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mini spindles: A gene encoding a conserved microtubule-associated protein required for the integrity of the mitotic spindle in Drosophila.

Cullen CF, Deák P, Glover DM, Ohkura H - J. Cell Biol. (1999)

Bottom Line: Mutation in msps disrupts the structural integrity of the mitotic spindle, resulting in the formation of one or more small additional spindles in diploid cells.The msps gene encodes a 227-kD protein with high similarity to the vertebrate microtubule-associated proteins (MAPs), human TOGp and Xenopus XMAP215, and with limited similarity to the Dis1 and STU2 proteins from fission yeast and budding yeast.In the embryonic division cycles, Msps protein localizes to centrosomal regions at all mitotic stages, and spreads over the spindles during metaphase and anaphase.

View Article: PubMed Central - PubMed

Affiliation: Institute of Cell and Molecular Biology, The University of Edinburgh, Edinburgh EH9 3JR, United Kingdom.

ABSTRACT
We describe a new Drosophila gene, mini spindles (msps) identified in a cytological screen for mitotic mutant. Mutation in msps disrupts the structural integrity of the mitotic spindle, resulting in the formation of one or more small additional spindles in diploid cells. Nucleation of microtubules from centrosomes, metaphase alignment of chromosomes, or the focusing of spindle poles appears much less affected. The msps gene encodes a 227-kD protein with high similarity to the vertebrate microtubule-associated proteins (MAPs), human TOGp and Xenopus XMAP215, and with limited similarity to the Dis1 and STU2 proteins from fission yeast and budding yeast. Consistent with their sequence similarity, Msps protein also associates with microtubules in vitro. In the embryonic division cycles, Msps protein localizes to centrosomal regions at all mitotic stages, and spreads over the spindles during metaphase and anaphase. The absence of centrosomal staining in interphase of the cellularized embryos suggests that the interactions between Msps protein and microtubules or centrosomes may be regulated during the cell cycle.

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Localization of Msps protein in colchicine or taxol treated embryos. Syncytial embryos were incubated with colchicine (a) or taxol (b–d). (a–c) DNA (left, blue in merge), tubulin (middle, green), and Msps (right, red) were visualized by immunostaining. Overlap between tubulin and Msps staining resulted in yellow color. (d) DNA (left, blue), CP190 (middle, green), and Msps (right, red) were visualized. (a) Microtubules were depolymerized except weak tubulin staining of centrosomes. Msps protein remains on centrosomes. (b) After taxol treatment, Msps protein remains in the centrosomal region during interphase. (c and d) In mitotic cells, Msps protein follows taxol induced microtubules, while CP190 stays on centrosomes. Bars, 10 μm.
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Figure 9: Localization of Msps protein in colchicine or taxol treated embryos. Syncytial embryos were incubated with colchicine (a) or taxol (b–d). (a–c) DNA (left, blue in merge), tubulin (middle, green), and Msps (right, red) were visualized by immunostaining. Overlap between tubulin and Msps staining resulted in yellow color. (d) DNA (left, blue), CP190 (middle, green), and Msps (right, red) were visualized. (a) Microtubules were depolymerized except weak tubulin staining of centrosomes. Msps protein remains on centrosomes. (b) After taxol treatment, Msps protein remains in the centrosomal region during interphase. (c and d) In mitotic cells, Msps protein follows taxol induced microtubules, while CP190 stays on centrosomes. Bars, 10 μm.

Mentions: To determine whether the localization of Msps protein is dependent on microtubules, we looked at the effects of microtubule inhibitors. When we treated syncytial embryos with colchicine, microtubules appeared depolymerized but weak tubulin staining remained around the centrosomes (Fig. 9 a). This is the case even when microtubules were depolymerized by other methods (Materials and Methods). In all cases a significant amount of Msps protein was detected around the centrosomes. This result indicates that long microtubules are not essential for the centrosomal localization of at least some of Msps protein. It is possible, however, that short microtubules or tubulin may be required for Msps localization on centrosomes.


mini spindles: A gene encoding a conserved microtubule-associated protein required for the integrity of the mitotic spindle in Drosophila.

