Project description:The GATA transcription factor GtaG is conserved in Dictyostelids and essential for terminal differentiation in Dictyostelium discoideum, but its function is not well understood. Here we show that gtaG is expressed in prestalk cells at the anterior region of fingers and in the extending stalk during culmination. The gtaG- phenotype is cell-autonomous in prestalk cells and non-cell-autonomous in prespore cells. Transcriptome analyses reveal that GtaG regulates prestalk gene expression during cell differentiation before culmination and is required for progression into culmination. GtaG-dependent genes include genetic suppressors of the Dd-STATa-defective phenotype as well as Dd-STATa target-genes, including extra cellular matrix genes. We show that GtaG may be involved in the production of two culmination-signaling molecules, cyclic di-GMP and the spore differentiation factor SDF-1 and that addition of c-di-GMP rescues the gtaG- culmination and spore formation deficiencies. We propose that GtaG is a regulator of terminal differentiation that functions in concert with Dd-STATa and controls culmination through regulating c-di-GMP and SDF-1 production in prestalk cells.
Project description:ATP-binding cassette (ABC) transporters can translocate a broad spectrum of molecules across the cell membrane including physiological cargo and toxins. ABC transporters are known for the role they play in resistance towards anticancer agents in chemotherapy of cancer patients. There are 68 ABC transporters annotated in the genome of the social amoeba Dictyostelium discoideum. We have characterized more than half of these ABC transporters through a systematic study of mutations in their genes. We have analyzed morphological and transcriptional phenotypes for these mutants during growth and development and found that most of the mutants exhibited rather subtle phenotypes. A few of the genes may share physiological functions, as reflected in their transcriptional phenotypes. Since most of the abc-transporter mutants showed subtle morphological phenotypes, we utilized these transcriptional phenotypes to identify genes that are important for development by looking for transcripts whose abundance was unperturbed in most of the mutants. We found a set of 668 genes that includes many validated D. discoideum developmental genes. We have also found that abcG6 and abcG18 may have potential roles in intercellular signaling during terminal differentiation of spores and stalks. Transcriptional phenotyping during development of abc transporter mutants in Dictyostelium discoideum
Project description:In many developmental systems, morphogenesis is coupled with dramatic changes in spatiotemporal gene expression, often orchestrated by the coordinated action of transcription factors. Development of the social soil amoebae Dictyostelium discoideum proceeds through a sequence of morphological and transcriptional changes, but the role of transcription factors in development is not well understood. GtaC, a GATA-type zinc-finger transcription factor, is essential for Dictyostelium development. It decodes pulsatile extracellular cAMP signals during early development and mediates cell-type differentiation at later stages. Here, we studied the developmental regulatory roles of GtaC through the concerted analysis of temporal ChIP- and RNA-sequencing data from strains that carry different alleles of gtaC. We show that GtaC exhibits temporally distinctive DNA-binding patterns throughout early development, accompanied by largely cotemporaneous expression of its target genes. We also show that GtaC binds DNA in two modes. One of these modes exhibits binding preferences for canonical GATA-like sequences, the regulatory consequences accompanying which is predominantly up-regulation of target gene expression. The other binding mode is mostly associated with down-regulation. Among its targets we find transcription factors that are essential for development as well as genes involved in cAMP signaling and cell-type specification. Our results suggest that GtaC is a master regulator that regulates multiple physiological processes during early development, when Dictyostelium transitions from a group of unicellular amoebae to an integrated multicellular organism. Cotemporaneous transcriptional profiling and ChIP sequencing during early Dictyostelium development
Project description:ATP-binding cassette (ABC) transporters can translocate a broad spectrum of molecules across the cell membrane including physiological cargo and toxins. ABC transporters are known for the role they play in resistance towards anticancer agents in chemotherapy of cancer patients. There are 68 ABC transporters annotated in the genome of the social amoeba Dictyostelium discoideum. We have characterized more than half of these ABC transporters through a systematic study of mutations in their genes. We have analyzed morphological and transcriptional phenotypes for these mutants during growth and development and found that most of the mutants exhibited rather subtle phenotypes. A few of the genes may share physiological functions, as reflected in their transcriptional phenotypes. Since most of the abc-transporter mutants showed subtle morphological phenotypes, we utilized these transcriptional phenotypes to identify genes that are important for development by looking for transcripts whose abundance was unperturbed in most of the mutants. We found a set of 668 genes that includes many validated D. discoideum developmental genes. We have also found that abcG6 and abcG18 may have potential roles in intercellular signaling during terminal differentiation of spores and stalks.