TheDrosophila ribbongene encodes a nuclear BTB domain protein that promotes epithelial migration and morphogenesis

Development ◽  
2001 ◽  
Vol 128 (23) ◽  
pp. 4923-4933 ◽  
Author(s):  
Katherine Shim ◽  
Kimberly J. Blake ◽  
Joseph Jack ◽  
Mark A. Krasnow
Keyword(s):  
Apical Cell ◽  
Basal Membrane ◽  
Binding Motif ◽  
Apical Surface ◽  
Basal Surface ◽  
Tracheal System ◽  
Epithelial Migration ◽  
Tracheal Cell ◽  
Branch Formation ◽  
Membrane Protrusions

During development of the Drosophila tracheal (respiratory) system, the cell bodies and apical and basal surfaces of the tracheal epithelium normally move in concert as new branches bud and grow out to form tubes. We show that mutations in the Drosophila ribbon (rib) gene disrupt this coupling: the basal surface continues to extend towards its normal targets, but movement and morphogenesis of the tracheal cell bodies and apical surface is severely impaired, resulting in long basal membrane protrusions but little net movement or branch formation. rib mutant tracheal cells are still responsive to the Branchless fibroblast growth factor (FGF) that guides branch outgrowth, and they express apical membrane markers normally. This suggests that the defect lies either in transmission of the FGF signal from the basal surface to the rest of the cell or in the apical cell migration and tubulogenesis machinery. rib encodes a nuclear protein with a BTB/POZ domain and Pipsqueak DNA-binding motif. It is expressed in the developing tracheal system and other morphogenetically active epithelia, many of which are also affected in rib mutants. We propose that Rib is a key regulator of epithelial morphogenesis that promotes migration and morphogenesis of the tracheal cell bodies and apical surface and other morphogenetic movements.

scholarly journals DAPLE and MPDZ bind to each other and cooperate to promote apical cell constriction

2019 ◽  
Vol 30 (16) ◽  
pp. 1900-1910 ◽  
Author(s):  
Arthur Marivin ◽  
Mikel Garcia-Marcos
Keyword(s):  
G Protein ◽  
Cultured Cells ◽  
Apical Cell ◽  
Cell Junctions ◽  
Binding Motif ◽  
Apical Constriction ◽  
Protein Activation ◽  
Neuroepithelial Cells ◽  
Two Factors ◽  
Apical Junctions

Dishevelled-Associating Protein with a high frequency of LEucines (DAPLE) belongs to a group of unconventional activators of heterotrimeric G-proteins that are cytoplasmic factors rather than membrane proteins of the G-protein–coupled receptor superfamily. During neurulation, DAPLE localizes to apical junctions of neuroepithelial cells and promotes apical cell constriction via G-protein activation. While junctional localization of DAPLE is necessary for this function, the factors it associates with at apical junctions or how they contribute to DAPLE-mediated apical constriction are unknown. MPDZ is a multi-PDZ (PSD95/DLG1/ZO-1) domain scaffold present at apical cell junctions whose mutation in humans is linked to nonsyndromic congenital hydrocephalus (NSCH). DAPLE contains a PDZ-binding motif (PBM) and is also mutated in human NSCH, so we investigated the functional relationship between both proteins. DAPLE colocalized with MPDZ at apical cell junctions and bound directly to the PDZ3 domain of MPDZ via its PBM. Much like DAPLE, MPDZ is induced during neurulation in Xenopus and is required for apical constriction of neuroepithelial cells and subsequent neural plate bending. MPDZ depletion also blunted DAPLE-­mediated apical constriction of cultured cells. These results show that DAPLE and MPDZ, two factors genetically linked to NSCH, function as cooperative partners at apical junctions and are required for proper tissue remodeling during early stages of neurodevelopment.

Adhesion of uric acid crystals to the surface of renal epithelial cells

2000 ◽  
Vol 278 (6) ◽  
pp. F989-F998 ◽  
Author(s):  
Rima M. Koka ◽  
Erick Huang ◽  
John C. Lieske
Keyword(s):  
Uric Acid ◽  
Epithelial Cells ◽  
Cell Surface ◽  
Hydrophobic Interactions ◽  
Calcium Phosphates ◽  
Apical Cell ◽  
Apical Surface ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Renal Tubular Cells

