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M Goulding

Publications and source records attributed to M Goulding.

At least 19 recordsLinked to original sources
PubMed2001

Cloning and expression of Munc 30: a member of the paired -like homeodomain gene family.

The temporal and spatial expression of transcription factors is of critical importance in the organization and specification of cellular phenotypes in the anterior structures of the head and in particular the CNS. In order to identify further genes which might play a role in such patterning we have cloned the Munc 30 gene, a new isoform of the paired -like homeodomain gene Ptx2. Using RT-PCR, Munc 30 expression was detected in embryonic head and brain and in a wide panel of adult mouse tissues including brain, spinal cord, eye and tongue. In situ hybridization showed the expression domain of Munc 30 to be localized to a wide variety of developing organs and primordial tissues of the embryo with extremely high levels of expression in Rathke's pouch, tooth primordia and the hypothalamus. In situ RT-PCR was used to localize gene expression to cells of the cortex, striatum and thalamus of adult mouse forebrain. Together, these expression patterns suggest that this gene may not only play a critical role in patterning of anterior structures of the head during development but may also be responsible for the maintenance and/or modulation of cell identity in adult.

Animals↗
PubMed2001

Control of interneuron fate in the developing spinal cord by the progenitor homeodomain protein Dbx1.

Spinal interneurons help to coordinate motor behavior. During spinal cord development, distinct classes of interneurons are generated from progenitor cells located at different positions within the ventral neural tube. V0 and V1 interneurons derive from adjacent progenitor domains that are distinguished by expression of the homeodomain proteins Dbx1 and Dbx2. The spatially restricted expression of Dbx1 has a critical role in establishing the distinction in V0 and V1 neuronal fate. In Dbx1 mutant mice, neural progenitors fail to generate V0 neurons and instead give rise to interneurons that express many characteristics of V1 neurons-their transcription factor profile, neurotransmitter phenotype, migratory pattern, and aspects of their axonal trajectory. Thus, a single progenitor homeodomain transcription factor coordinates many of the differentiated properties of one class of interneurons generated in the ventral spinal cord.

Animals↗
PubMed2001

Evx1 is a postmitotic determinant of v0 interneuron identity in the spinal cord.

Interneurons in the ventral spinal cord are essential for coordinated locomotion in vertebrates. During embryogenesis, the V0 and V1 classes of ventral interneurons are defined by expression of the homeodomain transcription factors Evx1/2 and En1, respectively. In this study, we show that Evx1 V0 interneurons are locally projecting intersegmental commissural neurons. In Evx1 mutant embryos, the majority of V0 interneurons fail to extend commissural axons. Instead, they adopt an En1-like ipsilateral axonal projection and ectopically express En1, indicating that V0 interneurons are transfated to a V1 identity. Conversely, misexpression of Evx1 represses En1, suggesting that Evx1 may suppress the V1 interneuron differentiation program. Our findings demonstrate that Evx1 is a postmitotic determinant of V0 interneuron identity and reveal a critical postmitotic phase for neuronal determination in the developing spinal cord.

Alleles↗
PubMed2001

The winged-helix transcription factor Foxd3 suppresses interneuron differentiation and promotes neural crest cell fate.

The neural crest is a migratory cell population that gives rise to multiple cell types in the vertebrate embryo. The intrinsic determinants that segregate neural crest cells from multipotential dorsal progenitors within the neural tube are poorly defined. In this study, we show that the winged helix transcription factor Foxd3 is expressed in both premigratory and migratory neural crest cells. Foxd3 is genetically downstream of Pax3 and is not expressed in regions of Pax3 mutant mice that lack neural crest, implying that Foxd3 may regulate aspects of the neural crest differentiation program. We show that misexpression of Foxd3 in the chick neural tube promotes a neural crest-like phenotype and suppresses interneuron differentiation. Cells that ectopically express Foxd3 upregulate HNK1 and Cad7, delaminate and emigrate from the neural tube at multiple dorsoventral levels. Foxd3 does not induce Slug and RhoB, nor is its ability to promote a neural crest-like phenotype enhanced by co-expression of Slug. Together these results suggest Foxd3 can function independently of Slug and RhoB to promote the development of neural crest cells from neural tube progenitors.

