Temporal and spatial expression of ammonium transporter genes during growth and development of Dictyostelium discoideum

Follstaedt, Susan C.; Kirsten, Janet H.; Singleton, Charles K.

doi:10.1111/j.1432-0436.2003.07109002.x

Cited by 20 publications

(21 citation statements)

References 37 publications

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“…Nevertheless, the previous study and our current study clearly demonstrate that AmtA is expressed during development. Furthermore, we confirmed the localization of amtA mRNA in prespore cells in slugs (20), using Northern blotting (Fig. 3B).…”

Section: Strainssupporting

confidence: 63%

“…However, the molecular mechanisms underlying ammonia homeostasis are poorly understood. Previous studies have suggested that AmtA functions in ammonia transport or ammonia sensing (20,62). In this paper, supporting a role for AmtA in ammonium transport, we have shown that AmtA is required for normal ammonia homeostasis in Dictyostelium during growth and development.…”

Section: Discussionsupporting

confidence: 49%

“…The expression level increased continuously during development. This is in contrast with previous studies using reverse transcription-PCR that showed that amtA mRNA levels do not change during development (20). The apparent difference may result from different methods used to measure mRNA levels.…”

Section: Strainscontrasting

confidence: 54%

“…Previous studies have shown that developmental phenotypes in cells lacking AmtC can be rescued by deleting the AmtA protein (62). These studies suggest that AmtC and AmtA antagonistically regulate developmental processes and that AmtA and AmtC function in either ammonium transport or ammonium sensing (20,37,62). In this study, we show that AmtA regulates intracellular ammonium/ammonia levels during growth and development and is critical for the morphogenesis of multicellular aggregates and normal spore formation.…”

mentioning

confidence: 55%

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Regulation of Ammonia Homeostasis by the Ammonium Transporter AmtA in Dictyostelium discoideum

et al. 2007

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Ammonia has been shown to function as a morphogen at multiple steps during the development of the cellular slime mold Dictyostelium discoideum; however, it is largely unknown how intracellular ammonia levels are controlled. In the Dictyostelium genome, there are five genes that encode putative ammonium transporters: amtA, amtB, amtC, rhgA, and rhgB. Here, we show that AmtA regulates ammonia homeostasis during growth and development. We found that cells lacking amtA had increased levels of ammonia/ammonium, whereas their extracellular ammonia/ ammonium levels were highly decreased. These results suggest that AmtA mediates the excretion of ammonium. In support of a role for AmtA in ammonia homeostasis, AmtA mRNA is expressed throughout the life cycle, and its expression level increases during development. Importantly, AmtA-mediated ammonia homeostasis is critical for many developmental processes. amtA ؊ cells are more sensitive to NH 4 Cl than wild-type cells in inhibition of chemotaxis toward cyclic AMP and of formation of multicellular aggregates. Furthermore, even in the absence of exogenously added ammonia, we found that amtA ؊ cells produced many small fruiting bodies and that the viability and germination of amtA ؊ spores were dramatically compromised. Taken together, our data clearly demonstrate that AmtA regulates ammonia homeostasis and plays important roles in multiple developmental processes in Dictyostelium.

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Section: Strainssupporting

confidence: 63%

Section: Discussionsupporting

confidence: 49%

Section: Strainscontrasting

confidence: 54%

mentioning

confidence: 55%

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Regulation of Ammonia Homeostasis by the Ammonium Transporter AmtA in Dictyostelium discoideum

et al. 2007

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“…Thus, during the evolutionary period of their co-occurrence, Rh and Amt had been subject to independent divergent changes, probably driven by their own functional adaptation or selection. Indeed, the knockdown or knockout of Rh vs. Amt found in same organisms produced different phenotypes, as seen in green alga (7,8) or slime mold (21,49). It should be noted that the embryonic phenotypes caused by rhr-1 RNAi cannot be compensated by endogenously expressed amt genes.…”

Section: Embryonic Lethality Of Cerh1 Rnai Mutants Can Be Rescued Bymentioning

confidence: 99%

CeRh1 ( rhr-1 ) is a dominant Rhesus gene essential for embryonic development and hypodermal function in Caenorhabditis elegans

