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C Marcelle

Publications and source records attributed to C Marcelle.

At least 19 recordsLinked to original sources
PubMed1999

In vivo regulation of somite differentiation and proliferation by Sonic Hedgehog.

In vertebrates, somite differentiation is mediated in part by Sonic Hedgehog (Shh), secreted by the notochord and the floor plate. However, Shh-null mice display close to normal expression of molecular markers for dermomytome, myotome, and sclerotome, indicating that Shh might not be required for their initial induction. In this paper, we have addressed the capacity of Shh to regulate in vivo the expression of the somite differentiation markers Pax-1, MyoD, and Pax-3 after separation of paraxial mesoderm from axial structures. We show that Pax-1, which is lost under these experimental conditions, is rescued by Shh. In contrast, Shh maintains, but cannot induce MyoD expression, while Pax-3 expression is independent of the presence of axial structures or Shh. Finally, we demonstrate that Shh is a potent mitogen for somitic cells, supporting the idea that it may serve to expand subpopulations of cells within the somite.

Animals↗
PubMed1999

Competence, specification and induction of Pax-3 in the trigeminal placode.

Placodes are discrete regions of thickened ectoderm that contribute extensively to the peripheral nervous system in the vertebrate head. The paired-domain transcription factor Pax-3 is an early molecular marker for the avian ophthalmic trigeminal (opV) placode, which forms sensory neurons in the ophthalmic lobe of the trigeminal ganglion. Here, we use collagen gel cultures and heterotopic quail-chick grafts to examine the competence, specification and induction of Pax-3 in the opV placode. At the 3-somite stage, the whole head ectoderm rostral to the first somite is competent to express Pax-3 when grafted to the opV placode region, though competence is rapidly lost thereafter in otic-level ectoderm. Pax-3 specification in presumptive opV placode ectoderm occurs by the 8-somite stage, concomitant with robust Pax-3 expression. From the 8-somite stage onwards, significant numbers of cells are committed to express Pax-3. The entire length of the neural tube has the ability to induce Pax-3 expression in competent head ectoderm and the inductive interaction is direct. We propose a detailed model for Pax-3 induction in the opV placode.

Animals↗
PubMed1997

Coordinate actions of BMPs, Wnts, Shh and noggin mediate patterning of the dorsal somite.

Shortly after their formation, somites of vertebrate embryos differentiate along the dorsoventral axis into sclerotome, myotome and dermomyotome. The dermomyotome is then patterned along its mediolateral axis into medial, central and lateral compartments, which contain progenitors of epaxial muscle, dermis and hypaxial muscle, respectively. Here, we used Wnt-11 as a molecular marker for the medial compartment of dermomyotome (the 'medial lip') to demonstrate that BMP in the dorsal neural tube indirectly induces formation of the medial lip by up-regulating Wnt-1 and Wnt-3a (but not Wnt-4) expression in the neural tube. Noggin in the dorsal somite may inhibit the direct action of BMP on this tissue. Wnt-11 induction is antagonized by Sonic Hedgehog, secreted by the notochord and the floor plate. Together, our results show that the coordinated actions of the dorsal neural tube (via BMP and Wnts), the ventral neural tube/notochord (via Shh) and the somite itself (via noggin) mediates patterning of the dorsal compartment of the somite.

Animals↗
PubMed1997

Neural tube-ectoderm interactions are required for trigeminal placode formation.

