| Biphasic expression of rnrB in Dictyostelium discoideum suggests a direct relationship between cell cycle control and cell differentiation. | |
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MedLine Citation:
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PMID: 11270119 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Cell differentiation in Dictyostelium is strongly affected by the cell cycle. Cell cycle control is well-understood in other systems, but this has had almost no impact on the study of Dictyostelium cell differentiation, in part because the cell cycle in Dictyostelium is unusual, lacking a G1 phase. Here we describe the cell-cycle regulated expression of rnrB, which codes for the small subunit of ribonucleotide reductase and is a marker of late G1 in many systems. There appear to be two expression peaks, one in mid-G2 and the other near the G2/M transition. Using Xgal/anti-BrdU double staining, we show that cells in asynchronously growing cultures express in both phases, with a gap between them during which the gene is transcriptionally silent. Cold-synchronized cells show exclusively G2/M expression, while mid-G2 expression is seen in high-density synchronized cells and can also be inferred in cells undergoing synchronization by either method. rnrB expression occurs in other systems shortly after cells pass a point (the "restriction point" or "start") at which they commit to complete their current cell cycle. We demonstrate a similar commitment point in Dictyostelium and show that this occurs shortly before the mid-G2 rnrB expression peak. The Dictyostelium cell cycle thus appears to include a well-defined though inconspicuous event, between early and mid-G2, with some features which are normally associated with the G1/S transition. Others have described a switch from stalk to spore differentiation preference at about this time. Since Dictyostelium cells switch back from spore to stalk preference approximately at the G2/M rnrB expression maximum, cell differentiation as well as rnrB expression may be regulated directly by fundamental cell cycle control processes. |
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Authors:
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H MacWilliams; P Gaudet; H Deichsel; C Bonfils; A Tsang |
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Publication Detail:
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Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Differentiation; research in biological diversity Volume: 67 ISSN: 0301-4681 ISO Abbreviation: Differentiation Publication Date: 2001 Feb |
Date Detail:
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Created Date: 2001-03-28 Completed Date: 2001-05-21 Revised Date: 2008-11-21 |
Medline Journal Info:
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Nlm Unique ID: 0401650 Medline TA: Differentiation Country: Germany |
Other Details:
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Languages: eng Pagination: 12-24 Citation Subset: IM |
Affiliation:
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Zoologisches Institut, Ludwig-Maximilians-Universitat Luisenstrasse 14, 80333 München 2, Germany. macw@zi.biologie.uni-muenchen.de |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Cell Cycle / genetics* Cell Differentiation / genetics* Cell Division / genetics Cold Temperature Cytological Techniques Dictyostelium / cytology*, genetics* Gene Expression Regulation, Developmental Promoter Regions, Genetic Ribonucleotide Reductases / genetics* |
| Chemical | |
Reg. No./Substance:
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EC 1.17.4.-/Ribonucleotide Reductases |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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