Adhesion of microcrystals that nucleate in tubular fluid to the apical surface of renal tubular cells could be a critical step in the formation of kidney stones, 12% of which contain uric acid (UA) either alone or admixed with calcium oxalates or calcium phosphates. UA crystals bind rapidly to monolayer cultures of monkey kidney epithelial cells (BSC-1 line), used to model the surface of the nephron, in a concentration-dependent manner. The urinary glycoproteins osteopontin, nephrocalcin, and Tamm-Horsfall glycoprotein had no effect on binding of UA crystals to the cell surface, whereas other polyanions including specific glycosaminoglycans blocked UA crystal adhesion. Specific polycations also inhibited adhesion of UA crystals and appeared to exert their inhibitory effect by coating cells. However, removal of anionic cell surface molecules with neuraminidase, heparitinase I, or chondroitinase ABC each increased UA crystal binding, and sialic acid-binding lectins had no effect. These observations suggest that hydrogen bonding and hydrophobic interactions play a major role in adhesion of electrostatically neutral UA crystals to renal cells, unlike the interaction of calcium-containing crystals with negatively charged molecules on the apical cell surface via ionic forces. After adhesion to the plasma membrane, subsequent cellular events could contribute to UA crystal retention in the kidney and the development of UA or mixed calcium and UA calculi.

Epithelial sorting of a glycosylphosphatidylinositol-anchored bacterial protein expressed in polarized renal MDCK and intestinal Caco-2 cells

1995 ◽  
Vol 108 (1) ◽  
pp. 369-377 ◽  
Author(s):  
K.L. Soole ◽  
M.A. Jepson ◽  
G.P. Hazlewood ◽  
H.J. Gilbert ◽  
B.H. Hirst
Keyword(s):  
Epithelial Cells ◽  
Cell Surface ◽  
Intestinal Epithelial Cells ◽  
Mdck Cells ◽  
Basolateral Membrane ◽  
Apical Cell ◽  
Apical Surface ◽  
Intestinal Epithelial ◽  
Gpi Anchor ◽  
Sorting Signal

To evaluate whether a glycosylphosphatidylinositol (GPI) anchor can function as a protein sorting signal in polarized intestinal epithelial cells, the GPI-attachment sequence from Thy-1 was fused to bacterial endoglucanase E' (EGE') from Clostridium thermocellum and polarity of secretion of the chimeric EGE'-GPI protein was evaluated. The chimeric EGE'-GPI protein was shown to be associated with a GPI anchor by TX-114 phase-partitioning and susceptibility to phosphoinositol-specific phospholipase C. In polarized MDCK cells, EGE' was localized almost exclusively to the apical cell surface, while in polarized intestinal Caco-2 cells, although 80% of the extracellular form of the enzyme was routed through the apical membrane over a 24 hour period, EGE' was also detected at the basolateral membrane. Rates of delivery of EGE'-GPI to the two membrane domains in Caco-2 cells, as determined with a biotinylation protocol, revealed apical delivery was approximately 2.5 times that of basolateral. EGE' delivered to the basolateral cell surface was transcytosed to the apical surface. These data indicate that a GPI anchor does represent a dominant apical sorting signal in intestinal epithelial cells. However, the mis-sorting of a proportion of EGE'GPI to the basolateral surface of Caco-2 cells provides an explanation for additional sorting signals in the ectodomain of some endogenous GPI-anchored proteins.

The Notch pathway helps to pattern the tips of the Drosophila tracheal branches by selecting cell fates

Development ◽  
1999 ◽  
Vol 126 (11) ◽  
pp. 2355-2364 ◽  
Author(s):  
M. Llimargas
Keyword(s):  
Notch Pathway ◽  
Cell Types ◽  
Notch Signalling ◽  
Branching Pattern ◽  
Cell Fates ◽  
Tracheal System ◽  
Notch Signalling Pathway ◽  
Tracheal Cell ◽  
Mutant Phenotypes ◽  
Selection Of

The Drosophila tracheal system consists of a stereotyped network of epithelial tubes formed by several tracheal cell types. By the end of embryogenesis, when the general branching pattern is established, some specialised tracheal cells then mediate branch fusion while others extend fine terminal branches. Here evidence is presented that the Notch signalling pathway acts directly in the tracheal cells to distinguish individual fates within groups of equivalent cells. Notch helps to single out those tracheal cells that mediate branch fusion by blocking their neighbours from adopting the same fate. This function of Notch would require the restricted activation of the pathway in specific cells. In addition, and probably later, Notch also acts in the selection of those tracheal cells that extend the terminal branches. Both the localised expression and the mutant phenotypes of Delta, a known ligand for Notch, suggest that Delta may activate Notch to specify cell fates at the tips of the developing tracheal branches.

