Cell-type specific calcium signalling in a Drosophila epithelium

1997 ◽  
Vol 110 (15) ◽  
pp. 1683-1692 ◽  
Author(s):  
P. Rosay ◽  
S.A. Davies ◽  
Y. Yu ◽  
A. Sozen ◽  
K. Kaiser ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Critical Role ◽  
Cell Signalling ◽  
Calcium Signalling ◽  
Malpighian Tubule ◽  
Fluid Secretion ◽  
Cell Types ◽  
Cytosolic Calcium ◽  
Atpase Inhibitor ◽  
Principal Cells

Calcium is a ubiquitous second messenger that plays a critical role in both excitable and non-excitable cells. Calcium mobilisation in identified cell types within an intact renal epithelium, the Drosophila melanogaster Malpighian tubule, was studied by GAL4-directed expression of an aequorin transgene. CAP2b, a cardioactive neuropeptide that stimulates fluid secretion by a mechanism involving nitric oxide, causes a rapid, dose-dependent rise in cytosolic calcium in only a single, genetically-defined, set of 77 principal cells in the main (secretory) segment of the tubule. In the absence of external calcium, the CAP2b-induced calcium response is abolished. In Ca2+-free medium, the endoplasmic reticulum Ca2+-ATPase inhibitor, thapsigargin, elevates [Ca2+]i only in the smaller stellate cells, suggesting that principal cells do not contain a thapsigargin-sensitive intracellular pool. Assays for epithelial function confirm that calcium entry is essential for CAP2b to induce a physiological response in the whole organ. Furthermore, the data suggest a role for calcium signalling in the modulation of the nitric oxide signalling pathway in this epithelium. The GAL4-targeting system allows general application to studies of cell-signalling and pharmacology that does not rely on invasive or cytotoxic techniques.

Interactions between epithelial nitric oxide signaling and phosphodiesterase activity in Drosophila

2003 ◽  
Vol 285 (5) ◽  
pp. C1207-C1218 ◽  
Author(s):  
Kate E. Broderick ◽  
Matthew R. MacPherson ◽  
Michael Regulski ◽  
Tim Tully ◽  
Julian A. T. Dow ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Calcium Signaling ◽  
Fluid Transport ◽  
Malpighian Tubule ◽  
Cytosolic Calcium ◽  
Type I ◽  
Renal Tubules ◽  
Nitric Oxide Signaling ◽  
Principal Cells

Signaling by nitric oxide (NO) and guanosine 3′,5′-cyclic monophosphate (cGMP) modulates fluid transport in Drosophila melanogaster. Expression of an inducible transgene encoding Drosophila NO synthase ( dNOS) increases both NOS activity in Malpighian (renal) tubules and DNOS protein in both type I (principal) and type II (stellate) cells. However, cGMP content is increased only in principal cells. DNOS overexpression results in elevated basal rates of fluid transport in the presence of the phosphodiesterase (PDE) inhibitor, Zaprinast. Direct assay of tubule cGMP-hydrolyzing phosphodiesterase (cG-PDE) activity in wild-type and dNOS transgenic lines shows that cG-PDE activity is Zaprinast sensitive and is elevated upon dNOS induction. Zaprinast treatment increases cGMP content in tubules, particularly at the apical regions of principal cells, suggesting localization of Zaprinast-sensitive cG-PDE to these areas. Potential cross talk between activated NO/cGMP and calcium signaling was assessed in vivo with a targeted aequorin transgene. Activated DNOS signaling alone does not modify either neuropeptide (CAP2b)- or cGMP-induced increases in cytosolic calcium levels. However, in the presence of Zaprinast, both CAP2b-and cGMP-stimulated calcium levels are potentiated upon DNOS overexpression. Use of the calcium channel blocker, verapamil, abolishes the Zaprinast-induced transport phenotype in dNOS-overexpressing tubules. Molecular genetic intervention in the NO/cGMP signaling pathway has uncovered a pivotal role for cell-specific cG-PDE in regulating the poise of the fluid transporting Malpighian tubule via direct effects on intracellular cGMP concentration and localization and via interactions with calcium signaling mechanisms.

scholarly journals A SLC4-like anion exchanger from renal tubules of the mosquito (Aedes aegypti): evidence for a novel role of stellate cells in diuretic fluid secretion

2010 ◽  
Vol 298 (3) ◽  
pp. R642-R660 ◽  
Author(s):  
Peter M. Piermarini ◽  
Laura F. Grogan ◽  
Kenneth Lau ◽  
Li Wang ◽  
Klaus W. Beyenbach
Keyword(s):  
Aedes Aegypti ◽  
Anion Exchanger ◽  
Xenopus Oocytes ◽  
Malpighian Tubule ◽  
Stellate Cells ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Renal Tubules ◽  
Basal Region ◽  
Principal Cells

