Search PubMed⌕ Search

Biomedical subjects

E Boncinelli

Publications and source records attributed to E Boncinelli.

At least 127 records · Page 7Linked to original sources
PubMed1989

The human HOX gene family.

We report the identification of 10 new human homeobox sequences. Altogether, we have isolated and sequenced 30 human homeoboxes clustered in 4 chromosomal regions called HOX loci. HOX1 includes 8 homeoboxes in 90 kb of DNA on chromosome 7. HOX2 includes 9 homeoboxes in 180 kb on chromosome 17. HOX3 contains at least 7 homeoboxes in 160 kb on chromosome 12. Finally, HOX4 includes 6 homeoboxes in 70 kb on chromosome 2. Homeodomains obtained from the conceptual translation of the isolated homeoboxes can be attributed to 13 homology groups on the basis of their primary peptide sequence. Moreover, it is possible to align the 4 HOX loci so that corresponding homeodomains in all loci share the maximal sequence identity. The complex of these observations supports and extends an evolutionary hypothesis concerning the origin of mammalian and fly homeobox gene complexes. We also determined the coding region present in 3 HOX2 cDNA clones corresponding to HOX2G, HOX2H and HOX2I.

Amino Acid Sequence↗
PubMed1989

Segmental expression of Hox-2 homoeobox-containing genes in the developing mouse hindbrain.

The vertebrate hindbrain develops in a segmental pattern, with distinctive groups of neurons originating from different segments. We report here that members of the Hox-2 cluster of murine homoeobox genes are expressed in segment-specific patterns in the developing hindbrain, with successive genes having boundaries at two-segment intervals. These data indicate that Hox genes specify segment phenotype, a role analogous to that of their Drosophila homologues.

Animals↗
PubMed1989

Posttranscriptional control of human homeobox gene expression in induced NTERA-2 embryonal carcinoma cells.

We have studied the expression of four human homeobox genes representative of four different clusters (i.e., HOX-1, HOX-2, HOX-3 and HOX-5) in the embryonal carcinoma (EC) cell line NT2/D1. Following treatment with retinoic acid (RA), these cells differentiate into several cell types, including neurons, and steadily accumulate polyadenylated transcripts derived from the genes in a period ranging from 18 hr to 14 days of RA treatment. The sizes of major transcripts in differentiated EC cells coincide with those previously detected by the same probes in human embryos. Nuclear run-on transcriptional analysis showed no difference in the transcription rate of the four homeobox genes in differentiated vs. undifferentiated EC cells. Inhibition of protein synthesis by 5-18 hr of treatment of undifferentiated cells with cycloeximide causes accumulation of some homeobox transcripts at levels comparable to those observed after 18 hr of RA induction, although it does not cause superinduction in fully differentiated cells. These data suggest that the activation of homeobox gene expression in RA-induced EC cells is controlled, at least in part, by posttranscriptional mechanisms.

Amino Acid Sequence↗
PubMed1989

Three new class I HLA alleles: structure of mRNAs and alternative mechanisms of processing.

Sixteen HLA class I clones have been isolated from a SV40-transformed human fibroblast line (GM637) cDNA library. The clones, characterized by hybridization to ABC locus-specific probes and sequence analysis, correspond to transcripts from four different class I genes: A2, A10, Cw4, and Cw6 (or Cw7), as implied by cell typing. Only the A2 sequence was known. The nucleotide and deduced amino acid sequence of the new alleles are reported here, and their structural features are discussed. Two independent cDNAs of A2 specificity display an unusual polyadenylation site located 100 bp upstream from the canonical one. Moreover, two cDNAs pertaining to the same C allele display two alternative mechanisms of splicing, which cause either presence or absence in mature transcripts of the transmembrane exon 5 sequence. Transcripts missing this region are predicted to synthesize a nonmembrane-bound, secreted antigen. A soluble protein, specifically reacting with class I-specific HLA antibodies, is found in the supernatant of the GM637 cells. The significance of HLA class I transcripts generated by differential processing is discussed.

Alleles↗
PubMed1989

Organization of human class I homeobox genes.

We report the genomic organization of 20 human class I homeoboxes and the predicted primary sequence of the encoded homeodomains. These homeoboxes are clustered in four complex HOX loci on chromosomes 2, 7, 12, and 17. The homeoboxes of one HOX locus can be aligned to the homeoboxes of the other HOX loci so that corresponding homeodomains in all loci can share the maximal peptide sequence identity. This correspondence of individual homeoboxes in different chromosomal loci suggests the hypothesis of large-scale duplications of a single complex locus. The existence of an ancestral complex locus might have predated the divergence of vertebrates and invertebrates.

