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E Boncinelli

Publications and source records attributed to E Boncinelli.

At least 73 records · Page 4Linked to original sources
PubMed1996

Emx1 and Emx2 show different patterns of expression during proliferation and differentiation of the developing cerebral cortex in the mouse.

Insights into the complex structure of the forebrain and its regulation have recently come from the analysis of the expression of genes that are likely to be involved in regionalization of this structure. We cloned four new homeo box genes, Emx1, Emx2, Otx1 and Otx2, and showed that in day 10 mouse embryos their expression domains are continuous regions of the developing brain contained within each other in the sequence Emx1 < Emx2 < Otx1 < Otx2. Recently Otx1 has been found to be specifically expressed during neurogenesis of layer 5 and 6 in the developing cerebral cortex. In order to better understand the role of Emx1 and Emx2 in the maturation of the cortex we analysed by in situ hybridization their expression patterns in the developing mouse cerebral cortex, from embryonic day 12.5 to adulthood. We found that Emx2 is expressed exclusively in proliferating cells of the ventricular zone whereas Emx1 is expressed in both proliferating and differentiated neurons, throughout the cortical layers and during all the developmental stages examined. Therefore, Emx2 gene products might control some biological parameters of the proliferation of cortical neuroblasts or of the subsequent cell migration of postmitotic neurons, leaving the cortical germinal zone. Conversely, Emx1 expression, which is confined exclusively to the dorsal telencephalon, characterizes most cortical neurons during proliferation, differentiation, migration and postnatal development and maturation.

Animals↗
PubMed1996

Dentate gyrus formation requires Emx2.

Emx 1 and 2 are the murine homologues of the Drosophila empty spiracles gene and based on their expression pattern may be involved in the regional specification of the mammalian forebrain. During early embryogenesis, Emx2 is expressed in the presumptive cerebral cortex and olfactory bulbs and later, in the hippocampus proper and dentate gyrus. The latter are involved in memory processes. To understand the role of Emx2 in vivo, we have mutated the gene in mice. Homozygous embryos die postnatally because of severe urogenital alterations. These mice present cerebral hemispheres with a reduced size and exhibit specific morphological alterations in allocortical structures of the medial wall of the brain. The dentate gyrus is missing and the hippocampus proper is reduced. The medial limbic cortex is also severely shortened. The development of the dentate gyrus is affected at the onset of its formation with defects in the neuroepithelium from which it originates. These findings demonstrate that Emx2 is required for the development of several forebrain structures.

Animals↗
PubMed1996

Vascular endothelial growth factor messenger ribonucleic acid expression in human ovarian and endometrial cancer.

Vascular endothelial growth factor (VEGF) is a previously discovered angiogenic factor that seems to influence the neoangiogenesis of neoplastic and non-neoplastic tissues. Substantial experimental evidence links tumor growth and metastasis with blood vessel formation. Tumor angiogenesis can be induced by factors released by the tumor cells themselves. A variety of transformed cell lines expresses the VEGF transcript and secretes an EGF-like protein, suggesting that this angiogenic factor may be one of the mediators of tumor angiogenesis. By Northern blot analysis and in situ hybridization, we investigated the expression of VEGF transcript in human ovarian and endometrial neoplasms. Messenger RNA encoding VEGF was detected in all tissues studied and was more densely expressed in endometrial carcinoma. VEGF expression was also identified in cells obtained from ovarian and endometrial ascitic fluid. VEGF mRNA, detected by in situ hybridization, was identified in the epithelial cells of endometrial adenocarcinoma. This distribution was localized primarily in the apices of the papillae. The prominence of VEGF mRNA levels in human ovarian and endometrial tumors demonstrates that VEGF may be involved in promoting tumor angiogenesis and stroma generation, acting as an endothelial cell mitogen.

Adenocarcinoma↗
PubMed1995

Transcriptional repression by the human homeobox protein EVX1 in transfected mammalian cells.

The human homeobox protein EVX1 (EVX1) is thought to play an important role during embryogenesis. In this study, the effect of EVX1 on gene transcription has been investigated in transfected mammalian cells. EVX1 expression represses transcription of a reporter gene directed by either cell-specific or viral promoter/enhancer sequences in a variety of mammalian cell lines and in a concentration-dependent manner. Transcriptional repression is independent of the presence of DNA-binding sites for EVX1 in all the promoters we tested. Furthermore, repression by EVX1 is evident also using a TATA-less minimal promoter in the reporter construct. A carboxyl-terminal proline/alanine-rich region of EVX1 seems to be responsible for the transcriptional repression activity, as suggested by transfection of EVX1 mutants. We speculate that the repressor function of EVX1 contributes to its proposed role in embryogenesis.

