scholarly journals The septate junction protein Mesh is required for epithelial morphogenesis, ion transport, and paracellular permeability in the Drosophila Malpighian tubule

2020 ◽  
Vol 318 (3) ◽  
pp. C675-C694 ◽  
Author(s):  
Sima Jonusaite ◽  
Klaus W. Beyenbach ◽  
Heiko Meyer ◽  
Achim Paululat ◽  
Yasushi Izumi ◽  
...  
Keyword(s):  
Ion Transport ◽  
Malpighian Tubule ◽  
Paracellular Permeability ◽  
Malpighian Tubules ◽  
Septate Junction ◽  
Cell Junctions ◽  
Chloride Permeability ◽  
Transepithelial Potential ◽  
Junction Protein ◽  
Urine Production

Septate junctions (SJs) are occluding cell-cell junctions that have roles in paracellular permeability and barrier function in the epithelia of invertebrates. Arthropods have two types of SJs, pleated SJs and smooth SJs (sSJs). In Drosophila melanogaster, sSJs are found in the midgut and Malpighian tubules, but the functions of sSJs and their protein components in the tubule epithelium are unknown. Here we examined the role of the previously identified integral sSJ component, Mesh, in the Malpighian tubule. We genetically manipulated mesh specifically in the principal cells of the tubule at different life stages. Tubules of flies with developmental mesh knockdown revealed defects in epithelial architecture, sSJ molecular and structural organization, and lack of urine production in basal and kinin-stimulated conditions, resulting in edema and early adult lethality. Knockdown of mesh during adulthood did not disrupt tubule epithelial and sSJ integrity but decreased the transepithelial potential, diminished transepithelial fluid and ion transport, and decreased paracellular permeability to 4-kDa dextran. Drosophila kinin decreased transepithelial potential and increased chloride permeability, and it stimulated fluid secretion in both control and adult mesh knockdown tubules but had no effect on 4-kDa dextran flux. Together, these data indicate roles for Mesh in the developmental maturation of the Drosophila Malpighian tubule and in ion and macromolecular transport in the adult tubule.

scholarly journals STRUCTURE OF COUPLED AND UNCOUPLED CELL JUNCTIONS

1968 ◽  
Vol 37 (3) ◽  
pp. 621-632 ◽  
Author(s):  
Stanley Bullivant ◽  
Werner R. Loewenstein
Keyword(s):  
Honeycomb Structure ◽  
Cellular Adhesion ◽  
Malpighian Tubules ◽  
Septate Junction ◽  
Cell Junctions ◽  
Electron Microscopic ◽  
Salivary Gland Cells ◽  
Projection Pattern ◽  
Fixed Cell ◽  
Junctional Structure

Cells of Chironomus salivary glands and Malpighian tubules have junctions of the "septate" kind. This is the only kind of junction discerned which is large enough to effect the existing degree of intercellular communication. The electron microscopic observations of the "septate" junction conform to a honeycomb structure, with 80-A-thick electron-opaque walls and 90-A-wide transparent cores, connecting the cellular surface membranes. A projection pattern of light and dark bands (the "septa") with a 150-A periodicity results when the electron beam is directed normal to any set of honeycomb walls. Treatment of the salivary gland cells with media, which interrupt cellular communication (without noticeable alteration of cellular adhesion) by reducing junctional membrane permeability or perijunctional insulation, produces no alterations in the junctional structure discernible in electron micrographs of glutaraldehyde-fixed cell material.

Anti-diuretic activity of a CAPA neuropeptide can compromise Drosophila chill tolerance

2018 ◽  
Author(s):  
Heath A. MacMillan ◽  
Basma Nazal ◽  
Sahr Wali ◽  
Gil Y. Yerushalmi ◽  
Lidiya Misyura ◽  
...  
Keyword(s):  
Ion Transport ◽  
Cold Tolerance ◽  
Malpighian Tubule ◽  
Malpighian Tubules ◽  
Low Doses ◽  
Ion Balance ◽  
The Central Nervous System ◽  
Summary Statement ◽  
Cell Depolarization ◽  
High Doses

