A Serum Response Factor homolog is required for spore differentiation in Dictyostelium.
A homolog of the Serum Response Factor (SRF) has been isolated from Dictyostelium discoideum and its function studied by analyzing the consequences of its gene disruption. The MADS-box region of Dictyostelium SRF (DdSRF) is highly conserved with those of the human, Drosophila and yeast homologs. srfA is a developmentally regulated gene expressed in prespore and spore cells. This gene plays an essential role in sporulation as its disruption leads to abnormal spore morphology and loss of viability. The mutant spores were round and cellulose deposition seemed to be partially affected. Initial prestalk and prespore cell differentiation did not seem to be compromised in the mutant since the expression of several cell-type-specific markers were found to be unaffected. However, the mRNA level of the spore marker spiA was greatly reduced. Activation of the cAMP-dependent protein kinase (PKA) by 8-Br-cAMP was not able to fully bypass the morphological defects of srfA- mutant spores, although this treatment induced spiA mRNA expression. Our results suggest that DdSRF is required for full maturation of spores and participates in the regulation of the expression of the spore-coat marker spiA and probably other maturation genes necessary for proper spore cell differentiation.
Escalante
R
R
Instituto de Investigaciones Biomédicas del Consejo Superior de Investigaciones Científicas, C/Arturo Duperier 4, Spain. rescalante@iib.uam.es
Sastre
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D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000502:physiology; D004023:Dictyostelium / Q000166:cytology / Q000235:genetics* / Q000254:growth & development*; D004789:Enzyme Activation / Q000187:drug effects; D018507:Gene Expression Regulation, Developmental; D017125:Genes, Protozoan; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics* / Q000502:physiology; D015800:Protozoan Proteins / Q000235:genetics* / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016053:RNA, Protozoan / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D026362:Serum Response Factor; D013170:Spores / Q000166:cytology / Q000254:growth & development*
D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D015800:Protozoan Proteins; D012333:RNA, Messenger; D016053:RNA, Protozoan; D026362:Serum Response Factor; D015124:8-Bromo Cyclic Adenosine Monophosphate; D017868:Cyclic AMP-Dependent Protein Kinases