Animals↗
PubMed1995

Expression of HOXC4 homeoprotein in the nucleus of activated human lymphocytes.

We have analyzed the expression of homeoproteins of the HOX family in resting and activated lymphoid cells and in neoplastic lymphoid cell lines by the use of monoclonal antibodies (MoAbs) already shown to react with the homeoproteins HOXA10, HOXC6, and HOXD4, respectively. Anti-HOXA10 and C6 MoAbs DIDi not show any reactivity with the lymphoid cells tested, whereas anti-HOXD4 MoAb stained few resting peripheral blood lymphocytes (PBLs) and most phytohemagglutinin (PHA)-stimulated PBLs as early as 6 hours after stimulation. The pattern of staining of PHA-activated PBLs is reminiscent of the stages of nucleolar fragmentation in different phases of the cell cycle. The MoAb reacted also with activated or Epstein-Barr virus-transformed B cells, with clonal or polyclonal T and natural killer (NK) cells, with leukemic T-cell lines, and with a Burkitt's lymphoma cell line. RNAse protection experiments, per formed with probes specific for HOXD4 or for the highly homologous HOXA4, HOXB4, and HOXC4, belonging to the same paralogy group, indicated that only HOXC4 mRNA is present in resting or activated PBLs. Northern blot analysis on polyA+ RNA from activated PBLs or Raji cells showed the presence of two different HOXC4 transcripts of 2.8 and 1.9 kb. Gel retardation and Southwestern blot assays showed the presence of a 32-kD homeoprotein with DNA-binding properties typical of a HOX4 homeoprotein in nucleolar extracts of PHA-activated, but not of resting, lymphocytes. Taken together, these data indicate that the HOXC4 homeoprotein is expressed in activated and/or proliferating lymphocytes of the T-, B-, or NK-cell lineage, whereas it is weakly expressed in a minority of resting cells. The early expression and the nucleolar localization suggest an involvement of HOXC4 in the regulation of genes controlling lymphocyte activation and/or proliferation.

Antibodies, Monoclonal↗
PubMed1995

Emx and Otx gene expression in the developing mouse brain.

The homeobox genes Emx1, Emx2, Otx1 and Otx2 are all expressed in the rostral brain of embryos at E10. Their expression domains are continuous regions of the developing brain contained within each other, such that the expression domain of Otx2 contains that of the other three genes, the expression domain of Otx1 contains that of Emx1 and Emx2, and the expression domain of Emx2 contains that of Emx1. The Emx1 expression domain includes the dorsal telencephalon and it has a posterior boundary slightly anterior to that between the presumptive diencephalon and telencephalon, whereas the Otx2 expression domain covers almost the entire forebrain and midbrain. Starting from E10.75, Otx2 expression disappears progressively from the presumptive cerebral cortex, whereas Emx1, Emx2 and Otx1 are expressed in this structure until late gestation. In particular, Emx2 appears to be expressed exclusively in the germinal ventricular zone of the developing cerebral cortex.

Animals↗
PubMed1995

c-otx2 is expressed in two different phases of gastrulation and is sensitive to retinoic acid treatment in chick embryo.

We cloned the chick homologue of the mouse Otx2 gene, c-otx2, and analyzed its expression pattern during gastrulation. During mouse embryogenesis, Otx2 expression is first detected in the entire epiblast and after the formation of the primitive streak becomes confined to the most anterior region of the embryo corresponding to presumptive fore- and mid-brain. Similarly, two distinct phases of c-otx2 expression were observed in the chick. c-otx2 transcripts were first detected in the unincubated egg and up to stage XIII, in all epiblast, and forming hypoblast and mesoblast cells. During primitive streak progression, c-otx2 expression becomes progressively restricted to anterior regions and is mainly associated with Hensen's node. When the extension of the streak is maximal, transcripts are only found in Hensen's node. A second phase of c-otx2 expression starts during streak regression. c-otx2 transcripts are lost from the node and present in higher abundance in anterior neuroectoderm and mesendoderm, with the exception of forming notochord and floor plate. The first phase of expression bears strong similarity with that of c-gsc, a gene shown to be a marker for cells that have organizer activity in the chick. Therefore, we compared the expression of the two genes by double staining on the same embryo. This analysis demonstrated that c-otx2 is transcribed first and its expression in the hypoblast precedes that of c-gsc. On the other hand, c-gsc is an earlier marker of primitive streak cells. The expression domains of the two genes transiently overlap in Hensen's node and anterior mesendoderm, whereas only c-otx2 is expressed in neuroectodermal areas. The second phase of c-otx2 expression is sensitive to an early treatment with retinoic acid. This treatment abolishes c-otx2 expression in mesendoderm and restricts it to most anterior regions in the forming neural plate. In conclusion, our results suggest that c-otx2 expression is first associated with cells with an anterior mesendoderm fate and subsequently extends to anterior neuroectoderm.