Amino Acid Sequence↗
PubMed1988

The relationship of modulation of major histocompatibility complex class I antigens to retrovirus transformation in rat cell lines.

The expression of major histocompatibility complex (MHC) Class I antigens has been studied, by means of monoclonal antibodies directed against nonpolymorphic determinants of MHC Class I molecules, in two epithelial differentiated cell lines (FRTL-5 clone 2 and PC clone 3) and in one fibroblast cell line (FRT Fibro) of Fischer rat thyroid origin, before and after infection with various acute retroviruses carrying the v-ras-Ha, v-mos, v-src, polyoma middle T, and c-myc oncogenes. The results obtained indicate that a single virus does not produce identical changes in MHC Class I molecule expression in all tested lines, but a general increase occurs in lines derived from FRTL-5 clone 2 and a decrease occurs in lines derived from PC clone 3 and from FRT Fibro. Thus the modulation of expression seems to proceed always in the same direction in each cell line regardless of the infecting retrovirus and appears to involve posttranscriptional mechanisms, since no modification of expression of mRNA levels has been observed between normal and transformed cells. Only one line of PC clone 3 origin, transformed by the cooperation of two oncogenes (human c-myc and middle T), almost completely lost MHC Class I antigens on the cell surface and presented a significantly reduced synthesis of Class I mRNA.

Animals↗
PubMed1988

At least three human homeoboxes on chromosome 12 belong to the same transcription unit.

Mammalian homeoboxes show a clustered chromosomal organization. In the mouse, at least seven homeoboxes on chromosome 6 and at least six on chromosome 11 identify the murine Hox-1 and Hox-2 loci, respectively. A number of homeoboxes on chromosome 7 define the human HOX-1 locus and homeoboxes on chromosome 17 define the human HOX-2 locus. We studied the genomic organization of three homeobox sequences of the HOX-3 locus on chromosome 12 and analyzed transcripts from this region. Structural characterization and sequencing of several cDNA clones reveal that the three homeobox sequences present in this chromosomal region identify a single transcription unit. Primary transcripts are alternatively processed to give mature messengers with a common 5' noncoding exon encoding different proteins containing one of the three homeodomains.

Amino Acid Sequence↗
PubMed1988

Organization of human homeobox genes.

The chromosomal localization of 17 human homeoboxes and the predicted primary sequence of the encoded homeodomains is reported. These homeoboxes are clustered in four complex HOX loci on chromosomes 2, 7, 12 and 17. Although the identification of human homeoboxes has not been completed, existing data permit preliminary conclusions on the origin and evolution of these complex loci to be drawn. The homeo-domains of one HOX locus can be unambiguously aligned to the homeodomains of the other HOX loci, so that corresponding homeodomains in all loci can share the maximal peptide sequence identity. This one-to-one correspondence of individual homeodomains in different chromosomal loci suggests the hypothesis of large-scale duplications of a single complex locus and subsequent spreading in different chromosomes. The existence of an ancestral complex locus might have predated the divergence of the arthropod/annelid and vertebrate evolutive lineages.

Amino Acid Sequence↗
PubMed1988

Activation of four homeobox gene clusters in human embryonal carcinoma cells induced to differentiate by retinoic acid.

We have studied the expression of nine homeobox genes from Hox 1, Hox 2, Hox 3 and Hox 5 clusters in human embryonal carcinoma (EC) cell lines analyzed as both stem cells and after exposure to the differentiation-inducing agents retinoic acid (RA), hexamethylenebisacetamide (HMBA) and bromodeoxyuridine (BUdR). None of the homeobox genes was expressed in stem cells, whereas all were activated, although with different kinetics, in cultures of the pluripotent EC cell line NTERA-2, clone D1 (NT2/D1), following differentiation induced by RA. At least some homeobox genes were stably expressed in differentiated cells several weeks after removal of RA from the culture medium. However, the length of initial exposure to RA is a critical factor in achieving stable gene expression, and differs among the different sets of genes and, at least in one case, among different transcripts from the same gene. No homeobox gene expression was detected in NT2/D1 cells induced to differentiate with HMBA or BUdR. Also, no expression was detectable in xenograft tumors generated by NT2/D1 cells in nude mice, even though tumors of this type contain mostly differentiated cells. Other human EC lines tested, i.e., 833KE, 2102Ep or 1156QE, did not differentiate in response to RA and did not express homeobox genes. No expression was detectable in xenograft tumors of 833KE and 2102Ep, containing essentially EC cells. These data indicate that homeobox-gene activation specifically accompanies RA-induced differentiation of NT2/D1 cells, thereby providing an excellent model for studying the molecular basis of homeobox-gene regulation and the possible role of the homeobox in cell differentiation.