AbstractFor insects, chilling injuries that occur in the absence of freezing are often related to a systemic loss of ion and water balance that leads to extracellular hyperkalemia, cell depolarization, and the triggering of apoptotic signalling cascades. The ability of insect ionoregulatory organs (e.g. the Malpighian tubules) to maintain ion balance in the cold has been linked to improved chill tolerance, and many neuroendocrine factors are known to influence ion transport rates of these organs. Injection of micromolar doses of CAPA (an insect neuropeptide) have been previously demonstrated to improve Drosophila cold tolerance, but the mechanisms through which it impacts chill tolerance are unclear, and low doses of CAPA have been demonstrated to cause anti-diuresis in other insects, including dipterans. Here, we provide evidence that low (fM) and high (µM) doses of CAPA impair and improve chill tolerance, respectively, via two different effects on Malpighian tubule ion and water transport. While low doses of CAPA are anti-diuretic, reduce tubule K+ clearance rates and reduce chill tolerance, high doses facilitate K+ clearance from the haemolymph and increase chill tolerance. By quantifying CAPA peptide levels in the central nervous system, we estimated the maximum achievable hormonal titres of CAPA, and found evidence to suggest that CAPA may function as an anti-diuretic peptide in Drosophila. We provide the first evidence of a neuropeptide that can negatively affect cold tolerance in an insect, and the first evidence of CAPA as an anti-diuretic peptide in this ubiquitous insect model.Summary StatementMany insects ion balance in the cold. We show how one neuropeptide can slow ion transport and reduce the cold tolerance of a fly.

scholarly journals Tricellular junction proteins promote disentanglement of daughter and neighbour cells during epithelial cytokinesis

2018 ◽  
Author(s):  
Zhimin Wang ◽  
Floris Bosveld ◽  
Yohanns Bellaïche
Keyword(s):  
De Novo ◽  
Cell Structure ◽  
Adherens Junction ◽  
Septate Junction ◽  
Cell Junctions ◽  
Epithelial Tissue ◽  
Neighbouring Cell ◽  
Daughter Cells ◽  
Junction Protein ◽  
Discs Large

AbstractIn epithelial tissue, new cell-cell junctions are formed upon cytokinesis. To understand junction formation during cytokinesis, we explored in Drosophila epithelium, de novo formation of tricellular septate junctions (TCJs). We found that upon midbody formation, the membranes of the two daughter cells and of the neighbouring cells located below the adherens junction (AJ) remain entangled in a 4-cell structure apposed to the midbody. The septate junction protein Discs-Large and components of the TCJ, Gliotactin and Anakonda accumulate in this 4-cell structure. Subsequently, a basal movement of the midbody parallels the detachment of the neighbouring cell membranes from the midbody, the disengagement of the daughter cells from their neighbours and the reorganisation of TCJs between the two daughter cells and their neighbouring cells. While the movement of midbody is independent of the Alix and Shrub abscission regulators, the loss of Gliotactin or Anakonda function impedes both the resolution of the connection between the daughter-neighbour cells and midbody movement. TCJ proteins therefore control an additional step of cytokinesis necessary for the disentanglement of the daughter cells and their neighbours during cytokinesis.

scholarly journals The septate junction protein Tetraspanin 2A is critical to the structure and function of Malpighian tubules in Drosophila melanogaster

2020 ◽  
Vol 318 (6) ◽  
pp. C1107-C1122 ◽  
Author(s):  
Klaus W. Beyenbach ◽  
Frederike Schöne ◽  
Leonhard F. Breitsprecher ◽  
Felix Tiburcy ◽  
Mikio Furuse ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Drosophila Melanogaster ◽  
Extracellular Volume ◽  
Adult Life ◽  
Malpighian Tubules ◽  
Septate Junction ◽  
Transepithelial Transport ◽  
Septate Junctions ◽  
Junction Protein

Tetraspanin-2A (Tsp2A) is an integral membrane protein of smooth septate junctions in Drosophila melanogaster. To elucidate its structural and functional roles in Malpighian tubules, we used the c42-GAL4/UAS system to selectively knock down Tsp2A in principal cells of the tubule. Tsp2A localizes to smooth septate junctions (sSJ) in Malpighian tubules in a complex shared with partner proteins Snakeskin (Ssk), Mesh, and Discs large (Dlg). Knockdown of Tsp2A led to the intracellular retention of Tsp2A, Ssk, Mesh, and Dlg, gaps and widening spaces in remaining sSJ, and tumorous and cystic tubules. Elevated protein levels together with diminished V-type H+-ATPase activity in Tsp2A knockdown tubules are consistent with cell proliferation and reduced transport activity. Indeed, Malpighian tubules isolated from Tsp2A knockdown flies failed to secrete fluid in vitro. The absence of significant transepithelial voltages and resistances manifests an extremely leaky epithelium that allows secreted solutes and water to leak back to the peritubular side. The tubular failure to excrete fluid leads to extracellular volume expansion in the fly and to death within the first week of adult life. Expression of the c42-GAL4 driver begins in Malpighian tubules in the late embryo and progresses upstream to distal tubules in third instar larvae, which can explain why larvae survive Tsp2A knockdown and adults do not. Uncontrolled cell proliferation upon Tsp2A knockdown confirms the role of Tsp2A as tumor suppressor in addition to its role in sSJ structure and transepithelial transport.

