Aberrant folate response and premature development in a mutant of Dictyostelium discoideum.
Growth and development are mutually exclusive in Dictyostelium discoideum. The transition between the two stages of the life cycle is regulated by the relative abundance of nutrients and proteins secreted by the cells which reflect population density. At the transition from growth to development, the discoidin genes--developmental markers--are induced by the "quorum" protein PSF. The effect of PSF is counteracted by food bacteria and by folate [8]. We show that folate treatment during growth delays morphologic development. Furthermore, we demonstrate that in a mutant of Dictyostelium discoideum (V188, renamed HBW3), which expresses discoidinI during growth and which develops rapidly [46], discoidinI expression is less sensitive to folate than in wild type cells. Finally, we present evidence that fragments of the discoidinI gamma promoter which are unresponsive to PSF and CM are sufficient for misregulation in the mutant. The only known regulator of these promoter elements is folate. Changes in the expression of other early developmental genes are also shown. Taken together, these data suggest that the reduced sensitivity to folate might be the cause for the "rapid development" phenotype of the mutant and that folate regulates developmental timing.
Zoologisches Institut, Ludwig-Maximilians-Universität of München, Luisenstrasse 14, D-80333 München, Germany.
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Salger
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Wetterauer
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000096:biosynthesis / Q000235:genetics; D000818:Animals; D004023:Dictyostelium / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development*; D000070821:Discoidins; D005492:Folic Acid / Q000378:metabolism / Q000494:pharmacology*; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D037102:Lectins; D009154:Mutation; D000072670:PTB-Associated Splicing Factor; D010641:Phenotype; D011401:Promoter Regions, Genetic; D015800:Protozoan Proteins / Q000096:biosynthesis / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics; D011953:Receptors, Cyclic AMP / Q000096:biosynthesis / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D014158:Transcription, Genetic
D000070821:Discoidins; D037102:Lectins; D000072670:PTB-Associated Splicing Factor; D015800:Protozoan Proteins; D016601:RNA-Binding Proteins; D011953:Receptors, Cyclic AMP; C068125:cyclic AMP receptor cAR1; D005492:Folic Acid; D015105:3',5'-Cyclic-AMP Phosphodiesterases