The Dictyostelium discoideum acaA gene is transcribed from alternative promoters during aggregation and multicellular development.
BACKGROUND
Extracellular cAMP is a key extracellular signaling molecule that regulates aggregation, cell differentiation and morphogenesis during multi-cellular development of the social amoeba Dictyostelium discoideum. This molecule is produced by three different adenylyl cyclases, encoded by the genes acaA, acrA and acgA, expressed at different stages of development and in different structures.


RESULTS
This article describes the characterization of the promoter region of the acaA gene, showing that it is transcribed from three different alternative promoters. The distal promoter, promoter 1, is active during the aggregation process while the more proximal promoters are active in tip-organiser and posterior regions of the structures. A DNA fragment containing the three promoters drove expression to these same regions and similar results were obtained by in situ hybridization. Analyses of mRNA expression by quantitative RT-PCR with specific primers for each of the three transcripts also demonstrated their different temporal patterns of expression.


CONCLUSIONS
The existence of an aggregation-specific promoter can be associated with the use of cAMP as chemo-attractant molecule, which is specific for some Dictyostelium species. Expression at late developmental stages indicates that adenylyl cyclase A might play a more important role in post-aggregative development than previously considered.
Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Cientificas/Universidad Autónoma de Madrid, Madrid, Spain.
Maria
M
Galardi-Castilla
Ane
A
Garciandía
Teresa
T
Suarez
Leandro
L
Sastre
D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D016054:DNA, Protozoan / Q000235:genetics; D004023:Dictyostelium / Q000235:genetics*; D017125:Genes, Protozoan; D017403:In Situ Hybridization; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D001616:beta-Galactosidase / Q000235:genetics
D017931:DNA Primers; D016054:DNA, Protozoan; D012333:RNA, Messenger; D001616:beta-Galactosidase