Septate and Scalariform Junctions in Arthropods

Noirot-Timothée, C.; Noirot, Ch.

doi:10.1016/s0074-7696(08)61758-1

Cited by 196 publications

(49 citation statements)

References 101 publications

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“…Because these structures probably contribute to the permeability barrier they will be referred to as tricellular plugs. First described in 1980 by Noirot-Timoth~e and Noirot (15) and now identified in imag- Inset, a transversely sectioned three-cell intersection, x 100,000.…”

Section: The Organization Of the Septate Junction In Disksmentioning

confidence: 97%

“…It is generally envisioned as a girdle encircling the periphery of cells. However, Noirot-Timoth6e and Noirot (15) have shown that this is not the case in the adult gut epithelium of several insects. Instead, individual septa connect pairs of adjacent cells and, at the intersection with a third cell, turn basally and run parallel to the intersection until they terminate.…”

mentioning

confidence: 97%

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Septate junctions in imaginal disks of Drosophila: a model for the redistribution of septa during cell rearrangement.

Fristrom¹

1982

The Journal of Cell Biology

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The organization of septate junctions during morphogenesis of imaginal disks is described from freeze-fracture replicas and thin sections with a view to understanding junction modulation during rearrangements of cells in epithelia. The septate junctions of each epithelial cell of the disk are distributed in a number of discrete domains equal to the number of neighboring cells. Individual septa traverse domains of contact between pairs of adjacent cells, turn downwards at the lateral boundary of the domain and run parallel to the intersection with a third cell. This arrangement leaves small channels at three-cell intersections that are occupied by specialized structures termed "tricellular plugs." Cell rearrangement involves a progressive change in the width of contact domains between adjacent cells, until old contacts are broken and new ones established. It is proposed that the septate junction adjusts to the changing width of domains by the compaction or extension of existing septa. This redistribution of septa theoretically allows a transepithelial barrier to be maintained during cell rearrangements. The applicability of this model to other epithelial tissues is discussed.The morphogenesis of an epithelium has previously been assumed to be limited to movements of entire epithelial sheets, with each cell within the epithelium retaining its immediate neighbors (1, 2). The presence of specialized connections between adjacent epithelial cells and the absence of morphological evidence of locomotion undoubtedly contributed to this view. However, rearrangements of cells (i.e., cell movements involving change of neighbors within a contiguous epithelial sheet) have recently been described during the evagination of imagined disks in Drosophila (3,4), neurulation in newts (5), gastrulation in Xenopus (6), regeneration in Hydra (7), and epiboly in teleosts (8). Thus, cell rearrangement appears to be a widespread phenomenon in epithelial morphogenesis.In most of the examples cited above, intercellular junctions persist during cell rearrangement (3,(6)(7)(8). Because junctions are sites of intercellular adhesion between pairs of adjacent cells, the exchange of neighbors requires some form ofjnnction modulation (9). Tight junctions of vertebrates and septate junctions of invertebrates present particularly formidable bartiers to cell rearrangement because they bridge or close off the intercellular space between a given cell and all of its neighbors, ensuring contiguity of the epithelial layer and providing a barrier to the extracellular movement of molecules across the epithelium (10-12). Thus, each cell appears to be fixed with respect to its neighbors. This paper focuses on the distribution of septa and the potentially dynamic organization of the septate junction during cell rearrangement in imagined disks. The detailed structure of the septate junction is well known. Rows of septa connect adjacent ceils and separate the apical from the basal intercellular space. The plasma membranes on both sides of a septum conta...

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Section: The Organization Of the Septate Junction In Disksmentioning

confidence: 97%

mentioning

confidence: 97%

Septate junctions in imaginal disks of Drosophila: a model for the redistribution of septa during cell rearrangement.