The effects of cytochalasin D and phorbol myristate acetate on the apical endocytosis of ricin in polarised Caco-2 cells

1996 ◽  
Vol 109 (12) ◽  
pp. 2927-2935 ◽  
Author(s):  
W. Shurety ◽  
N.A. Bright ◽  
J.P. Luzio
Keyword(s):  
Cell Surface ◽  
Apical Cell ◽  
Microscopic Investigation ◽  
Electron Microscopic Investigation ◽  
Cytochalasin D ◽  
Apical Surface ◽  
Electron Microscopic ◽  
Coated Pits ◽  
Acid Media ◽  
Kinase C

Apical endocytosis of 125I-ricin in Caco-2 cells was inhibited > 95% by hypertonic and/or acid media, consistent with the major uptake route being clathrin-mediated. The presence of apical cell surface bound ricin-gold in clathrin coated pits and vesicles was observed by electron microscopy. An electron microscopic investigation in which ricin-gold bound to the apical surface was quantitated, showed that cytochalasin D, which inhibits apical but not basolateral endocytosis, prevented movement of ricin-gold along the microvillar surface. This was consistent with an actin bound mechanochemical motor within microvilli driving the movement of membranous components towards the cell body. Cytochalasin D also caused an increase in the number of coated pits observed at the apical cell surface relative to the number observed in untreated cells. Stimulation of apical endocytosis of ricin by phorbol 12-myristate 13-acetate showed the characteristics of being mediated by protein kinase C, was not due to an effect on ricin movement along the microvillar surface, and may be explained by increases in formation and pinching off of clathrin coated pits at the apical cell surface.

scholarly journals Par3 functions in the biogenesis of the primary cilium in polarized epithelial cells

2007 ◽  
Vol 179 (6) ◽  
pp. 1133-1140 ◽  
Author(s):  
Jeff Sfakianos ◽  
Akashi Togawa ◽  
Sandra Maday ◽  
Mike Hull ◽  
Marc Pypaert ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Primary Cilium ◽  
Basolateral Membrane ◽  
Intraflagellar Transport ◽  
Binding Motif ◽  
Apical Surface ◽  
Anterograde Transport ◽  
Ciliary Membrane ◽  
Microtubule Motor ◽  
Dependent Transport

Par3 is a PDZ protein important for the formation of junctional complexes in epithelial cells. We have identified an additional role for Par3 in membrane biogenesis. Although Par3 was not required for maintaining polarized apical or basolateral membrane domains, at the apical surface, Par3 was absolutely essential for the growth and elongation of the primary cilium. The activity reflected its ability to interact with kinesin-2, the microtubule motor responsible for anterograde transport of intraflagellar transport particles to the tip of the growing cilium. The Par3 binding partners Par6 and atypical protein kinase C interacted with the ciliary membrane component Crumbs3 and we show that the PDZ binding motif of Crumbs3 was necessary for its targeting to the ciliary membrane. Thus, the Par complex likely serves as an adaptor that couples the vectorial movement of at least a subset of membrane proteins to microtubule-dependent transport during ciliogenesis.

Extracellular glutamate flux regulates intracellular glutaminase activity in LLC-PK1-F+ cells

1995 ◽  
Vol 268 (6) ◽  
pp. C1418-C1424 ◽  
Author(s):  
T. C. Welbourne ◽  
X. Mu
Keyword(s):  
Time Course ◽  
Glutamate Uptake ◽  
Fold Increase ◽  
Cellular Level ◽  
Glutamine Metabolism ◽  
Apical Surface ◽  
Extracellular Glutamate ◽  
Basal Surface ◽  
F Cells ◽  
Glutaminase Activity

The role of extracellular glutamate flux in regulating intracellular glutaminase activity was assessed in confluent monolayers of proximal tubule-like LLC-PK1-F+ cells grown on porous supports. Glutamate is a well-known inhibitor of phosphate-dependent glutaminase (PDG). We hypothesized that, by restricting the flux of glutamate from the extracellular media, cellular level would fall, effecting deinhibition of the cellular glutaminase activity. To test this, cellular glutamate uptake and extracellular production were inhibited for 18 h by the addition of D-aspartate (10 mM) or acivicin (0.7 mM) to both apical and basal media. Inhibiting glutamate flux depressed cellular glutamate content 43 and 41%, respectively. Intracellular relative glutaminase activity, monitored as the breakdown of 14C-radiolabeled glutamine to glutamate, measured over 60 s in the presence of D-aspartate or acivicin showed a 2- to 2.5-fold increase with the fall in cellular glutamate. Interestingly, enhanced glutamine uptake after PDG deinhibition was predominantly expressed on the basal surface. Indeed, measuring glutamine utilization after gamma-glutamyltranspeptidase inhibition over the entire 18-h time course revealed inhibition at the apical surface but relative enhancement of uptake at the basal surface. The increased intracellular glutaminase pathway was also reflected in increased alanine production measured over the 18-h time course, despite the reduction in overall glutamine utilization. These results point to a major role for extracellular glutamate fluxes in regulating cellular glutamine metabolism and suggest that the intracellular pathway may be suppressed under these conditions.

scholarly journals Interactions between actin filaments and between actin filaments and membranes in quick-frozen and deeply etched hair cells of the chick ear.

