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Yannick Arlot-Bonnemains

Publications and source records attributed to Yannick Arlot-Bonnemains.

8 recordsLinked to original sources
PubMed2006

Expression of Aurora kinases in human thyroid carcinoma cell lines and tissues.

The Aurora kinases are involved in the regulation of cell cycle progression, and alterations in their expression have been shown to associate with cell malignant transformation. In the present study, we demonstrated that human thyrocytes express all 3 Aurora kinases (A, B and C) at both protein and mRNA level and this expression is cell cycle-regulated. An increase in the protein level of the 3 kinases was found, with respect to normal human thyrocytes (HTU5), in the human cell lines derived from follicular (FTC-133), papillary (B-CPAP) and anaplastic (8305C) thyroid carcinomas, but not in cells derived from a follicular adenoma (HTU42). These observations were mirrored in RT-PCR experiments for Aurora-A and B. In contrast, Aurora-C mRNA levels were not significantly different among the different cell types analyzed, suggesting that posttranscriptional mechanism(s) modulate its expression. The expression at the protein level of all 3 Aurora kinases was significantly higher in 3 thyroid papillary carcinomas with respect to normal matched tissues obtained from the same patients. Similar modifications, at the mRNA level, could be observed in 7 papillary carcinoma tissues for Aurora-A and B, but not for Aurora-C. In conclusion, we demonstrated that normal human thyrocytes express all 3 members of the Aurora kinase family, and their expression is amplified in malignant thyroid cell lines and tissues. These results suggest that the Aurora kinases may play a relevant role in malignant thyroid cancers, and may represent a putative therapeutic target for thyroid neoplasms.

Adenocarcinoma, Follicular↗
PubMed2005

Phosphorylation of maskin by Aurora-A participates in the control of sequential protein synthesis during Xenopus laevis oocyte maturation.

At the end of oogenesis, Xenopus laevis stage VI oocytes are arrested at the G2/M transition (prophase) waiting for progesterone to release the block and begin maturation. Progesterone triggers a cascade of phosphorylation events such as a decrease of pK(a) and an increase of maturating-promoting factor activity. Progression through meiosis was controlled by the sequential synthesis of several proteins. For instance, the MAPK kinase kinase c-Mos is the very first protein to be produced, whereas cyclin B1 appears only after meiosis I. After the meiotic cycles, the oocyte arrests at metaphase of meiosis II with an elevated c-Mos kinase activity (cytostatic factor). By using a two-hybrid screen, we have identified maskin, a protein involved in the control of mRNA sequential translation, as a binding partner of Aurora-A, a protein kinase necessary for oocyte maturation. Here we showed that, in vitro, Aurora-A directly binds to maskin and that both proteins can be co-immunoprecipitated from oocyte extracts, suggesting that they do associate in vivo. We also demonstrated that Aurora-A phosphorylates maskin on a Ser residue conserved in transforming acidic coiled coil proteins from Drosophila to human. When the phosphorylation of this Ser was inhibited in vivo by microinjection of synthetic peptides that mimic the maskin-phosphorylated sequence, we observed a premature maturation. Under these conditions, proteins such as cyclin B1 and Cdc6, which are normally detected only in meiosis II, were massively produced in meiosis I before the occurrence of the nuclear envelope breakdown. This result strongly suggests that phosphorylation of maskin by Aurora-A prevents meiosis II proteins from being produced during meiosis I.

Amino Acid Sequence↗
PubMed2005

Retro hydrazino-azapeptoids as peptidomimetics of proteasome inhibitors.

Several groups of proteasome inhibitors are widely used to study the role of the ubiquin proteasome pathway in various cellular processes or as anticancer drugs. Peptidomimetics have been developed to circumvent problems inherent in peptides such as poor bioavailability and protease-mediated degradation, while retaining biological activity. In this study, we introduce new pseudopeptides, the retro hydrazino-azapeptoids, designed as proteasome inhibitor peptidomimetics. Their proteasome inhibitory activity and antiproliferative properties are reported here.

Animals↗
PubMed2003

Hydrazino-aza and N-azapeptoids with therapeutic potential as anticancer agents.

