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DNA replication checkpoint control of Wee1 stability by vertebrate Hsl7.

Yamada A, Duffy B, Perry JA, Kornbluth S - J. Cell Biol. (2004)

Bottom Line: Although inhibiting Hsl7 delayed mitosis, Hsl7 overexpression overrode the replication checkpoint, accelerating Wee1 destruction.Replication checkpoint activation disrupted Hsl7-Wee1 interactions, but binding was restored by active polo-like kinase.These data establish Hsl7 as a component of the replication checkpoint and reveal that similar cell cycle control modules can be co-opted for use by distinct checkpoints in different organisms.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.

ABSTRACT
G2/M checkpoints prevent mitotic entry upon DNA damage or replication inhibition by targeting the Cdc2 regulators Cdc25 and Wee1. Although Wee1 protein stability is regulated by DNA-responsive checkpoints, the vertebrate pathways controlling Wee1 degradation have not been elucidated. In budding yeast, stability of the Wee1 homologue, Swe1, is controlled by a regulatory module consisting of the proteins Hsl1 and Hsl7 (histone synthetic lethal 1 and 7), which are targeted by the morphogenesis checkpoint to prevent Swe1 degradation when budding is inhibited. We report here the identification of Xenopus Hsl7 as a positive regulator of mitosis that is controlled, instead, by an entirely distinct checkpoint, the DNA replication checkpoint. Although inhibiting Hsl7 delayed mitosis, Hsl7 overexpression overrode the replication checkpoint, accelerating Wee1 destruction. Replication checkpoint activation disrupted Hsl7-Wee1 interactions, but binding was restored by active polo-like kinase. These data establish Hsl7 as a component of the replication checkpoint and reveal that similar cell cycle control modules can be co-opted for use by distinct checkpoints in different organisms.

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Amino acid sequence alignment of Xenopus, human and yeast Hsl7 proteins. The amino acid sequences of Hsl7 orthologs were aligned using the ClustalW alignment parameters in the program MacVector. Dark shading indicates identities and light shading indicates similarities.
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fig1: Amino acid sequence alignment of Xenopus, human and yeast Hsl7 proteins. The amino acid sequences of Hsl7 orthologs were aligned using the ClustalW alignment parameters in the program MacVector. Dark shading indicates identities and light shading indicates similarities.

Mentions: To identify potential Xenopus Hsl7 homologues, we searched the Washington University Xenopus EST database, and identified five Hsl7-related EST clones of various lengths. After DNA sequencing, we identified a full-length Xenopus Hsl7 cDNA (hereafter referred to as xHsl7) bearing 26% identity/44% similarity to yeast Hsl7 and 83% identity/92% similarity to human Hsl7 (known as JBP1 [Janus kinase binding protein 1]/PRMT5; Genbank/EMBL/DDBJ accession no. AY535008) (Fig. 1). We were further encouraged to pursue analysis of this clone as we found that recombinant S. cerevisiae Hsl7 protein readily bound Xenopus Wee1 in egg extracts (Fig. 2 A). This suggested that the Hsl7–Wee1 interaction might be conserved and that the Xenopus protein might also play a role in regulating Wee1 function and mitotic entry.


DNA replication checkpoint control of Wee1 stability by vertebrate Hsl7.

Yamada A, Duffy B, Perry JA, Kornbluth S - J. Cell Biol. (2004)

Amino acid sequence alignment of Xenopus, human and yeast Hsl7 proteins. The amino acid sequences of Hsl7 orthologs were aligned using the ClustalW alignment parameters in the program MacVector. Dark shading indicates identities and light shading indicates similarities.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172454&req=5

fig1: Amino acid sequence alignment of Xenopus, human and yeast Hsl7 proteins. The amino acid sequences of Hsl7 orthologs were aligned using the ClustalW alignment parameters in the program MacVector. Dark shading indicates identities and light shading indicates similarities.
Mentions: To identify potential Xenopus Hsl7 homologues, we searched the Washington University Xenopus EST database, and identified five Hsl7-related EST clones of various lengths. After DNA sequencing, we identified a full-length Xenopus Hsl7 cDNA (hereafter referred to as xHsl7) bearing 26% identity/44% similarity to yeast Hsl7 and 83% identity/92% similarity to human Hsl7 (known as JBP1 [Janus kinase binding protein 1]/PRMT5; Genbank/EMBL/DDBJ accession no. AY535008) (Fig. 1). We were further encouraged to pursue analysis of this clone as we found that recombinant S. cerevisiae Hsl7 protein readily bound Xenopus Wee1 in egg extracts (Fig. 2 A). This suggested that the Hsl7–Wee1 interaction might be conserved and that the Xenopus protein might also play a role in regulating Wee1 function and mitotic entry.

Bottom Line: Although inhibiting Hsl7 delayed mitosis, Hsl7 overexpression overrode the replication checkpoint, accelerating Wee1 destruction.Replication checkpoint activation disrupted Hsl7-Wee1 interactions, but binding was restored by active polo-like kinase.These data establish Hsl7 as a component of the replication checkpoint and reveal that similar cell cycle control modules can be co-opted for use by distinct checkpoints in different organisms.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.

ABSTRACT
G2/M checkpoints prevent mitotic entry upon DNA damage or replication inhibition by targeting the Cdc2 regulators Cdc25 and Wee1. Although Wee1 protein stability is regulated by DNA-responsive checkpoints, the vertebrate pathways controlling Wee1 degradation have not been elucidated. In budding yeast, stability of the Wee1 homologue, Swe1, is controlled by a regulatory module consisting of the proteins Hsl1 and Hsl7 (histone synthetic lethal 1 and 7), which are targeted by the morphogenesis checkpoint to prevent Swe1 degradation when budding is inhibited. We report here the identification of Xenopus Hsl7 as a positive regulator of mitosis that is controlled, instead, by an entirely distinct checkpoint, the DNA replication checkpoint. Although inhibiting Hsl7 delayed mitosis, Hsl7 overexpression overrode the replication checkpoint, accelerating Wee1 destruction. Replication checkpoint activation disrupted Hsl7-Wee1 interactions, but binding was restored by active polo-like kinase. These data establish Hsl7 as a component of the replication checkpoint and reveal that similar cell cycle control modules can be co-opted for use by distinct checkpoints in different organisms.

Show MeSH
Related in: MedlinePlus