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Philippe Soriano

Publications and source records attributed to Philippe Soriano.

At least 19 recordsLinked to original sources
PubMed2007

High-efficiency FLP and PhiC31 site-specific recombination in mammalian cells.

DNA site-specific recombinases (SSRs) such as Cre, FLPe, and phiC31, are powerful tools for analyzing gene function in vertebrates. While the availability of multiple high-efficiency SSRs would facilitate a wide array of genomic engineering possibilities, efficient recombination in mammalian cells has only been observed with Cre recombinase. Here we report the de novo synthesis of mouse codon-optimized FLP (FLPo) and PhiC31 (PhiC31o) SSRs, which result in recombination efficiencies similar to Cre.

Animals↗
PubMed2006

Ephrin-B2 forward signaling regulates somite patterning and neural crest cell development.

Genetic studies in the mouse have implicated ephrin-B2 (encoded by the gene Efnb2) in blood vessel formation, cardiac development and remodeling of the lymphatic vasculature. Here we report that loss of ephrin-B2 leads to defects in populations of cranial and trunk neural crest cells (NCC) and to defective somite development. In addition, we show that Efnb1/Efnb2 double heterozygous embryos exhibit phenotypes in a number of NCC derivatives. Expression of one copy of a mutant version of Efnb2 that lacks tyrosine phosphorylation sites was sufficient to rescue the embryonic phenotypes associated with loss of Efnb2. Our results uncover an important role for ephrin-B2 in NCC and somites during embryogenesis and suggest that ephrin-B2 exerts many of its embryonic function via activation of forward signaling.

Animals↗
PubMed2006

PDGF signaling specificity is mediated through multiple immediate early genes.

Growth factor signaling leads to the induction or repression of immediate early genes, but how these genes act collectively as effectors of downstream processes remains unresolved. We have used gene trap-coupled microarray analysis to identify and mutate multiple platelet-derived growth factor (PDGF) intermediate early genes in mice. Mutations in these genes lead to a high frequency of phenotypes that affect the same cell types and processes as those controlled by the PDGF pathway. We conclude that these genes form a network that controls specific processes downstream of PDGF signaling.

Animals↗
PubMed2006

Context-specific requirements for Fgfr1 signaling through Frs2 and Frs3 during mouse development.

Fibroblast growth factor receptor 1 (Fgfr1) plays pleiotropic roles during embryonic development, but the mechanisms by which this receptor signals in vivo have not previously been elucidated. Biochemical studies have implicated Fgf receptor-specific substrates (Frs2, Frs3) as the principal mediators of Fgfr1 signal transduction to the MAPK and PI3K pathways. To determine the developmental requirements for Fgfr1-Frs signaling, we generated mice (Fgfr1(Delta)Frs/DeltaFrs) in which the Frs2/3-binding site on Fgfr1 is deleted. Fgfr1(Delta)Frs/DeltaFrs embryos die during late embryogenesis, and exhibit defects in neural tube closure and in the development of the tail bud and pharyngeal arches. However, the mutant receptor is able to drive Fgfr1 functions during gastrulation and somitogenesis, and drives normal MAPK responses to Fgf. These findings indicate that Fgfr1 uses distinct signal transduction mechanisms in different developmental contexts, and that some essential functions of this receptor are mediated by Frs-independent signaling.

Adaptor Proteins, Signal Transducing↗
PubMed2006

The International Gene Trap Consortium Website: a portal to all publicly available gene trap cell lines in mouse.

Gene trapping is a method of generating murine embryonic stem (ES) cell lines containing insertional mutations in known and novel genes. A number of international groups have used this approach to create sizeable public cell line repositories available to the scientific community for the generation of mutant mouse strains. The major gene trapping groups worldwide have recently joined together to centralize access to all publicly available gene trap lines by developing a user-oriented Website for the International Gene Trap Consortium (IGTC). This collaboration provides an impressive public informatics resource comprising approximately 45 000 well-characterized ES cell lines which currently represent approximately 40% of known mouse genes, all freely available for the creation of knockout mice on a non-collaborative basis. To standardize annotation and provide high confidence data for gene trap lines, a rigorous identification and annotation pipeline has been developed combining genomic localization and transcript alignment of gene trap sequence tags to identify trapped loci. This information is stored in a new bioinformatics database accessible through the IGTC Website interface. The IGTC Website (www.genetrap.org) allows users to browse and search the database for trapped genes, BLAST sequences against gene trap sequence tags, and view trapped genes within biological pathways. In addition, IGTC data have been integrated into major genome browsers and bioinformatics sites to provide users with outside portals for viewing this data. The development of the IGTC Website marks a major advance by providing the research community with the data and tools necessary to effectively use public gene trap resources for the large-scale characterization of mammalian gene function.

