Inhibition of serine/threonine-specific protein phosphatases causes premature activation of cdc2MsF kinase at G2/M transition and early mitotic microtubule organisation in alfalfa

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Abstract

Reversible phosphorylation of serine/threonine residues of cell cycle-regulatory proteins is one of the key molecular mechanisms controlling eukaryotic cell division. In plants, the protein kinase partners (i.e. p34(cdc2/CDC28)-related kinases) have been extensively studied, while the role of counter-acting protein phosphatases is less well understood. We used endothall (ET) as a cell-permeable inhibitor of serine/threonine-specific protein phosphatases to alter cytological and biochemical characteristics of cell division in cultured alfalfa cells. A high concentration of ET (10 and 50 μM) inhibited both protein phosphatases 1 and 2 (PP1 and PP2A), while a low concentration (1 μM) of ET-treatment primarily reduced the PP2A activity. High concentrations of the inhibitor increased the frequency of hypercondensed early and late prophase chromosomes that could not enter metaphase. In contrast, a low concentration of ET did not interfere with chromosomal events but caused significant alterations in the organisation of microtubules. Exposure of cells to 1 μM ET resulted in disturbance of preprophase band formation, increase in the number of nuclei with prophase microtubule assembly, premature polarisation of the spindle, and abnormal phragmoplast maturation. Under the same conditions, the ET-treated cells exhibited an early increase in cdc2MsF kinase activity. These results suggest that PP2A contributes to the control of mitotic kinase activities and microtubule organisation. Normal chromosome condensation and mitotic progression are dependent on both PP1 and PP2A activities. The presented data support the functional role of protein phosphatases in the co-ordination of chromosomal and microtubule events in dividing plant cells.

Original languageEnglish
Pages (from-to)85-96
Number of pages12
JournalPlant Journal
Volume23
Issue number1
DOIs
Publication statusPublished - Jul 2000

Fingerprint

Medicago sativa
Phosphoprotein Phosphatases
threonine
Microtubules
serine
microtubules
alfalfa
phosphotransferases (kinases)
Phosphotransferases
prophase
Prophase
proteins
cells
cell division
CDC2-CDC28 Kinases
Cell Division
chromosomes
phosphoprotein phosphatase
Chromosomes
regulatory proteins

Keywords

  • Cdc2-related kinase
  • Chromosome condensation
  • Endothall
  • Medicago sativa L
  • Preprophase band
  • Serine/threonine phosphatases

ASJC Scopus subject areas

  • Plant Science

Cite this

@article{c2e40be88815465e8d8381b9d491172d,
title = "Inhibition of serine/threonine-specific protein phosphatases causes premature activation of cdc2MsF kinase at G2/M transition and early mitotic microtubule organisation in alfalfa",
abstract = "Reversible phosphorylation of serine/threonine residues of cell cycle-regulatory proteins is one of the key molecular mechanisms controlling eukaryotic cell division. In plants, the protein kinase partners (i.e. p34(cdc2/CDC28)-related kinases) have been extensively studied, while the role of counter-acting protein phosphatases is less well understood. We used endothall (ET) as a cell-permeable inhibitor of serine/threonine-specific protein phosphatases to alter cytological and biochemical characteristics of cell division in cultured alfalfa cells. A high concentration of ET (10 and 50 μM) inhibited both protein phosphatases 1 and 2 (PP1 and PP2A), while a low concentration (1 μM) of ET-treatment primarily reduced the PP2A activity. High concentrations of the inhibitor increased the frequency of hypercondensed early and late prophase chromosomes that could not enter metaphase. In contrast, a low concentration of ET did not interfere with chromosomal events but caused significant alterations in the organisation of microtubules. Exposure of cells to 1 μM ET resulted in disturbance of preprophase band formation, increase in the number of nuclei with prophase microtubule assembly, premature polarisation of the spindle, and abnormal phragmoplast maturation. Under the same conditions, the ET-treated cells exhibited an early increase in cdc2MsF kinase activity. These results suggest that PP2A contributes to the control of mitotic kinase activities and microtubule organisation. Normal chromosome condensation and mitotic progression are dependent on both PP1 and PP2A activities. The presented data support the functional role of protein phosphatases in the co-ordination of chromosomal and microtubule events in dividing plant cells.",
keywords = "Cdc2-related kinase, Chromosome condensation, Endothall, Medicago sativa L, Preprophase band, Serine/threonine phosphatases",
author = "Ferhan Ayaydin and Emese Vissi and Tam{\'a}s M{\'e}sz{\'a}ros and P{\'a}l Miskolczi and Izabella Kov{\'a}cs and Attila Feh{\'e}r and Viktor Dombr{\'a}di and Ferenc Erd{\"o}di and P{\'a}l Gergely and D{\'e}nes Dudits",
year = "2000",
month = "7",
doi = "10.1046/j.1365-313X.2000.00798.x",
language = "English",
volume = "23",
pages = "85--96",
journal = "Plant Journal",
issn = "0960-7412",
publisher = "Wiley-Blackwell",
number = "1",

