Biomedical subjects

E Boncinelli

Publications and source records attributed to E Boncinelli.

At least 91 records · Page 5Linked to original sources

PubMed1994

From fly head to mammalian forebrain: the story of otd and Otx.

Many of the genes responsible for axial patterning have been conserved throughout evolution. Recent studies of invertebrates and vertebrates are extending our understanding of this molecular conservation into the anterior region of the animal embryo, including the developing brain. These studies suggest that this domain is specified according to a genetic paradigm that is different from that governing trunk development, and are also beginning to provide insights into the structures that underlie the rostral brain.

Animals↗

PubMed1994

Early CNS development: distal-less related genes and forebrain development.

The ever increasing number of molecular markers available for the study of developing structures is revolutionizing developmental neurobiology. It is now possible to identify entirely new groups of cells and trace their lineages among all other cell populations. Recent studies on the expression domains of a variety of genes specifically expressed in the developing CNS are beginning to give us a better understanding of the early regionalization of the CNS and, in particular, of the forebrain.

Amino Acid Sequence↗

PubMed1994

Cloning and characterization of a new human Xq13 gene, encoding a putative helicase.

We describe the cloning and characterization of a new human Xq13 gene (XH2), extending over a 220 kb genomic stretch between MNK and DXS56. The gene, which undergoes X-inactivation, contains a 4 kb open reading frame and encodes a putative NTP-binding nuclear protein homologous to several members of the helicase II superfamily. The murine homologue maps to the syntenic genetic interval, between Pgk1 and Xist. In situ hybridization studies in mouse reveal precocious, widespread expression of the murine homologue of XH2 at early stages of embryogenesis, and more restricted expression during late developmental stages and at birth. XH2 is a new member of an expanding family of proven and putative helicases, sharing six conserved, collinear domains. In particular, the XH2 protein shows homology with yeast RAD54. Type II helicases have been implicated in nucleotide excision repair and the initiation of transcription. This new gene, represents a potential candidate for several genetic disorders mapped to human Xq13.

Amino Acid Sequence↗

PubMed1994

Differential expression of two different homeobox gene families during mouse tegument morphogenesis.

The expression of six genes belonging to two different homeobox gene families was studied during the embryonic and postnatal morphogenesis of head and body regions of the mouse integument. The first family included the Otx1 and Otx2 genes, both related to the orthodenticle Drosophila gene and the second was represented by four members of the Antennapedia class HOX genes: Hoxc8 and three Hoxd genes, d9, d11 and d13. In situ hybridizations with 35S labeled antisense RNA probes were performed on head serial frontonasal sections, as well as entire embryo and postnatal tail longitudinal sections. The expression of these genes shows a differential spatiotemporal pattern along the cephalo-caudal axis. In 12.5-day and 15.5-day embryos, the Otx2 gene expression is restricted to the nasal epithelium and its associated glands, while the Otx1 transcripts are present in both nasal and facial integuments, including nasal glands and hair vibrissa follicles. The Hoxc8 expression first appears in skin at 14.5 days of gestation in the sternal region and is extended at 16.5 days to the thoracic ventral and lumbar dorsal regions. The Hoxd9 and Hoxd11 genes are only expressed in the caudal skin from 14.5 days of gestation. The Hoxd13 transcripts are the last to appear, 2 days after birth, and are limited to the last epidermal cells to differentiate, i.e. those of the hair matrix of the caudal pelage hair follicles. Taken together, these observations strengthen the hypothesis that different homeobox gene families specify the regional identity of the skin in the cephalic and body regions.

Animals↗

PubMed1993

Characteristic patterns of HOX gene expression in different types of human leukemia.

Homeobox-containing genes are a network of genes encoding DNA-binding proteins highly conserved throughout evolution. They are involved in the control of normal development as well as in the regulation of gene expression in adult differentiating systems, including hematopoiesis. Aberrant expression of homeobox-containing genes has recently been related to leukemic phenotype. Human homeobox-containing genes of the HOX family are organized into 4 large clusters. We have analyzed the expression of HOX genes in different types of human leukemia to investigate whether the physical organization of HOX loci reflects a regulatory hierarchy involved in the differentiation of hematopoietic cells or whether HOX gene expression might contribute to the leukemic phenotype. Our results show that HOX genes are coordinately regulated in blocks in myeloid cells whereas they appear to function as isolated genes in lymphoid cells. Six contiguous genes of the HOX2 locus, highly expressed in acute non-lymphocytic leukemia, are switched off in chronic myelogenous leukemia, suggesting that down-regulation of HOX2 genes might be required for cell maturation of the myeloid lineages. In contrast, a few scattered genes are active in lymphoid populations. These observations suggest that hematopoietic cells express a repertoire of HOX genes characteristic of a particular cell lineage at a specific stage of differentiation. The characteristic patterns of HOX gene expression may reflect the potentially important role that these genes play in cell lineage determination during both normal and leukemic hematopoiesis.

