Microcystin-LR, a protein phosphatase inhibitor, induces alterations in mitotic chromatin and microtubule organization leading to the formation of micronuclei in Vicia faba

Dániel Beyer, Ildikó Tándor, Zoltán Kónya, Róbert Bátori, Janos Roszik, G. Vereb, F. Erdődi, G. Vasas, Márta M-Hamvas, Károly Jambrovics, Csaba Máthé

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Abstract

Background and AimsMicrocystin-LR (MCY-LR) is a cyanobacterial toxin, a specific inhibitor of type 1 and 2A protein phosphatases (PP1 and PP2A) with significant impact on aquatic ecosystems. It has the potential to alter regulation of the plant cell cycle. The aim of this study was improved understanding of the mitotic alterations induced by cyanotoxin in Vicia faba, a model organism for plant cell biology studies.MethodsVicia faba seedlings were treated over the long and short term with MCY-LR purified in our laboratory. Short-term treatments were performed on root meristems synchronized with hydroxylurea. Sections of lateral root tips were labelled for chromatin, phosphorylated histone H3 and β-tubulin via histochemical and immunohistochemical methods. Mitotic activity and the occurrence of mitotic alterations were detected and analysed by fluorescence microscopy. The phosphorylation state of histone H3 was studied by Western blotting.Key ResultsLong-term MCY-LR exposure of lateral root tip meristems increased the percentage of either early or late mitosis in a concentration-dependent manner. We observed hypercondensed chromosomes and altered sister chromatid segregation (lagging chromosomes) leading to the formation of micronuclei, accompanied by the formation of disrupted, multipolar and monopolar spindles, disrupted phragmoplasts and the hyperphosphorylation of histone H3 at Ser10. Short-term MCY-LR treatment of synchronized cells showed that PP1 and PP2A inhibition delayed the onset of anaphase at 1 g mL-1 MCY-LR, accelerated cell cycle at 10 g mL-1 MCY-LR and induced the formation of lagging chromosomes. In this case mitotic microtubule alterations were not detected, but histone H3 was hyperphosphorylated.ConclusionsMCY-LR delayed metaphaseanaphase transition. Consequently, it induced aberrant chromatid segregation and micronucleus formation that could be associated with both H3 hyperphosphorylation and altered microtubule organization. However, these two phenomena seemed to be independent. The toxin may be a useful tool in the study of plant cell cycle regulation.

Original languageEnglish
Pages (from-to)797-808
Number of pages12
JournalAnnals of Botany
Volume110
Issue number4
DOIs
Publication statusPublished - Sep 2012

Fingerprint

microcystin-LR
Vicia faba
histones
microtubules
chromatin
cyanobacterial toxins
phosphoprotein phosphatase
cell cycle
chromatids
root tips
proteins
chromosomes
chromosome segregation
root meristems
plant biology
anaphase
tubulin
fluorescence microscopy
meristems
cell biology

Keywords

  • chromatin
  • Microcystin-LR
  • micronucleus
  • microtubule
  • mitosis
  • phospho-histone H3
  • protein phosphatase
  • Vicia faba

ASJC Scopus subject areas

  • Plant Science

Cite this

Microcystin-LR, a protein phosphatase inhibitor, induces alterations in mitotic chromatin and microtubule organization leading to the formation of micronuclei in Vicia faba. / Beyer, Dániel; Tándor, Ildikó; Kónya, Zoltán; Bátori, Róbert; Roszik, Janos; Vereb, G.; Erdődi, F.; Vasas, G.; M-Hamvas, Márta; Jambrovics, Károly; Máthé, Csaba.

In: Annals of Botany, Vol. 110, No. 4, 09.2012, p. 797-808.

Research output: Contribution to journalArticle

Beyer, Dániel ; Tándor, Ildikó ; Kónya, Zoltán ; Bátori, Róbert ; Roszik, Janos ; Vereb, G. ; Erdődi, F. ; Vasas, G. ; M-Hamvas, Márta ; Jambrovics, Károly ; Máthé, Csaba. / Microcystin-LR, a protein phosphatase inhibitor, induces alterations in mitotic chromatin and microtubule organization leading to the formation of micronuclei in Vicia faba. In: Annals of Botany. 2012 ; Vol. 110, No. 4. pp. 797-808.
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abstract = "Background and AimsMicrocystin-LR (MCY-LR) is a cyanobacterial toxin, a specific inhibitor of type 1 and 2A protein phosphatases (PP1 and PP2A) with significant impact on aquatic ecosystems. It has the potential to alter regulation of the plant cell cycle. The aim of this study was improved understanding of the mitotic alterations induced by cyanotoxin in Vicia faba, a model organism for plant cell biology studies.MethodsVicia faba seedlings were treated over the long and short term with MCY-LR purified in our laboratory. Short-term treatments were performed on root meristems synchronized with hydroxylurea. Sections of lateral root tips were labelled for chromatin, phosphorylated histone H3 and β-tubulin via histochemical and immunohistochemical methods. Mitotic activity and the occurrence of mitotic alterations were detected and analysed by fluorescence microscopy. The phosphorylation state of histone H3 was studied by Western blotting.Key ResultsLong-term MCY-LR exposure of lateral root tip meristems increased the percentage of either early or late mitosis in a concentration-dependent manner. We observed hypercondensed chromosomes and altered sister chromatid segregation (lagging chromosomes) leading to the formation of micronuclei, accompanied by the formation of disrupted, multipolar and monopolar spindles, disrupted phragmoplasts and the hyperphosphorylation of histone H3 at Ser10. Short-term MCY-LR treatment of synchronized cells showed that PP1 and PP2A inhibition delayed the onset of anaphase at 1 g mL-1 MCY-LR, accelerated cell cycle at 10 g mL-1 MCY-LR and induced the formation of lagging chromosomes. In this case mitotic microtubule alterations were not detected, but histone H3 was hyperphosphorylated.ConclusionsMCY-LR delayed metaphaseanaphase transition. Consequently, it induced aberrant chromatid segregation and micronucleus formation that could be associated with both H3 hyperphosphorylation and altered microtubule organization. However, these two phenomena seemed to be independent. The toxin may be a useful tool in the study of plant cell cycle regulation.",
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T1 - Microcystin-LR, a protein phosphatase inhibitor, induces alterations in mitotic chromatin and microtubule organization leading to the formation of micronuclei in Vicia faba

