Assembly of Drosophila centromeric chromatin proteins during mitosis
| Autor: | Gary H. Karpen, Barbara G. Mellone, Isaac M. Oderberg, Kathryn J. Grive, Vladimir Shteyn, Sarion R. Bowers |
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| Přispěvatelé: | Biggins, Sue |
| Jazyk: | angličtina |
| Rok vydání: | 2011 |
| Předmět: |
Cancer Research
Proteasome Endopeptidase Complex Nucleosome assembly lcsh:QH426-470 1.1 Normal biological development and functioning Centromere Mitosis Cyclin A macromolecular substances Biology Microtubules Prophase 03 medical and health sciences 0302 clinical medicine Underpinning research Genetics Sister chromatids Animals Humans Molecular Biology Metaphase Genetics (clinical) Ecology Evolution Behavior and Systematics 030304 developmental biology 0303 health sciences Chromatin Cell biology Spindle apparatus lcsh:Genetics Drosophila Generic health relevance 030217 neurology & neurosurgery Research Article Developmental Biology |
| Zdroj: | PLoS Genetics, Vol 7, Iss 5, p e1002068 (2011) PLoS genetics, vol 7, iss 5 PLoS Genetics |
| ISSN: | 1553-7404 1553-7390 |
| Popis: | Semi-conservative segregation of nucleosomes to sister chromatids during DNA replication creates gaps that must be filled by new nucleosome assembly. We analyzed the cell-cycle timing of centromeric chromatin assembly in Drosophila, which contains the H3 variant CID (CENP-A in humans), as well as CENP-C and CAL1, which are required for CID localization. Pulse-chase experiments show that CID and CENP-C levels decrease by 50% at each cell division, as predicted for semi-conservative segregation and inheritance, whereas CAL1 displays higher turnover. Quench-chase-pulse experiments demonstrate that there is a significant lag between replication and replenishment of centromeric chromatin. Surprisingly, new CID is recruited to centromeres in metaphase, by a mechanism that does not require an intact mitotic spindle, but does require proteasome activity. Interestingly, new CAL1 is recruited to centromeres before CID in prophase. Furthermore, CAL1, but not CENP-C, is found in complex with pre-nucleosomal CID. Finally, CENP-C displays yet a different pattern of incorporation, during both interphase and mitosis. The unusual timing of CID recruitment and unique dynamics of CAL1 identify a distinct centromere assembly pathway in Drosophila and suggest that CAL1 is a key regulator of centromere propagation. Author Summary The centromere is essential for kinetochore formation, chromosome attachment to spindle microtubules, and equal segregation of the genome to daughter cells. Centromeres are epigenetically inherited through a unique type of chromatin which contains centromere-specific proteins. At each round of DNA replication, centromeric proteins become diluted and must be replenished to ensure faithful maintenance of the centromere locus through cell division. Whether divergent eukaryotes share a common strategy for centromere identity and propagation remains an unanswered question. Here, we examine how Drosophila centromere proteins re-distribute after replication, and we determine the cell-cycle dynamics of their replenishment. We show that three chromatin components required for centromere maintenance display distinct dynamics during the cell cycle; surprisingly, two components are assembled at centromeres during mitosis. These results suggest a new model for regulation of centromere assembly in Drosophila, which emphasizes a key role for the Dipteran-specific protein CAL1. |
| Databáze: | OpenAIRE |
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