Hashmi

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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Rhesus (Rh) proteins share a conserved 12-transmembrane topology and specify a family of putative CO 2 channels found in diverse species from microbes to human, but their functional essentiality and physiological importance in metazoans is unknown. To address this key issue and analyze Rh-engaged physiologic processes, we sought to explore model organisms with fewer Rh genes yet are tractable to genetic manipulations. In this article, we describe the identification in nematodes of two Rh homologues that are highly conserved and similar to human Rh glycoproteins, and we focus on their characterization in Caenorhabditis elegans. RNA analysis revealed that CeRh1 is abundantly expressed in all developmental stages, with highest levels in adults, whereas CeRh2 shows a differential and much lower expression pattern. In transient expression in human cells, both CeRh1 and CeRh2-GFP fusion proteins were routed to the plasma membrane. Transgenic analysis with GFP or LacZ-fusion reporters showed that CeRh1 is mainly expressed in hypodermal tissue, although it is also in other cell types. Mutagenesis analysis using deletion constructs mapped a minimal promoter region driving CeRh1 gene expression. Although CeRh2 was dispensable, RNA interference with CeRh1 caused a lethal phenotype mainly affecting late stages of C. elegans embryonic development, which could be rescued by the CbRh1 homologue from the worm Caenorhabditis briggsae. Taken together, our data provide direct evidence for the essentiality of the CeRh1 gene in C. elegans, establishing a useful animal model for investigating CO2 channel function by cross-species complementation.animal development ͉ CO2 channels ͉ genetic rescue ͉ Rhesus family ͉ RNA interference R hesus (Rh) defines a family of Rh blood group-related membrane proteins found in red cells and other tissues (1-3). It is now clear that this family is of ancient origin and has members not only spread in unicellular organisms from photosynthetic green algae (4) to social amoeba slime molds (5) but also is ubiquitous in metazoans. Although variable from one to six genes depending on species, Rh proteins are unified by their high primary sequence identities and their characteristic 12-transmembrane (TM)-spanning organization (1, 5). Such cross-phyla structural features pinpoint Rh family homologues as sharing a conserved transport function and constituting a unique division within the extended major facilitator superfamily (6).The function of Rh proteins has long been puzzling, but increasing evidence indicates that they specify a family of gas channels for CO 2 , a discovery made by studying Rh1 in Chlamydomonas reinhardtii, a green alga (4, 7). In this organism, Rh1 is specifically induced by 3% CO 2 (4), and its knockdown by RNA interference (RNAi) deters the cells from rapid growth at high CO 2 levels (7). Consistent with this substrate specificity, Rh differs from related ammonium transporters (Amt) in evolutionary history and functional diversification (5), and the phenotypes of an AMT mutant strain a...

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Differentiation‐inducing factor 2 modulates chemotaxis via the histidine kinase DhkC‐dependent pathway in Dictyostelium discoideum

Kuwayama

Kubohara

2016

FEBS Letters

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Edited by Dietmar MansteinDifferentiation-inducing factor 1(DIF-1) and DIF-2 are signaling molecules that control chemotaxis in Dictyostelium discoideum. Whereas DIF-1 suppresses chemotaxis in shallow cAMP gradients, DIF-2 enhances chemotaxis under the same conditions via a phosphodiesterase, response regulator A (RegA), which is a part of the DhkC-RdeA-RegA two-component signaling system. In this study, to investigate the mechanism of the chemotaxis regulation by DIF-2, we examined the effects of DIF-2 (and DIF-1) on chemotaxis in rdeA À and dhkC À mutant strains. In the parental wild-type strains, chemotactic cell movement was suppressed with DIF-1 and enhanced with DIF-2 in shallow cAMP gradients. In contrast, in both rdeA À and dhkC À strains, chemotaxis was suppressed with DIF-1 but unaffected by DIF-2. The results suggest that DIF-2 modulates chemotaxis via the DhkC-RdeA-RegA signaling system.

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Temporal and spatial expression of ammonium transporter genes during growth and development of Dictyostelium discoideum

Cited by 20 publications

References 37 publications

Regulation of Ammonia Homeostasis by the Ammonium Transporter AmtA in Dictyostelium discoideum

Regulation of Ammonia Homeostasis by the Ammonium Transporter AmtA in Dictyostelium discoideum

CeRh1 ( rhr-1 ) is a dominant Rhesus gene essential for embryonic development and hypodermal function in Caenorhabditis elegans

Differentiation‐inducing factor 2 modulates chemotaxis via the histidine kinase DhkC‐dependent pathway in Dictyostelium discoideum

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