Dynamics and function of the inositolcycle in <i>Dictyostelium discoideum</i>

Bominaar, Anthony A.; Vanderkaay, J; Vanhaastert, Pjm

doi:10.1002/dvg.1020120106

Cited by 9 publications

(4 citation statements)

References 13 publications

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“…The current model for signal transduction in Dictyostelium is largely based on the observations made withfgd A. This mutant lacks one G-protein and is defective in nearly all sensory transduction in vivo, including the activation of adenylate cyclase, guanylate cyclase and phospholipase C [14,15,17]. Since GTP[S] stimulation of adenylate and guanylate cyclases in vitro are essentially normal, and GTP[S] stimulation of phospholipase C is absent, a hierarchy of signal transduction was proposed, with G2 and its effector (possibly phospholipase C) at the heart and adenylate and guanylate cyclases downstream.…”

Section: Discussionmentioning

confidence: 99%

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Phospholipase C in Dictyostelium discoideum. Identification of stimulatory and inhibitory surface receptors and G-proteins

Bominaar

Haastert

1994

Biochemical Journal

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A combined biochemical and genetic approach was used to show that phospholipase C in the cellular slime mould Dictyostelium is under dual regulation by the chemoattractant cyclic AMP (cAMP). This dual regulation involves stimulatory and inhibitory surface receptors and G-proteins. In wild-type cells both cAMP and guanosine 5'-[gamma-thio]triphosphate (GTP[S]) stimulated phospholipase C. In contrast, mutant fgd A, lacking the G-protein alpha-subunit G alpha 2, showed no stimulation by either cAMP or GTP[S], indicating that G alpha 2 is the stimulatory G-protein. In mutant fgd C cAMP did not stimulate phospholipase C, but stimulation by GTP[S] was normal, suggesting that the defect in this mutant is upstream of the stimulatory G alpha 2. Inhibition of phospholipase C was achieved in wild-type cells by the partial antagonist 3'-deoxy-3'-aminoadenosine 3',5'-phosphate (3'NH-cAMP). This inhibition was no longer observed in transformed cell lines lacking either the surface cAMP receptor cAR1 or the G-protein alpha-subunit G alpha 1; in these cells the agonist cAMP still activated phospholipase C. These results indicate that Dictyostelium phospholipase C is regulated via a stimulatory and an inhibitory pathway. The inhibitory pathway is composed of the surface receptor cAR1 and the G-protein G1. The stimulatory pathway consists of an unknown cAMP receptor (possibly the fgd C gene product) and the G-protein G2.

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Section: Discussionmentioning

confidence: 99%

“…Mutants of the frigid class (fgd) are defective in cAMP-induced development [14]. Previous work showed that Ins(1,4,5)P3 signalling is impaired in mutants fgd A and fgd C [15][16][17]. In the mutant fgd A nearly all signal transduction is blocked, due to a deletion in one of the a-subunits of G-proteins, Ga2 [15,18].…”

Section: Introductionmentioning

confidence: 99%

Phospholipase C in Dictyostelium discoideum. Identification of stimulatory and inhibitory surface receptors and G-proteins

Bominaar

Haastert

1994

Biochemical Journal

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“…These advances have themselves led to significant insights into the regulation of gene expression in Dictyostelium, but are only the first stage in developing a complete understanding of how Dictyostelium development is co-ordinated. The next stage in expanding this knowledge is to determine which secondmessenger systems are activated in response to each receptor subtype, and at what stages in development they function. Recent results have identified at least three second-messenger systems activated by cyclic AMP via G-protein-coupled pathways in Dictyosteliupn: adenylate cyclase [9,10], guanylate cyclase [11,12] and inositol phospholipid/Ca2+ messenger systems that have been shown to be essential in regulating gene expression, as well as chemotaxis and morphogenesis [13][14][15][16]. Although all three systems have been demonstrated to be activated by extracellular cyclic AMP bound to cell-surface receptors and guanosine 5'-[y-thio]triphosphate (GTP[S]) in membranes or permeabilized cell preparations [17][18][19], the Gac subunits with which they interact, and the times in development when they are active,…”

Section: Introductionmentioning

confidence: 99%

Characterization of phospholipase activity in Dictyostelium discoideum. Identification of a Ca2+-dependent polyphosphoinositide-specific phospholipase C

Cubitt

Firtel

1992

Biochemical Journal

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We have identified a Ca(2+)-dependent polyphosphoinositide-specific phospholipase C activity in Dictyostelium discoideum. Addition of Ca2+ (20 microM) results in the rapid formation of Ins(1,4,5)P3 within 5 s and leads to sustained inositol phosphate production for up to 40 min in membranes prepared from [3H]inositol-labelled cells. The phospholipase C activity is primarily membrane-bound under the conditions used to lyse the cells. In addition to this activity we also identified a family of Ca(2+)-regulated phospholipase activities active on a range of phospholipid substrates, using [3H]palmitate labelling. Inositol-specific phospholipase C activity is highest in vegetatively growing cells and in starved cells during the first 6 h in development, during which time Ca2+ elicited a 5-fold stimulation of inositol phosphate formation. After this time, total activity decreased progressively until 15 h, after which the activity remained constant up until 24 h. During this period, Ca2+ was able to stimulate a 2-fold increase in inositol phosphates.

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“…When [ 3 H]inositol is introduced into Dictyostelium cells by electroporation, the label is rapidly converted to PtdIns reaching a maximum after 10 min [9, 10]. It then takes a relatively long time to form PtdIns4P (maximal after 45 min), which is converted within 15 min to PtdIns(4,5)P 2 .…”

Section: De Novo Synthesis Of Inositol and Formation Of Inositol Phosmentioning

confidence: 99%

Biochemistry and genetics of inositol phosphate metabolism in Dictyostelium

Haastert

Dijken

1997

FEBS Letters

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Biochemical and genetic data on the metabolism of inositol phosphates in the microorganism Dictyostelium are combined in a scheme composed of in five subroutes. The first subroute is the inositol cycle as found in other organisms: inositol is incorporated into phospholipids that are hydrolysed by PLC producing Ins(l,4,5)P 3 which is dephosphorylated to inositol. The second subroute is the sequential phosphorylation of inositol to InsP 6 ; the Ins(3,4,6)P 3 intermediate does not release Ca 2+ . The third subroute is the sequential phosphorylation of Ins(l,4,5)P 3 to InsP 6 in a nucleus associated fraction, whereas the fourth subroute is the dephosphorylation of Ins(l,3,4,5,6)P 5 to Ins(l,4,5)P 3 at the plasma membrane. This last route mediates Ins(l,4,5)P 3 formation in cells with a disruption of the single PLC gene. Finally, we recognize the formation of InsP7 and InsP g as the fifth subroute.

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Dynamics and function of the inositolcycle in Dictyostelium discoideum

Abstract: The inositolcycle in Dictyostelium discoideum was studied under several conditions both in vitro and in vivo. The results are compared with the inositolcycle as it is known from higher eukaryotes: although there is a strong resemblance both cycles are different at some essential points.

Cited by 9 publications

References 13 publications

Phospholipase C in Dictyostelium discoideum. Identification of stimulatory and inhibitory surface receptors and G-proteins

Phospholipase C in Dictyostelium discoideum. Identification of stimulatory and inhibitory surface receptors and G-proteins

Characterization of phospholipase activity in Dictyostelium discoideum. Identification of a Ca2+-dependent polyphosphoinositide-specific phospholipase C

Biochemistry and genetics of inositol phosphate metabolism in Dictyostelium

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