scholarly journals The septate junction protein Snakeskin is critical for epithelial barrier function and tissue homeostasis in the Malpighian tubules of adult Drosophila

2020 ◽  
Author(s):  
Anthony J Dornan ◽  
Kenneth A Halberg ◽  
Liesa-Kristin Beuter ◽  
Shireen-Anne Davies ◽  
Julian A.T. Dow
Keyword(s):  
Barrier Function ◽  
Tissue Homeostasis ◽  
Malpighian Tubules ◽  
Septate Junction ◽  
Epithelial Barrier ◽  
Renal Tubules ◽  
Epithelial Barrier Function ◽  
Adhesion Protein ◽  
Junction Protein ◽  
Secretory Transport

Transporting epithelia provide a protective physical barrier while directing appropriate transport of ions, solutes and water. In invertebrates, epithelial integrity is dependent on formation, and maintenance, of ′tight′ septate junctions (SJs). We demonstrated that Drosophila Malpighian (renal) tubules undergo an age-dependent decline in secretory transport capacity, which correlates with mislocalisation of SJ proteins and coincident progressive degeneration in cellular morphology and tissue homeostasis. By restrictively impairing, in adult tubules, the cell adhesion protein Snakeskin, which is essential for smooth SJ formation, we observed progressive changes in cellular and tissue morphology that phenocopied these effects, including mislocalisation of junctional proteins with concomitant loss of cell polarity and barrier function. Resulting in significant accelerated decline in tubule secretory capacity and organismal viability. Our investigations highlight the tubule′s essential role in maintenance of organismal health, while providing measurable markers of compromised epithelial barrier and tissue function that manifest in advanced morbidity and death.

scholarly journals Septate junction in the distal ileac plexus of larval lepidopteran Trichoplusia ni: alterations in paracellular permeability during ion transport reversal

2019 ◽  
Vol 222 (11) ◽  
pp. jeb204750 ◽  
Author(s):  
Dennis Kolosov ◽  
Sima Jonusaite ◽  
Andrew Donini ◽  
Scott P. Kelly ◽  
Michael J. O'Donnell
Keyword(s):  
Ion Transport ◽  
Trichoplusia Ni ◽  
Paracellular Permeability ◽  
Septate Junction

Measurements of osmotic permeability in the Malpighian tubules of an insect, Rhodnius prolixus Stål

1982 ◽  
Vol 216 (1204) ◽  
pp. 267-277 ◽  
Keyword(s):  
Ion Transport ◽  
Experimental Method ◽  
Malpighian Tubule ◽  
Rhodnius Prolixus ◽  
Malpighian Tubules ◽  
Unstirred Layer ◽  
Osmotic Permeability

(i) With use of a novel experimental method, an improved estimate has been obtained for the value of the osmotic permeability ( P os ) of Rhodnius Malpighian tubules, 4.3 x 10 -3 cm s -1 osmol -1 l. Corrections for unstirred layer effects permit a further 35% increase in the value of P os , to 5.8 x 10 -3 cm s -1 osmol -1 l. (ii) In the lower Malpighian tubule, P os decreases from 3.4 x 10 -3 cm s -1 osmol -1 l at the junction with the upper Malpighian tubule to 0.4 x 10 -3 cm s -1 osmol -1 l at the junction with the gut. In lower tubules stimulated with 5-HT, P os is reduced over most of their length by about 50% . It is suggested that reduced values of P os in the lower portions of the lower tubule prevent water movements accompanying 5-HT-stimulated KCl resorption over the same area of the tubule. (iii) Values of P os in the upper segment of the upper tubule are discussedin relation to proposed mechanisms for coupling water movements to ion transport during isosmotic secretion by the tubule.

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.

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