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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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Caspase-3 activation and gelsolin translocation in HuLEC in the presence of xanthurenic acid for 96 hours. Cells stained for active caspase-3 (A, B), and gelsolin (C, D): (A) control cells stained with Hoechst 33342 and for cleaved caspase-3, (B) cells exposed to 10 μM xanthurenic acid and stained for cleaved caspase-3, (C) control cells, (D) in the presence of 10 μM xanthurenic acid.
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Figure 1: Caspase-3 activation and gelsolin translocation in HuLEC in the presence of xanthurenic acid for 96 hours. Cells stained for active caspase-3 (A, B), and gelsolin (C, D): (A) control cells stained with Hoechst 33342 and for cleaved caspase-3, (B) cells exposed to 10 μM xanthurenic acid and stained for cleaved caspase-3, (C) control cells, (D) in the presence of 10 μM xanthurenic acid.

Mentions: We observed that 10 μM xanthurenic acid in the HuLEC cell culture medium activate caspase-3 (Fig. 1B). In the same cells the translocation of gelsolin from perinuclear region to cytoskeleton was observed (Fig. 1C, 1D). Previously it was reported that caspase-3 and -9 are associated with mitochondrial membranes [19]. Gelsolin is the cytoskeletal protein responsible for the disintegration of F actin during apoptosis induced by Fas [20]. It was also suggested that gelsolin keeps caspases in the inactive state [21]. We reported previously that gelsolin is abnormally cleaved during apoptosis induced by xanthurenic acid. This abnormal gelsolin cleavage could be a reason of absence of cytoskeleton breakdown in the presence of active caspase-3 (Fig. 1B, 1D).


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)

Caspase-3 activation and gelsolin translocation in HuLEC in the presence of xanthurenic acid for 96 hours. Cells stained for active caspase-3 (A, B), and gelsolin (C, D): (A) control cells stained with Hoechst 33342 and for cleaved caspase-3, (B) cells exposed to 10 μM xanthurenic acid and stained for cleaved caspase-3, (C) control cells, (D) in the presence of 10 μM xanthurenic acid.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 1: Caspase-3 activation and gelsolin translocation in HuLEC in the presence of xanthurenic acid for 96 hours. Cells stained for active caspase-3 (A, B), and gelsolin (C, D): (A) control cells stained with Hoechst 33342 and for cleaved caspase-3, (B) cells exposed to 10 μM xanthurenic acid and stained for cleaved caspase-3, (C) control cells, (D) in the presence of 10 μM xanthurenic acid.
Mentions: We observed that 10 μM xanthurenic acid in the HuLEC cell culture medium activate caspase-3 (Fig. 1B). In the same cells the translocation of gelsolin from perinuclear region to cytoskeleton was observed (Fig. 1C, 1D). Previously it was reported that caspase-3 and -9 are associated with mitochondrial membranes [19]. Gelsolin is the cytoskeletal protein responsible for the disintegration of F actin during apoptosis induced by Fas [20]. It was also suggested that gelsolin keeps caspases in the inactive state [21]. We reported previously that gelsolin is abnormally cleaved during apoptosis induced by xanthurenic acid. This abnormal gelsolin cleavage could be a reason of absence of cytoskeleton breakdown in the presence of active caspase-3 (Fig. 1B, 1D).

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