Xenopus Cdc14α/β are localized to the nucleolus and centrosome and are required for embryonic cell division

Brett K Kaiser,Bryan E Gardner,Maxence V Nachury,Peter K Jackson

doi:10.1186/1471-2121-5-27

Brett K Kaiser, Bryan E Gardner + Show 2 more

Open Access

https://doi.org/10.1186/1471-2121-5-27

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Abstract

BackgroundThe dual specificity phosphatase Cdc14 has been shown to be a critical regulator of late mitotic events in several eukaryotes, including S. cerevisiae, S. pombe. C. elegans and H. sapiens. However, Cdc14 homologs have clearly evolved to regulate distinct cellular processes and to respond to regulatory signals important for these processes. The human paralogs hCdc14A and B are the only vertebrate Cdc14 homologues studied to date, but their functions are not well understood. Therefore, it is of great interest to examine the function Cdc14 homologs in other vertebrate species.ResultsWe identified two open reading frames from Xenopus laevis closely related to human Cdc14A, called XCdc14α and XCdc14β, although no obvious paralog of the hCdc14B was found. To begin a functional characterization of Xcdc14α and XCdc14β, we raised polyclonal antibodies against a conserved region. These antibodies stained both the nucleolus and centrosome in interphase Xenopus tissue culture cells, and the mitotic centrosomes. GFP-tagged version of XCdc14α localized to the nucleulus and GFP-XCdc14β localized to the centrosome, although not exclusively. XCdc14α was also both meiotically and mitotically phosphorylated. Injection of antibodies raised against a conserved region of XCdc14/β into Xenopus embryos at the two-cell stage blocked division of the injected blastomeres, suggesting that activities of XCdc14α/β are required for normal cell division.ConclusionThese results provide evidence that XCdc14α/β are required for normal cellular division and are regulated by at least two mechanisms, subcellular localization and possibly phosphorylation. Due to the high sequence conservation between Xcdc14α and hCdc14A, it seems likely that both mechanisms will contribute to regulation of Cdc14 homologs in vertebrates.

Highlights

The dual specificity phosphatase Cdc14 has been shown to be a critical regulator of late mitotic events in several eukaryotes, including S. cerevisiae, S. pombe
The mitotic exit network (MEN) is a GTPase-driven signaling network regulated by the small Ras-like molecule Tem1p that becomes activated upon entry of the yeast spindle pole body (SPB) into the bud [4]
Isolation of XCdc14 cDNA To study Xenopus Cdc14 (XCdc14), we identified and cloned two Xenopus Cdc14 open reading frames

Summary

Introduction

The dual specificity phosphatase Cdc has been shown to be a critical regulator of late mitotic events in several eukaryotes, including S. cerevisiae, S. pombe. Much of our understanding of how late mitotic events are regulated has come from studies in budding and fission yeast. In the budding yeast S. cerevisiae, a signaling pathway called the mitotic exit network (MEN) initiates mitotic exit only after correct positioning of the spindle in the mother-neck bud [1,2,3]. The MEN is a GTPase-driven signaling network regulated by the small Ras-like molecule Tem1p that becomes activated upon entry of the yeast spindle pole body (SPB) into the bud [4]. The downstream effector of the mitotic exit network is the Cdc14p dual-specificity phosphatase, which promotes Cdk inactivation by dephosphorylating specific substrates including the Cdk inhibitor Sic1p, the APC activator Cdh1p, and the transcription factor Swi5 [5,6,7]

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