Identification of new modes of Dd-STATa regulation of gene expression in Dictyostelium by in situ hybridisation.

Signal Transducers and Activators of Transcription (STATs) are transcription factors which lie at the end of cytokine and growth signal transduction pathways. Dictyostelium Dd-STATa is a functional homologue of metazoan STATs. It is activated by cAMP and, at the slug stage, it translocates into the nuclei of the tip cells, which are a subset of the anterior, prestalk A (pstA) cells. Here we searched for novel Dd-STATa regulated genes by in situ hybridisation. A set of 54 cDNA clones whose gene expression patterns are known to be prestalk-specific (Maeda et al., 2003), were chosen as probes and we compared their expression patterns in parental and Dd-STATa-null strains. We identified 13 genes which are candidates for direct induction by Dd-STATa. In the parental strain, most of these genes are expressed in the cone shaped mass of pstAB cells which is located within the prestalk region. These cDNAs show little or no expression in the Dd-STATa-null strain. This contrasts markedly with the paradigmatic ecmB gene which is expressed in pstAB cells in parental cells, but which is expressed throughout the prestalk zone in the Dd-STATa-null strain. We also identified several genes which are normally expressed in pstA cells, or throughout the prestalk region, but whose expression is markedly down-regulated in the null mutant. Again, this contrasts with markers derived from the paradigmatic, ecmA gene which are expressed normally in the Dd-STATa-null strain. The identification of these novel genes provides valuable tools to investigate the role of Dd-STATa.

[1]  H. Urushihara,et al.  Extracellular matrix family proteins that are potential targets of Dd-STATa in Dictyostelium discoideum , 2004, Journal of Plant Research.

[2]  M. Zvelebil,et al.  Dd-STATb, a Dictyostelium STAT protein with a highly aberrant SH2 domain, functions as a regulator of gene expression during growth and early development , 2003, Development.

[3]  W. Loomis,et al.  Changing Patterns of Gene Expression in Dictyostelium Prestalk Cell Subtypes Recognized by In Situ Hybridization with Genes from Microarray Analyses , 2003, Eukaryotic Cell.

[4]  N. Perrimon,et al.  The Jak/STAT pathway in model organisms: emerging roles in cell movement. , 2002, Developmental cell.

[5]  Massimo Gadina,et al.  Cytokine Signaling in 2002 New Surprises in the Jak/Stat Pathway , 2002, Cell.

[6]  J. Williams,et al.  Tyrosine phosphorylation-independent nuclear translocation of a dictyostelium STAT in response to DIF signaling. , 2001, Molecular cell.

[7]  M. Katoh,et al.  Developmental changes in the spatial expression of genes involved in myosin function in Dictyostelium. , 2000, Developmental biology.

[8]  J. Williams,et al.  Analysis of the promoter of the cudA gene reveals novel mechanisms of Dictyostelium cell type differentiation. , 2000, Development.

[9]  R. Firtel,et al.  Evidence that the Dictyostelium Dd-STATa protein is a repressor that regulates commitment to stalk cell differentiation and is also required for efficient chemotaxis. , 1999, Development.

[10]  R. Firtel,et al.  Developmentally and spatially regulated activation of a Dictyostelium STAT protein by a serpentine receptor , 1998, The EMBO journal.

[11]  J. Darnell.  STATs and gene regulation. , 1997, Science.

[12]  M. Mann,et al.  SH2 Signaling in a Lower Eukaryote: A STAT Protein That Regulates Stalk Cell Differentiation in Dictyostelium , 1997, Cell.

[13]  J. Williams,et al.  The initiation of basal disc formation in Dictyostelium discoideum is an early event in culmination. , 1996, Development.

[14]  W. Loomis,et al.  Whole-mount in situ hybridization of cell-type-specific mRNAs in Dictyostelium. , 1995, Developmental biology.

[15]  W. Leonard,et al.  The Jak-STAT pathway. , 2000, Molecular immunology.

[16]  T. Saito,et al.  The Dictyostelium developmental cDNA project: generation and analysis of expressed sequence tags from the first-finger stage of development. , 1998, DNA research : an international journal for rapid publication of reports on genes and genomes.