Amino Acid Sequence↗
PubMed1995

Homeobox genes in vertebrate gastrulation.

The formation and anteroposterior patterning of the three definitive germ layers, ectoderm, or epiblast, is the common theme of vertebrate gastrulation. What changes from system to system is the geometry of these events and the nature of the non-epiblast transient structures implicated. A number of molecular markers, including a few homeobox genes and in particular goosecoid and Otx2, are now available that will hopefully allow us to explore the underlying molecular mechanisms and to establish biologically relevant homologies between the various systems.

Animals↗
PubMed1995

The Xenopus homologue of Otx2 is a maternal homeobox gene that demarcates and specifies anterior body regions.

In this paper we study Xotx2, a Xenopus homeobox gene related to orthodenticle, a gene expressed in the developing head of Drosophila. The murine cognate, Otx2, is first expressed in the entire epiblast of prestreak embryos and later in very anterior regions of late-gastrulae, including the neuroectoderm of presumptive fore- and mid-brain. In Xenopus, RNase protection experiments reveal that Xotx2 is expressed at low levels throughout early development from unfertilized egg to late blastula, when its expression level significantly increases. Whole-mount in situ hybridization shows a localized expression in the dorsal region of the marginal zone at stage 9.5. At stage 10.25 Xotx2 is expressed in dorsal bottle cells and in cells of the dorsal deep zone fated to give rise to prechordal mesendoderm, suggesting a role in the specification of very anterior structures. In stage 10.5 gastrulae, Xotx2 transcripts start to be detectable also in presumptive anterior neuroectoderm, where they persist in subsequent stages. Various treatments of early embryos cause a general reorganization of Xotx2 expression. In particular, retinoic acid treatment essentially abolishes Xotx2 expression in neuroectoderm. Microinjection of Xotx2 mRNA in 1-, 2- and 4-cell stage embryos causes the appearance of secondary cement glands and partial secondary axes in embryos with reduced trunk and tail structures. The presence of the Xotx2 homeodomain is required to produce these effects. In particular, this homeodomain contains a specific lysine residue at position 9 of the recognition helix. Microinjected transcripts of Xotx2 constructs containing a homeodomain where this lysine is substituted by a glutamine or a glutamic acid residue fail to cause these effects.

Amino Acid Sequence↗
PubMed1995

Nucleolar localisation of three Hox homeoproteins.

Homeoproteins encoded by genes of the Hox family are nuclear proteins believed to act as transcription factors and to participate in the determination of the body plan. Here we show that in several vertebrate cells, they exhibit a subnuclear localisation associated with the nucleolus. We used monoclonal antibodies to study the distribution of three homeoproteins, namely HOXB7, HOXC6 and HOXD4. The immunoreactivity to antibodies against HOXC6 protein in Xenopus laevis embryonic tissues is restricted to one or two spots within the nucleus; this distribution partially overlaps that of fibrillarin, a protein of the fibrillar zone of the nucleoli. Indirect immunofluorescence analysis of the distribution of HOXB7 protein in 3T3 cells, and of HOXD4 protein in human neuroblastoma and Raji lymphoma cell lines and activated lymphocytes, results invariably in a nucleolar localisation. Purified nucleoli from stimulated T lymphocytes, and Raji cells contain an activity capable of binding, in a gel retardation assay, to an oligonucleotide specifically recognised by the HOXD4 homeoprotein. This activity is specifically removed by anti-HOXD4 antibodies and is found associated in southwestern blots with a single band with an apparent M(r) of 30,000, corresponding to that of recombinant HOXD4. The functional significance of the nucleolar localisation of Hox proteins remains to be determined.

Animals↗
PubMed1995

Expression pattern of two otx genes suggests a role in specifying anterior body structures in zebrafish.