Animals↗
PubMed2006

Engineering mutations: deconstructing the mouse gene by gene.

Over the past years new vectors and methodologies have been developed to carry out large-scale genome-wide insertional mutagenesis screens in the mouse. Gene trapping, the most commonly used technique, is based on the insertion of a retroviral- or plasmid-based vector into a gene, resulting in a loss-of-function mutation, while simultaneously reporting its expression pattern and providing a molecular tag to facilitate cloning. The discovery of vertebrate DNA transposons in the mouse and recent improvements has also led to their increased use in insertional mutagenesis screens. Several public resources have been set-up recently by the academic community to distribute information and materials generated from these large-scale screens. These new resources should accelerate the study and understanding of biological and developmental processes.

Animals↗
PubMed2006

Inhibition of gap junction communication at ectopic Eph/ephrin boundaries underlies craniofrontonasal syndrome.

Mutations in X-linked ephrin-B1 in humans cause craniofrontonasal syndrome (CFNS), a disease that affects female patients more severely than males. Sorting of ephrin-B1-positive and -negative cells following X-inactivation has been observed in ephrin-B1(+/-) mice; however, the mechanisms by which mosaic ephrin-B1 expression leads to cell sorting and phenotypic defects remain unknown. Here we show that ephrin-B1(+/-) mice exhibit calvarial defects, a phenotype autonomous to neural crest cells that correlates with cell sorting. We have traced the causes of calvarial defects to impaired differentiation of osteogenic precursors. We show that gap junction communication (GJC) is inhibited at ectopic ephrin boundaries and that ephrin-B1 interacts with connexin43 and regulates its distribution. Moreover, we provide genetic evidence that GJC is implicated in the calvarial defects observed in ephrin-B1(+/-) embryos. Our results uncover a novel role for Eph/ephrins in regulating GJC in vivo and suggest that the pleiotropic defects seen in CFNS patients are due to improper regulation of GJC in affected tissues.

Animals↗
PubMed2005

PDGFR-alpha signaling is critical for tooth cusp and palate morphogenesis.

Platelet-derived growth factor receptor alpha (PDGFR-alpha) and PDGF ligands are key regulators for embryonic development. Although Pdgfralpha is spatially expressed in the cranial neural crest (CNC)-derived odontogenic mesenchyme, mice deficient for Pdgfralpha are embryonic lethal, making it impossible to investigate the functional significance of PDGF signaling in regulating the fate of CNC cells during tooth morphogenesis. Taking advantage of the kidney capsule assay, we investigated the biological function of PDGF signaling in regulating tooth morphogenesis. Pdgfralpha and Pdgfa are specifically and consistently expressed in the CNC-derived odontogenic mesenchyme and the dental epithelium, respectively, throughout all stages of tooth development, suggesting a paracrine function of PDGF signaling in regulating tooth morphogenesis. Highly concentrated expression patterns of Pdgfralpha and Pdgfa are associated with the developing dental cusp, suggesting possible functional importance of PDGF signaling in regulating cusp formation. Loss of the Pdgfralpha gene does not affect proper odontoblasts proliferation and differentiation in the CNC-derived odontogenic mesenchyme but perturbs the formation of extracellular matrix and the organization of odontoblast cells at the forming cusp area, resulting in dental cusp growth defect. Pdgfralpha-/- mice have complete cleft palate. We show that the cleft palate in Pdgfralpha mutant mice results from an extracellular matrix defect within the CNC-derived palatal mesenchyme. The midline epithelium of the mutant palatal shelf remains functionally competent to mediate palatal fusion once the palatal shelves are placed in close contact in vitro. Collectively, our data suggests that PDGFRalpha and PDGFA are critical regulators for the continued epithelial-mesenchymal interaction during tooth and palate morphogenesis. Disruption of PDGFRalpha signaling disturbs the growth of dental cusp and interferes with the critical extension of palatal shelf during craniofacial development.

Animals↗
PubMed2005

Ephrin signaling in vivo: look both ways.

