Identification and analysis of a gene that is essential for morphogenesis and prespore cell differentiation in Dictyostelium.
We have identified a gene (PslA) that is expressed throughout Dictyostelium development and encodes a novel protein that is required for proper aggregation and subsequent cell-type differentiation and morphogenesis. pslA null (pslA-) cells produce large aggregation streams under conditions in which wild-type cells form discrete aggregates. Tips form along the stream, elongate to produce a finger, and eventually form a terminal structure that lacks a true sorus (spore head). More than half of the cells remain as a mass at the base of the developing fingers. The primary defect in the pslA- strain is the inability to induce prespore cell differentiation. Analyses of gene expression show a complete lack of prespore-specific gene expression and no mature spores are produced. In chimeras with wild-type cells, pslA- cells form the prestalk domain and normal, properly proportioned fruiting bodies can be produced. This indicates that pslA- cells are able to interact with wild-type cells and regulate patterning, even though pslA- cells are unable to express prespore cell-type-specific genes, do not participate in prespore cell differentiation and do not produce pslA- spores in the chimeras. While pslA- cells produce mature, vacuolated stalk cells during multicellular development, pslA- cells are unable to do so in vitro in response to exogenous DIF (a morphogen required for prestalk and stalk cell differentiation). These results indicate that pslA- cells exhibit a defect in the prestalk/stalk cell pathways under these experimental conditions. Our results suggest that PslA's primary function is to regulate prespore cell determination very early in the prespore pathway via a cell-autonomous mechanism, possibly at the time of the initial prestalk/prespore cell-fate decision. Indirect immunofluorescence of myc-tagged PslA localizes the protein to the nucleus, suggesting that PslA may function to control the prespore pathway at the level of transcription.
Yasukawa
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H
Department of Biology, Center for Molecular Genetics, University of California, San Diego, La Jolla CA 92093-0634, USA.
Mohanty
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Firtel
R A
RA
D000595:Amino Acid Sequence; D000818:Animals; D002449:Cell Aggregation / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics*; D002678:Chimera / Q000235:genetics; D003001:Cloning, Molecular; D004023:Dictyostelium / Q000254:growth & development*; D005656:Fungal Proteins / Q000737:chemistry*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D006588:Hexanones / Q000494:pharmacology; D006651:Histocytochemistry; D008853:Microscopy; D008969:Molecular Sequence Data; D009024:Morphogenesis / Q000502:physiology*; D016296:Mutagenesis / Q000235:genetics; D009687:Nuclear Proteins / Q000502:physiology; D011401:Promoter Regions, Genetic / Q000235:genetics; D015800:Protozoan Proteins; D012333:RNA, Messenger / Q000378:metabolism; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000737:chemistry*
D005656:Fungal Proteins; D006588:Hexanones; D009687:Nuclear Proteins; D015800:Protozoan Proteins; C113862:PslA protein, Dictyostelium discoideum; D012333:RNA, Messenger; D014157:Transcription Factors; C053433:1-((3,5-dichloro)-2,6-dihydroxy-4-methoxyphenyl)-1-hexanone