Document Detail


A conserved G₁ regulatory circuit promotes asynchronous behavior of nuclei sharing a common cytoplasm.
MedLine Citation:
PMID:  20930528     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Synthesis and accumulation of conserved cell cycle regulators such as cyclins are thought to promote G₁/S and G₂/M transitions in most eukaryotes. When cells at different stages of the cell cycle are fused to form heterokaryons, the shared complement of regulators in the cytoplasm induces the nuclei to become synchronized. However, multinucleate fungi often display asynchronous nuclear division cycles, even though the nuclei inhabit a shared cytoplasm. Similarly, checkpoints can induce nuclear asynchrony in multinucleate cells by arresting only the nucleus that receives damage. The cell biological basis for nuclear autonomy in a common cytoplasm is not known. Here we show that in the filamentous fungus Ashbya gossypii, sister nuclei born from one mitosis immediately lose synchrony in the subsequent G₁ interval. A conserved G₁ transcriptional regulatory circuit involving the Rb-analogue Whi5p promotes the asynchronous behavior yet Whi5 protein is uniformly distributed among nuclei throughout the cell cycle. The homologous Whi5p circuit in S. cerevisiae employs positive feedback to promote robust and coherent entry into the cell cycle. We propose that positive feedback in this same circuit generates timing variability in a multinucleate cell. These unexpected findings indicate that a regulatory program whose products (mRNA transcripts) are translated in a common cytoplasm can nevertheless promote variability in the individual behavior of sister nuclei.
Authors:
Dhanalakshmi R Nair; Cori A D'Ausilio; Patricia Occhipinti; Mark E Borsuk; Amy S Gladfelter
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2010-09-13
Journal Detail:
Title:  Cell cycle (Georgetown, Tex.)     Volume:  9     ISSN:  1551-4005     ISO Abbreviation:  Cell Cycle     Publication Date:  2010 Sep 
Date Detail:
Created Date:  2010-10-27     Completed Date:  2011-02-17     Revised Date:  2012-04-26    
Medline Journal Info:
Nlm Unique ID:  101137841     Medline TA:  Cell Cycle     Country:  United States    
Other Details:
Languages:  eng     Pagination:  3771-9     Citation Subset:  IM    
Affiliation:
Department of Biological Sciences, Dartmouth College, Hanover, NH, USA.
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MeSH Terms
Descriptor/Qualifier:
Cell Cycle Proteins / metabolism*
Cell Nucleus / metabolism*
Cyclins / metabolism
Cytoplasm / metabolism*
Fungal Proteins / metabolism
G1 Phase / genetics*
Mitosis
Repressor Proteins / metabolism
Saccharomyces cerevisiae Proteins / metabolism
Saccharomycetales / metabolism
Transcription Factors / metabolism
Grant Support
ID/Acronym/Agency:
T32GM008704/GM/NIGMS NIH HHS; //Howard Hughes Medical Institute
Chemical
Reg. No./Substance:
0/Cell Cycle Proteins; 0/Cyclins; 0/Fungal Proteins; 0/Repressor Proteins; 0/Saccharomyces cerevisiae Proteins; 0/Transcription Factors
Comments/Corrections
Comment In:
Cell Cycle. 2010 Oct 1;9(19):3843-4   [PMID:  20948281 ]
Cell Cycle. 2010 Oct 1;9(19):3844   [PMID:  20948282 ]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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