scholarly journals CDC42 and Rac1 control different actin-dependent processes in the Drosophila wing disc epithelium.

1995 ◽  
Vol 131 (1) ◽  
pp. 151-164 ◽  
Author(s):  
S Eaton ◽  
P Auvinen ◽  
L Luo ◽  
Y N Jan ◽  
K Simons
Keyword(s):  
Epithelial Cells ◽  
Cell Shape ◽  
Larval Instar ◽  
Cell Types ◽  
Wing Disc ◽  
Dominant Negative ◽  
The Third ◽  
Drosophila Wing ◽  
Cell Shape Changes ◽  
Shape Changes

Cdc42 and Rac1 are members of the rho family of small guanosinetriphosphatases and are required for a diverse set of cytoskeleton-membrane interactions in different cell types. Here we show that these two proteins contribute differently to the organization of epithelial cells in the Drosophila wing imaginal disc. Drac1 is required to assemble actin at adherens junctions. Failure of adherens junction actin assembly in Drac1 dominant-negative mutants is associated with increased cell death. Dcdc42, on the other hand, is required for processes that involve polarized cell shape changes during both pupal and larval development. In the third larval instar, Dcdc42 is required for apico-basal epithelial elongation. Whereas normal wing disc epithelial cells increase in height more than twofold during the third instar, cells that express a dominant-negative version of Dcdc42 remain short and are abnormally shaped. Dcdc42 localizes to both apical and basal regions of the cell during these events, and mediates elongation, at least in part, by effecting a reorganization of the basal actin cytoskeleton. These observations suggest that a common cdc42-based mechanism may govern polarized cell shape changes in a wide variety of cell types.

scholarly journals The Drosophila Ral GTPase Regulates Developmental Cell Shape Changes through the Jun NH2-terminal Kinase Pathway

1999 ◽  
Vol 146 (2) ◽  
pp. 361-372 ◽  
Author(s):  
Kazunobu Sawamoto ◽  
Per Winge ◽  
Shinya Koyama ◽  
Yuki Hirota ◽  
Chiharu Yamada ◽  
...  
Keyword(s):  
Cell Shape ◽  
Effector Proteins ◽  
Dominant Negative ◽  
Loss Of Function ◽  
Jnk Pathway ◽  
Cell Shape Changes ◽  
Ral Gtpase ◽  
Shape Changes ◽  
Constitutively Active

The Ral GTPase is activated by RalGDS, which is one of the effector proteins for Ras. Previous studies have suggested that Ral might function to regulate the cytoskeleton; however, its in vivo function is unknown. We have identified a Drosophila homologue of Ral that is widely expressed during embryogenesis and imaginal disc development. Two mutant Drosophila Ral (DRal) proteins, DRalG20V and DRalS25N, were generated and analyzed for nucleotide binding and GTPase activity. The biochemical analyses demonstrated that DRalG20V and DRalS25N act as constitutively active and dominant negative mutants, respectively. Overexpression of the wild-type DRal did not cause any visible phenotype, whereas DRalG20V and DRalS25N mutants caused defects in the development of various tissues including the cuticular surface, which is covered by parallel arrays of polarized structures such as hairs and sensory bristles. The dominant negative DRal protein caused defects in the development of hairs and bristles. These phenotypes were genetically suppressed by loss of function mutations of hemipterous and basket, encoding Drosophila Jun NH2-terminal kinase kinase (JNKK) and Jun NH2-terminal kinase (JNK), respectively. Expression of the constitutively active DRal protein caused defects in the process of dorsal closure during embryogenesis and inhibited the phosphorylation of JNK in cultured S2 cells. These results indicate that DRal regulates developmental cell shape changes through the JNK pathway.

scholarly journals Measurement of junctional tension in epithelial cells at the onset of primitive streak formation in the chick embryo via non-destructive optical manipulation

2018 ◽  
Author(s):  
Valentina Ferro ◽  
Manli Chuai ◽  
David McGloin ◽  
Cornelis Weijer
Keyword(s):  
Epithelial Cells ◽  
Cell Shape ◽  
Large Scale ◽  
Cell Sheet ◽  
Primitive Streak ◽  
Cell Junctions ◽  
Optical Manipulation ◽  
Cell Shape Changes ◽  
Non Destructive ◽  
Shape Changes

Oriented cell intercalations and cell shape changes are key determinants of large-scale epithelial cell sheet deformations occurring during gastrulation in many organisms. In several cases directional intercalation and cell shape changes have been shown to be associated with a planar cell polarity in the organisation of the actin-myosin cytoskeleton of epithelial cells. This polarised cytoskeletal organisation has been postulated to reflect the directional tension necessary to drive and orient directional cell intercalations. We have now further characterised and applied a recently introduced non-destructive optical manipulation technique to measure the tension in individual cell junctions in the epiblast of chick embryos in the early stages of primitive streak formation. We have measured junctional tension as a function of position and orientation. Junctional tension of mesendoderm cells, the tissue that drives the formation of the streak, is higher than tension of junctions of cells in other parts of the epiblast. Furthermore, in the mesendoderm junctional tension is higher in the direction of intercalation. The data are fitted best with a Maxwell model and we find that both junctional tension and relaxation time are dependent on myosin activity.

scholarly journals Division of Labor among the α6β4 Integrin, β1 Integrins, and an E3 Laminin Receptor to Signal Morphogenesis and β-Casein Expression in Mammary Epithelial Cells

1999 ◽  
Vol 10 (9) ◽  
pp. 2817-2828 ◽  
Author(s):  
John Muschler ◽  
André Lochter ◽  
Calvin D. Roskelley ◽  
Peter Yurchenco ◽  
Mina J. Bissell
Keyword(s):  
Epithelial Cells ◽  
Cell Shape ◽  
Mammary Epithelial Cells ◽  
Mammary Epithelial ◽  
Laminin Receptor ◽  
Blocking Antibody ◽  
Α6β4 Integrin ◽  
Cell Shape Changes ◽  
Blocking Antibodies ◽  
Shape Changes