Animals↗
PubMed2001

Identification of NKL, a novel Gli-Kruppel zinc-finger protein that promotes neuronal differentiation.

The proneural basic helix-loop-helix proteins play a crucial role in promoting the differentiation of postmitotic neurons from neural precursors. However, recent evidence from flies and frogs indicates that additional factors act together with the proneural bHLH proteins to promote neurogenesis. We have identified a novel zinc finger protein, neuronal Kruppel-like protein (NKL), that positively regulates neurogenesis in vertebrates. NKL is expressed in Xenopus primary neurons and in differentiating neuronal precursors in the intermediate zone of the mouse and chick neural tube. In frog embryos, NKL is induced by overexpression of Neurogenin (Ngn), arguing that NKL is downstream of the proneural determination genes. Our results show that NKL and a NKL/VP16 fusion protein promote differentiation of neuronal precursors in the embryonic chick spinal cord. Following in ovo misexpression of NKL, neuroepithelial cells exit the cell cycle and differentiate into neurons. Similarly, NKL/VP16 induces extra primary neurons in frogs and upregulates expression of the neural differentiation factors, Xath3 and MyT1, as well as the neuronal markers, N-tubulin and elrC. Our findings establish NKL as a novel positive regulator of neuronal differentiation and provide further evidence that non-bHLH transcription factors function in the neuronal differentiation pathway activated by the vertebrate neuronal determination genes.

Amino Acid Sequence↗
PubMed2000

Kidney development in cadherin-6 mutants: delayed mesenchyme-to-epithelial conversion and loss of nephrons.

During nephrogenesis, dynamic changes in the expression of cell adhesion molecules are evident as epithelial structures differentiate from the induced mesenchyme. The cadherins are thought to play an important role in the metanephric mesenchyme, when cells aggregate to form the renal vesicle, a polarized epithelial structure which eventually fuses with the ureteric bud to generate a continuous nascent nephron. We have generated and analyzed mice with a targeted mutation in the gene encoding cadherin-6 (Cad-6), a type II cadherin expressed during early stages of nephrogenesis. These mice are viable and fertile, and they complete both early and late aspects of nephrogenesis. However, upon closer examination in vitro and in vivo, a fraction of the induced metanephric mesenchyme in Cad-6 mutant kidneys fails to form a fully polarized epithelium on schedule. Moreover, a significant number of the renal vesicles in Cad-6 mutant kidneys apparently fail to fuse to the ureteric bud. These alterations in epithelialization and fusion apparently lead to a loss of nephrons in the adult. These studies support the idea that cadherins play an essential role in the formation of epithelial structures and underscore the importance of timing in orchestrating the morphogenesis of complex epithelial tissues.

Animals↗
PubMed2000

Lbx1 is required for muscle precursor migration along a lateral pathway into the limb.

In mammalian embryos, myogenic precursor cells emigrate from the ventral lip of the dermomyotome and colonize the limbs, tongue and diaphragm where they differentiate and form skeletal muscle. Previous studies have shown that Pax3, together with the c-Met receptor tyrosine kinase and its ligand Scatter Factor (SF) are necessary for the migration of hypaxial muscle precursors in mice. Lbx1 and Pax3 are co-expressed in all migrating hypaxial muscle precursors, raising the possibility that Lbx1 regulates their migration. To examine the function of Lbx1 in muscle development, we inactivated the Lbx1 gene by homologous recombination. Mice lacking Lbx1 exhibit an extensive loss of limb muscles, although some forelimb and hindlimb muscles are still present. The pattern of muscle loss suggests that Lbx1 is not required for the specification of particular limb muscles, and the muscle defects that occur in Lbx1(-/-) mice can be solely attributed to changes in muscle precursor migration. c-Met is expressed in Lbx1 mutant mice and limb muscle precursors delaminate from the ventral dermomyotome but fail to migrate laterally into the limb. Muscle precursors still migrate ventrally and give rise to tongue, diaphragm and some limb muscles, demonstrating Lbx1 is necessary for the lateral, but not ventral, migration of hypaxial muscle precursors. These results suggest that Lbx1 regulates responsiveness to a lateral migration signal which emanates from the developing limb.

