Expression of early developmental genes in Dictyostelium discoideum is initiated during exponential growth by an autocrine-dependent mechanism.
Throughout growth, Dictyostelium cells continuously produce an autocrine factor, PSF, that accumulates in proportion to cell density. Production of PSF declines rapidly when cells are shifted to starvation conditions, and the properties of PSF are distinct from those of regulatory factors produced by starving cells. During late exponential growth, PSF induces expression of several early developmental genes, including those for proteins important in cAMP signaling and cell aggregation. Examples are the aggregation stage cAMP receptor (cAR1), the aggregation-specific form of cyclic nucleotide phosphodiesterase, and gp24 (contact sites B). Through PSF, growing cells detect environmental conditions (cell number high, food approaching depletion) that are appropriate for production of the gene products needed to initiate aggregation and development.
Rathi
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Program in Molecular and Cell Biology, Oklahoma Medical Research Foundation, Oklahoma City 73104.
Clarke
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D000818:Animals; D015152:Blotting, Northern; D002449:Cell Aggregation; D002450:Cell Communication; D002454:Cell Differentiation / Q000235:genetics; D002478:Cells, Cultured / Q000187:drug effects; D003513:Cycloheximide / Q000494:pharmacology; D004023:Dictyostelium / Q000235:genetics*; D010450:Endopeptidases / Q000494:pharmacology; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D006133:Growth Substances / Q000235:genetics* / Q000378:metabolism; D010727:Phosphoric Diester Hydrolases / Q000032:analysis / Q000235:genetics; D011953:Receptors, Cyclic AMP / Q000032:analysis / Q000235:genetics
D006133:Growth Substances; D011953:Receptors, Cyclic AMP; D003513:Cycloheximide; D010727:Phosphoric Diester Hydrolases; D010450:Endopeptidases