Cell Differentiation↗

PubMed1993

A vertebrate gene related to orthodenticle contains a homeodomain of the bicoid class and demarcates anterior neuroectoderm in the gastrulating mouse embryo.

We studied the expression of two vertebrate homeobox genes, Otx1 and Otx2, related to orthodenticle, a gene expressed in the developing head of Drosophila. Both genes are expressed in restricted regions of the developing rostral brain including the presumptive cerebral cortex and olfactory bulbs. The expression patterns of the two genes in diencephalon suggest that they both have a role in establishing the boundary between presumptive dorsal and ventral thalamus. They are also expressed in regions of the developing olfactory, auricolar and ocular system, including the covering of the optic nerve. Otx1 expression is detectable from day 8 of gestation in telencephalic, diencephalic and mesencephalic regions. From day 10.5 of gestation its expression extends to some metencephalic areas. Otx2 appears to be already expressed in the epiblast of prestreak embryos. It persists in the entire embryonic ectoderm for some time after the onset of gastrulation. In midstreak embryos its expression appears progressively restricted to the anterior embryonic ectoderm corresponding to presumptive fore- and mid-brain. In early midgestation embryos it is expressed in telencephalic, diencephalic and mesencephalic regions but from day 11.75 of gestation its expression disappears from dorsal telencephalon and is confined to diencephalic and mesencephalic regions. Otx2 is one of the earliest genes expressed in the epiblast and immediately afterwards is expressed in anterior neuroectoderm, demarcating rostral brain regions even before headfold formation. Its gene product contains a homeodomain of the bicoid class and is able to recognize and transactivate a bicoid target sequence.

Amino Acid Sequence↗

PubMed1993

Emx and Otx homeobox genes in the developing mouse brain.

We have analyzed the expression of four mouse homeobox genes related to two Drosophila genes expressed in the developing head of the fly. Two of these genes, Emx1 and Emx2, are related to empty spiracles, and two genes, termed Otx1 and Otx2, are related to orthodenticle. These genes are all expressed in the developing rostral brain of E10 mouse embryos and their expression domains can be compared. Otx2 is expressed in all dorsal and most ventral regions of telencephalon, diencephalon, and mesencephalon. The Otx1 expression domain is similar to that of Otx2, but smaller and contained within it. The Emx2 expression domain is comprised of dorsal telencephalon and small diencephalic regions, both dorsally and ventrally. Finally, Emx1 expression is exclusively confined to the dorsal telencephalon. At the time when regional specification of major brain regions takes place, the expression domains of the four genes appear to be continuous regions contained within each other in the sequence Emx1 < Emx2 < Otx1 < Otx2. The first appearance of transcripts of the four genes is also sequential: Otx2 is expressed first (E5.5), followed by Otx1 and Emx2 (E8-8.5), and finally by Emx1 (E9.5). It is tempting to speculate about a possible role of the four genes in establishing and/or signalling the limits of the various embryonic brain regions in a discrete progressive process with its center in the dorsal telencephalon.

Animals↗

PubMed1993

Changes in the prevalence of an homeobox gene product during muscle differentiation.

We have studied by immunohistofluorescence and confocal microscopy the localization of the XlHbox-1 protein, the product of a Xenopus class 1 homeobox gene corresponding to the human HOX 3C, during the development of Xenopus laevis mesodermal derivatives. The protein, not present at early stages of embryonic development, can first be detected in the neurula where it is weakly expressed in the rostral part of the spinal cord and in the nuclei of the corresponding somites. At later stages of mesodermal development, very high levels of the molecule are present in the nuclei of a small group of myogenic cells in the most dorsal aspect of the myotome, while the nuclei of differentiated muscle fibers within the myotome are either stained weakly or completely negative. A similar transient expression of XlHbox-1 gene product during myogenesis occurs during muscle differentiation in the limb bud and during differentiation of visceral smooth muscles from the lateral plate mesoderm. In both cases the nuclei of precursor cells contain high level of this protein which is rapidly down regulated during further muscle differentiation. In myogenic areas the modulation of XlHbox-1 expression invariably parallels that of the neural cell adhesion molecule N-CAM. These data are the first evidence that a homeobox gene belonging to the Antennapedia-Bithorax complex is transiently expressed in early phases of muscle differentiation. The transient expression of homeobox genes in early phases of embryonic development could act synergistically with the expression of other myogenic transcriptional factors to specify a fine level of differentiation of the muscle cells along the body axis.