Cullen CF, Deák P, Glover DM, Ohkura H - J. Cell Biol. (1999)

Localization of Msps protein in colchicine or taxol treated embryos. Syncytial embryos were incubated with colchicine (a) or taxol (b–d). (a–c) DNA (left, blue in merge), tubulin (middle, green), and Msps (right, red) were visualized by immunostaining. Overlap between tubulin and Msps staining resulted in yellow color. (d) DNA (left, blue), CP190 (middle, green), and Msps (right, red) were visualized. (a) Microtubules were depolymerized except weak tubulin staining of centrosomes. Msps protein remains on centrosomes. (b) After taxol treatment, Msps protein remains in the centrosomal region during interphase. (c and d) In mitotic cells, Msps protein follows taxol induced microtubules, while CP190 stays on centrosomes. Bars, 10 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2169485&req=5

Figure 9: Localization of Msps protein in colchicine or taxol treated embryos. Syncytial embryos were incubated with colchicine (a) or taxol (b–d). (a–c) DNA (left, blue in merge), tubulin (middle, green), and Msps (right, red) were visualized by immunostaining. Overlap between tubulin and Msps staining resulted in yellow color. (d) DNA (left, blue), CP190 (middle, green), and Msps (right, red) were visualized. (a) Microtubules were depolymerized except weak tubulin staining of centrosomes. Msps protein remains on centrosomes. (b) After taxol treatment, Msps protein remains in the centrosomal region during interphase. (c and d) In mitotic cells, Msps protein follows taxol induced microtubules, while CP190 stays on centrosomes. Bars, 10 μm.
Mentions: To determine whether the localization of Msps protein is dependent on microtubules, we looked at the effects of microtubule inhibitors. When we treated syncytial embryos with colchicine, microtubules appeared depolymerized but weak tubulin staining remained around the centrosomes (Fig. 9 a). This is the case even when microtubules were depolymerized by other methods (Materials and Methods). In all cases a significant amount of Msps protein was detected around the centrosomes. This result indicates that long microtubules are not essential for the centrosomal localization of at least some of Msps protein. It is possible, however, that short microtubules or tubulin may be required for Msps localization on centrosomes.

Bottom Line: Mutation in msps disrupts the structural integrity of the mitotic spindle, resulting in the formation of one or more small additional spindles in diploid cells.The msps gene encodes a 227-kD protein with high similarity to the vertebrate microtubule-associated proteins (MAPs), human TOGp and Xenopus XMAP215, and with limited similarity to the Dis1 and STU2 proteins from fission yeast and budding yeast.In the embryonic division cycles, Msps protein localizes to centrosomal regions at all mitotic stages, and spreads over the spindles during metaphase and anaphase.

View Article: PubMed Central - PubMed

Affiliation: Institute of Cell and Molecular Biology, The University of Edinburgh, Edinburgh EH9 3JR, United Kingdom.

ABSTRACT
We describe a new Drosophila gene, mini spindles (msps) identified in a cytological screen for mitotic mutant. Mutation in msps disrupts the structural integrity of the mitotic spindle, resulting in the formation of one or more small additional spindles in diploid cells. Nucleation of microtubules from centrosomes, metaphase alignment of chromosomes, or the focusing of spindle poles appears much less affected. The msps gene encodes a 227-kD protein with high similarity to the vertebrate microtubule-associated proteins (MAPs), human TOGp and Xenopus XMAP215, and with limited similarity to the Dis1 and STU2 proteins from fission yeast and budding yeast. Consistent with their sequence similarity, Msps protein also associates with microtubules in vitro. In the embryonic division cycles, Msps protein localizes to centrosomal regions at all mitotic stages, and spreads over the spindles during metaphase and anaphase. The absence of centrosomal staining in interphase of the cellularized embryos suggests that the interactions between Msps protein and microtubules or centrosomes may be regulated during the cell cycle.

Show MeSH
Related in: MedlinePlus