Transepithelial fluid secretion across the renal (Malpighian) tubule epithelium of the mosquito ( Aedes aegypti ) is energized by the vacuolar-type (V-type) H+-ATPase and not the Na+-K+-ATPase. Located at the apical membrane of principal cells, the V-type H+-ATPase translocates protons from the cytoplasm to the tubule lumen. Secreted protons are likely to derive from metabolic H2CO3, which raises questions about the handling of HCO3−by principal cells. Accordingly, we tested the hypothesis that a Cl/HCO3anion exchanger (AE) related to the solute-linked carrier 4 (SLC4) superfamily mediates the extrusion of HCO3−across the basal membrane of principal cells. We began by cloning from Aedes Malpighian tubules a full-length cDNA encoding an SLC4-like AE, termed AeAE. When expressed heterologously in Xenopus oocytes, AeAE is both N- and O-glycosylated and mediates Na+-independent intracellular pH changes that are sensitive to extracellular Cl−concentration and to DIDS. In Aedes Malpighian tubules, AeAE is expressed as two distinct forms: one is O-glycosylated, and the other is N-glycosylated. Significantly, AeAE immunoreactivity localizes to the basal regions of stellate cells but not principal cells. Concentrations of DIDS that inhibit AeAE activity in Xenopus oocytes have no effects on the unstimulated rates of fluid secretion mediated by Malpighian tubules as measured by the Ramsay assay. However, in Malpighian tubules stimulated with kinin or calcitonin-like diuretic peptides, DIDS reduces the diuretic rates of fluid secretion to basal levels. In conclusion, Aedes Malpighian tubules express AeAE in the basal region of stellate cells, where this transporter may participate in producing diuretic rates of transepithelial fluid secretion.

Spatial and temporal aspects of cell signalling

1988 ◽  
Vol 320 (1199) ◽  
pp. 325-343 ◽  
Keyword(s):  
Intracellular Calcium ◽  
Calcium Release ◽  
Cell Signalling ◽  
Calcium Signalling ◽  
Cell Types ◽  
Calcium Oscillations ◽  
Temporal Organization ◽  
Oscillatory Activity ◽  
Free Calcium ◽  
Inositol Lipids

As new techniques are developed to measure intracellular messengers it becomes increasingly apparent that there is a remarkable spatial and temporal organization of cell signalling. Cells possess a small discrete hormone-sensitive pool of inositol lipid. In some cells such as Xenopus oocytes and Limulus photoreceptors this phosphoinositide signalling system is highly concentrated in one region of the cell, so establishing localized calcium gradients. Another example is the hydrolysis of inositol lipids in eggs at the point of sperm entry resulting in a localized increase in Ins(1,4,5) P 3 and calcium which spreads like a wave throughout the egg. In hamster eggs this burst of calcium at fertilization recurs at 1-3 min intervals for over 100 min, a particularly dramatic example of spontaneous activity. Spontaneous oscillations in intracellular calcium exist in many different cell types and are often induced by agonists that hydrolyse inositol lipids. We have made a distinction between oscillations that are approximately sinusoidal and occur at a higher frequency where free calcium is probably continuously involved in the oscillatory cycle and those where calcium falls to resting levels for many seconds between transients. In the former case, the oscillations are thought to be induced through a cytoplasmic oscillator based on the phenomenon of calcium-induced calcium release. Such oscillations can be induced in Xenopus oocytes after injection with Ins(1,4,5) P 3 . A receptor-controlled oscillator based on the periodic formation of I ns (1,4,5) P 3 is probably responsible for the generation of the widely spaced calcium transients. The function of such calcium oscillations is currently unknown. They may be a reflection of the feedback interactions that operate to control intracellular calcium. Another possibility emerged from observations that in some cells the frequency of calcium oscillations varied with agonist concentration, suggesting that cells might employ these oscillations as a way of encoding information. One advantage of using such a frequency-dependent mechanism may lie in an increase in fidelity, especially at low agonist concentrations. Whatever these functions might be, it is clear that uncovering the mechanisms responsible for such oscillatory activity will greatly enhance our understanding of the relation between the phosphoinositides and calcium signalling.

scholarly journals When two cells are better than one: specialized stellate cells provide a privileged route for uniquely rapid water flux in Drosophila renal tubule

2019 ◽  
Author(s):  
Pablo Cabrero ◽  
Selim Terhzaz ◽  
Anthony J. Dornan ◽  
Saurav Ghimire ◽  
Heather L. Holmes ◽  
...  
Keyword(s):  
Water Permeability ◽  
Plasma Membranes ◽  
Water Flux ◽  
Malpighian Tubule ◽  
Stellate Cells ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Principal Cells ◽  
Very High