Animals↗
PubMed1999

Engrailed-1 and netrin-1 regulate axon pathfinding by association interneurons that project to motor neurons.

During early development, multiple classes of interneurons are generated in the spinal cord including association interneurons that synapse with motor neurons and regulate their activity. Very little is known about the molecular mechanisms that generate these interneuron cell types, nor is it known how axons from association interneurons are guided toward somatic motor neurons. By targeting the axonal reporter gene &tgr;-lacZ to the En1 locus, we show the cell-type-specific transcription factor Engrailed-1 (EN1) defines a population of association neurons that project locally to somatic motor neurons. These EN1 interneurons are born early and their axons pioneer an ipsilateral longitudinal projection in the ventral spinal cord. The EN1 interneurons extend axons in a stereotypic manner, first ventrally, then rostrally for one to two segments where their axons terminate close to motor neurons. We show that the growth of EN1 axons along a ventrolateral pathway toward motor neurons is dependent on netrin-1 signaling. In addition, we demonstrate that En1 regulates pathfinding and fasciculation during the second phase of EN1 axon growth in the ventrolateral funiculus (VLF); however, En1 is not required for the early specification of ventral interneuron cell types in the embryonic spinal cord.

Animals↗
PubMed1998

Intra-amniotic inflammation in human gastroschisis: possible aetiology of postnatal bowel dysfunction.

OBJECTIVE: To assess amniotic fluid for evidence of an inflammatory exudate in association with fetal gastroschisis. SETTING: University College Hospital, London and Institute of Child Health, London. SAMPLE: Samples of amniotic fluid in the third trimester from pregnant women with a diagnosis of fetal gastroschisis (n = 10) and from a control group (n = 10) with a normal fetus. METHODS: Cytological analysis of the fluid was performed. Flow cytometry was performed on the amniotic fluid using antibodies for the myeloid cell antigen CD15, the leucocyte beta integrin CD11b/CD18 and CD3, CD19, CD56 and CD25. Tumour necrosis factor alpha and interleukin-8 levels were assayed in the amniotic fluid. RESULTS: An acute inflammatory exudate, composed predominantly of neutrophil polymorphs and mononuclear cells, was found in the amniotic fluid in fetal gastroschisis but not in control cases. When amniotic fluid samples from cases of fetal gastroschisis were stained with CD15, analysis by flow cytometry showed a clear positive population. This CD15 population showed markedly elevated levels of CD11b. No distinct population of CD15 positive cells was seen in amniotic fluid samples examined from the control group. No staining was seen with antibodies to CD3, CD19, CD56 or CD25 in amniotic fluid obtained from either group. There was no significant difference between tumour necrosis factor alpha levels measured in the amniotic fluid of cases of fetal gastroschisis (median 102 pg/mL; range 20-340) and those of the control group (140 pg/mL; range 20-548) (P = 0.1). The levels of interleukin-8 were markedly elevated in the amniotic fluid of cases of fetal gastroschisis (median 6320 pg/mL; range 4732-13,800) compared with the control group (median 1738 pg/mL; range 623 2861;) (P < 0.01). CONCLUSION: Human fetal gastroschisis is associated with an inflammatory exudate in the amniotic fluid which may have implications for postnatal bowel function.

Adult↗
PubMed1997

Ectopic Pax-3 activates MyoD and Myf-5 expression in embryonic mesoderm and neural tissue.

