scholarly journals Reassessing the Role and Dynamics of Nonmuscle Myosin II during Furrow Formation in Early Drosophila Embryos

2004 ◽  
Vol 15 (2) ◽  
pp. 838-850 ◽  
Author(s):  
Anne Royou ◽  
Christine Field ◽  
John C. Sisson ◽  
William Sullivan ◽  
Roger Karess
Keyword(s):  
Myosin Ii ◽  
Colchicine Treatment ◽  
Drosophila Embryo ◽  
Dependent Manner ◽  
Membrane Invagination ◽  
Nonmuscle Myosin Ii ◽  
Early Drosophila Embryo ◽  
Cytoskeleton Rearrangements ◽  
Drosophila Embryos

The early Drosophila embryo undergoes two distinct membrane invagination events believed to be mechanistically related to cytokinesis: metaphase furrow formation and cellularization. Both involve actin cytoskeleton rearrangements, and both have myosin II at or near the forming furrow. Actin and myosin are thought to provide the force driving membrane invagination; however, membrane addition is also important. We have examined the role of myosin during these events in living embryos, with a fully functional myosin regulatory light-chain-GFP chimera. We find that furrow invagination during metaphase and cellularization occurs even when myosin activity has been experimentally perturbed. In contrast, the basal closure of the cellularization furrows and the first cytokinesis after cellularization are highly dependent on myosin. Strikingly, when ingression of the cellularization furrow is experimentally inhibited by colchicine treatment, basal closure still occurs at the appropriate time, suggesting that it is regulated independently of earlier cellularization events. We have also identified a previously unrecognized reservoir of particulate myosin that is recruited basally into the invaginating furrow in a microfilament-independent and microtubule-dependent manner. We suggest that cellularization can be divided into two distinct processes: furrow ingression, driven by microtubule mediated vesicle delivery, and basal closure, which is mediated by actin/myosin based constriction.

scholarly journals Emerging Role of Nonmuscle Myosin II and Implications for NMMII Associated Deafness

2011 ◽  
Vol 145 (2_suppl) ◽  
pp. P209-P210
Author(s):  
Elliott Kozin ◽  
Bechara Kachar ◽  
Felipe Salles ◽  
Robert Adelstein ◽  
Xuefei Ma ◽  
...  
Keyword(s):  
Myosin Ii ◽  
Nonmuscle Myosin ◽  
Nonmuscle Myosin Ii

Second-Site Noncomplementation Identifies Genomic Regions Required for Drosophila Nonmuscle Myosin Function During Morphogenesis

Genetics ◽  
1998 ◽  
Vol 148 (4) ◽  
pp. 1845-1863
Author(s):  
Susan R Halsell ◽  
Daniel P Kiehart
Keyword(s):  
Cell Shape ◽  
Myosin Ii ◽  
Nonmuscle Myosin ◽  
Genetic Screens ◽  
Nonmuscle Myosin Ii ◽  
Cell Shape Changes ◽  
Genomic Regions ◽  
Shape Changes ◽  
Strong Interactors

Abstract Drosophila is an ideal metazoan model system for analyzing the role of nonmuscle myosin-II (henceforth, myosin) during development. In Drosophila, myosin function is required for cytokinesis and morphogenesis driven by cell migration and/or cell shape changes during oogenesis, embryogenesis, larval development and pupal metamorphosis. The mechanisms that regulate myosin function and the supramolecular structures into which myosin incorporates have not been systematically characterized. The genetic screens described here identify genomic regions that uncover loci that facilitate myosin function. The nonmuscle myosin heavy chain is encoded by a single locus, zipper. Contiguous chromosomal deficiencies that represent approximately 70% of the euchromatic genome were screened for genetic interactions with two recessive lethal alleles of zipper in a second-site noncomplementation assay for the malformed phenotype. Malformation in the adult leg reflects aberrations in cell shape changes driven by myosin-based contraction during leg morphogenesis. Of the 158 deficiencies tested, 47 behaved as second-site noncomplementors of zipper. Two of the deficiencies are strong interactors, 17 are intermediate and 28 are weak. Finer genetic mapping reveals that mutations in cytoplasmic tropomyosin and viking (collagen IV) behave as second-site noncomplementors of zipper during leg morphogenesis and that zipper function requires a previously uncharacterized locus, E3.10/J3.8, for leg morphogenesis and viability.

scholarly journals Differential role of nonmuscle myosin II isoforms during blebbing of MCF-7 cells

2017 ◽  
Vol 28 (8) ◽  
pp. 1034-1042 ◽  
Author(s):  
Sumit K. Dey ◽  
Raman K. Singh ◽  
Shyamtanu Chattoraj ◽  
Shekhar Saha ◽  
Alakesh Das ◽  
...  
Keyword(s):  
Life Cycle ◽  
Actin Filament ◽  
Myosin Ii ◽  
Nonmuscle Myosin ◽  
Nonmuscle Myosin Ii ◽  
Different Types ◽  
Membrane Protrusions ◽  
Bleb Formation ◽  
Mcf 7