Cranial sensory ganglia in vertebrates develop from the ectodermal placodes, the neural crest, or both. Although much is known about the neural crest contribution to cranial ganglia, relatively little is known about how placode cells form, invaginate and migrate to their targets. Here, we identify Pax-3 as a molecular marker for placode cells that contribute to the ophthalmic branch of the trigeminal ganglion and use it, in conjunction with DiI labeling of the surface ectoderm, to analyze some of the mechanisms underlying placode development. Pax-3 expression in the ophthalmic placode is observed as early as the 4-somite stage in a narrow band of ectoderm contiguous to the midbrain neural folds. Its expression broadens to a patch of ectoderm adjacent to the midbrain and the rostral hindbrain at the 8- to 10-somite stage. Invagination of the first Pax-3-positive cells begins at the 13-somite stage. Placodal invagination continues through the 35-somite stage, by which time condensation of the trigeminal ganglion has begun. To challenge the normal tissue interactions leading to placode formation, we ablated the cranial neural crest cells or implanted barriers between the neural tube and the ectoderm. Our results demonstrate that, although the presence of neural crest cells is not mandatory for Pax-3 expression in the forming placode, a diffusible signal from the neuroectoderm is required for induction and/or maintenance of the ophthalmic placode.

Animals↗
PubMed1996

Molecular cloning of Quek 1 and 2, two quail vascular endothelial growth factor (VEGF) receptor-like molecules.

We have previously reported the cloning of two partial cDNAs corresponding to two quail (Coturnix coturnix japonica) receptor tyrosine kinases (RTKs), named Quek 1 and Quek 2, and their expression in endothelial cells of the early avian embryo. We here report the cloning of the full-size cDNAs for both molecules. Sequence comparison shows that Quek 1 and 2 share an overall amino acid (aa) identity of 49%. They both comprise seven extracellular immunoglobulin-like (Ig-like) domains, a single transmembrane domain, and an intracellular kinase domain split into two by a 70 aa insertion. These structural characteristics are shared by the members of the recently discovered VEGF receptor (VEGFR) family. We have compared the sequences of Quek 1 and 2 to the other VEGFRs. At the aa level, Quek 1 is most closely related to KDR/flk-1 (VEGFR 2) (aa identity of 69% and 71%, respectively). Quek 2 shows a similar degree of aa identity to fit-4 (VEGFR 3). Quek 1 and 2 display a lower homology to fit-1 (VEGFR 1) (about 45% aa identity). These data suggest that Quek 1 and 2 are the avian homologues of VEGFRs 2 and 3, respectively.

Amino Acid Sequence↗
PubMed1995

The in vivo expression of the FGF receptor FREK mRNA in avian myoblasts suggests a role in muscle growth and differentiation.

Muscle growth during embryogenesis is the result of a balance between the proliferation of myoblasts and their differentiation into mature, contractile fibers. Fibroblast growth factors (FGFs) are potent stimulators of myoblast proliferation and inhibitors of myoblast differentiation in vitro. However, it is not clear at present if FGFs and their receptors regulate this process in vivo, partially because no FGF receptor was known to be expressed by myoblasts during embryogenesis. In this study, we have used quail/chick grafting and BrdU labeling techniques to demonstrate that a recently cloned avian FGF receptor, FREK, is expressed by replicating skeletal muscle myoblasts, while differentiated muscle cells no longer express this receptor. In the limb, muscle progenitors originating from the somite start expressing FREK at 3 days of development (E3). FREK expression in the limb myoblasts follows that of Pax-3 and Pax-7, but precedes that of MyoD. Since MyoD expression signals the onset of terminal differentiation, this demonstrates that FREK is expressed in muscle progenitors prior to overt muscle differentiation. A more complex situation is observed in the trunk region, where a first wave of MyoD-positive myocytes, which are postmitotic and never express FREK, appear in the early myotomal compartment of the somite. Slightly later, at E2.5, FREK-positive myoblasts migrate into the myotome as a second wave of muscle progenitors, 15 hr after the first MyoD-positive cells. FREK's expression by myoblasts arising at all stages of myogenesis indicates that this growth factor receptor represents one of the earliest molecular markers for this cell population. FREK's prominent expression during muscle differentiation sets it apart from other FGF receptors and suggests that this molecule plays an important role during muscle growth and differentiation.

Animals↗
PubMed1995

The receptor tyrosine kinase QEK5 mRNA is expressed in a gradient within the neural retina and the tectum.

