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Galectin-1 is implicated in the protein kinase C epsilon/vimentin-controlled trafficking of integrin-beta1 in glioblastoma cells.

Fortin S, Le Mercier M, Camby I, Spiegl-Kreinecker S, Berger W, Lefranc F, Kiss R - Brain Pathol. (2009)

Bottom Line: Galectin-1 depletion does not alter the gene expression level of integrin-beta1.Transient galectin-1 depletion effectuates as well the perinuclear accumulation of protein kinase C epsilon (PKCepsilon) and the intermediate filament vimentin, both of which have been shown to mediate integrin recycling in motile cells.Our results argue for the involvement of galectin-1 in the PKCepsilon/vimentin-controlled trafficking of integrin-beta1.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Toxicology, Institute of Pharmacy, Univesité Libre de Bruxelles, Brussels.

ABSTRACT
Cell motility and resistance to apoptosis characterize glioblastoma (GBM) growth and malignancy. In our current work we report that galectin-1, a homodimeric adhesion molecule and carbohydrate-binding protein with affinity for beta-galactosides, is linked with cell surface expression of integrin beta1 and the process of integrin trafficking. Using immunofluorescence, depletion of galectin-1 through both stable knockdown and transient-targeted small interfering RNA (siRNA) treatment induces an intracellular accumulation of integrin-beta1 coincident with a diminution of integrin-beta1 at points of cellular adhesion at the cell membrane. Galectin-1 depletion does not alter the gene expression level of integrin-beta1. Transient galectin-1 depletion effectuates as well the perinuclear accumulation of protein kinase C epsilon (PKCepsilon) and the intermediate filament vimentin, both of which have been shown to mediate integrin recycling in motile cells. Our results argue for the involvement of galectin-1 in the PKCepsilon/vimentin-controlled trafficking of integrin-beta1. The understanding of molecular mediators such as galectin-1 and the pathways through which they drive the cell invasion so descriptive of GBM is anticipated to reveal potential therapeutic targets that promote glioma malignancy.

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Related in: MedlinePlus

Galectin-1-targeted siRNA induces both a decrease of integrin-β1 at the edges of the cell membrane and an increase in the intracellular accumulation of integrin-β1. A. U87 control wild-type cells (Aa,Ab) and U87 cells containing stably transfected antisense galectin-1 vectors (Ac) were co-stained under non-permeabilized conditions for integrin-β1 [the red staining at the tip of actin stress fibers (in green fluorescence)], fibrillar actin (green) and globular actin (red staining inside the cells). Ab. Higher magnification of the control wild-type (Aa) image. B. U87 control wild-type cells (Ba) and U87 cells containing stably transfected antisense galectin-1 vectors (Bb) were stained under permeabilized conditions for integrin-β1 only (in green), without any staining to reveal actin (Ba,Bb). C. U87 and Hs683 cells were transiently transfected with either scrambled siRNA (scr) or siRNA targeted against galectin-1 (siGal1). Cells were stained for integrin-β1 (in red) under both permeablized and non-permeabilized conditions on either day 5 post-transfection (Hs683) or day 7 post-transfection (U87).
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fig03: Galectin-1-targeted siRNA induces both a decrease of integrin-β1 at the edges of the cell membrane and an increase in the intracellular accumulation of integrin-β1. A. U87 control wild-type cells (Aa,Ab) and U87 cells containing stably transfected antisense galectin-1 vectors (Ac) were co-stained under non-permeabilized conditions for integrin-β1 [the red staining at the tip of actin stress fibers (in green fluorescence)], fibrillar actin (green) and globular actin (red staining inside the cells). Ab. Higher magnification of the control wild-type (Aa) image. B. U87 control wild-type cells (Ba) and U87 cells containing stably transfected antisense galectin-1 vectors (Bb) were stained under permeabilized conditions for integrin-β1 only (in green), without any staining to reveal actin (Ba,Bb). C. U87 and Hs683 cells were transiently transfected with either scrambled siRNA (scr) or siRNA targeted against galectin-1 (siGal1). Cells were stained for integrin-β1 (in red) under both permeablized and non-permeabilized conditions on either day 5 post-transfection (Hs683) or day 7 post-transfection (U87).

Mentions: As galectin-1 is involved in adhesion complexes (8), we asked whether decreasing galectin-1 expression altered the pattern of integrin expression at the leading edge of cell migration. In both control U87 and U87 cells stably expressing an antisense galectin-1 vector we left the cells non-permeablized and co-stained them with integrin-β1 and fibrillar (polymerized) and globular (non-polymerized) actin. In control cells, we saw integrin-β1 localization at points of focal adhesion complexes along the cell membrane at the edge of fibrillar actin staining (Figure 3Aa,Ab), whereas in stable galectin-1 knockdown cells the cell membrane localization of integrin-β1 was lost (Figure 3Ac). In Figure 3Aa–Ac, the red fluorescence inside the cells corresponds to globular actin (DNaseI staining), not to integrin-β1. Thus, in comparison, we stained permeablized control and stable galectin-1 knockdown cells with integrin-β1, and found that the galectin-1 knockdown cells contained an intracellular accumulation of integrin-β1, with the cell membrane staining once again lost in comparison with control cells (Figure 3Ba,Bb).


