scholarly journals DIFFERENTIATION OF THE JUNCTIONAL COMPLEX OF SURFACE CELLS IN THE DEVELOPING FUNDULUS BLASTODERM

1971 ◽  
Vol 48 (3) ◽  
pp. 455-472 ◽  
Author(s):  
Thomas L. Lentz ◽  
J. P. Trinkaus
Keyword(s):  
Gap Junction ◽  
Teleost Fish ◽  
Intercellular Space ◽  
Fundulus Heteroclitus ◽  
Early Embryo ◽  
Intermediate Zone ◽  
Junctional Complex ◽  
Apical Region ◽  
Basic Organization ◽  
Zonula Occludens

The structure of the junctional complex between surface cells was investigated in blastula, mid gastrula, late gastrula, and early embryo of the teleost fish Fundulus heteroclitus. In blastulae, the intercellular complex is simple and consists of an apical region where the adjacent membranes are closely apposed (40–60 A) and in places touch, an intermediate zone with a wider intercellular space (> 100 A), and incipient desmosomes. In gastrulae, there are frequent points of fusion of membranes along the apical zone of the complex. Dilatations and an increased number of desmosomes in different stages of development are found along the intermediate zone. In mid gastrula, a close or gap junction with an intercellular space of 20 A occurs below the level of the desmosomes. In late gastrula, the gap junction is reduced in extent and desmosomes are better developed. In the early embryo, the basic organization of the complex is the same, although the deeply situated close junctions are no longer apparent and desmosomes and their associated system of filaments are well developed. At this time, the junctional complex is comparable to that of many epithelia and consists of an apical zonula occludens, a short zonula adherens, and deeply situated maculae adherentes.

scholarly journals JUNCTIONAL COMPLEXES IN VARIOUS EPITHELIA

1963 ◽  
Vol 17 (2) ◽  
pp. 375-412 ◽  
Author(s):  
Marilyn G. Farquhar ◽  
George E. Palade
Keyword(s):  
Tight Junction ◽  
Intercellular Space ◽  
Cell Membranes ◽  
Amorphous Material ◽  
Dense Material ◽  
Junctional Complex ◽  
Cytoplasmic Matrix ◽  
Pancreatic Acini ◽  
Zonula Occludens ◽  
Adjoining Cell

The epithelia of a number of glands and cavitary organs of the rat and guinea pig have been surveyed, and in all cases investigated, a characteristic tripartite junctional complex has been found between adjacent cells. Although the complex differs in precise arrangement from one organ to another, it has been regularly encountered in the mucosal epithelia of the stomach, intestine, gall bladder, uterus, and oviduct; in the glandular epithelia of the liver, pancreas, parotid, stomach, and thyroid; in the epithelia of pancreatic, hepatic, and salivary ducts; and finally, between the epithelial cells of the nephron (proximal and distal convolution, collecting ducts). The elements of the complex, identified as zonula occludens (tight junction), zonula adhaerens (intermediary junction), and macula adhaerens (desmosome), occupy a juxtaluminal position and succeed each other in the order given in an apical-basal direction. The zonula occludens (tight junction) is characterized by fusion of the adjacent cell membranes resulting in obliteration of the intercellular space over variable distances. Within the obliterated zone, the dense outer leaflets of the adjoining cell membranes converge to form a single intermediate line. A diffuse band of dense cytoplasmic material is often associated with this junction, but its development varies from one epithelium to another. The zonula adhaerens (intermediate junction) is characterized by the presence of an intercellular space (∼200 A) occupied by homogeneous, apparently amorphous material of low density; by strict parallelism of the adjoining cell membranes over distances of 0.2 to 0.5 µ; and by conspicuous bands of dense material located in the subjacent cytoplasmic matrix. The desmosome or macula adhaerens is also characterized by the presence of an intercellular space (∼240 A) which, in this case, contains a central disc of dense material; by discrete cytoplasmic plaques disposed parallel to the inner leaflet of each cell membrane; and by the presence of bundles of cytoplasmic fibrils converging on the plaques. The zonula occludens appears to form a continuous belt-like attachment, whereas the desmosome is a discontinuous, button-like structure. The zomula adhaerens is continuous in most epithelia but discontinuous in some. Observations made during experimental hemoglobinuria in rats showed that the hemoglobin, which undergoes enough concentration in the nephron lumina to act as an electron-opaque mass tracer, does not penetrate the intercellular spaces beyond the zonula occludens. Similar observations were made in pancreatic acini and ducts where discharged zymogen served as a mass tracer. Hence the tight junction is impervious to concentrated protein solutions and appears to function as a diffusion barrier or "seal." The desmosome and probably also the zonula adhaerens may represent intercellular attachment devices.