To understand how the skeletal muscle lineage is induced during vertebrate embryogenesis, we have sought to identify the regulatory molecules that mediate induction of the myogenic regulatory factors MyoD and Myf-5. In this work, we demonstrate that either signals from the overlying ectoderm or Wnt and Sonic hedgehog signals can induce somitic expression of the paired box transcription factors, Pax-3 and Pax-7, concomitant with expression of Myf-5 and prior to that of MyoD. Moreover, infection of embryonic tissues in vitro with a retrovirus encoding Pax-3 is sufficient to induce expression of MyoD, Myf-5, and myogenin in both paraxial and lateral plate mesoderm in the absence of inducing tissues as well as in the neural tube. Together, these findings imply that Pax-3 may mediate activation of MyoD and Myf-5 in response to muscle-inducing signals from either the axial tissues or overlying ectoderm and identify Pax-3 as a key regulator of somitic myogenesis.

Animals↗
PubMed1997

A novel fibroblast growth factor gene expressed in the developing nervous system is a downstream target of the chimeric homeodomain oncoprotein E2A-Pbx1.

Pbx1 is a homeodomain transcription factor that has the ability to form heterodimers with homeodomain proteins encoded by the homeotic selector (Hox) gene complexes and increase their DNA-binding affinity and specificity. A current hypothesis proposes that interactions with Pbx1 are necessary for Hox proteins to regulate downstream target genes that in turn control growth, differentiation and morphogenesis during development. In pre B cell leukemias containing the t(1;19) chromosome translocation, Pbx1 is converted into a strong transactivator by fusion to the activation domain of the bHLH transcription factor E2A. The E2A-Pbx1 fusion protein should therefore activate transcription of genes normally regulated by Pbx1. We have used the subtractive process of representational difference analysis to identify targets of E2A-Pbx1. We show that E2A-Pbx1 can directly activate transcription of a novel member of the fibroblast growth factor family of intercellular signalling molecules, FGF-15. The FGF-15 gene is expressed in a regionally restricted pattern in the developing nervous system, suggesting that FGF-15 may play an important role in regulating cell division and patterning within specific regions of the embryonic brain, spinal cord and sensory organs.

Amino Acid Sequence↗
PubMed1996

Expression of the Tyro4/Mek4/Cek4 gene specifically marks a subset of embryonic motor neurons and their muscle targets.

Tyro4 is a member of the eph family of receptor protein-tyrosine kinases. We present sequence analysis that identifies Tyro4 as the rat homolog of mouse Mek4 and chick Cek4. We also present expression studies that demonstrate an evolutionarily conserved pattern of expression for Tyro4, Mek4, and Cek4. Most strikingly, we find this receptor to be specifically expressed, in all three species, in a subset of motor neurons in the medial motor column and in a subset of axial, but not limb, muscles. Mek4 has previously been ascribed a role in guiding retinal axons to their targets in the optic tectum. Our results extend the purported role of Mek4 in axon guidance to include motor neurons of the medial motor column.

Amino Acid Sequence↗
PubMed1996

Pax-3 is necessary for migration but not differentiation of limb muscle precursors in the mouse.

The limb muscles of vertebrates are derived from precursor cells that migrate from the lateral edge of the dermomyotome into the limb bud. Previous studies have shown that the paired domain-containing transcription factor Pax-3 is expressed in the limb in cells that are precursors for limb muscles (Williams, B. and Ordahl, C.P. (1994) Development 120, 785-796). In splotch (Pax-3-) embryos, the limb muscles fail to develop and cells expressing Pax-3 are no longer found in the limb. In this paper we have analyzed the role of Pax-3 in the migration and subsequent differentiation of limb muscle precursors. By labeling somites adjacent to the prospective forelimb with the lipophilic dye DiI, we have shown that cells derived from these somites do not migrate into the limbs of splotch mice. The failure of limb muscle precursors to invade the limb in splotch mice is associated with the absence of c-met expression in premigratory cells, together with a change in the morphology of the ventral dermomyotome. In addition, we have shown the lateral half of somites derived from day E9.25 splotch embryos can undergo muscle differentiation when grafted into the limb bud stage 20 chick host embryos. Our results indicate that Pax-3 regulates the migration of limb muscle precursors into the limb and is not required for cells in the lateral somite to differentiate into muscle.

