Limits...
Invadolysin: a novel, conserved metalloprotease links mitotic structural rearrangements with cell migration.

McHugh B, Krause SA, Yu B, Deans AM, Heasman S, McLaughlin P, Heck MM - J. Cell Biol. (2004)

Bottom Line: Zymography reveals that a protease activity, present in wild-type larval brains, is missing from homozygous tissue, and we show that IX-14/invadolysin cleaves lamin in vitro.The IX-14/invadolysin protein is predominantly found in cytoplasmic structures resembling invadopodia in fly and human cells, but is dramatically relocalized to the leading edge of migrating cells.Strikingly, we find that the directed migration of germ cells is affected in Drosophila IX-14 mutant embryos.

View Article: PubMed Central - PubMed

Affiliation: Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland, UK.

ABSTRACT
The cell cycle is widely known to be regulated by networks of phosphorylation and ubiquitin-directed proteolysis. Here, we describe IX-14/invadolysin, a novel metalloprotease present only in metazoa, whose activity appears to be essential for mitotic progression. Mitotic neuroblasts of Drosophila melanogaster IX-14 mutant larvae exhibit increased levels of nuclear envelope proteins, monopolar and asymmetric spindles, and chromosomes that appear hypercondensed in length with a surrounding halo of loosely condensed chromatin. Zymography reveals that a protease activity, present in wild-type larval brains, is missing from homozygous tissue, and we show that IX-14/invadolysin cleaves lamin in vitro. The IX-14/invadolysin protein is predominantly found in cytoplasmic structures resembling invadopodia in fly and human cells, but is dramatically relocalized to the leading edge of migrating cells. Strikingly, we find that the directed migration of germ cells is affected in Drosophila IX-14 mutant embryos. Thus, invadolysin identifies a new family of conserved metalloproteases whose activity appears to be essential for the coordination of mitotic progression, but which also plays an unexpected role in cell migration.

Show MeSH

Related in: MedlinePlus

Centrosome and spindle phenotypes of l(3)IX-14. (A) Wild-type larval neuroblasts stained for α-tubulin (green), CP190 (red), and DAPI (blue). Wild-type metaphase figures contain normal bipolar spindles with two centrosomes. (B–D) IX-14 larval neuroblasts labeled as in A show extreme spindle abnormalities. Boxed mitotic figures in IX-14 mutant panels are enlarged in D to highlight mutant phenotypes of monopolar (1), disorganized (2 and 3), and asymmetric (4) spindles. Bar, 5 μm. (E) Wild-type larval neuroblasts stained for CP190 (green) and DAPI (red), showing duplicated and separated centrosomes at metaphase. (F) IX-14 larval neuroblast stained as in E, showing chromosome condensation and centrosome separation defects (arrow) in mitosis. Additionally, CP190 appears to persist on IX-14 mutant chromosomes longer than in wild-type cells. Bar, 5 μm. (G) Quantitation of centrosome number in the wild-type and IX-14 mitotic cells. Nearly 70% of mitotic figures in the IX-14 mutation appeared to have only one focus of centrosomal staining.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2172566&req=5

fig2: Centrosome and spindle phenotypes of l(3)IX-14. (A) Wild-type larval neuroblasts stained for α-tubulin (green), CP190 (red), and DAPI (blue). Wild-type metaphase figures contain normal bipolar spindles with two centrosomes. (B–D) IX-14 larval neuroblasts labeled as in A show extreme spindle abnormalities. Boxed mitotic figures in IX-14 mutant panels are enlarged in D to highlight mutant phenotypes of monopolar (1), disorganized (2 and 3), and asymmetric (4) spindles. Bar, 5 μm. (E) Wild-type larval neuroblasts stained for CP190 (green) and DAPI (red), showing duplicated and separated centrosomes at metaphase. (F) IX-14 larval neuroblast stained as in E, showing chromosome condensation and centrosome separation defects (arrow) in mitosis. Additionally, CP190 appears to persist on IX-14 mutant chromosomes longer than in wild-type cells. Bar, 5 μm. (G) Quantitation of centrosome number in the wild-type and IX-14 mitotic cells. Nearly 70% of mitotic figures in the IX-14 mutation appeared to have only one focus of centrosomal staining.

Mentions: The over-shortened mitotic chromosomes suggested that IX-14 mutants may experience a metaphase delay possibly caused by aberrant spindles. Neuroblasts of IX-14 mutants indeed exhibited abnormal spindle morphology (Fig. 2, B–D and F), and in fact only 2% of mitotic cells had a normal bipolar spindle. Spindle abnormalities included monopolar spindles (37%; Fig. 2 B, inset 1), disorganized spindles (34%; Fig. 2 B, insets 2 and 3), and mitotic figures where the spindle appeared bipolar, but asymmetric (27%, Fig. 2 C, inset 4). Mutant spindles also appeared to have thicker bundles of microtubules, compared with the finer fibers observed in wild type (Fig. 2 A). Almost no anaphase figures were observed in DAPI-stained neuroblasts from IX-14 mutant larvae, which is consistent with a metaphase delay or arrest.