Animals↗

PubMed1993

Colinearity in the Xenopus laevis Hox-2 complex.

Here we describe experiments detailing the developmental expression, and the inducibility by all-trans retinoic acid (RA) of six members of the Xenopus Hox-2 complex of homeobox-containing genes. We first report the cloning and characterisation of two novel Xenopus Hox-2 genes (Xhox2.7 and Xhox2.9), and provide evidence that the six genes studied are indeed closely linked in the same chromosomal complex. We next show that all six genes are expressed in a spatial sequence which is colinear with their putative 3' to 5' chromosomal sequence and that five of them are also expressed in a 3' to 5' colinear temporal sequence. The sixth gene (Xhox2.9) has an exceptional spatial and temporal expression pattern. The six genes all respond to RA by showing altered spatiotemporal expression patterns, and are also hyperinduced by RA, with a sequence of magnitudes which is colinear with their 3' to 5' chromosomal sequence and with their spatial and temporal expression sequences. Our data also suggest a pre-existing anteroposterior polarity in the embryo's competence to respond to RA. These results complement and extend previous findings made using murine and avian embryos and mammalian cell lines. They suggest a mechanism whereby an endogenous retinoid could help to provide positional information in the early embryo.

Amino Acid Sequence↗

PubMed1993

Expression of homeobox-containing genes in primary and metastatic colorectal cancer.

Homeobox genes are a network of genes encoding nuclear proteins functioning as transcriptional regulators. Human and murine homeobox genes of the HOX family are organised in four clusters on different chromosomes. Gene order within each cluster is highly conserved, perhaps in direct relation to their expression. Homeobox genes have recently been involved in normal development and oncogenesis. We have analysed HOX gene expression in normal human colon and in primary and metastatic colorectal carcinomas. The majority of HOX genes are active in normal adult colon and their overall expression pattern is characteristic of this organ. Furthermore, the expression of some HOX genes is identical in normal and neoplastic colon indicating that these genes may exert an organ-specific function. In contrast, other HOX genes exhibit altered expression in primary colon cancers and their hepatic metastases which may suggest an association with colon cancer progression.

Colon↗

PubMed1993

Conserved homeobox genes in the developing brain.

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 empty spiracles and Otx1 and Otx2, related to orthodenticle. The four genes are all expressed in the developing rostral brain of E10 mouse embryos in a specific manner. Otx2 is expressed in every dorsal and most ventral regions of telencephalon, diencephalon and mesencephalon. The Otx1 expression domain is similar to that of Otx2, but contained within it. The Emx2 expression domain is comprised of dorsal telencephalon and small diencephalic regions, both dorsally and ventrally. Finally, Emx1 expression is exclusively confined to the dorsal telencephalon. Thus, at this stage the expression domains of the four genes appear to be continuous regions contained within each other in the sequence Emx1 < Emx2 < Otx1 < Otx2. The first appearance of transcripts of these genes is also sequential: Otx2 is expressed first (E5.5), followed by Otx1 and Emx2 (E8-8.5) and finally by Emx1 (E9.5). These findings suggest a role of the four genes in establishing cell fates within the limits of the various embryonic brain regions in a discrete progressive process with its center in the dorsal telencephalon. The structural organization and the regulation of these genes appear remarkably conserved in evolution.

Animals↗

PubMed1993

Homeobox genes in the developing central nervous system.

A number of genes containing sequences coding for DNA-binding domains homologues to homeobox sequences in Drosophila have been isolated in vertebrate and their mechanism of action have been studied. In Particular Hox family genes share with Drosophila homeotic genes a genomic organization in gene clusters and an expression pattern that is similar in a number of important respects. In situ hybridization experiment have shown that there is a strict correspondence, or colinearity, between the order of the Hox genes (3' to 5') within the chromosomal cluster and that of their expression domains (anterior to posterior) in the embryo. Recent data obtained in embryonal carcinoma (EC) cells induced to differentiate by retinoic acid (RA) cast some light on the molecular mechanisms underlying the colinear expression of the Hox genes.