The ubiquitin-proteasome-mediated degradation pathway plays an important role in regulating protein turnover in eucaryotic cells and, consequently, regulates both cell proliferation and cell death. The proteasome influences many cellular regulatory signals and is thus a potential target for pharmacological agents. The study of proteasome function has led to the identification of several natural and synthetic compounds that can act as tumor cell growth inhibitors. In this study, we have developed a series of hydrazino-aza and N-azapeptoids, analogues of Ac-Leucyl-Leucyl-Norleucinal (ALLN) a non-specific peptidyl aldehyde inhibitor of the proteasome. These peptide analogues share a common backbone and bear different C- and N-terminal functions. Their antiproliferative activity on murine leukemia L1210 cells is reported here.

Animals↗
PubMed2003

Phosphorylation of histone and histone-like proteins by aurora kinases during mitosis.

Successful cell division requires that daughter cells inherit not only a complete set of chromosomes, but also only one centrosome, and similar amounts of organelles and cytoplasmic components. The different mitotic processes are driven by cell cycle-regulated protein kinases and phosphatases and their fidelity is closely monitored by a number of checkpoint mechanisms. Histone H3 is phosphorylated during mitosis, but the kinases involved were not known until recently. Recent work has revealed that Aurora kinases are required for mitotic phosphorylation of histone H3 and of its centromeric variant CENP-A. This finding has stimulated functional studies of the role(s) of Aurora kinases and H3 phosphorylation during mitosis, which are reviewed in this chapter.

Animals↗
PubMed2002

A Method for Analyzing the Ubiquitination and Degradation of Aurora-A.

The cell cycle machinery consists of regulatory proteins that control the progression through the cell cycle ensuring that DNA replication alternates with DNA segregation in mitosis to maintain cell integrity. Some of these key regulators have to be degraded at each cell cycle to prevent cellular dysfunction. Mitotic exit requires the inactivation of cyclin dependent kinase1 (cdk1) and it is the degradation of the cyclin subunit that inactivates the kinase. Cyclin degradation has been well characterized and it was shown that it is ubiquitin proteasome pathway that leads to the elimination of cyclins. By now, many other regulatory proteins were shown to be degraded by the same pathway, among them members of the aurora kinase family, degraded many other regulatory proteins. Aurora kinases are involved in mitotic spindle formation as well as in cytokinesis. The abundance and activity of the kinase is precisely regulated during the cell cycle. To understand how proteolysis regulates transitions through the cell cycle we describe two assays for ubiquitination and degradation of xenopus aurora kinase A using extracts from xenopus eggs or somatic cell lines.

Journal Article↗
PubMed2002

APC/Fizzy-Related targets Aurora-A kinase for proteolysis.

Aurora-A kinase is a mitotic spindle-pole-associated protein that has been implicated in duplication and separation of centrosomes and in spindle assembly. The proper timing and amplitude of Aurora-A expression seems to be important, as elevated levels of this protein have been associated with centrosome abnormalities and aneuploidy in mammalian cells. We show that Aurora-A increases at the G2-M transistion and disappears completely at G1 in XL2 cells. Using Xenopus oocyte extracts, we demonstrate that degradation of Aurora-A is mediated by the anaphase-promoting complex (APC) and is regulated by Fizzy-Related but not by Fizzy. Degradation of Aurora-A depends on a D-Box, but not on its KEN-Box motif, as mutation of its C-terminal D-Box sequence induces stabilization of the protein. Accordingly, addition into the extracts of a cyclin B-type D-Box-motif-containing peptide completely suppresses its degradation. Furthermore, APC/Fizzy-Related ubiquitylates the wild type but not a D-Box mutant form of Aurora-A in vitro. Consistent with these data, ectopic expression of Fizzy-Related in Xenopus oocytes induces complete degradation of endogenous Aurora-A. Aurora-A is thus the first protein, at least in our assay system, that undergoes a D-Box-dependent degradation mediated by APC/Fizzy-Related but not by APC/Fizzy.

Amino Acid Motifs↗