In the retinotectal system, positional information has long been postulated to take the form of molecular gradients within both the retina and the tectum. Recent reports have implicated Mek4, a member of the Eph (also named class V) family of tyrosine kinase receptors (RTKs), and two ligands, RAGS and ELF-1, in this process. Here, we report the cloning and distribution pattern of QEK5, another member of the Eph family of RTKs, isolated from a quail cDNA library. During retinal differentiation, QEK5 transcripts accumulate in a ventral to dorsal gradient within the retinal neuroepithelium, where its expression becomes restricted to the ganglion and bipolar cell layers. Within the tectum, QEK5 transcripts are detectable in a posterior to anterior gradient in the ventricular layer and newly formed superficial layers. The pattern of QEK5 expression in the retina and tectum is distinct from that of Mek4, suggesting that complex patterns of Eph RTKs and their ligands may play a role in cell-cell interactions involved in retinotectal projections and differentiation of the central nervous system.

Amino Acid Sequence↗
PubMed1994

A new avian fibroblast growth factor receptor in myogenic and chondrogenic cell differentiation.

We studied the expression of FREK (fibroblast growth factor receptor-like embryonic kinase), a new receptor recently cloned from quail embryo, during the differentiation of skeletal muscle satellite cells and epiphyseal growth-plate chondrocytes. Although FREK mRNA was expressed in both cell types, satellite cells expressed higher levels of this mRNA than chondrocytes. FREK gene expression was found to be modulated by b-FGF in a biphasic manner: low concentrations increased expression, whereas high concentrations attenuated it. In both cell cultures, the levels of FREK mRNA declined during terminal differentiation. Moreover, retinoic acid (RA), which induces skeletal muscle satellite cells to differentiate, also caused a reduction in FREK gene expression in these cells. Induction of chondrocyte differentiation with ascorbic acid was monitored by a decrease in collagen type II gene expression and an increase in alkaline phosphatase activity. Satellite cell differentiation was marked by morphological changes as well as by increased sarcomeric myogenin content and creatine kinase activity and changes in the expression of the regulatory muscle-specific genes, MyoD and myogenin. DNA synthesis in both cell types was stimulated by b-FGF. However, in satellite cells, the response was bell-shaped, peaking at 1 ng/ml b-FGF, whereas in chondrocytes, higher levels of b-FGF were needed. b-FGF-dependent DNA synthesis in satellite cells was decreased by RA at concentrations over 10(-7) M. The observed correlation between the level of FREK gene expression and various stages of differentiation, its modulation by b-FGF and RA, as well as the correlation between FREK gene expression and the physiological response to b-FGF, suggest that this specific FGF receptor plays an important role in muscle and cartilage cell differentiation.

Animals↗
PubMed1994

Distinct developmental expression of a new avian fibroblast growth factor receptor.

We have cloned a new member of the fibroblast growth factor receptor family from avian embryonic RNA. The FREK (for fibroblast growth factor receptor-like embryonic kinase) primary transcript can be alternatively spliced in a tissue- and stage-specific manner to give rise to molecules containing either two or three Ig-like domains. During elongating primitive streak stages, FREK is expressed in the rostral and lateral epiblast and in the Hensen's node. From 2.5 days of development (E 2.5) on, it is expressed in various ectoderm- and mesoderm-derived structures. Most striking is FREK expression in the skeletal muscle lineage. It is highly expressed in the early myotome and, at later stages, in all skeletal muscles of the embryo. From E9 to hatching, FREK expression in the muscles decreases dramatically but is maintained in satellite cells of adult muscles. FREK transcript is elevated upon addition of basic fibroblast growth factor to serum-starved satellite cells. From this study, we conclude: (1) that the structure and pattern of expression of FREK set it apart from other cloned fibroblast growth factor receptors (FGFR) and suggest that FREK is a new member of that family; (2) that FREK may play multiple roles in early avian development, including a specialized role in the early differentiation of skeletal muscle.