1982 ◽  
Vol 95 (1) ◽  
pp. 249-261 ◽  
Author(s):  
N Hirokawa ◽  
L G Tilney
Keyword(s):  
Hair Cells ◽  
Actin Filaments ◽  
Apical Cell ◽  
Apical Surface ◽  
Contractile Ring ◽  
Vestibular Organ ◽  
Apical Cell Membrane ◽  
Cuticular Plate ◽  
Quick Freezing ◽  
Two Populations

Replicas of the apical surface of hair cells of the inner ear (vestibular organ) were examined after quick freezing and rotary shadowing. With this technique we illustrate two previously undescribed ways in which the actin filaments in the stereocilia and in the cuticular plate are attached to the plasma membrane. First, in each stereocilium there are threadlike connectors running from the actin filament bundle to the limiting membrane. Second, many of the actin filaments in the cuticular plate are connected to the apical cell membrane by tiny branched connecting units like a "crow's foot." Where these "feet" contact the membrane there is a small swelling. These branched "feet" extend mainly from the ends of the actin filaments but some connect the lateral surfaces of the actin filaments as well. Actin filaments in the cuticular plate are also connected to each other by finer filaments, 3 nm in thickness and 74 +/- 14 nm in length. Interestingly, these 3-nm filaments (which measure 4 nm in replicas) connect actin filaments not only of the same polarity but of opposite polarities as documented by examining replicas of the cuticular plate which had been decorated with subfragment 1 (S1) of myosin. At the apicolateral margins of the cell we find two populations of actin filaments, one just beneath the tight junction as a network, the other at the level of the zonula adherens as a ring. The latter which is quite substantial is composed of actin filaments that run parallel to each other; adjacent filaments often show opposite polarities, as evidenced by S1 decoration. The filaments making up this ring are connected together by the 3-nm connectors. Because of the polarity of the filaments this ring may be a "contractile" ring; the implications of this is discussed.

scholarly journals Vesicular transport of cationized ferritin by the epithelium of the rat choroid plexus.

1981 ◽  
Vol 89 (1) ◽  
pp. 131-139 ◽  
Author(s):  
B Van Deurs ◽  
F Von Bülow ◽  
M Møller
Keyword(s):  
Choroid Plexus ◽  
Vesicular Transport ◽  
Apical Cell ◽  
Multivesicular Bodies ◽  
Apical Surface ◽  
Cationized Ferritin ◽  
Epithelial Surface ◽  
Apical Cell Membrane ◽  
Choroidal Epithelium ◽  
Limited Degree

We have studied the transport of ferritin that was internalized by coated micropinocytic vesicles at the apical surface of the choroid plexus epithelium in situ. After ventriculocisternal perfusion of native ferritin (NF) or cationized ferritin (CF), three routes followed by the tracers are revealed: (a) to lysosomes, (b) to cisternal compartments, and (c) to the basolateral cell surface. (a) NF is micropinocytosed to a very limited degree and appears in a few lysosomal elements whereas CF is taken up in large amounts and can be followed, via endocytic vacuoles and light multivesicular bodies, to dark multivesicular bodies and dense bodies. (b) Occasionally, CF particles are found in cisterns that may represent GERL or trans-Golgi elements, whereas stacked Golgi cisterns never contain CF. (c) Transepithelial vesicular transport of CF is distinctly revealed. The intercellular spaces of the epithelium, below the apical tight junctions, contain numerous clusters of CF particles, often associated with surface-connected, coated vesicles. Vesicles in the process of exocytosis of CF are also present at the basal epithelial surface, whereas connective tissue elements below the epithelium are unlabeled. Our conclusion is that fluid and solutes removed from the cerebrospinal fluid by endocytosis either become sequestered in the lysosomal apparatus of the choroidal epithelium or are transported to the basolateral surface. However, our results do not indicate any significant recycling via Golgi complexes of internalized apical cell membrane.

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