Bleb formation has been correlated with nonmuscle myosin II (NM-II) activity. Whether three isoforms of NM-II (NM-IIA, -IIB and -IIC) have the same or differential roles in bleb formation is not well understood. Here we report that ectopically expressed, GFP-tagged NM-II isoforms exhibit different types of membrane protrusions, such as multiple blebs, lamellipodia, combinations of both, or absence of any such protrusions in MCF-7 cells. Quantification suggests that 50% of NM-IIA-GFP–, 29% of NM-IIB-GFP–, and 19% of NM-IIC1-GFP–expressing MCF-7 cells show multiple bleb formation, compared with 36% of cells expressing GFP alone. Of interest, NM-IIB has an almost 50% lower rate of dissociation from actin filament than NM-IIA and –IIC1 as determined by FRET analysis both at cell and bleb cortices. We induced bleb formation by disruption of the cortex and found that all three NM-II-GFP isoforms can reappear and form filaments but to different degrees in the growing bleb. NM-IIB-GFP can form filaments in blebs in 41% of NM-IIB-GFP–expressing cells, whereas filaments form in only 12 and 3% of cells expressing NM-IIA-GFP and NM-IIC1-GFP, respectively. These studies suggest that NM-II isoforms have differential roles in the bleb life cycle.

scholarly journals The cell cycle-dependent localization of the CP190 centrosomal protein is determined by the coordinate action of two separable domains.

1995 ◽  
Vol 131 (5) ◽  
pp. 1261-1273 ◽  
Author(s):  
K Oegema ◽  
W G Whitfield ◽  
B Alberts
Keyword(s):  
Cell Cycle ◽  
Amino Acids ◽  
Nuclear Localization ◽  
Fusion Proteins ◽  
Drosophila Embryo ◽  
Dependent Manner ◽  
Fluorescence Confocal Microscopy ◽  
Early Drosophila Embryo ◽  
A Cell ◽  
Cycle Dependent

CP190, a protein of 1,096 amino acids from Drosophila melanogaster, oscillates in a cell cycle-specific manner between the nucleus during interphase, and the centrosome during mitosis. To characterize the regions of CP190 responsible for its dynamic behavior, we injected rhodamine-labeled fusion proteins spanning most of CP190 into early Drosophila embryos, where their localizations were characterized using time-lapse fluorescence confocal microscopy. A single bipartite 19-amino acid nuclear localization signal was detected that causes nuclear localization. Robust centrosomal localization is conferred by a separate region of 124 amino acids; two adjacent, nonoverlapping fusion proteins containing distinct portions of this region show weaker centrosomal localization. Fusion proteins that contain both nuclear and centrosomal localization sequences oscillate between the nucleus and the centrosome in a manner identical to native CP190. Fusion proteins containing only the centrosome localization sequence are found at centrosomes throughout the cell cycle, suggesting that CP190 is actively recruited away from the centrosome by its movement into the nucleus during interphase. Both native and bacterially expressed CP190 cosediment with microtubules in vitro. Tests with fusion proteins show that the domain responsible for microtubule binding overlaps the domain required for centrosomal localization. CP60, a protein identified by its association with CP190, also localizes to centrosomes and to nuclei in a cell cycle-dependent manner. Experiments in which colchicine is used to depolymerize microtubules in the early Drosophila embryo demonstrate that both CP190 and CP60 are able to attain and maintain their centrosomal localization in the absence of microtubules.

scholarly journals Carboxyl-terminal-dependent recruitment of nonmuscle myosin II to megakaryocyte contractile ring during polyploidization

Blood ◽  
2014 ◽  
Vol 124 (16) ◽  
pp. 2564-2568 ◽  
Author(s):  
Idinath Badirou ◽  
Jiajia Pan ◽  
Céline Legrand ◽  
Aibing Wang ◽  
Larissa Lordier ◽  
...  
Keyword(s):  
Myosin Ii ◽  
Specific Role ◽  
Nonmuscle Myosin ◽  
Contractile Ring ◽  
Terminal Domain ◽  
Nonmuscle Myosin Ii ◽  
Key Points ◽  
Carboxyl Terminal

Key Points C-terminal domain determines myosin II localization to the MK contractile ring and the specific role of NMII-B in MK polyploidization.

scholarly journals Role of Phosphatidylinositol 4,5-Bisphosphate in Ras/Rac-Induced Disruption of the Cortactin-Actomyosin II Complex and Malignant Transformation

1998 ◽  
Vol 18 (7) ◽  
pp. 3829-3837 ◽  
Author(s):  
Hong He ◽  
Takeshi Watanabe ◽  
Xi Zhan ◽  
Cai Huang ◽  
Ed Schuuring ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Malignant Transformation ◽  
Myosin Ii ◽  
Signal Transduction Pathway ◽  
Dependent Manner ◽  
Transduction Pathway ◽  
Membrane Ruffling ◽  
Oncogenic Ras ◽  
Cytoskeletal Change

