Cytokinins induce sporulation in<i>Dictyostelium</i>

Anjard, Christophe; Loomis, William F.

doi:10.1242/dev.018051

Cited by 54 publications

(98 citation statements)

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“…Encapsulated spores were recognized as phase bright by phase-contrast microscopy (7,8). The proportion of encapsulated cells rose from 14% to 35% by 90 min, which is the same timing and level of spore formation observed upon addition of SDF-1 and is significantly slower and less efficient than what is observed upon addition of SDF-2 or cytokinins (2,3,7,8). Moreover, the induction of spore differentiation by MPBD, like induction by SDF-1, could be blocked by simultaneous addition of cycloheximide to inhibit protein synthesis (Fig.…”

Section: Resultsmentioning

confidence: 53%

The Polyketide MPBD Initiates the SDF-1 Signaling Cascade That Coordinates Terminal Differentiation in Dictyostelium

Anjard

Loomis

2011

Eukaryot Cell

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Dictyostelium uses a wide array of chemical signals to coordinate differentiation as it switches from a unicellular to a multicellular organism. MPBD, the product of the polyketide synthase encoded by stlA, regulates stalk and spore differentiation by rapidly stimulating the release of the phosphopeptide SDF-1. By analyzing specific mutants affected in MPBD or SDF-1 production, we delineated a signal transduction cascade through the membrane receptor CrlA coupled to G␣1, leading to the inhibition of GskA so that the precursor of SDF-1 is released. It is then processed by the extracellular protease of TagB on prestalk cells. SDF-1 apparently acts through the adenylyl cyclase ACG to activate the cyclic AMP (cAMP)-dependent protein kinase A (PKA) and trigger the production of more SDF-1. This signaling cascade shows similarities to the SDF-2 signaling pathway, which acts later to induce rapid spore encapsulation.

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Section: Resultsmentioning

confidence: 53%

The Polyketide MPBD Initiates the SDF-1 Signaling Cascade That Coordinates Terminal Differentiation in Dictyostelium

Anjard

Loomis

2011

Eukaryot Cell

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“…3. iP, N 6 -isopentenyladenine; DZ,dihydrozeatin;tZ,cZ,Kin,kinetin;BA,mT,oT,orthotopolin;CPPU,TDZ,thidiazuron. animals shortly after the separation of plants and animals but which retained characteristics of both kingdoms (Anjard and Loomis 2008). Dictyostelium has three IPT genes -two coding proteins closely related to the bacterial and eukaryotic tRNA-IPTs and one IPT involved in de novo CK synthesis -and two genes coding for proteins similar to members of a twocomponent system (TCS; Anjard and Loomis 2008).…”

Section: Ck-related Genes Originate From Bacteriamentioning

confidence: 99%

“…Interestingly, Dictyostelium codes for two cyclases-histidine-kinaseassociated sensory extracellular (CHASE) domains that contain proteins that are similar to receptors sensing CK signals in plants. However, neither appears to be a cytokinin receptor and CKs that are essential inducers of Dictyostelium sporulation act through another pathway that is as yet unknown (Anjard and Loomis 2008). No other gene with significant homology to the CK-sensing CHASE domain has been found anywhere apart from land plants, including in algal or cyanobacterial genomes, except for the genome of the virus Ectocarpus siliculosus virus 1 (Pils and Heyl 2009;Frébort et al 2011).…”

Section: Ck-related Genes Originate From Bacteriamentioning

confidence: 99%

Cytokinins - recent news and views of evolutionally old molecules

Spíchal¹

2012

Functional Plant Biol.

159

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Cytokinins (CKs) are evolutionally old and highly conserved low-mass molecules that have been identified in almost all known organisms. In plants, they evolved into an important group of plant hormones controlling many physiological and developmental processes throughout the whole lifespan of the plant. CKs and their functions are, however, not unique to plants. In this review, the strategies and mechanisms of plants – and phylogenetically distinct plant-interacting organisms such as bacteria, fungi, nematodes and insects employing CKs or regulation of CK status in plants – are described and put into their evolutionary context. The major breakthroughs made in the last decade in the fields of CK biosynthesis, degradation and signalling are also summarised.

