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Spermidine/spermine N1-acetyltransferase specifically binds to the integrin alpha9 subunit cytoplasmic domain and enhances cell migration.

Chen C, Young BA, Coleman CS, Pegg AE, Sheppard D - J. Cell Biol. (2004)

Bottom Line: Overexpression of SSAT increased alpha9beta1-mediated migration, and small interfering RNA knockdown of SSAT inhibited this migration without affecting cell adhesion or migration that was mediated by other integrin cytoplasmic domains.The enzyme activity of SSAT is critical for this effect, because a catalytically inactive version did not enhance migration.We conclude that SSAT directly binds to the alpha9 cytoplasmic domain and mediates alpha9-dependent enhancement of cell migration, presumably by localized effects on acetylation of polyamines or of unidentified substrates.

View Article: PubMed Central - PubMed

Affiliation: Lung Biology Center, Department of Medicine, University of California-San Francisco, San Francisco, CA 94110, USA.

ABSTRACT
The integrin alpha9beta1 is expressed on migrating cells, such as leukocytes, and binds to multiple ligands that are present at sites of tissue injury and inflammation. alpha9beta1, like the structurally related integrin alpha4beta1, mediates accelerated cell migration, an effect that depends on the alpha9 cytoplasmic domain. alpha4beta1 enhances migration through reversible binding to the adapter protein, paxillin, but alpha9beta1-dependent migration is paxillin independent. Using yeast two-hybrid screening, we identified the polyamine catabolizing enzyme spermidine/spermine N(1)-acetyltransferase (SSAT) as a specific binding partner of the alpha9 cytoplasmic domain. Overexpression of SSAT increased alpha9beta1-mediated migration, and small interfering RNA knockdown of SSAT inhibited this migration without affecting cell adhesion or migration that was mediated by other integrin cytoplasmic domains. The enzyme activity of SSAT is critical for this effect, because a catalytically inactive version did not enhance migration. We conclude that SSAT directly binds to the alpha9 cytoplasmic domain and mediates alpha9-dependent enhancement of cell migration, presumably by localized effects on acetylation of polyamines or of unidentified substrates.

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The induction of SSAT by BE-3-3-3 enhances α9-mediated cell migration. (a) CHO cells stably expressing wild-type α9 or the α9α5 chimera were plated onto dishes coated with 5 μg/ml TNfn3RAA, scratch wounded at confluence in the presence or absence of BE-3-3-3, and allowed to migrate into the wound space for 8 h. The ratio of the final wound area to the area immediately after scratching is indicated as percent closure. (b) Cells transfected with wild-type α9 were incubated with or without BE-3-3-3 and fixed 8 h after scratch wounding.
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fig4: The induction of SSAT by BE-3-3-3 enhances α9-mediated cell migration. (a) CHO cells stably expressing wild-type α9 or the α9α5 chimera were plated onto dishes coated with 5 μg/ml TNfn3RAA, scratch wounded at confluence in the presence or absence of BE-3-3-3, and allowed to migrate into the wound space for 8 h. The ratio of the final wound area to the area immediately after scratching is indicated as percent closure. (b) Cells transfected with wild-type α9 were incubated with or without BE-3-3-3 and fixed 8 h after scratch wounding.

Mentions: Confluent CHO cells expressing wild-type α9 or the α9α5 chimera were plated on TNfn3RAA and scratch wounded. Closure of the wound was quantified by phase-contrast microscopy as a measure of directed cell migration. Cells expressing the α9α5 chimera showed markedly slower migration and wound closure than cells expressing wild-type α9. Wound closure was accelerated by BE-3-3-3 in cells expressing wild-type α9, but not in cells expressing the α9α5 chimera (Fig. 4 a). Photomicrographs of the wound edge did not reveal any systematic differences in cell morphology for cells expressing α9 in the presence or absence of treatment with BE-3-3-3 (Fig. 4 b).