Animals↗
PubMed1994

Molecular basis of splotch and Waardenburg Pax-3 mutations.

Pax genes control certain aspects of development, as mutations result in (semi)dominant defects apparent during embryogenesis. Pax-3 has been associated with the mouse mutant splotch (Sp) and the human Waardenburg syndrome type 1 (WS1). We have examined the molecular basis of splotch and WS1 by studying the effect of mutations on DNA binding, using a defined target sequence. Pax-3 contains two different types of functional DNA-binding domains, a paired domain and a homeodomain. Mutational analysis of Pax-3 reveals different modes of DNA binding depending on the presence of these domains. A segment of Pax-3 located between the two DNA-binding domains, including a conserved octapeptide, participates in protein homodimerization. Pax-3 mutations found in splotch alleles and WS1 individuals change DNA binding and, in the case of a protein product of the Sp allele, dimerization. These findings were taken as a basis to define the molecular nature of the mutants.

Animals↗
PubMed1994

Pax genes and neural tube defects in the mouse.

The Pax genes encode a family of transcription factors that are expressed in restricted regions of the developing embryo. Several Pax genes are expressed in the developing nervous system where they are believed to regulate the morphogenesis of neural structures. Loss-of-function mutations in the Pax-3 gene have been identified in a number of alleles of the mouse mutant splotch. In homozygous splotch embryos closure of the neural tube is defective with embryos exhibiting spina bifida and/or exencephaly. Other structures in which Pax-3 is expressed are also affected, most notably those tissues derived from the neural crest and somites.

Animals↗
PubMed1994

Regulation of Pax-3 expression in the dermomyotome and its role in muscle development.

The segmented mesoderm in vertebrates gives rise to a variety of cell types in the embryo including the axial skeleton and muscle. A number of transcription factors containing a paired domain (Pax proteins) are expressed in the segmented mesoderm during embryogenesis. These include Pax-3 and a closely related gene, Pax-7, both of which are expressed in the segmental plate and in the dermomyotome. In this paper, we show that signals from the notochord pattern the expression of Pax-3, Pax-7 and Pax-9 in somites and the subsequent differentiation of cell types that arise from the somitic mesoderm. We directly assess the role of the Pax-3 gene in the differentiation of cell types derived from the dermomyotome by analyzing the development of muscle in splotch mouse embryos which lack a functional Pax-3 gene. A population of Pax-3-expressing cells derived from the dermomyotome that normally migrate into the limb are absent in homozygous splotch embryos and, as a result, limb muscles are lost. No abnormalities were detected in the trunk musculature of splotch embryos indicating that Pax-3 is necessary for the development of the limb but not trunk muscle.

Animals↗
PubMed1993

Analysis of the Pax-3 gene in the mouse mutant splotch.

In a linkage analysis of Pax-3 and splotch no recombinations were found in 117 backcross mice. Molecular analysis of Pax-3 in three alleles of splotch shows a number of significant alterations to the Pax-3 gene. In Sp/Sp embryos, cDNA PCR analysis reveals a shortened transcript in which exon 4 of Pax-3 is deleted due to mutation of the splice acceptor site of intron 3. In the Sp4H allele, the Pax-3 gene is deleted and in Spd embryos, Pax-3 expression is significantly lower than that in normal littermate embryos. The linkage analysis, shortened Pax-3 transcript in Sp, and deletion of Pax-3 in Sp4H described here, together with the previous report of an intragenic deletion in Pax-3 in Sp2H mice and the deletion of Pax-3 in Spr mice, provide strong evidence for the allelic identity of Pax-3 and Sp.

Alleles↗