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“…SDF-1, another secreted peptide, acts on ACG to activate PKA (Anjard and Loomis, 2008), and discadenine acts on the histidine kinase DhkB and ACR to upregulate PKA. Discadenine also acts in parallel to high osmolality to keep spores dormant in the spore head (Anjard and Loomis, 2008;Zinda and Singleton, 1998). This redundancy of regulatory pathways highlights the crucial importance of making and germinating spores only at the correct time and place.…”

Section: The Spore Pathwaymentioning

confidence: 99%

Evolutionary crossroads in developmental biology: Dictyostelium discoideum

Schaap

2011

Development

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SummaryDictyostelium discoideum belongs to a group of multicellular life forms that can also exist for long periods as single cells. This ability to shift between uni-and multicellularity makes the group ideal for studying the genetic changes that occurred at the crossroads between uni-and multicellular life. In this Primer, I discuss the mechanisms that control multicellular development in Dictyostelium discoideum and reconstruct how some of these mechanisms evolved from a stress response in the unicellular ancestor.Key words: Evolution of multicellularity, Social amoeba, Encystation, Sporulation, Dictyostelium IntroductionThe social amoebas, or Dictyostelia, are a group of organisms that become multicellular by aggregation and then proceed to build fruiting bodies that consist of stalk cells and spores (see Glossary, Box 1). This developmental cycle is a response to starvation, and involves both highly coordinated cell movement and a tightly controlled programme of cell differentiation. Social amoebas belong to the supergroup of Amoebozoa (see Glossary, Box 1), a sister group to the clade of Opisthokonts (see Glossary, Box 1), which contains the animals and fungi. All supergroups contain unicellular protist-like organisms (see Glossary, Box 1) and, in several groups, multicellular life forms have evolved independently (Minge et al., 2009).The Amoebozoa supergroup consists mainly of unicellular amoeba-like organisms that have a simple life cycle. The feeding amoeba or trophozoite turns into a dormant cyst when faced with food shortage, drought or other life-threatening circumstances (Cavalier-Smith et al., 2004). Several clades of Amoebozoa have given rise to protostelid-like organisms (see Glossary, Box 1), which form a very simple fruiting body (see Glossary, Box 1) that consists of a single spore that sits on a simple stalk made by the same cell (Shadwick et al., 2009). However, only the Dictyostelia are able to form multicellular fruiting bodies that contain up to a million cells (Fig. 1).There are ~120 known species of Dictyostelia and a molecular phylogeny has been constructed to reveal the order in which they evolved (Schaap et al., 2006). The phylogeny subdivides species into four major groups (Fig. 2), with the model social amoeba Dictyostelium discoideum belonging to the most recently diverged group 4. Many species in groups 1-3 can still encyst as single cells when conditions are unfavourable for aggregation. However, group 4 species have lost the ability to encyst. Strikingly, all group 4 species tested secrete cyclic adenosine monophosphate (cAMP) to act as a chemoattractant for aggregation. This is most unusual, because almost all other organisms only use cAMP inside the cell to transduce the effect of other secreted stimuli, such as hormones, mating factors and neurotransmitters. None of the species in groups 1-3 uses cAMP for aggregation; some use glorin, a modified dipeptide of glutamate and ornithine, whereas others use folic acid, pterin or other as yet unidentified chemoattractants (Schaap e...

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Cytokinins induce sporulation inDictyostelium

Cited by 54 publications

References 36 publications

The Polyketide MPBD Initiates the SDF-1 Signaling Cascade That Coordinates Terminal Differentiation in Dictyostelium

The Polyketide MPBD Initiates the SDF-1 Signaling Cascade That Coordinates Terminal Differentiation in Dictyostelium

Cytokinins - recent news and views of evolutionally old molecules

Evolutionary crossroads in developmental biology: Dictyostelium discoideum

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