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Lens epithelial cell apoptosis and intracellular Ca2+ increase in the presence of xanthurenic acid.

Malina H, Richter C, Frueh B, Hess OM - BMC Ophthalmol (2002)

Bottom Line: In the control cells gelsolin stained the perinuclear region, whereas in the presence of 10 microM xanthurenic acid gelsolin is translocated to the cytoskeleton, but does not lead to cytoskeleton breakdown.At low (5 to 10 microM) of xanthurenic acid concentration, the elongation of the cytoskeleton was associated with migration of mitochondria and cytochrome c release.We observed an induction of calpain Lp 82 and an increase of free Ca2+ in the cells in a xanthurenic acid concentration-dependent manner.

View Article: PubMed Central - HTML - PubMed

Affiliation: Swiss Cardiovascular Research Center, Inselspital, CH-3010 Bern, Switzerland. halina.malina@dkf2.unibe.ch

ABSTRACT

Background: Xanthurenic acid is an endogenous product of tryptophan degradation by indoleamine 2,3-dioxygenase (IDO). We have previously reported that IDO is present in mammalian lenses, and xanthurenic acid is accumulated in the lenses with aging. Here, we studied the involvement of xanthurenic acid in the human lens epithelial cell physiology.

Methods: Human lens epithelial cells primary cultures were used. Control cells, and cells in the presence of xanthurenic acid grow in the dark. Western blot analysis and immunofluorescence studies were performed.

Results: In the presence of xanthurenic acid human lens epithelial cells undergo apoptosis-like cell death. In the control cells gelsolin stained the perinuclear region, whereas in the presence of 10 microM xanthurenic acid gelsolin is translocated to the cytoskeleton, but does not lead to cytoskeleton breakdown. In the same condition caspase-3 activation, and DNA fragmentation was observed. At low (5 to 10 microM) of xanthurenic acid concentration, the elongation of the cytoskeleton was associated with migration of mitochondria and cytochrome c release. At higher concentrations xanthurenic acid (20 microM and 40 microM) damaged mitochondria were observed in the perinuclear region, and nuclear DNA cleavage was observed. We observed an induction of calpain Lp 82 and an increase of free Ca2+ in the cells in a xanthurenic acid concentration-dependent manner.

Conclusions: The results show that xanthurenic acid accumulation in human lens epithelial cells disturbs the normal cell physiology and leads to a cascade of pathological events. Xanthurenic acid induces calpain Lp82 and caspases in the cells growing in the dark and can be involved in senile cataract development.

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Apoptotic death of HuLEC in the presence of xanthurenic acid.
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Figure 5: Apoptotic death of HuLEC in the presence of xanthurenic acid.

Mentions: In control cells about 5 percent are apoptotic (Fig. 4A, Fig. 5). In the presence of 10 μM xanthurenic acid condensed and/or cleaved nuclei were observed, which a mostly stained only with Hoechst 33342, and not with propidium iodide. This indicated that the observed cell death was apoptotic and not necrotic (Fig. 4B, 4C). With concentrations of xanthurenic acid of 20 μM (Fig. 4D,4E,4F) and 40 μM (Fig. 4G,4H,4I) the destruction of the mitochondrial structure, was associated with nuclear cleavage. Cell death depended on the xanthurenic acid concentration (Fig. 5). In the presence of 10 μM xanthurenic acid about 40 percent of cells were dead, and an increase of xanthurenic acid to 20 μM provoked about 70 percent of cell death.


Lens epithelial cell apoptosis and intracellular Ca2+ increase in the presence of xanthurenic acid.

Malina H, Richter C, Frueh B, Hess OM - BMC Ophthalmol (2002)

Apoptotic death of HuLEC in the presence of xanthurenic acid.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC103667&req=5

Figure 5: Apoptotic death of HuLEC in the presence of xanthurenic acid.
Mentions: In control cells about 5 percent are apoptotic (Fig. 4A, Fig. 5). In the presence of 10 μM xanthurenic acid condensed and/or cleaved nuclei were observed, which a mostly stained only with Hoechst 33342, and not with propidium iodide. This indicated that the observed cell death was apoptotic and not necrotic (Fig. 4B, 4C). With concentrations of xanthurenic acid of 20 μM (Fig. 4D,4E,4F) and 40 μM (Fig. 4G,4H,4I) the destruction of the mitochondrial structure, was associated with nuclear cleavage. Cell death depended on the xanthurenic acid concentration (Fig. 5). In the presence of 10 μM xanthurenic acid about 40 percent of cells were dead, and an increase of xanthurenic acid to 20 μM provoked about 70 percent of cell death.

Bottom Line: In the control cells gelsolin stained the perinuclear region, whereas in the presence of 10 microM xanthurenic acid gelsolin is translocated to the cytoskeleton, but does not lead to cytoskeleton breakdown.At low (5 to 10 microM) of xanthurenic acid concentration, the elongation of the cytoskeleton was associated with migration of mitochondria and cytochrome c release.We observed an induction of calpain Lp 82 and an increase of free Ca2+ in the cells in a xanthurenic acid concentration-dependent manner.

View Article: PubMed Central - HTML - PubMed

Affiliation: Swiss Cardiovascular Research Center, Inselspital, CH-3010 Bern, Switzerland. halina.malina@dkf2.unibe.ch

ABSTRACT

Background: Xanthurenic acid is an endogenous product of tryptophan degradation by indoleamine 2,3-dioxygenase (IDO). We have previously reported that IDO is present in mammalian lenses, and xanthurenic acid is accumulated in the lenses with aging. Here, we studied the involvement of xanthurenic acid in the human lens epithelial cell physiology.

Methods: Human lens epithelial cells primary cultures were used. Control cells, and cells in the presence of xanthurenic acid grow in the dark. Western blot analysis and immunofluorescence studies were performed.

Results: In the presence of xanthurenic acid human lens epithelial cells undergo apoptosis-like cell death. In the control cells gelsolin stained the perinuclear region, whereas in the presence of 10 microM xanthurenic acid gelsolin is translocated to the cytoskeleton, but does not lead to cytoskeleton breakdown. In the same condition caspase-3 activation, and DNA fragmentation was observed. At low (5 to 10 microM) of xanthurenic acid concentration, the elongation of the cytoskeleton was associated with migration of mitochondria and cytochrome c release. At higher concentrations xanthurenic acid (20 microM and 40 microM) damaged mitochondria were observed in the perinuclear region, and nuclear DNA cleavage was observed. We observed an induction of calpain Lp 82 and an increase of free Ca2+ in the cells in a xanthurenic acid concentration-dependent manner.

Conclusions: The results show that xanthurenic acid accumulation in human lens epithelial cells disturbs the normal cell physiology and leads to a cascade of pathological events. Xanthurenic acid induces calpain Lp82 and caspases in the cells growing in the dark and can be involved in senile cataract development.

Show MeSH
Related in: MedlinePlus