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Dive into the research topics where Laurent Paquereau is active.

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Featured researches published by Laurent Paquereau.


Mechanisms of Development | 1996

Expression of a new G protein-coupled receptor X-msr is associated with an endothelial lineage in Xenopus laevis.

Eric Devic; Laurent Paquereau; Philippe Vernier; Bernard Knibiehler; Yves Audigier

In order to determine whether G protein-coupled receptors play a role in early embryogenesis, we looked for cDNA fragments amplified between primers located in consensus sequences of transmembrane segments. Using one such amplified fragment as a probe, we cloned a novel member of the G protein-coupled receptor superfamily in Xenopus. Alignment of the deduced protein sequence with that of other receptors discloses some homology with angiotensin receptors. A single transcript of 2.5 kb is detected at the late blastula stage and its expression increases during gastrulation. In situ hybridization reveals transcripts initially in the ventrolateral involuting marginal zone and later in the lateral plate mesoderm. At larval stages, the transcript is expressed in procardiac tube and forming blood vessels, where it is localized in the inner endothelial layer. Thus, this gene traces an endothelial lineage and represents a very early and unique marker in Xenopus of the specification of cardiac and vascular endothelia. We propose the name of X-msr for mesenchyme-associated serpentine receptor.


Gene | 1991

Primary structure of the rat gene encoding an inhibitor of the insulin receptor tyrosine kinase.

Laurence Falquerho; Gilles Patey; Laurent Paquereau; Valérie Rossi; Olivier Lahuna; Josiane Szpirer; Claude Szpirer; Göran Levan; Alphonse Le Cam

The gene (PP63) encoding the inhibitor (PP63) of the insulin receptor tyrosine kinase was isolated from a rat genomic library. The intron/exon organization was deduced from Southern-blot analysis and sequence data (i.e., the exons + the boundaries). The PP63 gene, which maps to chromosome 11, spans approx. 8 kb and contains seven exons separated by six introns of different sizes. All of the boundaries match the consensus GT/AG sequence for donor and acceptor splice sites. Primer extension and S1 mapping experiments were used to locate the transcription start point (tsp) 73 nt upstream from the translational initiator. Both in vitro transcription assays and transcription of a chimeric gene in intact hepatoma cells indicated that the sequence located immediately upstream from the tsp contained a promoter. Several putative cis-regulatory elements, including a TATA box and a C/EBP-binding site were found within the 250 bp preceding the tsp.


FEBS Letters | 1997

Early expression of a β1-adrenergic receptor and catecholamines in Xenopus oocytes and embryos

Eric Devic; Laurent Paquereau; R. Steinberg; Daniel Caput; Yves Audigier

From a Xenopus stage 11 cDNA library, we have cloned a gene, termed X‐β 1AR, whose sequence is highly homologous to that of the human β1‐adrenergic receptor. As shown by RT‐PCR assay, X‐β 1AR RNA is present in the mature oocyte, decreases after fertilization up to stage 6 and then gradually increases during gastrulation. Binding studies performed with radiolabeled ligands reveal that X‐β 1AR RNA is translated into the receptor protein. Furthermore, noradrenaline and adrenaline are also detected in oocytes and early embryos. The concomitant presence of β1‐adrenergic receptors and catecholamines suggest that this ligand‐receptor couple could play a role in the very early stages of embryonic development.


Mechanisms of Development | 1996

The mRNA encoding a β subunit of heterotrimeric GTP-binding proteins is localized to the animal pole of Xenopus laevis oocyte and embryos

Eric Devic; Laurent Paquereau; Karine Rizzoti; Armelle Monier; Bernard Knibiehler; Yves Audigier

In order to provide evidence for a potential role of heterotrimeric GTP-binding proteins in the transduction of developmental signals, we prepared cDNAs from Xenopus laevis embryos and looked for fragments amplified between primers located in conserved sequences of the different subtypes of beta subunit. Using the amplified fragment as a probe, we cloned a member of the beta subunit family. The deduced protein sequence of the amphibian cDNA is highly homologous to the beta 1 subtype and, accordingly, we have named the Xenopus gene XG beta 1. In situ hybridization and RNase protection assay revealed that XG beta 1 mRNA is confined to the animal hemisphere of the mature oocyte. This localization of XG beta 1 mRNA is established at stage V during oogenesis. Following fertilization, the maternal mRNAs cosegregate with animal cells during cleavage stages. At gastrulation, transcripts are expressed in the dorsal ectoderm layer that will give rise to the central nervous system. Thus, XG beta 1 mRNA belongs to the small family of localized maternal mRNAs; as a transducing protein, its restriction to a subset of embryonic cells could mediate the distinct responsiveness which contributes to the patterning of the embryo.