Amino Acid Sequence↗
PubMed1993

Two molecules related to the VEGF receptor are expressed in early endothelial cells during avian embryonic development.

We present the partial cloning and the expression patterns of two putative growth factor receptor molecules named Quek1 and Quek2 (for quail endothelial kinase) in chick and quail embryos from gastrulation to embryonic day 9 (E9). Quek1 and Quek2 show high homology to three interrelated murine and human genes, flk-1, KDR and flt. Flt was recently shown to be the receptor for the endothelial cell mitogen vascular endothelial growth factor (VEGF). In situ hybridization of Quek1 and Quek2 to sections of avian embryos showed that they are both expressed essentially by endothelial cells, that we identified with a monoclonal antibody (Mab) QH1 specific for endothelial and white blood cells of the quail. Quek1 is expressed in the mesoderm from the onset of gastrulation, whereas Quek2 message is first detected on QH1-expressing endothelial cells. The expression pattern of Quek1 suggests that it could identify the putative precursor of both endothelial and hematopoietic lineages, the hemangioblast. Quek1 and Quek2 are not expressed in all endothelial cells throughout life. At E9, after the initial phase of vasculogenesis, these genes are switched off in various compartments of the vascular network.

Animals↗
PubMed1992

Molecular cloning of a family of protein kinase genes expressed in the avian embryo.

We have used the polymerase chain reaction (PCR) technique to clone kinase-related sequences from avian blastula, neural crest and neural tube mRNA. Twenty-three distinct protein kinase (PK) sequences were amplified, of which eight are identical to previously described PK genes. The cloned molecules fall into three classes: growth factor receptor tyrosine kinases (RTKs), cytosolic tyrosine kinases and serine/threonine kinases. Among the cloned RTKs were the insulin-like growth factor type I receptor, platelet-derived growth factor receptor alpha, the CEK1 fibroblast growth factor (FGF) receptor as well as the avian homolog of a recently cloned PCR fragment related to the eph/elk/eck family, tyro-5. Furthermore, we cloned a novel FGF receptor-like molecule as well as two novel putative RTKs related to the vascular endothelial growth factor (VEGF) receptor. The pattern of expression of the PCR clones was examined by Northern blot analysis of adult tissues: each molecule recognized one or more transcripts of various sizes, suggesting that PK genes may play regulatory roles both in early development and in adult regulation of tissue function. Together with recent studies, this survey confirms the hypothesis that PKs may play important roles in early vertebrate development.

Amino Acid Sequence↗
PubMed1989

Analysis of BCR-ABL mRNA in chronic myelogenous leukemia patients and identification of a new BCR-related sequence in human DNA.

The Philadelphia chromosome is present in more than 95% of chronic myelogenous leukemia patients and in up to 25% of patients with acute lymphocytic leukemia. The major consequence of the aberration is the fusion of the ABL and BCR genes. The position of the breakpoint on chromosome 22 determines which species of the potential three fused mRNAs and proteins will be synthesized. We have used the polymerase chain reaction (PCR) to detect these mRNAs in 53 patients and cell lines and found that around 20% contain simultaneously two BCR-ABL mRNAs, presumably due to a process of alternative splicing. The results also indicate that most patients in lymphocytic blast crisis of CML contain the mRNA in which bcr exon 2 is linked to ABL exon II. Finally, we identified, cloned, and characterized a BCR-related sequence that originated from mRNA.

Base Sequence↗
PubMed1989

Identification of a 130 Kda bcr related gene product.