Eph receptors and ephrins have captured the interest of the developmental biology community in recent years for their pleiotropic functions during embryogenesis. Loss-of-function studies using various animal models have demonstrated the involvement of Ephs and ephrins in many aspects of embryogenesis including segmentation, neural crest cells migration, angiogenesis, and axon guidance. An essential property of this signaling pathway is the ability of both Ephs and ephrins to behave as receptors or ligands and their consequent cell autonomous and nonautonomous mode of action. While many reports did not discriminate between Eph autonomous signaling (forward) and ephrin autonomous signaling (reverse), recent genetic and in vivo studies have shown that both forward and reverse signaling play important roles during embryogenesis.

Animals↗
PubMed2004

A specific requirement for PDGF-C in palate formation and PDGFR-alpha signaling.

PDGF-C is a member of the platelet-derived growth factor (PDGF) family, which signals through PDGF receptor (PDGFR) alphaalpha and alphabeta dimers. Here we show that Pdgfc(-/-) mice die in the perinatal period owing to feeding and respiratory difficulties associated with a complete cleft of the secondary palate. This phenotype was less severe than that of Pdgfra(-/-) embryos. Pdgfc(-/-) Pdgfa(-/-) embryos developed a cleft face, subepidermal blistering, deficiency of renal cortex mesenchyme, spina bifida and skeletal and vascular defects. Complete loss of function of both ligands, therefore, phenocopied the loss of PDGFR-alpha function, suggesting that both PDGF-A and PDGF-C signal through PDGFR-alpha to regulate the development of craniofacial structures, the neural tube and mesodermal organs. Our results also show that PDGF-C signaling is a new pathway in palatogenesis, different from, and independent of, those previously implicated.

Abnormalities, Multiple↗
PubMed2004

In vivo convergence of BMP and MAPK signaling pathways: impact of differential Smad1 phosphorylation on development and homeostasis.

Integration of diverse signaling pathways is essential in development and homeostasis for cells to interpret context-dependent cues. BMP and MAPK signaling converge on Smads, resulting in differential phosphorylation. To understand the physiological significance of this observation, we have generated Smad1 mutant mice carrying mutations that prevent phosphorylation of either the C-terminal motif required for BMP downstream transcriptional activation (Smad1(C) mutation) or of the MAPK motifs in the linker region (Smad1(L) mutation). Smad1(C/C) mutants recapitulate many Smad1(-/-) phenotypes, including defective allantois formation and the lack of primordial germ cells (PGC), but also show phenotypes that are both more severe (head and branchial arches) and less severe (allantois growth) than the null. Smad1(L/L) mutants survive embryogenesis but exhibit defects in gastric epithelial homeostasis correlated with changes in cell contacts, actin cytoskeleton remodeling, and nuclear beta-catenin accumulation. In addition, formation of PGCs is impaired in Smad1(L/L) mutants, but restored by allelic complementation in Smad1(C/L) compound mutants. These results underscore the need to tightly balance BMP and MAPK signaling pathways through Smad1.

Animals↗
PubMed2004

Ephrin-B1 forward and reverse signaling are required during mouse development.

Eph receptors and ephrin ligands are key players in many developmental processes including embryo patterning, angiogenesis, and axon guidance. Eph/ephrin interactions lead to the generation of a bidirectional signal, in which both the Eph receptors and the ephrins activate downstream signaling cascades simultaneously. To understand the role of ephrin-B1 and the importance of ephrin-B1-induced reverse signaling during embryonic development, we have generated mouse lines carrying mutations in the efnb1 gene. Complete ablation of ephrin-B1 resulted in perinatal lethality associated with a range of phenotypes, including defects in neural crest cell (NCC)-derived tissues, incomplete body wall closure, and abnormal skeletal patterning. Conditional deletion of ephrin-B1 demonstrated that ephrin-B1 acts autonomously in NCCs, and controls their migration. Last, a mutation in the PDZ binding domain indicated that ephrin-B1-induced reverse signaling is required in NCCs. Our results demonstrate that ephrin-B1 acts both as a ligand and as a receptor in a tissue-specific manner during embryogenesis.

Animals↗
PubMed2004

Identification and validation of PDGF transcriptional targets by microarray-coupled gene-trap mutagenesis.

We developed a versatile, high-throughput genetic screening strategy by coupling gene mutagenesis and expression profiling technologies. Using a retroviral gene-trap vector optimized for efficient mutagenesis and cloning, we randomly disrupted genes in mouse embryonic stem (ES) cells and amplified them to construct a cDNA microarray. With this gene-trap array, we show that transcriptional target genes of platelet-derived growth factor (PDGF) can be efficiently and reliably identified in physiologically relevant cells and are immediately accessible to genetic studies to determine their in vivo roles and relative contributions to PDGF-regulated developmental processes. The same platform can be used to search for genes of specific biological relevance in a broad array of experimental settings, providing a fast track from gene identification to functional validation.