Acetamides↗
PubMed1987

Modulated expression of human homeobox genes in differentiating intestinal cells.

Homeobox genes (Hox genes) control segmentation and segment specificity in Drosophila. Hox genes have been detected in several species from insects to vertebrates. Differential and stage-related expression has been observed in human embryonic tissues as well. We have investigated whether the cell line Caco-2 and human adult intestine express Hox genes. Caco-2 is a cell line derived from a human colon carcinoma and exhibits a spontaneous enterocytic differentiation after cellular confluency in vitro. At 7, 14 and 21 days after seeding we have found that Hox-2.3 and one Hox-3 gene hybridize to poly(A)+RNA in a stage-related fashion. Moreover, the 21 days pattern of hybridization resembles that one observed in adult small intestine. The Caco-2 cell line provides a model system that allows a detailed analysis of cellular factors controlling transcription and stability of Hox gene products.

Adult↗
PubMed1987

Two human homeobox genes, c1 and c8: structure analysis and expression in embryonic development.

Two human cDNA clones (HHO.c1.95 and HHO.c8.5111) containing a homeobox region have been characterized, and the respective genomic regions have been partially analyzed. Expression of the corresponding genes, termed c1 and c8, was evaluated in different organs and body parts during human embryonic/fetal development. HHO.c1.95 apparently encodes a 217-amino acid protein containing a class I homeodomain that shares 60 out of 61 amino acid residues with the Antennapedia homeodomain of Drosophila melanogaster. HHO.c8.5111 encodes a 153-amino acid protein containing a homeodomain identical to that of the frog AC1 gene. Clones HHO.c1 and HHO.c8 detect by blot-hydridization one and two specific polyadenylylated transcripts, respectively. These are differentially expressed in spinal cord, backbone rudiments, limb buds (or limbs), heart, and skin of human embryos and early fetuses in the 5- to 9-week postfertilization period, thus suggesting that the c1 and c8 genes play a key role in a variety of developmental processes. Together, the results of the embryonic/fetal expression of c1 and c8 and those of two previously analyzed genes (c10 and c13) indicate a coherent pattern of expression of these genes in early human ontogeny.

Amino Acid Sequence↗
PubMed1987

Human homoeobox-containing genes in development.

The homoeobox is a 183-bp DNA sequence conserved in several Drosophila genes controlling segmentation and segment identity. Homoeobox sequences have been detected in the genome of species ranging from insects and annelids to vertebrates, and homoeobox-containing genes have been cloned from sea urchin, Xenopus, mouse and man. We have recently isolated human homoeobox-containing complementary DNA clones which represent transcripts from four different human genes. We have studied the expression of these genes in tissues of human embryos and fetuses at 5-10 weeks post-conception. Most of them appear to be expressed in a stage- and tissue-specific pattern. We report here on the genomic organization of a number of human homoeoboxes and their transcriptional organization in human placenta.

Animals↗
PubMed1987

Human homeo box-containing genes located at chromosome regions 2q31----2q37 and 12q12----12q13.

Four human homeo box-containing cDNAs isolated from mRNA of an SV40-transformed human fibroblast cell line have been regionally localized on the human gene map. One cDNA clone, c10, was found to be nearly identical to the previously mapped Hox-2.1 gene at 17q21. A second cDNA clone, c1, which is 87% homologous to Hox-2.2 at the nucleotide level but is distinct from Hox-2.1 and Hox-2.2, also maps to this region of human chromosome 17 and is probably another member of the Hox-2 cluster of homeo box-containing genes. The third cDNA clone, c8, in which the homeo box is approximately 84% homologous to the mouse Hox-1.1 homeo box region on mouse chromosome 6, maps to chromosome region 12q12----12q13, a region that is involved in chromosome abnormalities in human seminomas and teratomas. The fourth cDNA clone, c13, whose homeo box is approximately 73% homologous to the Hox-2.2 homeo box sequence, is located at chromosome region 2q31----q37. The human homeo box-containing cluster of genes at chromosome region 17q21 is the human cognate of the mouse homeo box-containing gene cluster on mouse chromosome 11. Other mouse homeo box-containing genes of the Antennapedia class (class I) map to mouse chromosomes 6 (Hox-1, proximal to the IgK locus) and 15 (Hox-3). A mouse gene, En-1, with an engrailed-like homeo box (class II) and flanking region maps to mouse chromosome 1 (near the dominant hemimelia gene). Neither of the class I homeo box-containing genes--c8 and c13--maps to a region of obvious homology to chromosomal positions of the presently known mouse homeo box-containing genes.