Fristrom¹

1982

The Journal of Cell Biology

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“…The role of these junctions is unknown, although they have often been consid ered the invertebrate equivalent of vertebrate tight junctions (Noirot-Timothee and Noirot, 1980). The Dig protein is required for septate junction structure as shown by the absence or reduction of septate junctions in dig mutant larvae (D. F. Woods and P. J. Bryant, unpublished).…”

Section: Neoplastic Overgrowth Mutantsmentioning

confidence: 99%

Drosophila in cancer research: the first fifty tumor suppressor genes

Watson

Justice

Bryant

1994

Journal of Cell Science

110

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SUMMARYIn Drosophila, over 50 genes have been identified in which loss-of-function mutations lead to excess cell proliferation in the embryo, in the central nervous system, imaginal discs or hematopoietic organs of the larva, or in the adult gonads. Twenty-two of these genes have been cloned and characterized at the molecular level, and nine of them show clear homology to mammalian genes. Most of these mammalian genes had not been previously implicated in cell proliferation control. Overgrowth in some of the mutants involves conversion to a cell type that, in normal development, shows more cell proliferation than the original cell type. Thus the neurogenic mutants, including Notch, show conversion of epidermal cells to neuroblasts, leading to the 'neurogenic' phenotype of excess nervous tissue. The ovarian tumor mutants show conversion of the female germ line to a cell type resembling the male germ line, which undergoes more proliferation than the female germ line. Mutations of the fa t locus cause hyperplastic overgrowth of imaginal discs, in which the epithelial structure is largely intact. The predicted fat protein product is a giant relative of cadherins, supporting indica tions from human cancer that cadherins play an important role in tumor suppression. Mutations in the lethal(2)giant larvae and lethal(l)discs large genes cause neoplastic over growth of imaginal discs as well as the larval brain. The dig gene encodes a membrane-associated guanylate kinase homolog that is localized at septate junctions between epithelial cells. This protein is a member of a family of homologs that also includes two proteins found at mammalian tight junctions (ZO-1 and ZO-2) and a protein found at mammalian synaptic junctions (PSD-95/SAP90). Genes in which mutations cause blood cell overproduction include aberrant immune response-8, which encodes the RpS6 ribosomal protein and hopscotch, which encodes a putative non-receptor protein tyrosine kinase. The gene products identified by ovarian tumor mutants do not show clear amino acid sequence homology to known proteins. Drosophila provides an opportunity to rapidly identify and characterize tumor suppressor genes, many of which have mammalian homologs that might also be involved in cell proliferation control and tumor suppression.

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“…They first appear midway through embryogenesis and are characterized by a ladder-like arrangement of septa crossing the intercellular cleft. SJs have been proposed to play a role in the formation of a trans-epithelial diffusion barrier, establishing and/or maintaining cell polarity, cell adhesion and cell-cell interactions (Tepass and Hartenstein, 1994;Tepass et al, 2001;Lane and Skaer, 1980;Noirot-Timothée and Noirot, 1980). Several proteins are known to associate with SJs, and many of these form supramolecular complexes (Knust and Bossinger, 2002;Tepass et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Lachesin is a component of a septate junction-based mechanism that controls tube size and epithelial integrity in theDrosophilatracheal system

et al. 2004

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Organ morphogenesis requires the coordinated activity of many mechanisms involved in cell rearrangements, size control, cell proliferation and organ integrity. Here we report that Lachesin (Lac), a cell surface protein, is required for the proper morphogenesis of the Drosophila tracheal system. Homozygous embryos for Lac mutations, which we find fail to complement the previous identified bulbous (

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Septate and Scalariform Junctions in Arthropods

Cited by 196 publications

References 101 publications

Septate junctions in imaginal disks of Drosophila: a model for the redistribution of septa during cell rearrangement.

Septate junctions in imaginal disks of Drosophila: a model for the redistribution of septa during cell rearrangement.

Drosophila in cancer research: the first fifty tumor suppressor genes

Lachesin is a component of a septate junction-based mechanism that controls tube size and epithelial integrity in theDrosophilatracheal system

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