Animals↗
PubMed2004

The knockout mouse project.

Mouse knockout technology provides a powerful means of elucidating gene function in vivo, and a publicly available genome-wide collection of mouse knockouts would be significantly enabling for biomedical discovery. To date, published knockouts exist for only about 10% of mouse genes. Furthermore, many of these are limited in utility because they have not been made or phenotyped in standardized ways, and many are not freely available to researchers. It is time to harness new technologies and efficiencies of production to mount a high-throughput international effort to produce and phenotype knockouts for all mouse genes, and place these resources into the public domain.

Alleles↗
PubMed2003

Additive effects of PDGF receptor beta signaling pathways in vascular smooth muscle cell development.

The platelet-derived growth factor beta receptor (PDGFRbeta) is known to activate many molecules involved in signal transduction and has been a paradigm for receptor tyrosine kinase signaling for many years. We have sought to determine the role of individual signaling components downstream of this receptor in vivo by analyzing an allelic series of tyrosine-phenylalanine mutations that prevent binding of specific signal transduction components. Here we show that the incidence of vascular smooth muscle cells/pericytes (v/p), a PDGFRbeta-dependent cell type, can be correlated to the amount of receptor expressed and the number of activated signal transduction pathways. A decrease in either receptor expression levels or disruption of multiple downstream signaling pathways lead to a significant reduction in v/p. Conversely, loss of RasGAP binding leads to an increase in this same cell population, implicating a potential role for this effector in attenuating the PDGFRbeta signal. The combined in vivo and biochemical data suggest that the summation of pathways associated with the PDGFRbeta signal transduction determines the expansion of developing v/p cells.

Alleles↗
PubMed2003

Cryptic boundaries in roof plate and choroid plexus identified by intersectional gene activation.

The hindbrain roof plate and choroid plexus are essential organizing centers for inducing dorsal neuron fates and sustaining neuron function. To map the formation of these structures, we developed a broadly applicable, high resolution, recombinase-based method for mapping the fate of cells originating from coordinates defined by intersecting combinations of expressed genes. Using this method, we show that distinct regions of hindbrain roof plate originate from discrete subdomains of rhombencephalic neuroectoderm expressing Wnt1; that choroid plexus, a secretory epithelium important for patterning later-formed hindbrain structures and maintaining neuron function, derives from the same embryonic primordium as the hindbrain roof plate; and that, unlike the floor plate, these dorsal organizing centers develop in a patterned, segmental manner, built from lineage-restricted compartments. Our data suggest that the roof plate and choroid plexus may be formed of functional units that are capable of differentially organizing the generation of distinct neuronal cell types at different axial levels.

Alkaline Phosphatase↗
PubMed2003

Evolutionary divergence of platelet-derived growth factor alpha receptor signaling mechanisms.

Receptor tyrosine kinases (RTKs) direct diverse cellular and developmental responses by stimulating a relatively small number of overlapping signaling pathways. Specificity may be determined by RTK expression patterns or by differential activation of individual signaling pathways. To address this issue we generated knock-in mice in which the extracellular domain of the mouse platelet-derived growth factor alpha receptor (PDGFalphaR) is fused to the cytosolic domain of Drosophila Torso (alpha(Tor)) or the mouse fibroblast growth factor receptor 1 (alpha(FR)). alpha(Tor) homozygous embryos exhibit significant rescue of neural crest and angiogenesis defects normally found in PDGFalphaR-null embryos yet fail to rescue skeletal or extraembryonic defects. This phenotype was associated with the ability of alpha(Tor) to stimulate the mitogen-activated protein (MAP) kinase pathway to near wild-type levels but failure to completely activate other pathways, such as phosphatidylinositol (PI) 3-kinase. The alpha(FR) chimeric receptor fails to rescue any aspect of the PDGFalphaR-null phenotype. Instead, alpha(FR) expression leads to a gain-of-function phenotype highlighted by ectopic bone development. The alpha(FR) phenotype was associated with a failure to limit MAP kinase signaling and to engage significant PI3-kinase response. These results suggest that precise regulation of divergent downstream signaling pathways is critical for specification of RTK function.

Animals↗