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At least 919 records · Page 51Linked to original sources

PubMed2001

Expression of Deltex1 during mouse embryogenesis: comparison with Notch1, 2 and 3 expression.

The Notch signalling pathway defines a phylogenetically conserved cell-cell communication process that enables cell-fate specification in multicellular organisms. Deltex is a component of the Notch signalling network that physically interacts with the ankyrin repeats of Notch. Here, we report on the expression pattern of the Deltex1 gene during mouse embryonic development and, furthermore, we compare its expression with that of the Notch1, 2 and 3 genes. Complementary and combinatorial expression patterns between Deltex1 and the three Notch genes were observed throughout embryogenesis since Deltex1 expression was related either to cytodifferentiation (i.e. neuronal tissues) or to cell proliferation events (i.e. eye, vascular structures, hematopoiesis).

Animals↗

PubMed2002

Expression pattern of the lipocalin apolipoprotein D during mouse embryogenesis.

Apolipoprotein D (ApoD) is a secreted protein that belongs to the lipocalin family. We describe the expression pattern of ApoD during mouse embryogenesis by in situ hybridization using RNA probes. ApoD is expressed at E9 in mesenchymal cells in the rombencephalic-mesencephalic region. At E9.5 the cephalic ApoD-positive cells appear in the mesenchyme, and at later stages (starting at E10.5) ApoD expression is seen in meninges. Within the neuroepithelium, ApoD is expressed in pericytes surrounding brain and spinal cord capillaries from E10.5 to birth. Other places of expression of ApoD are the mesenchyme surrounding the olfactory epithelium and semicircular canals, as well as chondroblasts of skull and vertebrae.

Animals↗

PubMed2002

Degradation of hyaluronan by a Hyal2-type hyaluronidase affects pattern formation of vitelline vessels during embryogenesis of Xenopus laevis.

A Hyal2-type hyaluronidase of Xenopus laevis (Xhyal2) was characterized by molecular cloning, biochemical analysis and ectopic overexpression in embryos. When expressed in Xenopus oocytes, Xhyal2 exists as a soluble protein in the extracellular space and in intercellular compartments as well as being attached to the cell surface through a glycosyl-phosphatidyl-inositol anchor. This enzyme specifically degrades hyaluronan not only at acidic pH values but more slowly also under physiological conditions. Xhyal2 is differentially expressed during embryogenesis. Particularly striking is the high level of expression in the developing brain, the head mesenchyme and the pronephros. Elevated levels of mRNA were also found in endothelial cells which will later form vascular structures. Ectopic overexpression of Xhyal2 in frog embryos causes loss of hyaluronan in the cellular environment. This causes severe defects in the assembly of the highly structured plexus of the vitelline vessels from prevascular endothelial cells. Our data support the notion that the level of Xhyal2 expression determines the organization of the extracellular environment so that cells can merge and/or migrate within an originally impenetrable matrix.

Amino Acid Sequence↗

PubMed2002

Cloning of the mouse Sef gene and comparative analysis of its expression with Fgf8 and Spry2 during embryogenesis.

We report the cloning and expression analysis of a mouse gene encoding a novel transmembrane protein. Expression of Sef is similar to that of Fgf8 and Spry2 during early embryogenesis, being prominent in the forebrain, mid-hindbrain boundary, branchial arches, somites, limb bud and tailbud of mouse embryos. These expression profiles indicate that Fgf8, Spry2 and Sef belong to a synexpression group and suggest that these genes may functionally interact during embryonic development. From E12.5 onwards, partially distinct patterns of expression of these genes are observed in the neuroepithelium, sense organs and endodermal-derived organs, that are known sites of expression of other Fgfs.

Adaptor Proteins, Signal Transducing↗

PubMed2002

Na,K-ATPase alpha and beta subunit genes exhibit unique expression patterns during zebrafish embryogenesis.

