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Lava lamp, a novel peripheral golgi protein, is required for Drosophila melanogaster cellularization.

Sisson JC, Field C, Ventura R, Royou A, Sullivan W - J. Cell Biol. (2000)

Bottom Line: Lva is a coiled-coil protein and, unlike other proteins previously implicated in cellularization or cytokinesis, it is Golgi associated.Biochemical analysis demonstrates that Lva physically interacts with the MMAPs Spectrin and CLIP190.We suggest that Lva and Spectrin may form a Golgi-based scaffold that mediates the interaction of Golgi bodies with microtubules and facilitates Golgi-derived membrane secretion required for the formation of furrows during cellularization.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular, Cell and Developmental Biology, Sinsheimer Labs, University of California at Santa Cruz, Santa Cruz, California 95064, USA. sisson@darwin.ucsc.edu

ABSTRACT
Drosophila cellularization and animal cell cytokinesis rely on the coordinated functions of the microfilament and microtubule cytoskeletal systems. To identify new proteins involved in cellularization and cytokinesis, we have conducted a biochemical screen for microfilament/microtubule-associated proteins (MMAPs). 17 MMAPs were identified; seven have been previously implicated in cellularization and/or cytokinesis, including KLP3A, Anillin, Septins, and Dynamin. We now show that a novel MMAP, Lava Lamp (Lva), is also required for cellularization. Lva is a coiled-coil protein and, unlike other proteins previously implicated in cellularization or cytokinesis, it is Golgi associated. Our functional analysis shows that cellularization is dramatically inhibited upon injecting anti-Lva antibodies (IgG and Fab) into embryos. In addition, we show that brefeldin A, a potent inhibitor of membrane trafficking, also inhibits cellularization. Biochemical analysis demonstrates that Lva physically interacts with the MMAPs Spectrin and CLIP190. We suggest that Lva and Spectrin may form a Golgi-based scaffold that mediates the interaction of Golgi bodies with microtubules and facilitates Golgi-derived membrane secretion required for the formation of furrows during cellularization. Our results are consistent with the idea that animal cell cytokinesis depends on both actomyosin-based contraction and Golgi-derived membrane secretion.

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BFA inhibits furrow progression. (Left) DMSO-injected embryo undergoing normal furrowing. (Right) BFA-injected embryo displaying arrested furrowing at the fast phase. Arrowheads indicate unusually high levels of subcortical Myo-GFP, and arrows indicate a defective nucleus. Time (minutes) is relative to the start of cycle 14. The dorsal, injected surface of each embryo is shown. All views are sagittal. Bar, 10 μm.
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Figure 8: BFA inhibits furrow progression. (Left) DMSO-injected embryo undergoing normal furrowing. (Right) BFA-injected embryo displaying arrested furrowing at the fast phase. Arrowheads indicate unusually high levels of subcortical Myo-GFP, and arrows indicate a defective nucleus. Time (minutes) is relative to the start of cycle 14. The dorsal, injected surface of each embryo is shown. All views are sagittal. Bar, 10 μm.

Mentions: The inhibition of furrow progression resulting from anti–Lva antibody injections suggested that Golgi-derived membrane vesicle export might be required for furrow progression. This predicts that the fungal toxin brefeldin A (BFA), a potent inhibitor of Golgi-derived membrane vesicle transport (Chardin and McCormick 1999), should inhibit furrow progression. DMSO, the solvent for BFA, was injected into early Myo-GFP cellularizing blastoderms as a control, and no effect on furrowing was observed (Fig. 8). However, injection of BFA severely inhibits furrow progression (Fig. 8). Although the Myo-GFP at the furrow front appears discontinuous during the slow phase, furrow progression is relatively normal; however, the fast phase is absent. By 60 min, the furrows in BFA-injected embryos have invaginated only 50% as far as those in the control embryo (Fig. 8). When BFA is injected later, at ∼25 min into cycle 14, furrow progression is only mildly affected (data not shown). Because BFA is a small, hydrophobic molecule (Chardin and McCormick 1999), it diffuses rapidly through the embryo, resulting in a uniform effect.