The Structure of Tight Junctions

1978 ◽  
Vol 36 (3) ◽  
pp. 659-672 ◽  
Author(s):  
S. Bullivant
Keyword(s):  
Tight Junction ◽  
Intercellular Space ◽  
Membrane Structure ◽  
Paracellular Permeability ◽  
Apical Region ◽  
Unit Membrane ◽  
Thin Sections ◽  
Freeze Fracturing ◽  
Outer Leaflet ◽  
Zonula Occludens

The tight junction, or zonula occludens, is generally found as a continuous belt, joining adjacent cells in the apical region of the border between them. It forms a seal across the intercellular space and hence regulates paracellular permeability. Farquhar and Palade (1963), recognised the belt-like sealing character, and showed that in thin sections the junction was seen as either punctate or linear fusions of the two membranes, often with the loss of the outer leaflet of the unit membrane at the fusion. With thin sections it can only be inferred that the junction forms a continuous belt, but with freeze-fracturing it can be seen directly. Moreover, in the junctional region the membrane structure is modified by a series of interconnected fibrils approximately parallel to the line of the belt (Kreutziger, 1968; Staehelin et al, 1969; Goodenough and Revel, 1970), and within the interior of the membrane Tchalcroft and Bullivant, 1970). The fibrils are at the lines of membrane fusion.

Intercellular Junctions in the Organ of Corti

1978 ◽  
Vol 87 (1) ◽  
pp. 70-80 ◽  
Author(s):  
Joseph B. Nadol
Keyword(s):  
Tight Junctions ◽  
Intercellular Space ◽  
Basilar Membrane ◽  
Membrane Surface ◽  
Morphological Characteristics ◽  
Organ Of Corti ◽  
Intercellular Junctions ◽  
Junctional Complex ◽  
Supporting Cells ◽  
Zonula Occludens

The intercellular junctions between adjacent supporting cells and between apposed hair and supporting cells in the organ of Corti of cat and human were studied. At the endolymphatic surface, the intercellular space was closed by a series of tight junctions (zonula occludens), whereas there were no tight junctions at the basilar membrane surface of the neuro-epithelium. Beneath the adlumenal zonula occludens between adjacent supporting cells, a zonula adherens (intermediate junction, “desmosome”) was found. Many gap junctions joined apposed supporting cells both within and below the endolymphatic junctional complex. Below the zonula occludens between apposed hair and supporting cells, membrane specialization sharing the morphological characteristics of both the macula adherens and zonula adherens was found. Between areas of tight junctional specialization in the junctional complex between hair and supporting cells, there were short areas of parallel limiting membranes separated by a 20A intercellular space. These areas were suggestive but not characteristic of gap junctional specialization. The functional significance of the junctional specialization between cells in the organ of Corti was discussed.

Nonmitogenic morphoregulatory action of pp60v-src on multicellular epithelial structures

1987 ◽  
Vol 7 (4) ◽  
pp. 1326-1337
Author(s):  
S L Warren ◽  
W J Nelson
Keyword(s):  
Tyrosine Kinases ◽  
Mdck Cells ◽  
Growth Potential ◽  
Junctional Complex ◽  
Madin Darby Canine Kidney ◽  
Epithelial Monolayers ◽  
Zonula Occludens ◽  
Darby Canine Kidney ◽  
Canine Kidney

Madin-Darby canine kidney (MDCK) cells form polarized, multicellular epithelial structures in vitro. Low-level expression of pp60v-src in MDCK cells elicits plasticity in these multicellular structures. Plasticity was revealed by the displacement of cells from mechanically stressed regions of the epithelial monolayers; however, the two-dimensional relationship between the cells in the remainder of the monolayer was maintained. Electron microscopy of multicellular structures revealed abnormal separation of the lateral membranes of adjacent cells and selective uncoupling of the junctional complex; the zonula adherens was disrupted, but the zonula occludens and desmosomes were retained. Significantly, this result was not accompanied by transformation of the cells, as judged by the absence of anchorage-independent growth potential. These results demonstrate a nonmitogenic biological activity of pp60v-src which is experimentally dissociable from transformation. This morphoregulatory action on higher-order epithelial structures may reflect a function of related cellular tyrosine kinases.