Mechanisms of Development | 1998

A constitutively activated mutant of Gαq down-regulates EP-cadherin expression and decreases adhesion between ectodermal cells at gastrulation

Karine Rizzoti; Laurent Paquereau; Alison Shaw; Bernard Knibiehler; Yves Audigier

We have examined the expression and function of the heterotrimeric GTP-binding protein Gq during early Xenopus embryogenesis. Abundant XGalphaq transcripts were detected in oocytes and early embryos by Northern blot analysis. In situ hybridization revealed that these transcripts are confined to the animal hemisphere of the mature oocyte and to the presumptive ectoderm of cleaving embryos. Microinjection at the two-cell stage of alphaq and Q209Lalphaq, a constitutively activated mutant, causes a disruption in ectodermal cell adhesion at late gastrulation. Dissociation/reaggregation experiments performed on animal cap explants clearly demonstrate that the Q209Lalphaq-induced phenotype occurs after reaggregation of the explants with a time-course similar to that observed in whole embryos. RT-PCR experiments performed on the explants from Q209Lalphaq-injected embryos revealed a selective decrease in the amount of EP-cadherin mRNA. Co-injection of EP-cadherin RNA, but also E-cadherin RNA, rescued the disaggregated phenotype. These data emphasize the functional link between Gq protein-coupled signalling pathways and cadherin molecules in the ectodermal layer during the morphogenetic movements of gastrulation.


Cellular Signalling | 1995

GTP-binding proteins and early embryogenesis in Xenopus

Laurent Paquereau; Yves Audigier

During early embryogenesis the specification of body axes and the determination of cell subtypes proceeds through cell interactions and movements which involve the decoding of various signals in a spatial and temporal manner. An increasingly abundant literature has revealed the participation of growth factors and their receptors in the induction and regionalization of the mesoderm. The question therefore arises as to whether other signal transducing systems are expressed and play a role in early embryogenesis. In this mini review we describe the main developmental events occurring during early embryogenesis in Xenopus and the signalling pathways that are potentially involved; we then summarize the major properties of heterotrimeric GTP-binding proteins; finally, we present results suggesting that heterotrimeric GTP-binding proteins are expressed during early embryogenesis and discuss their potential function.


FEBS Journal | 1992

Regulation of two rat serine-protease inhibitor gene promoters by somatotropin and glucocorticoids : study with intact hepatocytes and cell-free systems

Laurent Paquereau; Marie José Vilarem; Valérie Rossi; Jean Francois Rouayrenc; Alphonse Le Cam


Nucleic Acids Research | 1992

Analysis of proteins binding to the proximal promoter region of two rat serine protease inhibitor genes

Valérie Rossi; Jean Francois Rouayrenc; Laurent Paquereau; Marie Joseé Vilarem; Alphonse Le Cam


Nucleic Acids Research | 1992

Functional characterization of the promoter of pp63, a gene encoding a natural inhibitor of the insulin receptor tyrosine kinase

Laurence Falquerho; Laurent Paquereau; Marie José Vilarem; Simon Galas; Gilles Patey; Alphonse Le Cam


Archive | 1994

cis-Acting Elements Controlling Transcription from Rat Serine Protease Inhibitor 2.1 Gene Promoter

Alphonse Le Cam; Vbronique Pantescu; Laurent Paquereau; Catherine Legraverend; GBrard Fauconnier; Guillermina Asins

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Eric Devic

French Institute of Health and Medical Research

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Simon Galas

University of Montpellier

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Alphonse Le Cam

French Institute of Health and Medical Research

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Philippe Vernier

Centre national de la recherche scientifique

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Claude Szpirer

Université libre de Bruxelles

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Josiane Szpirer

Université libre de Bruxelles

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Göran Levan

University of Gothenburg

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