We have used in situ hybridization to analyze Na,K-ATPase alpha and beta subunit gene expression during zebrafish embryogenesis. The most striking finding is that each of the 14 Na,K-ATPase genes exhibits a distinct expression profile. All alpha and beta subunit genes are expressed in the nervous system, although the pattern of expression in different regions varies dramatically. In peripheral tissues, three of the five alpha1-like genes are expressed in pronephros and mucous cells, one is expressed in heart, and one is predominant in skeletal muscle. The alpha2 gene is expressed in brain and heart but is most prominent in skeletal muscle, while the two alpha3 genes are restricted in their expression to the nervous system. Of the six beta subunit genes, beta1a is expressed at highest abundance in lens, pronephros, and heart, while beta1b transcripts are abundant in mucous cells. The two beta2-like genes are differentially expressed in the nervous system. One beta3 gene is expressed exclusively in brain while the other is abundantly expressed in skeletal muscle. Based on these expression patterns, we predict that at least 14 alpha/beta subunit pairs are likely to be formed in different tissues.

Animals↗

PubMed2002

The expression of SpRunt during sea urchin embryogenesis.

The runt box (runx) is a highly conserved DNA binding and protein-protein interaction domain that defines a family of heterodimeric transcription factors that regulate development in metazoans. The three mammalian runx genes are oncogenes with essential functions in normal development: Runx1 is required for hematopoiesis and is frequently mutated in human and murine leukemias; Runx2 is required for bone development and is associated with human cleidocranial dysplasia and murine leukemias; and Runx3 (the evolutionarily basal member of the mammalian family) regulates growth of the gut and functions as a tumor suppressor in the gastric epithelium (Westendorf and Hiebert, 1999; Li et al., 2002). The sea urchin Strongylocentrotus purpuratus contains a single runx gene, SpRunt. We present here the initial structural characterization of SpRunt, and its pattern of expression during embryogenesis. SpRunt contains two introns, the locations of which are identical to those of the second and third introns from promoter P2 of the mammalian runx genes. A approximately 6 kb transcript begins to accumulate during cleavage. At mesenchyme blastula stage, SpRunt transcripts are found throughout the embryo, but specifically enriched in the vegetal plate, skeletogenic mesenchyme, and part of the ectoderm. By late gastrula stage expression is localized to the endomesoderm and oral ectoderm. In the pluteus larva SpRunt transcripts remain confined to the endomesoderm and oral ectoderm, with highest levels of accumulation in the foregut and in the ciliary band. These data suggest that SpRunt expression is enhanced in proliferating cells.

Amino Acid Sequence↗

PubMed2002

The murine fork head gene Foxn2 is expressed in craniofacial, limb, CNS and somitic tissues during embryogenesis.

The fork head domain-containing gene family (Fox) comprises over 20 members in mammals and is defined by a conserved 110 amino-acid motif containing a winged helix structure DNA-binding domain. The members of this gene family have been implicated as key regulators of embryogenesis, cell cycling, cell lineage restriction and cancer. The Foxn2 gene (Ches1) is expressed in postgastrulation embryos in multiple tissues that serve as important signaling centers as well as end-stage-differentiated cell types that arise from different germ layers of the developing embryo. The dynamic and specific expression of Foxn2 during embryonic development suggest multiple independent roles for Foxn2 function during gestation.

Amino Acid Motifs↗

PubMed2003

Direct lineage tracing reveals the ontogeny of pancreatic cell fates during mouse embryogenesis.

Lineage tracing follows the progeny of labeled cells through development. This technique identifies precursors of mature cell types in vivo and describes the cell fate restriction steps they undergo in temporal order. In the mouse pancreas, direct cell lineage tracing reveals that Pdx1- expressing progenitors in the early embryo give rise to all pancreatic cells. The progenitors for the mature pancreatic ducts separate from the endocrine/exocrine tissues before E12.5. Expression of Ngn3 and pancreatic polypeptide marks endocrine cell lineages during early embryogenesis, and these cells behave as transient progenitors rather than stem cells. In adults, Ngn3 is expressed within the endocrine islets, and the NGN3+ cells seem to contribute to pancreatic islet renewal. These results indicate the stage at which each progenitor population is restricted to a particular fate and provide markers for isolating progenitors to study their growth, differentiation, and the genes necessary for their development.

