC

Self Cite

View full text Add to dashboard Cite

Discoidin I expression was used as a marker to screen for mutants affected in the growthdifferentiation transition (GDT) of Dictyostelium. By REMI mutagenesis we have isolated mutant 2-9, an overexpressor of discoidin I. It displays normal morphogenesis but shows premature entry into the developmental cycle. The disrupted gene was denominated gdt1. The mutant phenotype was reconstructed by disruptions in different parts of the gene, suggesting that all had a complete loss of function. gdt1 was expressed in growing cells; the levels of protein and mRNA appear to increase with cell density and rapidly decrease with the onset of development. gdt1 encodes a 175-kDa protein with four putative transmembrane domains. In the C terminus, the derived amino acid sequence displays some similarity to the catalytic domain of protein kinases. Mixing experiments demonstrate that the gdt1 Ϫ phenotype is cell autonomous. Prestarvation factor is secreted at wild-type levels. The response to folate, a negative regulator of discoidin expression, was not impaired in gdt1 mutants. Cells that lack the G protein ␣2 display a loss of discoidin expression and do not aggregate. gdt1 Ϫ /G␣2 Ϫ double mutants show no aggregation but strong discoidin expression. This suggests that gdt1 is a negative regulator of the GDT downstream of or in a parallel pathway to G␣2.

show abstract

Folate responsiveness during growth and development of Dictyostelium: separate but related pathways control chemotaxis and gene regulation

Cited by 20 publications

References 25 publications

Ras Proteins Have Multiple Functions in Vegetative Cells of Dictyostelium

Ras Proteins Have Multiple Functions in Vegetative Cells of Dictyostelium

Overexpression of an Activated rasG Gene during Growth Blocks the Initiation of Dictyostelium Development

gdt1, a New Signal Transduction Component for Negative Regulation of the Growth–Differentiation Transition inDictyostelium discoideum

Contact Info

Product

Resources

About