Invadolysin: a novel, conserved metalloprotease links mitotic structural rearrangements with cell migration.

McHugh B, Krause SA, Yu B, Deans AM, Heasman S, McLaughlin P, Heck MM - J. Cell Biol. (2004)

Centrosome and spindle phenotypes of l(3)IX-14. (A) Wild-type larval neuroblasts stained for α-tubulin (green), CP190 (red), and DAPI (blue). Wild-type metaphase figures contain normal bipolar spindles with two centrosomes. (B–D) IX-14 larval neuroblasts labeled as in A show extreme spindle abnormalities. Boxed mitotic figures in IX-14 mutant panels are enlarged in D to highlight mutant phenotypes of monopolar (1), disorganized (2 and 3), and asymmetric (4) spindles. Bar, 5 μm. (E) Wild-type larval neuroblasts stained for CP190 (green) and DAPI (red), showing duplicated and separated centrosomes at metaphase. (F) IX-14 larval neuroblast stained as in E, showing chromosome condensation and centrosome separation defects (arrow) in mitosis. Additionally, CP190 appears to persist on IX-14 mutant chromosomes longer than in wild-type cells. Bar, 5 μm. (G) Quantitation of centrosome number in the wild-type and IX-14 mitotic cells. Nearly 70% of mitotic figures in the IX-14 mutation appeared to have only one focus of centrosomal staining.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172566&req=5

fig2: Centrosome and spindle phenotypes of l(3)IX-14. (A) Wild-type larval neuroblasts stained for α-tubulin (green), CP190 (red), and DAPI (blue). Wild-type metaphase figures contain normal bipolar spindles with two centrosomes. (B–D) IX-14 larval neuroblasts labeled as in A show extreme spindle abnormalities. Boxed mitotic figures in IX-14 mutant panels are enlarged in D to highlight mutant phenotypes of monopolar (1), disorganized (2 and 3), and asymmetric (4) spindles. Bar, 5 μm. (E) Wild-type larval neuroblasts stained for CP190 (green) and DAPI (red), showing duplicated and separated centrosomes at metaphase. (F) IX-14 larval neuroblast stained as in E, showing chromosome condensation and centrosome separation defects (arrow) in mitosis. Additionally, CP190 appears to persist on IX-14 mutant chromosomes longer than in wild-type cells. Bar, 5 μm. (G) Quantitation of centrosome number in the wild-type and IX-14 mitotic cells. Nearly 70% of mitotic figures in the IX-14 mutation appeared to have only one focus of centrosomal staining.
Mentions: The over-shortened mitotic chromosomes suggested that IX-14 mutants may experience a metaphase delay possibly caused by aberrant spindles. Neuroblasts of IX-14 mutants indeed exhibited abnormal spindle morphology (Fig. 2, B–D and F), and in fact only 2% of mitotic cells had a normal bipolar spindle. Spindle abnormalities included monopolar spindles (37%; Fig. 2 B, inset 1), disorganized spindles (34%; Fig. 2 B, insets 2 and 3), and mitotic figures where the spindle appeared bipolar, but asymmetric (27%, Fig. 2 C, inset 4). Mutant spindles also appeared to have thicker bundles of microtubules, compared with the finer fibers observed in wild type (Fig. 2 A). Almost no anaphase figures were observed in DAPI-stained neuroblasts from IX-14 mutant larvae, which is consistent with a metaphase delay or arrest.

Bottom Line: Zymography reveals that a protease activity, present in wild-type larval brains, is missing from homozygous tissue, and we show that IX-14/invadolysin cleaves lamin in vitro.The IX-14/invadolysin protein is predominantly found in cytoplasmic structures resembling invadopodia in fly and human cells, but is dramatically relocalized to the leading edge of migrating cells.Strikingly, we find that the directed migration of germ cells is affected in Drosophila IX-14 mutant embryos.

View Article: PubMed Central - PubMed

Affiliation: Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland, UK.

ABSTRACT
The cell cycle is widely known to be regulated by networks of phosphorylation and ubiquitin-directed proteolysis. Here, we describe IX-14/invadolysin, a novel metalloprotease present only in metazoa, whose activity appears to be essential for mitotic progression. Mitotic neuroblasts of Drosophila melanogaster IX-14 mutant larvae exhibit increased levels of nuclear envelope proteins, monopolar and asymmetric spindles, and chromosomes that appear hypercondensed in length with a surrounding halo of loosely condensed chromatin. Zymography reveals that a protease activity, present in wild-type larval brains, is missing from homozygous tissue, and we show that IX-14/invadolysin cleaves lamin in vitro. The IX-14/invadolysin protein is predominantly found in cytoplasmic structures resembling invadopodia in fly and human cells, but is dramatically relocalized to the leading edge of migrating cells. Strikingly, we find that the directed migration of germ cells is affected in Drosophila IX-14 mutant embryos. Thus, invadolysin identifies a new family of conserved metalloproteases whose activity appears to be essential for the coordination of mitotic progression, but which also plays an unexpected role in cell migration.

Show MeSH
Related in: MedlinePlus