Animals↗

PubMed1996

Expression of receptor protein-tyrosine phosphatase alpha mRNA and protein during mouse embryogenesis.

Receptor protein-tyrosine phosphatase alpha (RPTP alpha) is a transmembrane member of the family of protein-tyrosine phosphatases (PTPs) that has been implicated in neuronal differentiation in vitro. Here we demonstrate that RPTP alpha is differentially expressed during mouse embryogenesis in a spatio-temporal manner. RPTP alpha expression was detectable in 6 days post coitum (dpc) embryos, but not in 7.5 dpc embryos. From 10.5 dpc onwards a striking RPTP alpha expression pattern was observed with elevated levels in the dorsal root ganglia, cranial ganglia and adrenal gland, suggesting that RPTP alpha levels are specifically enhanced in neural crest derivatives. Marked differences between RPTP alpha mRNA and protein levels indicated that RPTP alpha expression is regulated by transcriptional and (post-) translational mechanisms. The expression pattern of RPTP alpha suggests that RPTP alpha may play a role in neural crest cell differentiation in vivo.

Age Factors↗

PubMed1996

A new mouse member of the Wnt gene family, mWnt-8, is expressed during early embryogenesis and is ectopically induced by retinoic acid.

We have identified a novel mouse Wnt genc using a cDNA differential screening procedure for retinoic-acid-induced transcripts in P19 embryonal carcinoma cells. Sequence analysis showed that this gene represents the first murine Wnt-8 (mWnt-8) gene reported to date. The expression of the mWnt-8 gene, which is rapidly induced by retinoic acid in P19 and embryonic stem cells, appears to be restricted to early stages of mouse embryogenesis. mWnt-8 transcripts are first detected in the posterior region of the epiblast of early primitive streak-stage embryos. As gastrulation proceeds, mWnt-8 expression spreads into the embryonic ectoderm up to a sharp rostral boundary at the base of the developing headfolds. mWnt-8 is also transiently expressed in the newly formed mesoderm. mWnt-8 expression is rapidly down-regulated during early somitogenesis, the latest detectable expression domains corresponding to the presumptive fourth rhombomere and the caudal region of the neural plate. The expression pattern of mWnt-8 is clearly distinct from those of other murine Wnt genes expressed during gastrulation, but shows striking similarities with that of the chicken Cwnt-8C gene. We also show that mWnt-8 expression is ectopically induced in the rostral neural plate in response to RA exposure of presumitic (7-7.5 days post coitum) cultured mouse embryos.

Age Factors↗

PubMed1997

Lethal of scute requires overexpression of daughterless to elicit ectopic neuronal development during embryogenesis in Drosophila.

Classical genetics indicates that the achaete-scute gene complex (AS-C) of Drosophila promotes development of neural progenitor cells. To further analyze the function of proneural genes, we have studied the effects of Gal4-mediated expression of lethal of scute, a member of the AS-C, during embryogenesis. Expression of lethal of scute forces progenitor cells of larval internal sensory organs, which are normally committed to this fate independently of the activity of the AS-C, to take on features of external sensory organs. Supernumerary neural cells can be induced ectopically only if daughterless is overexpressed, either alone or together with lethal of scute: cells of the amnioserosa and the hindgut then express neuronal markers. Furthermore, cells of the proctodeal anlage, which normally lack neural competence, acquire the ability to develop as neuroblasts following transplantation into the neuroectoderm. We show here that activated Notch prevents the cells of the neuroectoderm from forming extra neural tissue when they express an excess of proneural proteins. Under the present conditions, lateral inhibition is thus dominant over the activity of proneural genes.