scholarly journals VARIATIONS IN TIGHT AND GAP JUNCTIONS IN MAMMALIAN TISSUES

1972 ◽  
Vol 53 (3) ◽  
pp. 758-776 ◽  
Author(s):  
Daniel S. Friend ◽  
Norton B. Gilula
Keyword(s):  
Smooth Muscle ◽  
Gap Junctions ◽  
Tight Junctions ◽  
Adrenal Cortex ◽  
Freeze Fracture ◽  
Junctional Complex ◽  
Exocrine Glands ◽  
Rat Pancreas ◽  
Zonula Occludens ◽  
Mammalian Tissues

The fine structure and distribution of tight (zonula occludens) and gap junctions in epithelia of the rat pancreas, liver, adrenal cortex, epididymis, and duodenum, and in smooth muscle were examined in paraformaldehyde-glutaraldehyde-fixed, tracer-permeated (K-pyroantimonate and lanthanum), and freeze-fractured tissue preparations. While many pentalaminar and septilaminar foci seen in thin-section and tracer preparations can be recognized as corresponding to well-characterized freeze-fracture images of tight and gap junction membrane modifications, many others cannot be unequivocally categorized—nor can all freeze-etched aggregates of membrane particles. Generally, epithelia of exocrine glands (pancreas and liver) have moderate-sized tight junctions and large gap junctions, with many of their gap junctions basal to the junctional complex. In contrast, the adrenal cortex, a ductless gland, may not have a tight junction but does possess large gap junctions. Mucosal epithelia (epididymis and intestine) have extensive tight junctions, but their gap junctions are not as well developed as those of glandular tissue. Smooth muscle contains numerous small gap junctions The incidence, size, and configuration of the junctions we observed correlate well with the known functions of the junctions and of the tissues where they are found.

scholarly journals Nonmitogenic morphoregulatory action of pp60v-src on multicellular epithelial structures.

1987 ◽  
Vol 7 (4) ◽  
pp. 1326-1337 ◽  
Author(s):  
S L Warren ◽  
W J Nelson
Keyword(s):  
Tyrosine Kinases ◽  
Mdck Cells ◽  
Growth Potential ◽  
Junctional Complex ◽  
Madin Darby Canine Kidney ◽  
Epithelial Monolayers ◽  
Zonula Occludens ◽  
Darby Canine Kidney ◽  
Canine Kidney

Madin-Darby canine kidney (MDCK) cells form polarized, multicellular epithelial structures in vitro. Low-level expression of pp60v-src in MDCK cells elicits plasticity in these multicellular structures. Plasticity was revealed by the displacement of cells from mechanically stressed regions of the epithelial monolayers; however, the two-dimensional relationship between the cells in the remainder of the monolayer was maintained. Electron microscopy of multicellular structures revealed abnormal separation of the lateral membranes of adjacent cells and selective uncoupling of the junctional complex; the zonula adherens was disrupted, but the zonula occludens and desmosomes were retained. Significantly, this result was not accompanied by transformation of the cells, as judged by the absence of anchorage-independent growth potential. These results demonstrate a nonmitogenic biological activity of pp60v-src which is experimentally dissociable from transformation. This morphoregulatory action on higher-order epithelial structures may reflect a function of related cellular tyrosine kinases.

Cell relationships in Hymenolepis diminuta

Parasitology ◽  
1970 ◽  
Vol 60 (2) ◽  
pp. 181-184 ◽  
Author(s):  
L. T. Threadgold ◽  
C. P. Read
Keyword(s):  
Electron Microscope ◽  
Tight Junction ◽  
Hymenolepis Diminuta ◽  
Excretory System ◽  
Junctional Complex ◽  
Dense Granules ◽  
Zonula Occludens ◽  
Rice University ◽  
Intercellular Region ◽  
Zoology Department

SUMMARYThe intimate cell relationships of Hymenolepis diminuta are described and occur between cells of the parenchyma, excretory system, muscle and tegument. The cell relationships are of three types: (a) a tight junction or zonula occludens; (b) a desmosome-like structure without tonofibrils or intercellular dense line; (c) a junctional complex with modified unit membranes and an intercellular region of dense granules and fibres.This research was begun while one of us (L.T.T.) was a Visiting Lecturer in the Biology Department, Rice University, and completed in the Zoology Department, Queen's University, Belfast. We should like to thank Dr C. W. Philpott for allowing us the full use of the facilities of his electron-microscope unit and Mr W. Ferguson for photographic assistance.

scholarly journals Zonula Occludens-1 Alters Connexin43 Gap Junction Size and Organization by Influencing Channel Accretion

2005 ◽  
Vol 16 (12) ◽  
pp. 5686-5698 ◽  
Author(s):  
Andrew W. Hunter ◽  
Ralph J. Barker ◽  
Ching Zhu ◽  
Robert G. Gourdie
Keyword(s):  
Image Analysis ◽  
Gap Junction ◽  
Peptide Inhibitor ◽  
Proper Function ◽  
Plaque Size ◽  
Confocal Image ◽  
Zonula Occludens ◽  
Genetic Tagging ◽  
Zonula Occludens 1 ◽  
Gap Junctional

