PubMed Health⌕ Search

Biomedical subjects

E Bellefroid

Publications and source records attributed to E Bellefroid.

8 recordsLinked to original sources
PubMed1998

Xenopus eomesodermin is expressed in neural differentiation.

Our initial description of the Xenopus gene Eomesodermin (Eomes) indicated that it is expressed largely if not entirely in mesodermal cells of gastrula stage embryos. A more detailed examination, described here, shows that it continues to be expressed in the most anterior (future head) mesoderm during gastrula and neurula stages. However, during tail-bud stages, Eomes expression is re-born in the most anterior part of the brain, becoming strongly transcribed in the olfactory region of the telencephalon. This later Eomes expression marks a very localized region of the forebrain distinct from that of Otx-2, anterior to that of En-1 and overlapping that of Sox-3.

Animals↗
PubMed1998

The Xenopus homologue of the Drosophila gene tailless has a function in early eye development.

Genetic circuits responsible for the development of photoreceptive organs appear to be evolutionarily conserved. Here, the Xenopus homologue Xtll of the Drosophila gene tailless (tll), which we find to be expressed during early eye development, is characterized with respect to its relationship to vertebrate regulators of eye morphogenesis, such as Pax6 and Rx. Expression of all three genes is first detected in the area corresponding to the eye anlagen within the open neural plate in partially overlapping, but not identical, patterns. During the evagination of the optic vesicle, Xtll expression is most prominent in the optic stalk, as well as in the distal tip of the forming vesicle. In tadpole-stage embryos, Xtll gene transcription is most prominent in the ciliary margin of the optic cup. Inhibition of Xtll function in Xenopus embryos interferes specifically with the evagination of the eye vesicle and, in consequence, Xpax6 gene expression is severely reduced in such manipulated embryos. These findings suggest that Xtll serves an important regulatory function in the earliest phases of vertebrate eye development.

Aging↗
PubMed1997

Transcription regulation and alternative splicing of an early zygotic gene encoding two structurally distinct zinc finger proteins in Xenopus laevis.

We describe the structural organization of a gene, termed XFDL 141/156, that is transiently activated during early Xenopus development. XFDL 141/156 is first transcribed at the midblastula transition (MBT) and during early gastrulation events. A roughly 200 nucleotide fragment immediately 5' to the transcription start site is sufficient for transient, early zygotic activation of gene expression. The primary transcript is subject to alternative splicing. Corresponding cDNAs encode two structurally related but completely distinct C2H2-type zinc finger proteins of unknown biological function.

Alternative Splicing↗
PubMed1996

Zinc finger proteins in early Xenopus development.

The C2H2-type zinc finger motif defines a large super family of specific DNA and specific RNA binding proteins. Individual members of this protein family have been demonstrated to carry important regulatory functions in embryogenesis. We have isolated a large collection of C2H2-type zinc finger proteins from Xenopus laevis. Some of these proteins are highly conserved in evolution and found to be differentially expressed during embryonic development of the central nervous system. We also summarize our recent findings on the biochemical characterization of RNA and DNA binding activities in vitro for other Xenopus zinc finger proteins, which fall into structurally defined, distinct subfamilies.

Amino Acid Sequence↗
PubMed1994

Perspectives on zinc finger protein function and evolution--an update.

Complexity is one of the hallmarks that applies to C2H2 type zinc finger proteins (ZFPs). Structurally distinct clusters of zinc finger modules define an extremely large superfamily of nucleic acid binding proteins with several hundred, perhaps thousands of different members in vertebrates. Recent discoveries have provided new insights into the biochemistry of RNA and DNA recognition, into ZFP evolution and genomic organization, and also into basic aspects of their biological function. However, as much as we have learned, other fundamental questions about ZFP function remain highly enigmatic. This essay is meant to define what we personally feel are important questions, rather than trying to provide a comprehensive, encyclopaedic review.

Amino Acid Sequence↗
PubMed1991

Multihormonal regulation of the human prolactin gene expression from 5000 bp of its upstream sequence.

We have cloned DNA sequences extending up to 6000 bp upstream from the first exon of the human prolactin (hPRL) gene. 5000 bp of these upstream sequences were fused to a CAT reporter gene and shown to provide tissue-specific transient expression in rat pituitary GH3 cells. Multihormonal response was found in this transient expression assay, leading to significant 2- to 5-fold induction by addition of 8-chlorophenylthio-cyclic AMP, thyrotropin-releasing hormone, epidermal growth factor, basic fibroblast growth factor, phorbol myristate acetate, a calcium channel agonist (Bay K-8644) and triiodothyronine. A 3-fold inhibition was observed in the presence of the glucocorticoid agonist dexamethasone. The sequence of the hPRL promoter was determined up to coordinate -3470. Computer similarity search between the rat and human sequences showed two highly conserved regions corresponding to the proximal and distal tissue specific enhancers described in both PRL promoters.

Animals↗
PubMed1986

[Localization of transcription regulatory sequences. Application to the genes of the prolactin family].

We are studying nucleotide sequences responsible for the regulation of eukaryotic gene expression. Our test system comprises the human genes coding for prolactin (hPRL), growth hormone (hGH-N) and placental lactogen (hCS-B). We have cloned these genes and are searching within their sequences for in vitro binding sites of the human glucocorticoid receptor on the hGH-N and hCS-B genes; the in vivo activity of such DNA sequences by assaying hybrid gene expression in transfected cells; in vivo "enhancer" activity of different hPRL gene fragments linked to a marker gene and transfected in cultured cells.

Base Sequence↗