Cell Line↗
PubMed1985

Molecular analysis of the heterogeneity region of the human ribosomal spacer.

The human ribosomal non-transcribed spacers are 30 X 10(3) base-pairs (or 30 kb) in length with a limited length heterogeneity localized in a specific region downstream from the 3' end of the transcribed region. Total DNA digested with EcoRI and BamHI and hybridized with a probe containing the 3' end of the 28 S ribosomal RNA coding region shows four major bands of 3.9 kb, 4.6 kb, 5.4 kb and 6.2 kb. The 5.4 kb band is the most abundant in every individual, followed by the 4.6 kb band. The longest and the shortest size classes are less well-represented and may even be absent. Every individual shows his own pattern of relative abundance of non-transcribed spacer length classes that can be followed through generations. We decided to investigate the molecular structure of the heterogeneity region, in order to cast light onto the mechanisms underlying the origin and maintenance of this length heterogeneity. Pertinent spacer regions of eight ribosomal clones from two human genomic libraries were subcloned and analyzed by restriction mapping and nucleotide sequencing. In the minimal length class, there is a sequence of 700 base-pairs that appears to be tandemly duplicated once, twice or three times in the other length classes. This repeated DNA module contains a region consisting of repetitions of simple pyrimidine groups like C-T, C-T-T-T or C-C-C-T. DNA module repeats may differ by the length of this pyrimidine-rich region. However, these length variations are not continuous, as revealed by Southern transfer analysis of several individuals and different cloned gene units: instead, the repeated modules fall into two discrete length classes of about 700 base-pairs and 800 base-pairs. An imperfect duplication of a short sequence of 86/89 base-pairs is present at the boundary between the heterogeneity region and the upstream flanking region, representing a very ancient duplication event.

Base Sequence↗
PubMed1985

Nucleotide sequence of a complete ribosomal spacer of D. melanogaster.

We determined the nucleotide sequence of a D. melanogaster ribosomal DNA spacer. Sequences of various portions of different cloned ribosomal spacers have been previously reported. We extend the analysis to cover the entire nontranscribed and external transcribed regions. Comparison to other cloned ribosomal DNA gene units of this species confirms a conserved general organization of the ribosomal spacer through different size classes. D. melanogaster ribosomal gene units interrupted by insertions are known to be transcribed at a much lower level than the continuous gene units. Nonetheless previous sequence analysis of a region around the transcription initiation site did not reveal significant differences in rDNA genes with and without insertions. We extend such analysis to cover the last two promoter duplications in the spacer and the entire external transcribed spacer up to the 5' cleavage site of the 18S rRNA.

Animals↗
PubMed1984

5'-Cleavage site of D. melanogaster 18 S rRNA.

We determined the nucleotide sequence of the DNA region around the 5'-terminus of 18 S rRNA in two cloned rDNA gene units of Drosophila melanogaster. The 5'-base is within a sequence CATTATT which is present also at the 3'-terminus of the 18 S rRNA coding region. In this case it is known that the situation is CATTA3' . TT. With various methods we determined that the precise 5'-cleavage site is CATT . 5'ATT.

Animals↗
PubMed1984

Isolation of a series of HLA class I clones from a human chromosome 6 genomic library.

Human metaphase chromosomes were fractionated by a fluorescent-activated cell sorter (FACS II) and the chromosome 6 fraction was sorted. A genomic library was constructed in lambda gtWES cloning arms using a partial EcoRI digest of the chromosomal DNA. We estimate that at least 60% of our library represents chromosome 6 material, and as 1.2 x 10(5) recombinants were obtained, this indicates that the majority of clonable chromosome 6 sequences are represented. The library was screened with a mouse H-2 class I clone and 18 HLA class I recombinants were isolated from 4 x 10(4) plaques.

Cell Fractionation↗