We isolated two zebrafish sequences containing a homeobox related to orthodenticle (otd), a gene expressed in the developing head of Drosophila. One of these is clearly homologous to Otx1, a homeobox gene previously reported to be expressed in the developing rostral brain of the mouse. We termed this zebrafish gene otx1. The second gene is not as closely related to Otx1 and is equally divergent from Otx2, a second homeobox gene expressed in the developing rostral brain of the mouse. We termed it otx3, even if a corresponding murine Otx3 gene has not been reported yet. Both genes are expressed in early-gastrula zebrafish embryos in the involuting presumptive anterior mesendoderm. With the extension of the body axis, the expression domain of both genes extends to neuroectodermal regions fated to become fore- and mid-brain. From this stage the expression domains of the two genes differ slightly from each other but both cover the rostral brain with a sharp posterior boundary coinciding with that between midbrain and hind-brain. This late expression closely corresponds to that of the murine Otx1 gene, whereas the earliest expression of both zebrafish otx genes is different from that of Otx1 and reminiscent of that of Otx2 in the mouse. In this light, the zebrafish otx1 and otx3 genes appear to share some expression features of both murine Otx1 and Otx2. It will be of considerable interest to study the specific role of the various genes of the otx family in the development of the zebrafish brain regions. The peculiar spatio-temporal pattern of these genes during early zebrafish gastrulation suggests a role of this gene family in interactions between anterior mesendoderm and neuroectoderm.

Amino Acid Sequence↗
PubMed1994

Order of six loci at 2q24-q31 and orientation of the HOXD locus.

HOXD, a gene cluster of 9 homeobox genes of the Antennapedia class; EVX2, a homeobox gene related to Drosophila-even-skipped gene; DLX1 and DLX2, two homeobox genes related to the Drosophila distal-less gene; and TTN and NEB, the genes for the two giant molecules titin and nebulin, both involved in the sarcomere structure, have been previously mapped to human 2q31-q32 and to mouse chromosome 2. We studied their relative order in human by applying FISH to three balanced chromosome rearrangements each with a breakpoint at 2q31. Unambiguous results led us to map these genes and to orient the HOXD locus along chromosome 2 according to the following order: cen, NEB, DLX1-DLX2, EVX2, HOXD (5'-3'), TTN, tel. All of these genes are part of a syntenic region covering 5-10 cM and conserved since the divergence of humans and rodents, and thus the same loci order should be present in mouse. FISH in metaphases of approximately 500 bands localized NEB to 2q24.1-q24.2, while HOXD and TTN were localized to 2q31.

Animals↗
PubMed1994

The thyroid transcription factor-1 gene is a candidate target for regulation by Hox proteins.

Vertebrate Hox homeobox genes are transcription factors which regulate antero-posterior axial identity in embryogenesis, presumably through activation and/or repression of downstream target genes. Some of these targets were reported to code for molecules involved in cell-cell interactions, whereas no relationship has yet been demonstrated between Hox genes and other transcription factors involved in determining and/or maintaining tissue specificity. The thyroid transcription factor-1 (TTF-1) is a homeodomain-containing protein required for expression of thyroid-specific genes. A 862 bp 5' genomic fragment of the rat TTF-1 gene, conferring thyroid-specific expression to a reporter gene, was sufficient to mediate transactivation by the human HOXB3 gene in co-transfection assay in both NIH3T3 or HeLa cells. HOXB3 is expressed in early mammalian embryogenesis in the anterior neuroectoderm, branchial arches and their derivatives, including the area of the thyroid primordia and thyroid gland. Transcription of the TTF-1 promoter is induced only by HOXB3, while its paralogous gene HOXD3 or other Hox genes expressed more posteriorly (HOXA4, HOXD4, HOXC5, HOXC6, HOXC8 and Hoxd-8) have no effect. Transactivation by HOXB3 is mediated by two binding sites containing an ATTA core located at -100 and +30 from the transcription start site. DNase I footprinting experiments show that the two sites bind HOXB3 protein synthesized in both Escherichia coli and eukaryotic cells, as well as nuclear factor(s) present in protein extracts obtained from mouse embryonic tissues which express group 3 Hox genes and TTF-1. Some of the DNA-protein complexes formed by the embryonic extracts are indistinguishable from those generated by HOXB3.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Chromosome locations of human EMX and OTX genes.