Galectin-1 is implicated in the protein kinase C epsilon/vimentin-controlled trafficking of integrin-beta1 in glioblastoma cells.

Fortin S, Le Mercier M, Camby I, Spiegl-Kreinecker S, Berger W, Lefranc F, Kiss R - Brain Pathol. (2009)

Galectin-1-targeted siRNA induces both a decrease of integrin-β1 at the edges of the cell membrane and an increase in the intracellular accumulation of integrin-β1. A. U87 control wild-type cells (Aa,Ab) and U87 cells containing stably transfected antisense galectin-1 vectors (Ac) were co-stained under non-permeabilized conditions for integrin-β1 [the red staining at the tip of actin stress fibers (in green fluorescence)], fibrillar actin (green) and globular actin (red staining inside the cells). Ab. Higher magnification of the control wild-type (Aa) image. B. U87 control wild-type cells (Ba) and U87 cells containing stably transfected antisense galectin-1 vectors (Bb) were stained under permeabilized conditions for integrin-β1 only (in green), without any staining to reveal actin (Ba,Bb). C. U87 and Hs683 cells were transiently transfected with either scrambled siRNA (scr) or siRNA targeted against galectin-1 (siGal1). Cells were stained for integrin-β1 (in red) under both permeablized and non-permeabilized conditions on either day 5 post-transfection (Hs683) or day 7 post-transfection (U87).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC2805865&req=5

fig03: Galectin-1-targeted siRNA induces both a decrease of integrin-β1 at the edges of the cell membrane and an increase in the intracellular accumulation of integrin-β1. A. U87 control wild-type cells (Aa,Ab) and U87 cells containing stably transfected antisense galectin-1 vectors (Ac) were co-stained under non-permeabilized conditions for integrin-β1 [the red staining at the tip of actin stress fibers (in green fluorescence)], fibrillar actin (green) and globular actin (red staining inside the cells). Ab. Higher magnification of the control wild-type (Aa) image. B. U87 control wild-type cells (Ba) and U87 cells containing stably transfected antisense galectin-1 vectors (Bb) were stained under permeabilized conditions for integrin-β1 only (in green), without any staining to reveal actin (Ba,Bb). C. U87 and Hs683 cells were transiently transfected with either scrambled siRNA (scr) or siRNA targeted against galectin-1 (siGal1). Cells were stained for integrin-β1 (in red) under both permeablized and non-permeabilized conditions on either day 5 post-transfection (Hs683) or day 7 post-transfection (U87).
Mentions: As galectin-1 is involved in adhesion complexes (8), we asked whether decreasing galectin-1 expression altered the pattern of integrin expression at the leading edge of cell migration. In both control U87 and U87 cells stably expressing an antisense galectin-1 vector we left the cells non-permeablized and co-stained them with integrin-β1 and fibrillar (polymerized) and globular (non-polymerized) actin. In control cells, we saw integrin-β1 localization at points of focal adhesion complexes along the cell membrane at the edge of fibrillar actin staining (Figure 3Aa,Ab), whereas in stable galectin-1 knockdown cells the cell membrane localization of integrin-β1 was lost (Figure 3Ac). In Figure 3Aa–Ac, the red fluorescence inside the cells corresponds to globular actin (DNaseI staining), not to integrin-β1. Thus, in comparison, we stained permeablized control and stable galectin-1 knockdown cells with integrin-β1, and found that the galectin-1 knockdown cells contained an intracellular accumulation of integrin-β1, with the cell membrane staining once again lost in comparison with control cells (Figure 3Ba,Bb).

Bottom Line: Galectin-1 depletion does not alter the gene expression level of integrin-beta1.Transient galectin-1 depletion effectuates as well the perinuclear accumulation of protein kinase C epsilon (PKCepsilon) and the intermediate filament vimentin, both of which have been shown to mediate integrin recycling in motile cells.Our results argue for the involvement of galectin-1 in the PKCepsilon/vimentin-controlled trafficking of integrin-beta1.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Toxicology, Institute of Pharmacy, Univesité Libre de Bruxelles, Brussels.

ABSTRACT
Cell motility and resistance to apoptosis characterize glioblastoma (GBM) growth and malignancy. In our current work we report that galectin-1, a homodimeric adhesion molecule and carbohydrate-binding protein with affinity for beta-galactosides, is linked with cell surface expression of integrin beta1 and the process of integrin trafficking. Using immunofluorescence, depletion of galectin-1 through both stable knockdown and transient-targeted small interfering RNA (siRNA) treatment induces an intracellular accumulation of integrin-beta1 coincident with a diminution of integrin-beta1 at points of cellular adhesion at the cell membrane. Galectin-1 depletion does not alter the gene expression level of integrin-beta1. Transient galectin-1 depletion effectuates as well the perinuclear accumulation of protein kinase C epsilon (PKCepsilon) and the intermediate filament vimentin, both of which have been shown to mediate integrin recycling in motile cells. Our results argue for the involvement of galectin-1 in the PKCepsilon/vimentin-controlled trafficking of integrin-beta1. The understanding of molecular mediators such as galectin-1 and the pathways through which they drive the cell invasion so descriptive of GBM is anticipated to reveal potential therapeutic targets that promote glioma malignancy.

Show MeSH
Related in: MedlinePlus