Animals↗

PubMed1997

Patterning the expression of a tissue-specific transcription factor in embryogenesis: HNF1 alpha gene activation during Xenopus development.

Tissue-specific transcription factors play an essential role in establishing cell identity during development. We review our knowledge of the molecular events involved in the activation of the gene encoding the tissue-specific transcription factor HNF1 alpha (LFB1). The available data suggest that the maternal factors OZ-1, HNF4 alpha and HNF4 beta act as initial activators of the HNF1 alpha promoter. We present evidence suggesting that the mesoderm-inducing factor activin A plays a critical role by acting through the HNF4 binding site of the HNF1 alpha promoter. The activity of this embryonic morphogen seems to form a gradient opposing the distribution of the maternal HNF4 proteins that are concentrated at the animal pole of the egg. After zygotic gene transcription the HNF1 alpha-related transcription factor HNF1 beta accumulates faster than HNF1 alpha itself and thus is likely to contribute to the activation of the HNF1 alpha transcription via the HNF1 binding site. The cofactor of the HNF1 proteins (DCoH) is present throughout development and thus cannot limit the activation potential of HNF1 alpha in early development. Our results provide a detailed description of setting up the expression pattern of a tissue-specific transcription factor during embryogenesis.

Activins↗

PubMed1997

A zebrafish Id homologue and its pattern of expression during embryogenesis.

We describe the cloning, sequencing and pattern of transcript distribution during embryogenesis of a zebrafish Id homologue that we have called Id6. Transcription of the gene is spatially regulated, and its pattern of transcription shows considerable overlaps with those of other zebrafish genes with homology to Drosophila neurogenic genes, such as Notch and Delta. Since all these genes are coexpressed in particular cells, they may function together in a single genetic circuit in zebrafish as they do in Drosophila. A zebrafish homologue of Drosophila AS-C proteins can activate transcription of a CAT reporter gene by binding to an E-box in mouse 3T3 cells, either alone or in conjunction with ZfE12. The activation of transcription is inhibited in the presence of Id6. This indicates that the zebrafish gene described here is a genuine member of the Id family, and suggests that it may serve a function similar to that of the Drosophila gene emc and mammalian Ids during development.

Amino Acid Sequence↗

PubMed1997

Ras is an essential component for notochord formation during ascidian embryogenesis.

In ascidian embryos, inductive interactions are necessary for the fate specification of notochord cells. Previous studies have shown that notochord induction occurs at the 32-cell stage and that basic fibroblast growth factor (bFGF) has notochord-inducing activity in ascidian embryos. In vertebrate, it is known that bFGF receptors have tyrosine kinase domain and the signaling pathway is mediated by the small-GTP binding protein, Ras. To study the role of Ras in ascidian embryos, we injected dominant negative Ras (RasN17) into fertilized eggs. RasN17 inhibited the formation of notochord, suggesting that the Ras signaling pathway is involved in signal transduction in the induction of notochord cells. When the presumptive-notochord (A6.2) blastomere was co-isolated with the inducer (A6.1) blastomere and then RasN17 was injected into the A6.2 blastomere, notochord differentiation was suppressed. The presumptive-notochord blastomeres injected with RasN17 were treated with bFGF. Many of them failed to develop notochord-specific features. Next, we examined the effect of injecting constitutively active Ras (RasV12) into the A6.2 blastomeres. However, microinjection of RasV12 into these cells did not bypass notochord induction. These results suggest that the Ras signaling pathway is essential for the formation of notochord and that another signaling pathway also must be activated simultaneously in notochord formation during ascidian embryogenesis.

Animals↗

PubMed1997

Xenopus Pax-2 displays multiple splice forms during embryogenesis and pronephric kidney development.