AU - Beyer, Dániel

AU - Tándor, Ildikó

AU - Kónya, Zoltán

AU - Bátori, Róbert

AU - Roszik, Janos

AU - Vereb, G.

AU - Erdődi, F.

AU - Vasas, G.

AU - M-Hamvas, Márta

AU - Jambrovics, Károly

AU - Máthé, Csaba

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N2 - Background and AimsMicrocystin-LR (MCY-LR) is a cyanobacterial toxin, a specific inhibitor of type 1 and 2A protein phosphatases (PP1 and PP2A) with significant impact on aquatic ecosystems. It has the potential to alter regulation of the plant cell cycle. The aim of this study was improved understanding of the mitotic alterations induced by cyanotoxin in Vicia faba, a model organism for plant cell biology studies.MethodsVicia faba seedlings were treated over the long and short term with MCY-LR purified in our laboratory. Short-term treatments were performed on root meristems synchronized with hydroxylurea. Sections of lateral root tips were labelled for chromatin, phosphorylated histone H3 and β-tubulin via histochemical and immunohistochemical methods. Mitotic activity and the occurrence of mitotic alterations were detected and analysed by fluorescence microscopy. The phosphorylation state of histone H3 was studied by Western blotting.Key ResultsLong-term MCY-LR exposure of lateral root tip meristems increased the percentage of either early or late mitosis in a concentration-dependent manner. We observed hypercondensed chromosomes and altered sister chromatid segregation (lagging chromosomes) leading to the formation of micronuclei, accompanied by the formation of disrupted, multipolar and monopolar spindles, disrupted phragmoplasts and the hyperphosphorylation of histone H3 at Ser10. Short-term MCY-LR treatment of synchronized cells showed that PP1 and PP2A inhibition delayed the onset of anaphase at 1 g mL-1 MCY-LR, accelerated cell cycle at 10 g mL-1 MCY-LR and induced the formation of lagging chromosomes. In this case mitotic microtubule alterations were not detected, but histone H3 was hyperphosphorylated.ConclusionsMCY-LR delayed metaphaseanaphase transition. Consequently, it induced aberrant chromatid segregation and micronucleus formation that could be associated with both H3 hyperphosphorylation and altered microtubule organization. However, these two phenomena seemed to be independent. The toxin may be a useful tool in the study of plant cell cycle regulation.

AB - Background and AimsMicrocystin-LR (MCY-LR) is a cyanobacterial toxin, a specific inhibitor of type 1 and 2A protein phosphatases (PP1 and PP2A) with significant impact on aquatic ecosystems. It has the potential to alter regulation of the plant cell cycle. The aim of this study was improved understanding of the mitotic alterations induced by cyanotoxin in Vicia faba, a model organism for plant cell biology studies.MethodsVicia faba seedlings were treated over the long and short term with MCY-LR purified in our laboratory. Short-term treatments were performed on root meristems synchronized with hydroxylurea. Sections of lateral root tips were labelled for chromatin, phosphorylated histone H3 and β-tubulin via histochemical and immunohistochemical methods. Mitotic activity and the occurrence of mitotic alterations were detected and analysed by fluorescence microscopy. The phosphorylation state of histone H3 was studied by Western blotting.Key ResultsLong-term MCY-LR exposure of lateral root tip meristems increased the percentage of either early or late mitosis in a concentration-dependent manner. We observed hypercondensed chromosomes and altered sister chromatid segregation (lagging chromosomes) leading to the formation of micronuclei, accompanied by the formation of disrupted, multipolar and monopolar spindles, disrupted phragmoplasts and the hyperphosphorylation of histone H3 at Ser10. Short-term MCY-LR treatment of synchronized cells showed that PP1 and PP2A inhibition delayed the onset of anaphase at 1 g mL-1 MCY-LR, accelerated cell cycle at 10 g mL-1 MCY-LR and induced the formation of lagging chromosomes. In this case mitotic microtubule alterations were not detected, but histone H3 was hyperphosphorylated.ConclusionsMCY-LR delayed metaphaseanaphase transition. Consequently, it induced aberrant chromatid segregation and micronucleus formation that could be associated with both H3 hyperphosphorylation and altered microtubule organization. However, these two phenomena seemed to be independent. The toxin may be a useful tool in the study of plant cell cycle regulation.

KW - chromatin

KW - Microcystin-LR

KW - micronucleus

KW - microtubule

KW - mitosis

KW - phospho-histone H3

KW - protein phosphatase

KW - Vicia faba

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