AbstractInsects are highly successful, in part through an excellent ability to osmoregulate. The renal (Malpighian) tubules can secrete fluid faster on a per-cell basis than any other epithelium, but the route for these remarkable water fluxes has not been established. In Drosophila melanogaster, we show that 4 members of the Major Intrinsic Protein family are expressed at very high level in the fly renal tissue; the aquaporins Drip and Prip, and the aquaglyceroporins Eglp2 and Eglp4. As predicted from their structure and by their transport function by expressing these proteins in Xenopus oocytes, Drip, Prip and Eglp2 show significant and specific water permeability, whereas Eglp2 and Eglp4 show very high permeability to glycerol and urea. Knockdowns of any of these genes impacts tubule performance resulting in impaired hormone-induced fluid secretion. The Drosophila tubule has two main secretory cell types: active cation-transporting principal cells with the aquaglyceroporins localize to opposite plasma membranes and small stellate cells, the site of the chloride shunt conductance, with these aquaporins localising to opposite plasma membranes. This suggests a model in which cations are pumped by the principal cells, causing chloride to follow through the stellate cells in order to balance the charge. As a consequence, osmotically obliged water follows through the stellate cells. Consistent with this model, fluorescently labelled dextran, an in vivo marker of membrane water permeability, is trapped in the basal infoldings of the stellate cells after kinin diuretic peptide stimulation, confirming that these cells provide the major route for transepithelial water flux. The spatial segregation of these components of epithelial water transport may help to explain the unique success of the higher insects.Significance statementThe tiny insect renal (Malpighian) tubule can transport fluid at unparalleled speed, suggesting unique specialisations. Here we show that strategic allocation of Major Intrinsic Proteins (MIPs) to specific cells within the polarized tubule allow the separation of metabolically intense active cation transport from chloride and water conductance. This body plan is general to at least many higher insects, providing a clue to the unique success of the class Insecta.

Fine Structure of the Malpighian Tubules of the Mosquito, Culex pipiens

1971 ◽  
Vol 29 ◽  
pp. 402-403
Author(s):  
Brendan Clifford
Keyword(s):  
Fine Structure ◽  
Culex Pipiens ◽  
Stellate Cell ◽  
Malpighian Tubule ◽  
Cell Types ◽  
Instar Larva ◽  
Malpighian Tubules ◽  
Calliphora Erythrocephala ◽  
Distinct Cell ◽  
Basal Plasma

An ultrastructural investigation of the Malpighian tubules of the fourth instar larva of Culex pipiens was undertaken as part of a continuing study of the fine structure of transport epithelia.Each of the five Malpighian tubules was found to be morphologically identical and regionally undifferentiated. Two distinct cell types, the primary and stellate, were found intermingled along the length of each tubule. The ultrastructure of the stellate cell was previously described in the Malpighian tubule of the blowfly, Calliphora erythrocephala by Berridge and Oschman.The basal plasma membrane of the primary cell is extremely irregular, giving rise to a complex interconnecting network of basal channels. The compartments of cytoplasm entrapped within this system of basal infoldings contain mitochondria, free ribosomes, and small amounts of rough endoplasmic reticulum. The mitochondria are distinctive in that the cristae run parallel to the long axis of the organelle.

A critical role of iNOS-derived Nitric Oxide (NO) and progesterone in implantation

1998 ◽  
Vol 5 (1) ◽  
pp. 115A-115A
Author(s):  
K CHWALISZ ◽  
E WINTERHAGER ◽  
T THIENEL ◽  
R GARFIELD
Keyword(s):  
Nitric Oxide ◽  
Critical Role

CHANGES OF NITRIC OXIDE SYNTHASE AND HYDROGEN SULFIDE IN BLOOD LYMPHOCYTES IN THE ACUTE PERIOD OF POLYTRAUMA

2019 ◽  
Vol 72 (8) ◽  
pp. 1473-1476
Author(s):  
Nataliya Matolinets ◽  
Helen Sklyarova ◽  
Eugene Sklyarov ◽  
Andrii Netliukh
Keyword(s):  
Nitric Oxide ◽  
Hydrogen Sulfide ◽  
Tissue Injury ◽  
Traumatic Injury ◽  
Cell Types ◽  
No Synthase ◽  
Septic Complications ◽  
Acute Period ◽  
Gaseous Transmitters ◽  
The Moment

