Genes Required for Osmoregulation and Apical Secretion in <i>Caenorhabditis elegans</i>

Liégeois, Samuel; Benedetto, Alexandre; Michaux, Grégoire; Belliard, Guillaume; Labouesse, Michel

doi:10.1534/genetics.106.066035

Cited by 76 publications

(62 citation statements)

References 60 publications

(111 reference statements)

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“…Possible targets of Ttk might be genes related to the apical surface and the underlying cytoskeleton, because several of these genes are involved in C. elegans excretory canal formation (Buechner, 2002;Gobel et al, 2004). Additionally, genes involved in intracellular vesicle trafficking might also be good candidates, as has been recently reported for C. elegans (Liegeois et al, 2007). In this respect, we have detected several abnormalities in ttk mutants that might reflect defects in vesicle trafficking.…”

Section: Ttk In Tube Sizesupporting

confidence: 68%

Tramtrack regulates different morphogenetic events duringDrosophilatracheal development

2007

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*Tramtrack (Ttk) is a widely expressed transcription factor, the function of which has been analysed in different adult and embryonic tissues in Drosophila. So far, the described roles of Ttk have been mainly related to cell fate specification, cell proliferation and cell cycle regulation. Using the tracheal system of Drosophila as a morphogenetic model, we have undertaken a detailed analysis of Ttk function. Ttk is autonomously and non-autonomously required during embryonic tracheal formation. Remarkably, besides a role in the specification of different tracheal cell identities, we have found that Ttk is directly involved and required for different cellular responses and morphogenetic events. In particular, Ttk appears to be a new positive regulator of tracheal cell intercalation. Analysis of this process in ttk mutants has unveiled cell shape changes as a key requirement for intercalation and has identified Ttk as a novel regulator of its progression. Moreover, we define Ttk as the first identified regulator of intracellular lumen formation and show that it is autonomously involved in the control of tracheal tube size by regulating septate junction activity and cuticle formation. In summary, the involvement of Ttk in different steps of tube morphogenesis identifies it as a key player in tracheal development.

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Section: Ttk In Tube Sizesupporting

confidence: 68%

Tramtrack regulates different morphogenetic events duringDrosophilatracheal development

2007

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“…In the case of the C. elegans subunit a2, Vha-5, it is unclear at this point whether it is regulated by Ca 2ϩ ⅐CaM. However, Vha-5 is required for two genetically separable functions, one most consistent with secretion and the other most consistent with acidification (10,11). Similarly, subunit a3 in mouse has also been implicated in a secretory defect independent of acidification (12).…”

Section: Discussionmentioning

confidence: 99%

“…These roles include fusion of yeast vacuoles (9), synaptic vesicle exocytosis in fly neurons (8), exocytosis in apical secretion of exosomes and morphogens in worms (10,11), and insulin secretion from pancreatic islets in mice (12). Moreover, in the endocytic degradative pathway, subunit a2 has recently been shown to exert another function independent of proton pumping; subunit a2 interacts with the guanine nucleotide-exchange factor ARNO in a pH-dependent manner, suggesting its function as a pH sensor for controlling the recruitment of the GTPase activated by ARNO, Arf6, which in turn directly interacts with the V 0 sector (13).…”

