Disruption of the sporulation-specific gene spiA in Dictyostelium discoideum leads to spore instability.

Richardson, D.; Loomis, William F.

doi:10.1101/gad.6.6.1058

Cited by 44 publications

(37 citation statements)

References 39 publications

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“…We transformed both clones with the stalk-cell specific reporter ST-gal (Ceccarelli et al, 1991) and the spore-specific reporter spiA-gal (Richardson and Loomis, 1992), as well as the prestalk-specific construct ecmA-gal (Early et al, 1993). The staining patterns were all normal (not shown); rblA is not necessary in either the stalk or spore differentiation pathways.…”

Section: Research Articlementioning

confidence: 99%

A retinoblastoma ortholog controls stalk/spore preference inDictyostelium

MacWilliams¹,

Doquang

Pedrola

et al. 2006

Development

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We describe rblA, the Dictyostelium ortholog of the retinoblastoma susceptibility gene Rb. In the growth phase, rblA expression is correlated with several factors that lead to 'preference' for the spore pathway. During multicellular development, expression increases 200-fold in differentiating spores. rblA-null strains differentiate stalk cells and spores normally, but in chimeras with wild type, the mutant shows a strong preference for the stalk pathway. rblA-null cells are hypersensitive to the stalk morphogen DIF, suggesting that rblA normally suppresses the DIF response in cells destined for the spore pathway. rblA overexpression during growth leads to G1 arrest, but as growing Dictyostelium are overwhelmingly in G2 phase, rblA does not seem to be important in the normal cell cycle. rblA-null cells show reduced cell size and a premature growth-development transition; the latter appears anomalous but may reflect selection pressures acting on social ameba.

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Section: Research Articlementioning

confidence: 99%

A retinoblastoma ortholog controls stalk/spore preference inDictyostelium

MacWilliams¹,

Doquang

Pedrola

et al. 2006

Development

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“…6C). The spiA gene is normally expressed exclusively within encapsulating prespore cells and is required for the long-term stability of dormant spores (Richardson and Loomis, 1992;Richardson et al, 1994). The spiA mRNA displayed slightly lower spore/stalk enrichment in the tagA mutant samples compared to the wild type (Fig.…”

Section: Cell Type Specificity Of Gene Expression Is Compromised In Tmentioning

confidence: 99%

TagA, a putative serine protease/ABC transporter ofDictyosteliumthat is required for cell fate determination at the onset of development

et al. 2003

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The tag genes of Dictyostelium are predicted to encode multi-domain proteins consisting of serine protease and ATP-binding cassette transporter domains. We have identified a novel tag gene, tagA, which is involved in cell type differentiation. The tagA mRNA accumulates during the first four hours of development,whereas TagA protein accumulates between two and ten hours of development and decreases thereafter. Wild-type cells express tagA in prespore cells and mature spores, defining tagA expression as prespore specific. However, tagA mutant cells that activate the tagA promoter do not sporulate, but instead form part of the outer basal disc and lower cup of the fruiting body. tagA mutant aggregates elaborate multiple prestalk cell regions during development and produce spores asynchronously and with low viability. tagA mutants produce about twice as many prestalk cells as the wild type as judged by a prestalk cell reporter construct. When mixed with wild-type cells, tagA- cells become overrepresented in the prestalk cell population, suggesting that this phenotype is cell-autonomous. These results suggest that TagA is required for the specification of an initial population of prespore cells in which tagA is expressed. Expression profiling uncovered a delay in the transcriptional program between 2 and 6 hours, coincident with TagA expression, revealing an early function for TagA. TagA also appears to play a general role in cell fate determination since tagA mutants express a spore coat protein gene (cotB) within vacuolated cells that form part of the stalk and they express a prestalk/stalk-specific gene (ecmB)within cells that become spores. The expression of TagA at two hours of development, the observed coincident delay in the transcriptional program and the subsequent mis-expression of cell-type specific genes provide evidence for cell fate determination beginning in some cells much earlier than previously believed.

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“…To study the expression pattern of cell-type-specific genes and the spatial patterning of the individual cells types in chimeric organisms, lagC-null cells transformed with lacZ gene fusions driven by the ecmA, rasD, and SP60, spiA, and ecmBz189 promoters were mixed with wild-type cells in the original 1:3 ratio, and the pattern of B-gal expression was examined during development (for promoter references, see Haberstroh and Firtel 1990;Ceccarelli et al 1991;Esch and Firtel 1991;Jermyn and Williams 1991;Richardson and Loomis 1992;Mann and Firtel 1993;D. Richardson, W. Loomis, and A. Kimmel, in prep.…”

Section: Mosaic Analysis Of Lagc-null Cells Developed With Wild-type mentioning

confidence: 99%

LagC is required for cell-cell interactions that are essential for cell-type differentiation in Dictyostelium.

Dynes¹,

Clark²,

Shaulsky³

et al. 1994

Genes Dev.

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143

136

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Strain AK127 is a developmental mutant of Dictyostelium discoideum that was isolated by restriction enzyme-mediated integration (REMI). Mutant cells aggregate normally but are unable to proceed past the loose aggregate stage. The cloned gene, lagC (loose aggregate C), encodes a novel protein of 98 kD that contains an amino-terminal signal sequence and a putative carboxy-terminal transmembrane domain. The mutant strain AK127 shows no detectable lagC transcript upon Northern analysis, indicating that the observed phenotype is that of a null allele. Expression of the lagC cDNA in AKI27 cells complements the arrest at the loose aggregate stage, indicating that the mutant phenotype results from disruption of the lagC gene. In wild-type cells, lagC mRNA is induced at the loose aggregate stage and is expressed through the remainder of development, lagC-null cells aggregate but then disaggregate and reaggregate to form small granular mounds. Mature spores are produced at an extremely low efficiency (<0.1% of wild type), appearing only after -72 hr, whereas wild-type strains produce mature spores by 26 hr. lagC-null cells accumulate reduced levels of transcripts for the prestalk-enriched genes rasD and CP2 and do not express the DIF-induced prestalk-specific gene ecmA or the cAMP-induced prespore-specific gene SP60 to significant levels. In chimeric organisms resulting from the coaggregation of lagC-null and wild-type cells, cell-type-specific gene expression is rescued in the lagC-null cells; however, lagC-prespore cells are localized to the posterior of the prespore region and do not form mature spores, suggesting that LagC protein has both no cell-autonomous and cell-autonomous functions. Overexpression of lagC from an actin promoter in both wild-type and lagC-cells causes a delay at the tight aggregate stage, the first stage requiring LagC activity. These results suggest that the LagC protein functions as a nondiffusible cell-cell signaling molecule that is required for multicellular development.

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Disruption of the sporulation-specific gene spiA in Dictyostelium discoideum leads to spore instability.

Cited by 44 publications

References 39 publications

A retinoblastoma ortholog controls stalk/spore preference inDictyostelium

A retinoblastoma ortholog controls stalk/spore preference inDictyostelium

TagA, a putative serine protease/ABC transporter ofDictyosteliumthat is required for cell fate determination at the onset of development

LagC is required for cell-cell interactions that are essential for cell-type differentiation in Dictyostelium.

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