Human chronic myelogenous leukemia is characterized by a reciprocal translocation between chromosomes 9 and 22. This results in the transfer of the c-abl protooncogene from chromosome 9 into the bcr gene on chromosome 22. The purpose of this study was to characterize the bcr and related gene products. Antibodies were raised against a fused trpE-bcr protein induced in a bacterial expression vector. Immunoprecipitation with the monoclonal and polyclonal antibodies of metabolically [35S]methionine labeled leukemic cell lines shows a 210, 160 and 130 Kda protein in Philadelphia positive cells containing the bcr-abl fused transcript. Only the 160 and 130 Kda were present in the Philadelphia negative cells. In vitro kinase assay shows that the 130 Kda protein is a phosphoprotein mainly phosphorylated on serine. Partial proteolysis indicates that the p210 and p130 share common domains. In subcellular fractionation experiments, the p130 is colocalized with the p210 bcr-abl in the cytoplasmic fraction. Together with the mapping of 4 distinct bcr related loci our data suggest that the 130 Kda phosphoprotein belongs to a wider family of bcr related gene products.

Amino Acids↗
PubMed1989

Nucleotide sequence analysis of human abl and bcr-abl cDNAs.

The complete nucleotide sequence of human abl RNA containing exon Ia was determined. It spans 5598 nucleotides and codes for a protein of 1130 amino acids. The 3' untranslated region contains two short open reading frames and multiple ATTT(A) motifs characteristic of short lived mRNAs. Computer analysis of the abl protein predicts four domains distinct with regard to surface probability and chain flexibility. Nucleotide analysis of the abl segment within a bcr-abl cDNA cloned from the K562 cell line indicated no further alterations within the coding region. A bcr-abl construct containing this segment transformed, together with c-myc, RAT-1 cells and produced a highly active tyrosine kinase.

Amino Acid Sequence↗
PubMed1989

Long-term proliferation of human leukemia cells induced by mouse stroma.

Acute lymphocytic leukemias (ALL) of infants and children were found to preferentially survive in coculture with a cloned cell line of endothelial adipose cells (14F1.1) from mouse bone marrow. One of these ALLs expressed a phenotype compatible with an early stage of differentiation (HLA-DR+, CD19+, and CD34+) and exhibited extensive growth in the presence of the mouse stromal cells during a period greater than 25 weeks following seeding. These ALL cells were strictly dependent upon the mouse stromal clone 14F1.1 and failed to proliferate in the absence of the endothelial adipocytes or with a variety of "feeder cells." Throughout the culture period the cells died if removed from the stroma. No similarly proliferative cell population with strict dependence upon stromal cells was found among a variety of other leukemias including hairy cell, acute myeloid, and chronic lymphocytic leukemia. The 14F1.1 clone has been previously found to promote the renewal of mouse and human stem cells. It is therefore possible that leukemias with a stem cell-like phenotype depend upon stromal cell factors similar to those affecting the growth of normal stem cells. These factors appear to operate across genetic barriers.

Antibodies, Monoclonal↗
PubMed1988

bcr genes and transcripts.

Human chronic myelogenous leukemia (CML) is a clonal hematologic disorder. CML is characterized by the t(9:22) chromosome translocation which results in translocation of the oncogene abl from chromosome 9 into the breakpoint cluster region (bcr) gene on chromosome 22. We cloned and characterized the cDNA of the normal bcr gene. The bcr gene codes for a protein of 1271 amino acids. The open reading frame is preceded by a region high in GC. At the 5' of this region we identified several GC motifs which are probably involved in the initiation of bcr transcription. bcr transcripts of 7.0 and 4.5 kb are expressed in all cell types examined. These transcripts share all cDNA sequences analysed, including the 5' untranslated region. The latter as well as 902 or 927 amino acids are included within the CML-specific bcr-abl mRNA transcribed from the chimeric bcr-abl gene on chromosome 22. In addition to the complete bcr gene, the human genome contains 3 bcr-related genes containing the last seven exons of the intact bcr gene. One of these genes was analysed in detail and showed high sequence homology with the latter. The three bcr-related genes were probably derived from the intact gene by subsequent steps of duplication.

Base Sequence↗