We have determined the chromosomal localization of four human homeobox-containing genes, EMX1, EMX2, OTX1, and OTX2, related to Drosophila genes expressed in the developing head of the fly. Murine homologs of these genes are expressed in specific nested domains in the developing rostral brain of midgestation embryos. DNAs from a panel of 19 rodent-human hybrids, each carrying one or a few human chromosomes such that most human chromosome regions were represented, were tested for the presence of the four gene loci by filter hybridization to radiolabeled probes. Regional chromosomal localization was determined by similarly testing DNAs from hybrid mapping panels for each of the candidate chromosomes. Finally, fluorescence in situ hybridization of cosmid clones for these loci refined the locations, two of which were in the vicinity of previously mapped orphan homeobox genes and two of which were near each other. OTX2, the earliest and most widely expressed gene, maps to chromosome region 14q21-q22; the OTX1 locus maps to 2p13; EMX2 maps to 10q26.1; and EMX1, the most narrowly and lately expressed, maps to 2p14-p13. Thus, these homeobox-containing genes involved in brain development are not linked to any of the four HOX clusters on 7p15-p14, 17q21-q22, 12q12-q13, and 2q31. However, the OTX1 and EMX1 loci may be closely linked on or near 2p13, prompting speculation that a clustered gene structure could have functional significance, as is presumably the case for the HOX clusters.

Animals↗
PubMed1994

Inhibition of retinoic acid-induced activation of 3' human HOXB genes by antisense oligonucleotides affects sequential activation of genes located upstream in the four HOX clusters.

Most homeobox genes belonging to the Hox family are sequentially activated in embryonal carcinoma cells upon treatment with retinoic acid. Genes located at the 3' end of each one of the four Hox clusters are activated first, whereas upstream Hox genes are activated progressively later. This activation has been extensively studied for human HOX genes in the NT2/D1 cell line and shown to take place at the transcriptional level. To understand the molecular mechanisms of sequential HOX gene activation in these cells, we tried to modulate the expression of 3' HOX genes through the use of antisense oligonucleotides added to the culture medium. We chose the HOXB locus. A 5- to 15-fold reduction of the expression of HOXB1 and HOXB3 was sufficient to produce a significant inhibition of the activation of the upstream HOXB genes, as well as of their paralogs in the HOXA, HOXC, and HOXD clusters. Conversely, no effect was detectable on downstream HOX genes. The extent of this inhibition increased for progressively more-5' genes. The stability of the corresponding mRNAs appeared to be unaffected, supporting the idea that the observed effect might be mediated at the transcriptional level. These data suggest a cascade model of progressive activation of Hox genes, with a 3'-to-5' polarity.

Base Sequence↗
PubMed1994

Expression patterns of Hoxb genes in the Xenopus embryo suggest roles in anteroposterior specification of the hindbrain and in dorsoventral patterning of the mesoderm.

Hox genes are thought to participate in patterning the anteroposterior (a-p) axis during vertebrate embryogenesis. In this investigation, the spatial expression of six Hoxb genes was analyzed in early embryos of Xenopus laevis by in situ hybridization. Hoxb gene expression was first detected in late gastrulae/early neurulae, by which stage, the characteristic spatially colinear Hoxb gene expression sequence was already apparent. Dissection experiments indicated that the establishment of these localized expression patterns coincides with the acquisition of anteroposterior positional information along the main body axis. The Hoxb genes continued to be expressed in similar domains along the anteroposterior axis at all developmental stages examined, although there were some changes in expression at the cellular level. Interestingly, the 3' genes, Hoxb-1, Hoxb-3, and Hoxb-4 were expressed in very restricted domains in the future hindbrain, while Hoxb-5, Hoxb-7, and Hoxb-9 transcripts were present along the entire presumptive spinal cord. It was thus notable that the 5' Hoxb genes exhibited different types of expression domain than the 3' Hoxb genes. These observations suggest that there may be different mechanisms regulating the expression of the 3' and 5' Hoxb genes. Expression of all of the Hoxb genes analyzed, except Hoxb-4, was predominantly detectable in the central nervous system or in neural crest-derived structures. Hoxb-4 mRNA was detected in the central nervous system, but interestingly, the major expression site for this gene was the somites. The other Hoxb genes tested failed to show significant expression in the somitic mesoderm, although transcripts from genes 5' from Hoxb-4 were detected in other mesodermal tissues. In the vertebrate trunk, anteroposterior patterning of the CNS is thought to be regulated by the somites. The results obtained here for Xenopus embryos did not explicitly support the idea of a Hoxb code for the somites, although we cannot rule this out. Instead, interestingly, the data were consistent with a role for Hoxb genes in dorsoventral patterning of the mesoderm.

Animals↗
PubMed1994

Vertebrate homeobox genes.

In the former part of the review the principal available data about Hox genes, their molecular organisation and their expression in vertebrate embryos, with particular emphasis for mammals, are briefly summarized. In the latter part we analysed the expression of four mouse homeobox genes related to two Drosophila genes expressed in the developing head of the fly: Emx1 and Emx2, related to ems, and Otx1 and Otx2, related to otd.

Animals↗