Kidney organogenesis is initiated with the formation of the pronephric kidney and requires Pax-2 gene function. We report here the cloning and characterization of Pax-2 cDNAs from the frog Xenopus laevis, a model system suitable for the study of early kidney organogenesis. We show that expression of Xenopus Pax-2 (XPax-2) genes was confined to the nervous system, sensory organs, the visceral arches, and the developing excretory system. DNA sequencing of XPax-2 cDNAs isolated from head and pronephric kidney libraries revealed seven novel alternatively spliced Pax-2 isoforms. They all retain DNA-binding domains, but can differ significantly in their C termini with some isoforms containing a novel Pax-2 exon. We investigated the spectrum of XPax-2 splice events in pronephric kidneys, animal cap cultures and in whole embryos. Splicing of XPax-2 transcripts was found to be extensive and temporally regulated during Xenopus embryogenesis. Since all investigated tissues expressed essentially the full spectrum of XPax-2 splice variants, we conclude that splicing of XPax-2 transcripts does not occur in a tissue-specific manner.

Alternative Splicing↗

PubMed1998

Msg1 and Mrg1, founding members of a gene family, show distinct patterns of gene expression during mouse embryogenesis.

Msg1 and Mrg1 are founding members of a gene family which exhibit distinct patterns of gene expression during mouse embryogenesis. Sequence analysis reveals that these genes are unlike any other gene identified to date, but they share two near-identical sequence domains. The Msg1 and Mrg1 expression profiles during early development are distinct from each other. Msg1 is predominantly expressed in nascent mesoderm, the heart tube, limb bud and sclerotome. Intriguingly, Msg1 expression is restricted, within these developing mesodermal sites, to posterior domains. Mrg1 is expressed prior to gastrulation in the anterior visceral endoderm. Expression is maintained in the endoderm once gastrulation has begun and commences in the rostralmost embryonic mesoderm which underlies the anterior visceral endoderm. Mrg1 expression persists in this rostral mesoderm as it is translocated caudalwards during the invagination of the foregut and the formation of the heart. Later Mrg1 expression predominates in the septum transversum caudal to the heart. This expression pattern suggests that the septum transversum originates from the rostralmost embryonic mesoderm which first expressed Mrg1 at the late primitive streak stage.

Amino Acid Sequence↗

PubMed1998

Expression pattern of the winged helix factor XFD-11 during Xenopus embryogenesis.

We have identified a cDNA encoding a novel Xenopus winged helix transcription factor termed as XFD-11 (Xenopus fork head domain). The DNA binding domain is most closely related to those of human or murine FREAC-3 (FKHL7/MF-1/FKH-1) proteins. The XFD-11 gene is activated at late blastula/early gastrula and transcription proceeds throughout embryogenesis. Early expression is found in ventral and lateral but not in dorsal mesoderm. At neurula stages, transcripts are found in posterior mesoderm except for the dorsal midline, and the gene is also transcribed at the lateral border of the neural plate and within anterior neuroectoderm. At later stages of development, transcripts are detected within the pronephros, the heart, within neural crest cells surrounding the eye, in the mandibular, hyoid and branchial arches, and within the tail.

Amino Acid Sequence↗

PubMed1998

The two mature transcripts of the chick calcitonin gene are expressed within the central nervous system during embryogenesis.

Calcitonin mRNA and calcitonin gene-related peptide (CGRP) mRNA both are generated from the calcitonin gene because of tissue-specific alternative splicing of the primary transcript. It is currently established that, of the two mature transcripts, calcitonin mRNA is far the predominant transcript produced in thyroid C-cells whereas only CGRP mRNA is produced in the nervous system. However, here we provide evidence that the two splicing forms of the chick calcitonin primary transcript are found within the developing central nervous system, although displaying specific patterns of expression. While CGRP mRNA is first expressed in motor neurons at rather advanced stages of embryogenesis, calcitonin mRNA is expressed in the floor plate and dorsal rhombencephalon from earliest stages.

Animals↗