Introduction: Polytrauma patients have high risk of shock, septic complications and death during few years of follow-up. In recent years a lot of attention is paid to gaseous transmitters, among which are nitrogen oxide (NO) and hydrogen sulfide (H2S). It is known that the rise of NO and its metabolites levels occurs during the acute period of polytrauma. Nitric oxide and hydrogen sulfide are produced in different cell types, among which are lymphocytes. The aim: To investigate the levels of NO, NOS, iNOS, еNOS, H2S in lymphocytes lysate in patients at the moment of hospitalization and 24 hours after trauma. Materials and methods: We investigated the levels of NO, NO-synthase, inducible NO-synthase, endothelial NO-synthase, H2S in lymphocytes lysate in patients at the moment of hospitalization and 24 hours after trauma. Results: The study included 20 patients with polytrauma who were treated in the intensive care unit (ICU) of the Lviv Emergency Hospital. Tissue injury was associated with an increased production of NO, NOS, iNOS, еNOS during the acute period of polytrauma. At the same time, the level of H2S decreased by the end of the first day of traumatic injury. Conclusions: In acute period of polytrauma, significant increasing of iNOS and eNOS occurs with percentage prevalence of iNOS over eNOS on the background of H2S decreasing.

New Insights on KCa3.1 Channel Modulation

2020 ◽  
Vol 26 (18) ◽  
pp. 2096-2101
Author(s):  
Giuseppe Manfroni ◽  
Francesco Ragonese ◽  
Lorenzo Monarca ◽  
Andrea Astolfi ◽  
Loretta Mancinelli ◽  
...  
Keyword(s):  
Potassium Channel ◽  
Critical Role ◽  
Calcium Signalling ◽  
Typical Feature ◽  
Open Probability ◽  
Pharmacological Agents ◽  
Channel Modulation ◽  
Calcium Dependent ◽  
Modelling Techniques ◽  
Calcium Activated Potassium Channel

The human intermediate conductance calcium-activated potassium channel, KCa3.1, is involved in several pathophysiological conditions playing a critical role in cell secretory machinery and calcium signalling. The recent cryo-EM analysis provides new insights for understanding the modulation by both endogenous and pharmacological agents. A typical feature of this channel is the low open probability in saturating calcium concentrations and its modulation by potassium channel openers (KCOs), such as benzo imidazolone 1-EBIO, without changing calcium-dependent activation. In this paper, we proposed a model of KCOs action in the modulation of channel activity. The KCa3.1 channel has a very rich pharmacological profile with several classes of molecules that selectively interact with different binding sites of the channel. Among them, benzo imidazolones can be openers (positive modulators such as 1-EBIO, DC-EBIO) or blockers (negative modulators such as NS1619). Through computation modelling techniques, we identified the 1,4-benzothiazin-3-one as a promising scaffold to develop new KCa3.1 channel modulators. Further studies are needed to explore the potential use of 1-4 benzothiazine- 3-one in KCa3.1 modulation and its pharmacological application.

NITRIC OXIDE, FREE RADICALS AND CELL SIGNALLING IN CARDIOVASCULAR DISEASE

1997 ◽  
Vol 25 (3) ◽  
pp. 384S-384S
Author(s):  
Victor M. Darley-Usmar ◽  
Joanne McAndrew ◽  
Roger White ◽  
Rakesh Patel ◽  
Doug Moellering ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Cardiovascular Disease ◽  
Free Radicals ◽  
Cell Signalling

scholarly journals B2M overexpression correlates with malignancy and immune signatures in human gliomas

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hao Zhang ◽  
Biqi Cui ◽  
Yulai Zhou ◽  
Xinxing Wang ◽  
Wantao Wu ◽  
...  
Keyword(s):  
Critical Role ◽  
Cell Types ◽  
Potential Candidate ◽  
Egfr Amplification ◽  
Immune Signatures ◽  
Idh Mutations ◽  
Pten Deletion ◽  
R Project ◽  
Patient Prognosis ◽  
Worse Prognosis

AbstractBecause of the limited treatment strategy of gliomas, the key of diagnosis and treatment is finding new molecular biomarkers. Here, we explored the potential of β2-microglobulin (B2M) to serve as a hopeful candidate for immunotherapy or diagnostic biomarker in gliomas. The genomic profiles, clinical characteristics, and immune signatures were analyzed based on TCGA and CGGA databases. We carried out the whole statistical analyses using R project. High B2M expression correlated with worse prognosis. Somatic mutations of gliomas with high B2M expression are associated with PTEN deletion and EGFR amplification. Isocitrate dehydrogenase (IDH) mutations accounted for 82% in gliomas with low B2M expression. In addition, B2M positively correlated with ESTIMATE scores, interacted with infiltrating immune and stromal cell types. B2M also suppressed anti-tumor immunity through immune related processes. Meanwhile, B2M was associated with immune checkpoint molecules and inflammatory activities. Finally, functional annotation of the identified B2M related genes verified that B2M was a potential candidate for immunotherapy. We confirmed that B2M played a critical role in tumor progression, patient prognosis and immunotherapy of gliomas.

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