Abstract
BackgroundTranscription factors from the MADS-box family play a relevant role in cell differentiation and development and include the animal SRF (serum response factor) and MEF2 (myocyte enhancer factor 2) proteins. The social amoeba Dictyostelium discoideum contains four genes coding for MADS-box transcription factors, two of these genes code for proteins that are more similar to SRF, and the other two code for proteins that are more similar to MEF2 animal factors.ResultsThe biological function of one of the two genes that codes for MEF2-related proteins, a gene known as mef2A, is described in this article. This gene is expressed under the transcriptional control of two alternative promoters in growing cells, and its expression is induced during development in prespore cells. Mutant strains where the mef2A gene has been partially deleted were generated to study its biological function. The mutant strains showed reduced growth when feeding on bacteria and were able to develop and form fruiting bodies, but spore production was significantly reduced. A study of developmental markers showed that prespore cells differentiation was impaired in the mutant strains. When mutant and wild-type cells were set to develop in chimeras, mutant spores were underrepresented in the fruiting bodies. The mutant cells were also unable to form spores in vitro. In addition, mutant cells also showed a poor contribution to the formation of the tip-organizer and the upper region of slugs and culminant structures. In agreement with these observations, a comparison of the genes transcribed by mutant and wild-type strains during development indicated that prestalk gene expression was enhanced, while prespore gene expression decreased in the mef2A- strain.ConclusionsOur data shows that mef2A plays a role in cell differentiation in D. discoideum and modulates the expression of prespore and prestalk genes.
Highlights
Transcription factors from the MADS-box family play a relevant role in cell differentiation and development and include the animal SRF and MEF2 proteins
By analyzing the phenotype of mutant strains and gene expression levels during development, we clearly show that this protein is involved in D. discoideum development and, in particular, in the differentiation of prespore cells and one group of prestalk cells
Characterization of the mef2A gene The analysis of the D. discoideum genome identified four genes coding for proteins with regions similar to the MADS-box domain
Summary
Transcription factors from the MADS-box family play a relevant role in cell differentiation and development and include the animal SRF (serum response factor) and MEF2 (myocyte enhancer factor 2) proteins. Mef-2-related transcription factors belong to a family of proteins that are present in all eukaryotic organisms [1,2] These proteins share a very conserved DNA-binding and protein-dimerization domain, the MADS-box, named after the transcription factors MCM1 (from yeast), Agamous, Deficiens (from plants) and SRF (from animals) [3,4]. Two subfamilies of MADS-box transcription factors have been defined according to the MADS-box sequence: MADS-box transcription factors accomplish various biological functions In plants, they are critically involved in floral formation and development [5]. MCM1 participates in the regulation of pheromone expression, metabolism [10] and DNA replication [11] In animals, these transcription factors are mainly involved in the regulation of cell-differentiation processes. Additional studies have demonstrated that SRF regulates the expression of a large number of genes coding for actin-cytoskeleton-related proteins [15,16]
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