Spermidine/spermine N1-acetyltransferase specifically binds to the integrin alpha9 subunit cytoplasmic domain and enhances cell migration.

Chen C, Young BA, Coleman CS, Pegg AE, Sheppard D - J. Cell Biol. (2004)

The induction of SSAT by BE-3-3-3 enhances α9-mediated cell migration. (a) CHO cells stably expressing wild-type α9 or the α9α5 chimera were plated onto dishes coated with 5 μg/ml TNfn3RAA, scratch wounded at confluence in the presence or absence of BE-3-3-3, and allowed to migrate into the wound space for 8 h. The ratio of the final wound area to the area immediately after scratching is indicated as percent closure. (b) Cells transfected with wild-type α9 were incubated with or without BE-3-3-3 and fixed 8 h after scratch wounding.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172529&req=5

fig4: The induction of SSAT by BE-3-3-3 enhances α9-mediated cell migration. (a) CHO cells stably expressing wild-type α9 or the α9α5 chimera were plated onto dishes coated with 5 μg/ml TNfn3RAA, scratch wounded at confluence in the presence or absence of BE-3-3-3, and allowed to migrate into the wound space for 8 h. The ratio of the final wound area to the area immediately after scratching is indicated as percent closure. (b) Cells transfected with wild-type α9 were incubated with or without BE-3-3-3 and fixed 8 h after scratch wounding.
Mentions: Confluent CHO cells expressing wild-type α9 or the α9α5 chimera were plated on TNfn3RAA and scratch wounded. Closure of the wound was quantified by phase-contrast microscopy as a measure of directed cell migration. Cells expressing the α9α5 chimera showed markedly slower migration and wound closure than cells expressing wild-type α9. Wound closure was accelerated by BE-3-3-3 in cells expressing wild-type α9, but not in cells expressing the α9α5 chimera (Fig. 4 a). Photomicrographs of the wound edge did not reveal any systematic differences in cell morphology for cells expressing α9 in the presence or absence of treatment with BE-3-3-3 (Fig. 4 b).

Bottom Line: Overexpression of SSAT increased alpha9beta1-mediated migration, and small interfering RNA knockdown of SSAT inhibited this migration without affecting cell adhesion or migration that was mediated by other integrin cytoplasmic domains.The enzyme activity of SSAT is critical for this effect, because a catalytically inactive version did not enhance migration.We conclude that SSAT directly binds to the alpha9 cytoplasmic domain and mediates alpha9-dependent enhancement of cell migration, presumably by localized effects on acetylation of polyamines or of unidentified substrates.

View Article: PubMed Central - PubMed

Affiliation: Lung Biology Center, Department of Medicine, University of California-San Francisco, San Francisco, CA 94110, USA.

ABSTRACT
The integrin alpha9beta1 is expressed on migrating cells, such as leukocytes, and binds to multiple ligands that are present at sites of tissue injury and inflammation. alpha9beta1, like the structurally related integrin alpha4beta1, mediates accelerated cell migration, an effect that depends on the alpha9 cytoplasmic domain. alpha4beta1 enhances migration through reversible binding to the adapter protein, paxillin, but alpha9beta1-dependent migration is paxillin independent. Using yeast two-hybrid screening, we identified the polyamine catabolizing enzyme spermidine/spermine N(1)-acetyltransferase (SSAT) as a specific binding partner of the alpha9 cytoplasmic domain. Overexpression of SSAT increased alpha9beta1-mediated migration, and small interfering RNA knockdown of SSAT inhibited this migration without affecting cell adhesion or migration that was mediated by other integrin cytoplasmic domains. The enzyme activity of SSAT is critical for this effect, because a catalytically inactive version did not enhance migration. We conclude that SSAT directly binds to the alpha9 cytoplasmic domain and mediates alpha9-dependent enhancement of cell migration, presumably by localized effects on acetylation of polyamines or of unidentified substrates.

Show MeSH
Related in: MedlinePlus