Molecular Genetic Analysis of Signal Transduction Pathways Controlling Multicellular Development in Dictyostelium

Cubitt, A B; Carrel, Faculte Alexis; Dharmawardhane, Su; Gaskins, Chris J.; Hadwiger, Jeffrey A.; Howard, Peter K.; Mann, Sandra K.O.; Okaichi, Kumio; Zhou, Kailiang; Firtel, Richard A.

doi:10.1101/sqb.1992.057.01.023

Cited by 23 publications

(18 citation statements)

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“…PLD activity has been detected in D. discoideum during the final stage of development prior to the formation of the "fruiting body" (39). Although little is known about the physiological role of PLD during Dictyostelium development, the slime mold does harbor a single PLC gene, which structurally resembles mammalian PLC-␦ (40).…”

Section: Resultsmentioning

confidence: 99%

Expression of a Novel Murine Phospholipase D Homolog Coincides with Late Neuronal Development in the Forebrain

Pedersen¹,

Finsen²,

Celis³

et al. 1998

Journal of Biological Chemistry

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Members of the phospholipase D (PLD) superfamily are defined by the conserved HXKXXXXD motif, which is essential for the catalytic function of mammalian PLD. PLD enzymes are thought to play roles in signal transduction and membrane vesicular trafficking in mammalian cells. Here we describe a 54-kDa novel murine polypeptide (designated SAM-9) that is predicted to be a membrane-associated member of the PLD superfamily. SAM-9 shares 40, 30, and 29% amino acid identity with potential orthologs, in vaccinia virus, Caenorhabditis elegans, and Dictyostelium discoideum, respectively, and belongs to a subclass of PLD homologs in which the second HXKXXXXD motif is imperfect and harbors a conserved Asp to Glu substitution. The sam-9 gene has more than eight exons, and the two HXKXXXXD motifs are encoded by two highly conserved exons. The expression of the sam-9 gene is greater in the brain than in non-nervous tissue and appears to be predominantly of neuronal origin. sam-9 expression is pronounced in mature neurons of the forebrain and appears to be turned on at late stages of neurogenesis as revealed by in situ hybridization analysis of sam-9 expression during postnatal development of the hippocampal formation and the primary somatosensory cortex.

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Section: Resultsmentioning

confidence: 99%

Expression of a Novel Murine Phospholipase D Homolog Coincides with Late Neuronal Development in the Forebrain

Pedersen¹,

Finsen²,

Celis³

et al. 1998

Journal of Biological Chemistry

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“…CMF Activates Phospholipase C-Under some circumstances, cells lacking G␣1 show altered patterns of IP 3 and diacylglycerol accumulation, suggesting that G␣1 may regulate PLC (27,38). To examine whether CMF activation of G␣1 affects PLC activity, production of IP 3 was measured after cells were stimulated with CMF.…”

Section: G␣1 Mediates Cmf Signal Transduction and The Absence Of G␣1mentioning

confidence: 99%

“…During late development, the absence of G␣1 causes fruiting bodies to have abnormally thin stalks (24,26) and causes decreased 1,2-diacylglycerol accumulation (27). Cells overexpressing G␣1 or containing a constitutively active form of G␣1 have roughly normal aggregation and form normal looking slugs but then form very abnormal fruiting bodies with thick basal disks, which are accompanied by increased 1,2-diacylglycerol accumulation (26,27).…”

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confidence: 99%

Cell Density Sensing Mediated by a G Protein-coupled Receptor Activating Phospholipase C

Brazill

Lindsey

Bishop

et al. 1998

Journal of Biological Chemistry

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When the unicellular eukaryote Dictyostelium discoideum starves, it senses the local density of other starving cells by simultaneously secreting and sensing a glycoprotein called conditioned medium factor (CMF). When the density of starving cells is high, the corresponding high density of CMF permits signal transduction through cAR1, the chemoattractant cAMP receptor. cAR1 activates a heterotrimeric G protein whose ␣-subunit is G␣2. CMF regulates cAMP signal transduction in part by regulating the lifetime of the cAMP-stimulated G␣2-GTP configuration. We find here that guanosine 5-3-O-(thio)triphosphate (GTP␥S) inhibits the binding of CMF to membranes, suggesting that the putative CMF receptor is coupled to a G protein. Cells lacking G␣1 (G␣1 null) do not exhibit GTP␥S inhibition of CMF binding and do not exhibit CMF regulation of cAMP signal transduction, suggesting that the putative CMF receptor interacts with G␣1. Work by others has suggested that G␣1 inhibits phospholipase C (PLC), yet when cells lacking either G␣1 or PLC were starved at high cell densities (and thus in the presence of CMF), they developed normally and had normal cAMP signal transduction. We find that CMF activates PLC. G␣1 null cells starved in the absence or presence of CMF behave in a manner similar to control cells starved in the presence of CMF in that they extend pseudopods, have an activated PLC, have a low cAMP-stimulated GTPase, permit cAMP signal transduction, and aggregate. Cells lacking G␤ have a low PLC activity that cannot be stimulated by CMF. Cells lacking PLC exhibit IP 3 levels and cAMPstimulated GTP hydrolysis rates intermediate to what is observed in wild-type cells starved in the absence or in the presence of an optimal amount of CMF. We hypothesize that CMF binds to its receptor, releasing G␤␥ from G␣1. This activates PLC, which causes the G␣2 GTPase to be inhibited, prolonging the lifetime of the cAMPactivated G␣2-GTP configuration. This, in turn, allows cAR1-mediated cAMP signal transduction to take place.

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“…As the aggregate forms, cAMP and other extracellular signaling molecules regulate morphogenesis and cellular differentiation, and within 24 h, a mature fruiting body is formed. While a significant amount is known about the signaling pathways that control cellular differentiation and gene regulation, little is known about the nuclear factors that mediate this regulation (4,6,25,26,45). The only cloned transcription factor with a known function is G box binding factor (GBF), which is essential for cAMPmediated induction of cell differentiation and late gene expression during multicellular development (37).…”

mentioning

confidence: 99%

Growth and Developmental Functions of a Human Immunodeficiency Virus Tat-Binding Protein/26S Protease Subunit Homolog from Dictyostelium discoideum

Cao

Firtel

1995

Molecular and Cellular Biology

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Molecular Genetic Analysis of Signal Transduction Pathways Controlling Multicellular Development in Dictyostelium

Cited by 23 publications

References 0 publications

Expression of a Novel Murine Phospholipase D Homolog Coincides with Late Neuronal Development in the Forebrain

Expression of a Novel Murine Phospholipase D Homolog Coincides with Late Neuronal Development in the Forebrain

Cell Density Sensing Mediated by a G Protein-coupled Receptor Activating Phospholipase C

Growth and Developmental Functions of a Human Immunodeficiency Virus Tat-Binding Protein/26S Protease Subunit Homolog from Dictyostelium discoideum

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