Two transmembrane signaling mechanisms control expression of the cAMP receptor gene CAR1 during Dictyostelium development.
Dictyostelium discoideum is among the best characterized organisms for the study of receptor/guanine nucleotide binding protein-mediated control of differentiation. Dictyostelium grow unicellularly but form fully differentiated multicellular organisms through a developmental program regulated by secreted cAMP activating specific cell-surface receptors. Dictyostelium respond differentially to cAMP at different developmental stages. During early development, expression of certain genes is induced by low-level oscillations of extracellular cAMP. Later, continuous, high cAMP concentrations will promote expression of specific genes in multicellular structures. Here, we show that the cAMP receptor gene CAR1, which is essential for development, utilizes two promoters that are activated at distinct stages of development and respond to different extracellular cAMP conditions. One promoter is active with low-level oscillations of cAMP; exposure to high cAMP concentrations will repress this promoter and induce a second promoter. The CAR1 mRNAs are alternatively spliced but encode identical proteins. Thus, through differential sensitivity to its own ligand, cAMP, two promoters and alternative splicing regulate CAR1 expression during Dictyostelium development.
Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892.
J M
JM
Louis
C L
CL
Saxe
A R
AR
Kimmel
D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D000242:Cyclic AMP / Q000494:pharmacology; D004023:Dictyostelium / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics*; D019204:GTP-Binding Proteins / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011953:Receptors, Cyclic AMP / Q000235:genetics*; D015398:Signal Transduction
D005656:Fungal Proteins; D011953:Receptors, Cyclic AMP; C068125:cyclic AMP receptor cAR1; D000242:Cyclic AMP; D019204:GTP-Binding Proteins