Lava lamp, a novel peripheral golgi protein, is required for Drosophila melanogaster cellularization.

Sisson JC, Field C, Ventura R, Royou A, Sullivan W - J. Cell Biol. (2000)

BFA inhibits furrow progression. (Left) DMSO-injected embryo undergoing normal furrowing. (Right) BFA-injected embryo displaying arrested furrowing at the fast phase. Arrowheads indicate unusually high levels of subcortical Myo-GFP, and arrows indicate a defective nucleus. Time (minutes) is relative to the start of cycle 14. The dorsal, injected surface of each embryo is shown. All views are sagittal. Bar, 10 μm.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2169433&req=5

Figure 8: BFA inhibits furrow progression. (Left) DMSO-injected embryo undergoing normal furrowing. (Right) BFA-injected embryo displaying arrested furrowing at the fast phase. Arrowheads indicate unusually high levels of subcortical Myo-GFP, and arrows indicate a defective nucleus. Time (minutes) is relative to the start of cycle 14. The dorsal, injected surface of each embryo is shown. All views are sagittal. Bar, 10 μm.
Mentions: The inhibition of furrow progression resulting from anti–Lva antibody injections suggested that Golgi-derived membrane vesicle export might be required for furrow progression. This predicts that the fungal toxin brefeldin A (BFA), a potent inhibitor of Golgi-derived membrane vesicle transport (Chardin and McCormick 1999), should inhibit furrow progression. DMSO, the solvent for BFA, was injected into early Myo-GFP cellularizing blastoderms as a control, and no effect on furrowing was observed (Fig. 8). However, injection of BFA severely inhibits furrow progression (Fig. 8). Although the Myo-GFP at the furrow front appears discontinuous during the slow phase, furrow progression is relatively normal; however, the fast phase is absent. By 60 min, the furrows in BFA-injected embryos have invaginated only 50% as far as those in the control embryo (Fig. 8). When BFA is injected later, at ∼25 min into cycle 14, furrow progression is only mildly affected (data not shown). Because BFA is a small, hydrophobic molecule (Chardin and McCormick 1999), it diffuses rapidly through the embryo, resulting in a uniform effect.

Bottom Line: Lva is a coiled-coil protein and, unlike other proteins previously implicated in cellularization or cytokinesis, it is Golgi associated.Biochemical analysis demonstrates that Lva physically interacts with the MMAPs Spectrin and CLIP190.We suggest that Lva and Spectrin may form a Golgi-based scaffold that mediates the interaction of Golgi bodies with microtubules and facilitates Golgi-derived membrane secretion required for the formation of furrows during cellularization.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular, Cell and Developmental Biology, Sinsheimer Labs, University of California at Santa Cruz, Santa Cruz, California 95064, USA. sisson@darwin.ucsc.edu

ABSTRACT
Drosophila cellularization and animal cell cytokinesis rely on the coordinated functions of the microfilament and microtubule cytoskeletal systems. To identify new proteins involved in cellularization and cytokinesis, we have conducted a biochemical screen for microfilament/microtubule-associated proteins (MMAPs). 17 MMAPs were identified; seven have been previously implicated in cellularization and/or cytokinesis, including KLP3A, Anillin, Septins, and Dynamin. We now show that a novel MMAP, Lava Lamp (Lva), is also required for cellularization. Lva is a coiled-coil protein and, unlike other proteins previously implicated in cellularization or cytokinesis, it is Golgi associated. Our functional analysis shows that cellularization is dramatically inhibited upon injecting anti-Lva antibodies (IgG and Fab) into embryos. In addition, we show that brefeldin A, a potent inhibitor of membrane trafficking, also inhibits cellularization. Biochemical analysis demonstrates that Lva physically interacts with the MMAPs Spectrin and CLIP190. We suggest that Lva and Spectrin may form a Golgi-based scaffold that mediates the interaction of Golgi bodies with microtubules and facilitates Golgi-derived membrane secretion required for the formation of furrows during cellularization. Our results are consistent with the idea that animal cell cytokinesis depends on both actomyosin-based contraction and Golgi-derived membrane secretion.

Show MeSH
Related in: MedlinePlus