Constitutively Active Myosin Light Chain Kinase Alters Axon Guidance Decisions in Drosophila Embryos

Kim, You Seung; Fritz, Janice L.; Seneviratne, Ananda K.; VanBerkum, Mark F. A.

doi:10.1006/dbio.2002.0768

Cited by 45 publications

(53 citation statements)

References 96 publications

(113 reference statements)

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“…Myosin II is involved in neurite outgrowth, and myosin IIB genedeleted mice showed changes in growth cone motility (35). Hyperactivity of myosin induced by constitutively active myosin light chain kinase altered axon guidance in Drosophila (36), and both myosin IIA and -B can form bipolar filament networks in growth cones (37). Apart from phosphorylation events affecting the activity of myosin, the motor properties of the molecule may also be regulated directly by MRLC (38).…”

Section: Discussionmentioning

confidence: 99%

MSAP Is a Novel MIR-interacting Protein That Enhances Neurite Outgrowth and Increases Myosin Regulatory Light Chain

Bornhäuser¹,

Olsson

Lindholm

2003

Journal of Biological Chemistry

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Interactions between the cell membrane and the cytoskeleton play a major role in different aspects of cell differentiation, such as cell motility, cell division, and establishment of cellular architecture. Of particular importance in this context is the association of cortical actin with the cell membrane. The ERM 1 proteins, ezrin, radixin, and moesin, are members of the large 4.1 protein family and are involved in membrane-cytoskeleton interactions. They link the actin cytoskeleton to membranebound proteins located at different membrane sites, i.e. microvilli, membrane ruffles, and cell-cell contacts (1-3). This is accomplished by binding of the C-terminal part of the ERM proteins to actin and of the N-terminal FERM domain to specific membrane proteins (4). FERM domains have been found in many different proteins and are thought to be modules for protein-protein and protein-membrane interactions (5). The ERM proteins are involved in cell adhesion and signal transduction events through phosphorylation (6, 7) and interaction with phosphoinositides (8). The ERM proteins play an important role in the activation of Rho family proteins and can interact both downstream (9) and upstream (10) of Rho.In addition, the ERM proteins are involved in membrane dynamics (11). When ezrin, radixin, and moesin were simultaneously inactivated by antisense treatment in epithelial cells, cell-cell and cell-substratum adhesion was altered (12). Double suppression of radixin and moesin, but not ezrin and radixin or moesin, alters growth cone motility, inhibiting neurite extension (13). In contrast, overexpression of ezrin in insect cells leads to enhanced cell adhesion (14). The mechanisms behind these effects are, however, not well understood, but ERM proteins are known to interact with various proteins such as CD44 and ICAM-1, -2, and -3, which helps in establishing membrane specializations (for review, see Ref. 7). The identification and characterization of further binding partners for ERM proteins can give new insights into the function of these proteins.We have recently identified a novel ERM family protein, MIR, which has an ERM domain at the N terminus and lacks actin binding, instead possessing a RING domain in the Cterminal region (15). Overexpression of MIR abrogated neurite outgrowth in PC12 cells, an effect that may be brought about by its interaction with the myosin regulatory light chain (MRLC). We describe here a novel protein interacting with MIR, called MIR-interacting saposin-like protein (MSAP), which stimulates neurite outgrowth. Sequence comparisons showed that MSAP contains a saposin domain, which is found, among others, in the sphingolipid activator proteins, the saposins (16), and in some saposin-like proteins with a similar structure (17). The effects of MSAP on neurite outgrowth were reduced by MIR. MIR was shown to induce a decrease in the levels of MRLC, which could be blocked by overexpression of MSAP or by inhibition of proteasome activity. Evidence was obtained that the decrease in MRLC levels by MIR invo...

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Section: Discussionmentioning

confidence: 99%

MSAP Is a Novel MIR-interacting Protein That Enhances Neurite Outgrowth and Increases Myosin Regulatory Light Chain

Bornhäuser¹,

Olsson

Lindholm

2003

Journal of Biological Chemistry

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“…The following stocks were used: ubiECad-GFP (Oda and Tsukita, 2001), Moe-GFP (Edwards et al, 1997;Kiehart et al, 2000), Spaghetti squash (Sqh)-GFP (Royou et al, 2002), Sqh-mCherry (Martin et al, 2009), c381Gal4 (an AS driver), UAS-ctMLCK [a constitutively active form of myosin light chain kinase (Kim et al, 2002) (García Fernández et al, 2007). UAS lines were expressed using the Gal4 system (Brand and Perrimon, 1993).…”