ABSTRACT Oncogenic Ras mutants such as v-Ha-Ras cause a rapid rearrangement of actin cytoskeleton during malignant transformation of fibroblasts or epithelial cells. Both PI-3 kinase and Rac are required for Ras-induced malignant transformation and membrane ruffling. However, the signal transduction pathway(s) downstream of Rac that leads to membrane ruffling and other cytoskeletal change(s) as well as the exact biochemical nature of the cytoskeletal change remain unknown. Cortactin/EMS1 is the first identified molecule that is dissociated in a Rac–phosphatidylinositol 4,5-biphosphate (PIP2)-dependent manner from the actin-myosin II complex during Ras-induced malignant transformation; either the PIP2 binder HS1 or the Rac blocker SCH51344 restores the ability of EMS1 to bind the complex and suppresses the oncogenicity of Ras. Furthermore, while PIP2 inhibits the actin-EMS1 interaction, HS1 reverses the PIP2 effect. Thus, we propose that PIP2, an end-product of the oncogenic Ras/PI-3 kinase/Rac pathway, serves as a second messenger in the Ras/Rac-induced disruption of the actin cytoskeleton and discuss the anticancer drug potential of PIP2-binding molecules.

Drosophila nonmuscle myosin II has multiple essential roles in imaginal disc and egg chamber morphogenesis

Development ◽  
1996 ◽  
Vol 122 (5) ◽  
pp. 1499-1511 ◽  
Author(s):  
K.A. Edwards ◽  
D.P. Kiehart
Keyword(s):  
Myosin Ii ◽  
Cell Sheet ◽  
Follicle Cell ◽  
Nonmuscle Myosin ◽  
Filamentous Actin ◽  
Nonmuscle Myosin Ii ◽  
Egg Chambers ◽  
Mutant Phenotypes ◽  
Shape Changes ◽  
Drosophila Embryos

Morphogenesis is characterized by orchestrated changes in the shape and position of individual cells. Many of these movements are thought to be powered by motor proteins. However, in metazoans, it is often difficult to match specific motors with the movements they drive. The nonmuscle myosin II heavy chain (MHC encoded by zipper is required for cell sheet movements in Drosophila embryos. To determine if myosin II is required for other processes, we examined the phenotypes of strong and weak larval lethal mutations in spaghetti squash (sqh), which encodes the nonmuscle myosin II regulatory light chain (RLC). sqh mutants can be rescued to adulthood by daily induction of a sqh cDNA transgene driven by the hsp70 promoter. By transiently ceasing induction of the cDNA, we depleted RLC at specific times during development. When RLC is transiently depleted in larvae, the resulting adult phenotypes demonstrate that RLC is required in a stage-specific fashion for proper development of eye and leg imaginal discs. When RLC is depleted in adult females, oogenesis is reversibly disrupted. Without RLC induction, developing egg chambers display a succession of phenotypes that demonstrate roles for myosin II in morphogenesis of the interfollicular stalks, three morphologically and mechanistically distinct types of follicle cell migration, and completion of nurse cell cytoplasm transport (dumping). Finally, we show that in sqh mutant tissues, MHC is abnormally localized in punctate structures that do not contain appreciable amounts of filamentous actin or the myosin tail-binding protein p127. This suggests that sqh mutant phenotypes are chiefly caused by sequestration of myosin into inactive aggregates. These results show that myosin II is responsible for a surprisingly diverse array of cell shape changes throughout development.

Cyclin A and B functions in the early Drosophila embryo

Development ◽  
1999 ◽  
Vol 126 (23) ◽  
pp. 5505-5513 ◽  
Author(s):  
L.A. Stiffler ◽  
J.Y. Ji ◽  
S. Trautmann ◽  
C. Trusty ◽  
G. Schubiger
Keyword(s):  
Cyclin A ◽  
Cyclin B ◽  
Drosophila Embryo ◽  
Late Prophase ◽  
Early Drosophila Embryo ◽  
Nuclear Events ◽  
The Relationship ◽  
Maternal Gene ◽  
Drosophila Embryos

In eukaryotes, mitotic cyclins localize differently in the cell and regulate different aspects of the cell cycle. We investigated the relationship between subcellular localization of cyclins A and B and their functions in syncytial preblastoderm Drosophila embryos. During early embryonic cycles, cyclin A was always concentrated in the nucleus and present at a low level in the cytoplasm. Cyclin B was predominantly cytoplasmic, and localized within nuclei only during late prophase. Also, cyclin B colocalized with metaphase but not anaphase spindle microtubules. We changed maternal gene doses of cyclins A and B to test their functions in preblastoderm embryos. We observed that increasing doses of cyclin B increased cyclin B-Cdk1 activity, which correlated with shorter microtubules and slower microtubule-dependent nuclear movements. This provides in vivo evidence that cyclin B-Cdk1 regulates microtubule dynamics. In addition, the overall duration of the early nuclear cycles was affected by cyclin A but not cyclin B levels. Taken together, our observations support the hypothesis that cyclin B regulates cytoskeletal changes while cyclin A regulates the nuclear cycles. Varying the relative levels of cyclins A and B uncoupled the cytoskeletal and nuclear events, so we speculate that a balance of cyclins is necessary for proper coordination during these embryonic cycles.

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