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confidence: 99%

V-ATPase V0 Sector Subunit a1 in Neurons Is a Target of Calmodulin

Zhang¹,

Wang

Volk

et al. 2008

Journal of Biological Chemistry

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The V 0 complex forms the proteolipid pore of a vesicular ATPase that acidifies vesicles. In addition, an independent function in membrane fusion has been suggested in vacuolar fusion in yeast and synaptic vesicle exocytosis in fly neurons. Evidence for a direct role in secretion has also recently been presented in mouse and worm. The molecular mechanisms of how the V 0 components might act or are regulated are largely unknown. Here we report the identification and characterization of a calmodulin-binding site in the large cytosolic N-terminal region of the Drosophila protein V100, the neuron-specific V 0 subunit a1. V100 forms a tight complex with calmodulin in a Ca 2؉ -dependent manner. Mutations in the calmodulin-binding site in Drosophila lead to a loss of calmodulin recruitment to synapses. Neuronal expression of a calmodulin-binding deficient V100 uncovers an incomplete rescue at low levels and cellular toxicity at high levels. Our results suggest a vesicular ATPase V 0 -dependent function of calmodulin at synapses. Calmodulin (CaM)4 is a small, ubiquitous Ca 2ϩ -binding protein that has been implicated in the Ca 2ϩ -dependent regulation of a plethora of cell biological processes. Characterized roles during cellular development and function include metabolic regulation, response to inflammation, apoptosis, intracellular trafficking, and membrane fusion (1-3). The vacuolar or vesicular ATPase (V-ATPase) is a multisubunit proton pump that acidifies mostly intracellular compartments and consists of two sectors: V 1 (the cytoplasmic ATPase) and V 0 (the transmembrane proteolipid pore) (4, 5). The largest (100 kDa) subunit of V 0 , subunit a, is encoded by four orthologous genes, named a1-a4, in worm, mouse, and human.The same four orthologous genes exist in Drosophila, but a fifth gene encoding a less homologous variant is listed in the public database as vha100-3. In yeast, subunit a is the only V 0 component encoded by more than one gene, namely the two homologs, vph1 and stv1. The two yeast versions or four animal versions of subunit a principally exhibit cell-specific and intracellular compartment-specific distribution; in many cases, they have been shown to target the complex to separate compartments (e.g. Vph1 to the vacuole and Stv1 to endosomal compartments (6, 7)). Of the four orthologous genes in animals, subunit a1 has consistently been shown to be highly enriched in, if not restricted to, neurons. In Drosophila, neuronal expression of subunit a1 in homozygous mutant animals fully rescues the lethality associated with the loss of a1, demonstrating its sole requirement in the nervous system (8).Recently, subunit a has been implicated in membrane fusion or secretion independent of intracompartmental acidification. These roles include fusion of yeast vacuoles (9), synaptic vesicle exocytosis in fly neurons (8), exocytosis in apical secretion of exosomes and morphogens in worms (10, 11), and insulin secretion from pancreatic islets in mice (12). Moreover, in the endocytic degradative pathway, subunit a2...

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“…We visualized actin dynamics in the G1 and duct cells using a GFP-tagged VAB-10 (spectraplakin) actin-binding domain (ABD) (Liegeois et al, 2007) under control of the dct-5 promoter (Fig. 2).…”

Section: G1 and G2 Migrate Over A Luminal Matrix During Delamination mentioning

confidence: 99%

A non-cell-autonomous role for Ras signaling inC. elegansneuroblast delamination

Parry

Sundaram

2014

Development

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Receptor tyrosine kinase (RTK) signaling through Ras influences many aspects of normal cell behavior, including epithelial-tomesenchymal transition, and aberrant signaling promotes both tumorigenesis and metastasis. Although many such effects are cellautonomous, here we show a non-cell-autonomous role for RTK-Ras signaling in the delamination of a neuroblast from an epithelial organ. The C. elegans renal-like excretory organ is initially composed of three unicellular epithelial tubes, namely the canal, duct and G1 pore cells; however, the G1 cell later delaminates from the excretory system to become a neuroblast and is replaced by the G2 cell. G1 delamination and G2 intercalation involve cytoskeletal remodeling, interconversion of autocellular and intercellular junctions and migration over a luminal extracellular matrix, followed by G1 junction loss. LET-23/EGFR and SOS-1, an exchange factor for Ras, are required for G1 junction loss but not for initial cytoskeletal or junction remodeling. Surprisingly, expression of activated LET-60/ Ras in the neighboring duct cell, but not in the G1 or G2 cells, is sufficient to rescue sos-1 delamination defects, revealing that Ras acts non-cell-autonomously to permit G1 delamination. We suggest that, similarly, oncogenic mutations in cells within a tumor might help create a microenvironment that is permissive for other cells to detach and ultimately metastasize.

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Genes Required for Osmoregulation and Apical Secretion in Caenorhabditis elegans

Cited by 76 publications

References 60 publications

Tramtrack regulates different morphogenetic events duringDrosophilatracheal development

Tramtrack regulates different morphogenetic events duringDrosophilatracheal development

V-ATPase V0 Sector Subunit a1 in Neurons Is a Target of Calmodulin

A non-cell-autonomous role for Ras signaling inC. elegansneuroblast delamination

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