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TY - JOUR

T1 - Inhibition of serine/threonine-specific protein phosphatases causes premature activation of cdc2MsF kinase at G2/M transition and early mitotic microtubule organisation in alfalfa

AU - Ayaydin, Ferhan

AU - Vissi, Emese

AU - Mészáros, Tamás

AU - Miskolczi, Pál

AU - Kovács, Izabella

AU - Fehér, Attila

AU - Dombrádi, Viktor

AU - Erdödi, Ferenc

AU - Gergely, Pál

AU - Dudits, Dénes

PY - 2000/7

Y1 - 2000/7

N2 - Reversible phosphorylation of serine/threonine residues of cell cycle-regulatory proteins is one of the key molecular mechanisms controlling eukaryotic cell division. In plants, the protein kinase partners (i.e. p34(cdc2/CDC28)-related kinases) have been extensively studied, while the role of counter-acting protein phosphatases is less well understood. We used endothall (ET) as a cell-permeable inhibitor of serine/threonine-specific protein phosphatases to alter cytological and biochemical characteristics of cell division in cultured alfalfa cells. A high concentration of ET (10 and 50 μM) inhibited both protein phosphatases 1 and 2 (PP1 and PP2A), while a low concentration (1 μM) of ET-treatment primarily reduced the PP2A activity. High concentrations of the inhibitor increased the frequency of hypercondensed early and late prophase chromosomes that could not enter metaphase. In contrast, a low concentration of ET did not interfere with chromosomal events but caused significant alterations in the organisation of microtubules. Exposure of cells to 1 μM ET resulted in disturbance of preprophase band formation, increase in the number of nuclei with prophase microtubule assembly, premature polarisation of the spindle, and abnormal phragmoplast maturation. Under the same conditions, the ET-treated cells exhibited an early increase in cdc2MsF kinase activity. These results suggest that PP2A contributes to the control of mitotic kinase activities and microtubule organisation. Normal chromosome condensation and mitotic progression are dependent on both PP1 and PP2A activities. The presented data support the functional role of protein phosphatases in the co-ordination of chromosomal and microtubule events in dividing plant cells.

AB - Reversible phosphorylation of serine/threonine residues of cell cycle-regulatory proteins is one of the key molecular mechanisms controlling eukaryotic cell division. In plants, the protein kinase partners (i.e. p34(cdc2/CDC28)-related kinases) have been extensively studied, while the role of counter-acting protein phosphatases is less well understood. We used endothall (ET) as a cell-permeable inhibitor of serine/threonine-specific protein phosphatases to alter cytological and biochemical characteristics of cell division in cultured alfalfa cells. A high concentration of ET (10 and 50 μM) inhibited both protein phosphatases 1 and 2 (PP1 and PP2A), while a low concentration (1 μM) of ET-treatment primarily reduced the PP2A activity. High concentrations of the inhibitor increased the frequency of hypercondensed early and late prophase chromosomes that could not enter metaphase. In contrast, a low concentration of ET did not interfere with chromosomal events but caused significant alterations in the organisation of microtubules. Exposure of cells to 1 μM ET resulted in disturbance of preprophase band formation, increase in the number of nuclei with prophase microtubule assembly, premature polarisation of the spindle, and abnormal phragmoplast maturation. Under the same conditions, the ET-treated cells exhibited an early increase in cdc2MsF kinase activity. These results suggest that PP2A contributes to the control of mitotic kinase activities and microtubule organisation. Normal chromosome condensation and mitotic progression are dependent on both PP1 and PP2A activities. The presented data support the functional role of protein phosphatases in the co-ordination of chromosomal and microtubule events in dividing plant cells.

KW - Cdc2-related kinase

KW - Chromosome condensation

KW - Endothall

KW - Medicago sativa L

KW - Preprophase band

KW - Serine/threonine phosphatases

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U2 - 10.1046/j.1365-313X.2000.00798.x

DO - 10.1046/j.1365-313X.2000.00798.x

M3 - Article

C2 - 10929104

AN - SCOPUS:0033897847

VL - 23

SP - 85

EP - 96

JO - Plant Journal

JF - Plant Journal

SN - 0960-7412

IS - 1

ER -