Regulation of gap junction (GJ) organization is critical for proper function of excitable tissues such as heart and brain, yet mechanisms that govern the dynamic patterning of GJs remain poorly defined. Here, we show that zonula occludens (ZO)-1 localizes preferentially to the periphery of connexin43 (Cx43) GJ plaques. Blockade of the PDS95/dlg/ZO-1 (PDZ)-mediated interaction between ZO-1 and Cx43, by genetic tagging of Cx43 or by a membrane-permeable peptide inhibitor that contains the Cx43 PDZ-binding domain, led to a reduction of peripherally associated ZO-1 accompanied by a significant increase in plaque size. Biochemical data indicate that the size increase was due to unregulated accumulation of gap junctional channels from nonjunctional pools, rather than to increased protein expression or decreased turnover. Coexpression of native Cx43 fully rescued the aberrant tagged-connexin phenotype, but only if channels were composed predominately of untagged connexin. Confocal image analysis revealed that, subsequent to GJ nucleation, ZO-1 association with Cx43 GJs is independent of plaque size. We propose that ZO-1 controls the rate of Cx43 channel accretion at GJ peripheries, which, in conjunction with the rate of GJ turnover, regulates GJ size and distribution.

scholarly journals Phosphorylation regulates connexin43/ZO-1 binding and release, an important step in gap junction turnover

2017 ◽  
Vol 28 (25) ◽  
pp. 3595-3608 ◽  
Author(s):  
Anastasia F. Thévenin ◽  
Rachel A. Margraf ◽  
Charles G. Fisher ◽  
Rachael M. Kells-Andrews ◽  
Matthias M. Falk
Keyword(s):  
Protein Kinase ◽  
Gap Junction ◽  
Wild Type ◽  
Madin Darby Canine Kidney ◽  
Kinase C ◽  
Zonula Occludens ◽  
Zonula Occludens 1 ◽  
Darby Canine Kidney ◽  
Canine Kidney

To investigate whether connexin phosphorylation regulates the known role of zonula occludens-1 protein (ZO-1) in gap junction (GJ) function, we generated and analyzed a series of phosphomimetic and phosphorylation-dead mutants by mutating known conserved regulatory serine (S) residues 255, 279/282, 365, 368, and 373 located in the C-terminal domain of connexin43 (Cx43) into glutamic acid (E) or alanine (A) residues. All connexin mutants were translated into stable, full-length proteins and assembled into GJs when expressed in HeLa or Madin–Darby canine kidney epithelial cells. However, mutants with S residues exchanged at positions 365, 368, and 373 exhibited a significantly altered ZO-1 interaction profile, while mutants with S residues exchanged at 255 and 279/282 did not. Unlike wild-type Cx43, in which ZO-1 binding is restricted to the periphery of GJ plaques, S365A, S365E, S368A, S368E, and S373A mutants bound ZO-1 throughout the GJ plaques, while the S373E mutant did not bind ZO-1 at all. Inability to disengage from ZO-1 correlated with increased GJ plaque size and increased connexin protein half-life, while maintaining GJ channels in an open, functional state. Quantitative clathrin-binding analyses revealed no significant alterations in clathrin-binding efficiency, suggesting that the inability to disengage from ZO-1 prevented maturation of functional into nonfunctional/endocytic channels, rather than ZO-1 interfering with GJ endocytosis directly. Collectively, our results indicate that ZO-1 binding regulates channel accrual, while disengagement from ZO-1 is critical for GJ channel closure and transitioning GJ channels for endocytosis. Intriguingly, these transitional ZO-1 binding/release and channel-aging steps are mediated by a series of hierarchical phosphorylation/dephosphorylation events at S373, S365, and S368, well-known Cx43 Akt, protein kinase A, and protein kinase C phosphorylation sites located in the vicinity of the ZO-1 binding site.

scholarly journals Ion regulation in eurythermic teleost fish Fundulus heteroclitus: Cold shock vs. cold acclimation

2013 ◽  
Vol 27 (S1) ◽  
Author(s):  
William S Marshall ◽  
Kaitlyn R Barnes ◽  
Alicia M Malone ◽  
Hannah EC Buhariwalla ◽  
Emily M Osmond
Keyword(s):  
Cold Acclimation ◽  
Teleost Fish ◽  
Fundulus Heteroclitus ◽  
Cold Shock ◽  
Ion Regulation
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