Amino Acid Sequence↗

PubMed1993

Expression of HOX C homeobox genes in lymphoid cells.

The class I homeobox genes located in four clusters in mammalian genomes (HOX A, HOX B, HOX C, and HOX D) appear to play a major role in fetal development. Previous surveys of homeobox gene expression in human leukemic cell lines have shown that certain HOX A genes are expressed only in myeloid cell lines, whereas HOX B gene expression is largely restricted to cells with erythroid potential. We now report a survey of the expression patterns of 9 homeobox genes from the HOX C locus in a panel of 24 human and 7 murine leukemic cell lines. The most striking observation is the lymphoid-specific pattern of expression of HOX C4, located at the 3' end of the locus. A major transcript of 1.9 kilobases is observed in both T-cell and B-cell lines. HOX C4 expression is also detected in normal human marrow and peripheral blood lymphocytes, but not in mature granulocytes or monocytes. HOX C8 is also expressed in human lymphoid cells but is expressed in other blood cell types as well. However, the HOX C8 transcript pattern is lineage specific. These data, in conjunction with earlier findings, suggest that homeobox gene expression influences lineage determination during hematopoiesis.

Animals↗

PubMed1992

Differential DNA binding properties of three human homeodomain proteins.

The products of three human homeobox containing (HOX) genes, 2C, 3C and 4B, were produced in insect cells using the Baculovirus expression system and purified to near homogeneity. In this system we observed that the DNA binding forms of the three proteins are not glycosylated. HOX 3C and 4B are phosphorylated in insect cells, while HOX 2C is not. The three HOX proteins bind to a DNA sequence known to be a target site for Antennapedia protein with a very similar affinity (Kd = 1-2 x 10(-9) M). We then measured their binding properties to four human sequences present in the HOX 3D, 4C, 1C and 4B promoters. Two of these sequences have been reported to be binding sites for HOX proteins. HOX 2C, 3C and 4B behaved quite differently, showing low affinity for promoters of genes located upstream from their own gene in the HOX clusters and a higher affinity for regulatory sequences of their own gene and downstream HOX genes.

Animals↗

PubMed1992

Nested expression domains of four homeobox genes in developing rostral brain.

Insight into the genetic control of the identity of specific regions along the body axis of vertebrates has resulted primarily from the study of vertebrate homologues of regulatory genes operating in the Drosophila trunk, but little is known about the development of most anterior regions of the body either in flies or vertebrates. Three Drosophila genes have been identified that are important in controlling the development of the head, two of which, empty spiracles and orthodenticle, have been cloned and shown to contain a homeobox. We previously cloned and characterized Emx1 and Emx2, two mouse genes related to empty spiracles that are expressed in restricted regions of the developing forebrain, including the presumptive cerebral cortex and olfactory bulbs. Here we report the identification of Otx1 and Otx2, which are related to orthodenticle. We have compared the expression domains of the four genes in the developing rostral brain of mouse embryos at a developmental stage, day 10 post coitum, when they are all expressed. Otx2 is expressed in every dorsal and most ventral regions of telencephalon, diencephalon and mesencephalon. The Otx1 expression domain is similar to that of Otx2, but contained within it. The Emx2 expression domain is comprised of dorsal telencephalon and small diencephalic regions, both dorsally and ventrally. Finally, Emx1 expression is exclusively confined to the dorsal telencephalon. Thus at the time when regional specification of major brain regions takes place, the expression domains of the four genes seem to be continuous regions contained within each other in the sequence Emx1 less than Emx2 less than Otx1 less than Otx2.

Amino Acid Sequence↗

PubMed1992

HOX gene expression in normal and neoplastic human kidney.

