Document Detail

Okadaic acid (1 microM) accelerates S phase and mitosis but inhibits heterochromatin replication and metaphase anaphase transition in Vicia faba meristem cells.
MedLine Citation:
PMID:  17609530     Owner:  NLM     Status:  MEDLINE    
Protein kinases and phosphatases are the foremost agents which take part in cell cycle regulation in both plants and other eukaryotes. Protein kinases are a very well examined group of proteins with respect to chemical structure and function. Nowadays protein phosphatases, including PP1 and PP2A belonging to the PSP family, are the focus of interest. Okadaic acid (OA) which is a specific inhibitor of protein phosphatase activity is widely used to study them. In the present research, the involvement of OA-sensitive phosphatases in the regulation of progression of the plant cell cycle was analysed (in planta) using Vicia faba root meristems synchronized with hydroxyurea and divided into five series. Each series was treated with 1 muM OA for 3 h for different time periods corresponding to the consecutive cell cycle phases. The results showed that in the OA-treated cells DNA replication and mitosis began earlier than in the control cells, since G(1) and G(2) phases were significantly shorter and the H1 histone kinases activity was higher. Moreover, autoradiography and morphological analyses of mitotic figures revealed that the OA-treated cells entered mitosis before the end of heterochromatin replication. An immunocytochemical search showed that earlier initiation of S phase in the OA-treated cells correlated with more abundant phosphorylation of Rb-like protein in comparison with the control cells. OA also induced significant condensation of metaphase chromosomes and blocked metaphase-anaphase transition.
Justyna Teresa Polit; Andrzej Kazmierczak
Publication Detail:
Type:  Journal Article     Date:  2007-07-03
Journal Detail:
Title:  Journal of experimental botany     Volume:  58     ISSN:  0022-0957     ISO Abbreviation:  J. Exp. Bot.     Publication Date:  2007  
Date Detail:
Created Date:  2007-09-28     Completed Date:  2008-01-29     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9882906     Medline TA:  J Exp Bot     Country:  England    
Other Details:
Languages:  eng     Pagination:  2785-97     Citation Subset:  IM    
Department of Cytophysiology, University of Łódź, 90-231 Łódź, ul. Pilarskiego 14, Poland.
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MeSH Terms
Anaphase / drug effects
Cell Nucleus Division / drug effects*
DNA Replication / drug effects*
Enzyme Inhibitors / pharmacology*
Heterochromatin / drug effects,  ultrastructure
Meristem / cytology,  drug effects*
Metaphase / drug effects
Mitosis / drug effects
Okadaic Acid / pharmacology*
Phosphoprotein Phosphatases / antagonists & inhibitors,  physiology
S Phase / drug effects
Vicia faba / cytology,  drug effects*,  ultrastructure
Reg. No./Substance:
0/Enzyme Inhibitors; 0/Heterochromatin; 78111-17-8/Okadaic Acid; EC Phosphatases

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