Section: Drosophila Strainsmentioning

confidence: 99%

Cytoskeletal dynamics and supracellular organisation of cell shape fluctuations during dorsal closure

et al. 2010

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SUMMARYFluctuations in the shape of amnioserosa (AS) cells during Drosophila dorsal closure (DC) provide an ideal system with which to understand contractile epithelia, both in terms of the cellular mechanisms and how tissue behaviour emerges from the activity of individual cells. Using quantitative image analysis we show that apical shape fluctuations are driven by the medial cytoskeleton, with periodic foci of contractile myosin and actin travelling across cell apices. Shape changes were mostly anisotropic and neighbouring cells were often, but transiently, organised into strings with parallel deformations. During the early stages of DC, shape fluctuations with long cycle lengths produced no net tissue contraction. Cycle lengths shortened with the onset of net tissue contraction, followed by a damping of fluctuation amplitude. Eventually, fluctuations became undetectable as AS cells contracted rapidly. These transitions were accompanied by an increase in apical myosin, both at cell-cell junctions and medially, the latter ultimately forming a coherent, but still dynamic, sheet across cells. Mutants with increased myosin activity or actin polymerisation exhibited precocious cell contraction through changes in the subcellular localisation of myosin. thickveins mutant embryos, which exhibited defects in the actin cable at the leading edge, showed similar timings of fluctuation damping to the wild type, suggesting that damping is an autonomous property of the AS. Our results suggest that cell shape fluctuations are a property of cells with low and increasing levels of apical myosin, and that medial and junctional myosin populations combine to contract AS cell apices and drive DC.

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“…GAL4 drivers were c381-Gal-4 [Bloomington Drosophila Stock Center (BDSC) 3734], daughterless-Gal-4 (BDSC 5460), paired-Gal-4 (BDSC 1947), and a baz Xi106 , maternal-α4-tubulin-Gal-4-VP16 recombinant chromosome (McKinley et al, 2012). UAS-constructs were UAS-CA-MLCK (Kim et al, 2002), UAS-Ed (Laplante and Nilson, 2011), UAS-Baz::GFP and UAS-Baz ∆aPKC ::GFP inserted into the attp2 integration site (McKinley et al, 2012), and Baz::GFP, Baz S980A ::GFP and Baz S980E ::GFP P-element insertions (Morais-de-Sá et al, 2010). Other stocks were: moeABD::GFP (Edwards et al, 1997), baz Xi106 (a gift from Andreas Wodarz, University of Gottingen, Germany), and a par-6 ∆226 , Par-6::GFP genomic rescue line (Wirtz-Peitz et al, 2008).…”

Section: Fly Stocksmentioning

confidence: 99%

Bazooka inhibits aPKC to limit antagonism of actomyosin networks during amnioserosa apical constriction

et al. 2013

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Cell shape changes drive tissue morphogenesis during animal development. An important example is the apical cell constriction that initiates tissue internalisation. Apical constriction can occur through a phase of cyclic assembly and disassembly of apicomedial actomyosin networks, followed by stabilisation of these networks. Delayed negative-feedback mechanisms typically underlie cyclic behaviour, but the mechanisms regulating cyclic actomyosin networks remain obscure, as do mechanisms that transform overall network behaviour. Here, we show that a known inhibitor of apicomedial actomyosin networks in Drosophila amnioserosa cells, the Par-6-aPKC complex, is recruited to the apicomedial domain by actomyosin networks during dorsal closure of the embryo. This finding establishes an actomyosin-aPKC negative-feedback loop in the system. Additionally, we find that aPKC recruits Bazooka to the apicomedial domain, and phosphorylates Bazooka for a dynamic interaction. Remarkably, stabilising aPKC-Bazooka interactions can inhibit the antagonism of actomyosin by aPKC, suggesting that Bazooka acts as an aPKC inhibitor, and providing a possible mechanism for delaying the actomyosin-aPKC negative-feedback loop. Our data also implicate an increasing degree of Par-6-aPKCBazooka interactions as dorsal closure progresses, potentially explaining a developmental transition in actomyosin behaviour from cyclic to persistent networks. This later impact of aPKC inhibition is supported by mathematical modelling of the system. Overall, this work illustrates how shifting chemical signals can tune actomyosin network behaviour during development.

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Constitutively Active Myosin Light Chain Kinase Alters Axon Guidance Decisions in Drosophila Embryos

Cited by 45 publications

References 96 publications

MSAP Is a Novel MIR-interacting Protein That Enhances Neurite Outgrowth and Increases Myosin Regulatory Light Chain

MSAP Is a Novel MIR-interacting Protein That Enhances Neurite Outgrowth and Increases Myosin Regulatory Light Chain

Cytoskeletal dynamics and supracellular organisation of cell shape fluctuations during dorsal closure

Bazooka inhibits aPKC to limit antagonism of actomyosin networks during amnioserosa apical constriction

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