As a consequence of transformation, cancer cells generally lose some of their differentiative properties. Thus, alterations interfering with the genetic mechanisms required to maintain embryonic determination could lead to tumorigenesis. Homeobox genes are a network of genes encoding nuclear proteins containing DNA-binding homeodomains that are highly conserved throughout evolution. They are expressed in a stage-related fashion in the developing embryo and, in adult life, in normal tissues. In mice and humans, homeobox genes of the HOX family are organized in 4 clusters on different chromosomes which have presumably evolved by duplication of a primordial gene cluster. Strikingly, the order of genes within each cluster is also highly conserved throughout evolution, suggesting that the physical organization of HOX genes might be essential for their expression. Recent reports indicate that homeobox mutant mice display morphological abnormalities or show neoplastic alterations, and that growth factors can turn on homeobox genes. We have studied the expression of the Antennapedia-like HOX genes in normal human kidney and in renal carcinomas. The great majority of the HOX genes analyzed are expressed in a peculiar manner in normal kidney: blocks of genes, even entire HOX loci, are coordinately regulated. Alterations in HOX gene expression in renal carcinoma can be observed in 2 genes of the HOX-2 locus, HOX-2A and HOX-2E, which are actively expressed in normal kidney and silent in cancer biopsies. The HOX-3H gene is not expressed in normal kidney whereas the HOX-3H transcripts are present in renal carcinomas. Homeobox genes within the 4 HOX loci can be aligned on the basis of the maximal sequence homology of their homeodomains: this alignment defines 13 paralogous gene groups. In renal carcinomas, genes of group 10 (HOX-1D, 2F, 3E, 4B) display a marked difference in their transcript classes when compared to those of normal kidney. Our findings suggest an association between altered HOX gene expression and kidney cancer.

Carcinoma, Renal Cell↗

PubMed1992

The upstream region of the human homeobox gene HOX3D is a target for regulation by retinoic acid and HOX homeoproteins.

We studied the structure, regulation and expression of HOX3D, a human homeobox gene located in the HOX3 cluster on chromosome 12. HOX3D is developmentally regulated during embryogenesis and is activated by retinoic acid (RA) in cultured embryonal carcinoma (EC) cells. Transfection of HOX3D upstream genomic sequences linked to a reporter gene allowed the functional definition of its promoter, containing a canonical TATA element. This promoter directs the expression of the reporter gene in EC cells after induction with RA, and binds RA-induced nuclear factor(s) through a conserved palindromic sequence located approximately 100 bp upstream of the transcription start site. The HOX3D promoter is transactivated in both human and murine cells when cotransfected with vectors expressing the protein product of the upstream gene HOX3C and the paralogs of further upstream genes in the HOX4 cluster (i.e. HOX4D, HOX4C and the murine Hox 4.3). The HOX3D protein, and those encoded by the downstream gene HOX3E and its paralog HOX4B are instead inactive. HOX4C and HOX4D proteins synthesized in bacteria bind to the same conserved sequence located around position -120, as well as to the TATA box and immediately upstream and downstream nucleotides. These data provide evidence that cross-regulatory interactions between mammalian homeogenes take place in cultured cells, thus raising the possibility that a regulatory network may exist in vivo. The sequences on the HOX3D promoter involved in cross-regulation are different from those binding nuclear factors induced by RA.

Amino Acid Sequence↗

PubMed1992

Analysis of the murine Hox-2.7 gene: conserved alternative transcripts with differential distributions in the nervous system and the potential for shared regulatory regions.

In this study we have investigated the organization and regulation of the mouse Hox-2.7 gene. There are several alternative transcripts some of which are conserved between mouse and humans. By Northern and in situ analysis we are able to identify at least three types of transcripts which are different in size and splicing pattern and have distinctly different boundaries of expression in the nervous system. One subset of the endogenous transcripts has a boundary of expression that corresponds to the adjacent Hox-2.8 gene instead of Hox-2.7. In another type of transcript there is an alternative reading frame which predicts a protein that has homology to an enzyme ATPase and suggests that a non-homeobox containing gene may be located in the Hox-2 cluster. A Hox-2.7-lacZ transgene is expressed in a similar pattern to the endogenous gene in that spatially-restricted domains of expression are seen in the branchial arches, neural tube, paraxial mesoderm (somites), cranial ganglia, neural crest and gut. However, the anterior boundaries of transgene expression only correspond to the subset of Hox-2.7 transcripts which map to the Hox-2.8 boundary. The proximity of a Hox-2.7 promoter to regions which regulate the adjacent Hox-2.6 gene and the expression of transgenic and endogenous transcripts in a Hox-2.8 pattern, suggest that regulatory elements may be shared by neighbouring genes to establish the complete expression pattern.

Amino Acid Sequence↗