Extracellular matrix family proteins that are potential targets of Dd-STATa in Dictyostelium discoideum

Byline: Nao Shimada (1), Keiko Nishio (2), Mineko Maeda (2), Hideko Urushihara (3), Takefumi Kawata (1) Keywords: Dictyostelium; Extracellular matrix protein; In situ hybridization; Morphogenesis; Transcription factor Abstract: Dd-STATa is a functional Dictyostelium homologue of metazoan STAT (signal transducers and activators of transcription) proteins, which is activated by cAMP and is thereby translocated into the nuclei of anterior tip cells of the prestalk region of the slug. By using in situ hybridization analyses, we found that the SLF308 cDNA clone, which contains the ecmF gene that encodes a putative extracellular matrix protein and is expressed in the anterior tip cells, was greatly down-regulated in the Dd-STATa-null mutant. Disruption of the ecmF gene, however, resulted in almost no phenotypic change. The absence of any obvious mutant phenotype in the ecmF-null mutant could be due to a redundancy of similar genes. In fact, a search of the Dictyostelium whole genome database demonstrates the existence of an additional 16 homologues, all of which contain a cellulose-binding module. Among these homologues, four genes show Dd-STATa-dependent expression, while the others are Dd-STATa-independent. We discuss the potential role of Dd-STATa in morphogenesis via its effect on the interaction between cellulose and these extracellular matrix family proteins. Author Affiliation: (1) Department of Biology, Faculty of Science, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan (2) Department of Biology, Graduate School of Science, Osaka University, Osaka, Japan (3) Biological Sciences, University of Tsukuba, Ibaraki, Japan Article History: Registration Date: 24/06/2004 Received Date: 20/05/2004 Accepted Date: 18/06/2004 Online Date: 10/08/2004