Contact of cultured mammary epithelial cells with the basement membrane protein laminin induces multiple responses, including cell shape changes, growth arrest, and, in the presence of prolactin, transcription of the milk protein β-casein. We sought to identify the specific laminin receptor(s) mediating the multiple cell responses to laminin. Using assays with clonal mammary epithelial cells, we reveal distinct functions for the α6β4 integrin, β1 integrins, and an E3 laminin receptor. Signals from laminin for β-casein expression were inhibited in the presence of function-blocking antibodies against both the α6 and β1 integrin subunits and by the laminin E3 fragment. The α6-blocking antibody perturbed signals mediated by the α6β4 integrin, and the β1-blocking antibody perturbed signals mediated by another integrin, the α subunit(s) of which remains to be determined. Neither α6- nor β1-blocking antibodies perturbed the cell shape changes resulting from cell exposure to laminin. However, the E3 laminin fragment and heparin both inhibited cell shape changes induced by laminin, thereby implicating an E3 laminin receptor in this function. These results elucidate the multiplicity of cell-extracellular matrix interactions required to integrate cell structure and signaling and ultimately permit normal cell function.

scholarly journals A genetic screen for temperature-sensitive morphogenesis-defectiveCaenorhabditis elegansmutants

2021 ◽  
Vol 11 (4) ◽  
Author(s):  
Molly C Jud ◽  
Josh Lowry ◽  
Thalia Padilla ◽  
Erin Clifford ◽  
Yuqi Yang ◽  
...  
Keyword(s):  
Cell Shape ◽  
The Body ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Fundamental Biological Process ◽  
Embryonic Morphogenesis ◽  
Cell Shape Changes ◽  
Development Temperature ◽  
Multicellular Organisms ◽  
Shape Changes

AbstractMorphogenesis involves coordinated cell migrations and cell shape changes that generate tissues and organs, and organize the body plan. Cell adhesion and the cytoskeleton are important for executing morphogenesis, but their regulation remains poorly understood. As genes required for embryonic morphogenesis may have earlier roles in development, temperature-sensitive embryonic-lethal mutations are useful tools for investigating this process. From a collection of ∼200 such Caenorhabditis elegans mutants, we have identified 17 that have highly penetrant embryonic morphogenesis defects after upshifts from the permissive to the restrictive temperature, just prior to the cell shape changes that mediate elongation of the ovoid embryo into a vermiform larva. Using whole genome sequencing, we identified the causal mutations in seven affected genes. These include three genes that have roles in producing the extracellular matrix, which is known to affect the morphogenesis of epithelial tissues in multicellular organisms: the rib-1 and rib-2 genes encode glycosyltransferases, and the emb-9 gene encodes a collagen subunit. We also used live imaging to characterize epidermal cell shape dynamics in one mutant, or1219ts, and observed cell elongation defects during dorsal intercalation and ventral enclosure that may be responsible for the body elongation defects. These results indicate that our screen has identified factors that influence morphogenesis and provides a platform for advancing our understanding of this fundamental biological process.

Estradiol promotes cell shape changes and glial fibrillary acidic protein redistribution in hypothalamic astrocytes in vitro: A neuronal-mediated effect

Glia ◽  
1992 ◽  
Vol 6 (3) ◽  
pp. 180-187 ◽  
Author(s):  
Ignacio Torres-Aleman ◽  
Maria Teresa Rejas ◽  
Sebastian Pons ◽  
Luis Miguel Garcia-Segura
Keyword(s):  
Glial Fibrillary Acidic Protein ◽  
Cell Shape ◽  
Acidic Protein ◽  
Cell Shape Changes ◽  
Shape Changes

scholarly journals Dependency relationships between IFT-dependent flagellum elongation and cell morphogenesis in Leishmania

Open Biology ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 180124 ◽  
Author(s):  
Jack Daniel Sunter ◽  
Flavia Moreira-Leite ◽  
Keith Gull
Keyword(s):  
Fluorescence Microscopy ◽  
Cell Shape ◽  
Electron Tomography ◽  
Intraflagellar Transport ◽  
Flagellar Pocket ◽  
Cell Morphogenesis ◽  
Multiple Functions ◽  
Cell Shape Changes ◽  
Shape Changes

Flagella have multiple functions that are associated with different axonemal structures. Motile flagella typically have a 9 + 2 arrangement of microtubules, whereas sensory flagella normally have a 9 + 0 arrangement. Leishmania exhibits both of these flagellum forms and differentiation between these two flagellum forms is associated with cytoskeletal and cell shape changes. We disrupted flagellum elongation in Leishmania by deleting the intraflagellar transport (IFT) protein IFT140 and examined the effects on cell morphogenesis. Δift140 cells have no external flagellum, having only a very short flagellum within the flagellar pocket. This short flagellum had a collapsed 9 + 0 (9v) axoneme configuration reminiscent of that in the amastigote and was not attached to the pocket membrane. Although amastigote-like changes occurred in the flagellar cytoskeleton, the cytoskeletal structures of Δift140 cells retained their promastigote configurations, as examined by fluorescence microscopy of tagged proteins and serial electron tomography. Thus, Leishmania promastigote cell morphogenesis does not depend on the formation of a long flagellum attached at the neck. Furthermore, our data show that disruption of the IFT system is sufficient to produce a switch from the 9 + 2 to the collapsed 9 + 0 (9v) axonemal structure, echoing the process that occurs during the promastigote to amastigote differentiation.

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