Biomedical subjects

D Cherif

Publications and source records attributed to D Cherif.

At least 19 recordsLinked to original sources

PubMed2002

Translocation t(5;14)(q35;q32) in three cases of childhood T cell acute lymphoblastic leukemia: a new recurring and cryptic abnormality.

We report three cases of T-ALL in which conventional cytogenetic analysis yielded normal karyotypes, but for which a new M-FISH technique (IPM-FISH) was able to detect a translocation. For these patients this technique highlighted a new, recurring and cryptic translocation t(5;14)(q35;q32) in childhood T-ALL which might be phenotypically restricted. The most innovative part of this technique is the use of interspersed polymerase chain reaction (IRS-PCR) painting probes that show an R-band pattern simultaneous with the combinatorial labeling. Contrary to the DOP-PCR, IRS-PCR-derived probes provide stronger hybridization signals at the telomeric ends that potentially increase the possibility of detecting cryptic translocations. All the IPM-FISH findings were validated by FISH with whole chromosome painting and unique sequence probes. These results demonstrate the efficient use of IPM-FISH as an improved, single-step method for the identification of cryptic chromosomal abnormalities. This new IPM-FISH technique is a good tool to display cryptic chromosomal abnormalities.

Child↗

PubMed2001

IPM-FISH, a new M-FISH approach using IRS-PCR painting probes: application to the analysis of seven human prostate cell lines.

We have developed an alternative multicolor karyotyping technique based on multiplex fluorescence in situ hybridization (M-FISH) and our own optical device with a specific filter set. The most innovative part of our development is the use of interspersed polymerase chain reaction (IRS-PCR) painting probes that show an R-band pattern simultaneous to the combinatorial labeling. This allows us not only to recognize the origin of chromosomal fragments, but to identify the breakpoints as well. We have used this technique to analyze seven cell lines: four prostate cancer cell lines (CA-HPV-10, LNCaP, DU145, and PC3), and three normal transformed epithelial prostate cell lines (PNT1B, PNT2, and PZ-HPV-7). In order to validate our IRS-PCR multiplex FISH (IPM-FISH) technique and to complement the results, we applied comparative genomic hybridization (CGH) and FISH analysis, showing good correlation with the IPM-FISH results. To date, molecular and cytogenetic studies have identified several chromosomal regions that are altered in human prostate cancer; several candidate genes have been suggested. However, reliable markers for predicting the aggressiveness of early prostate cancer are not yet available. Our results show several common, unbalanced rearrangements in the cell lines. These rearrangements are similar to regions already implicated in prostate cancer, validating these cell lines as a good model system.

Cell Line, Transformed↗

PubMed2000

Normal cardiovascular development in mice deficient for 16 genes in 550 kb of the velocardiofacial/DiGeorge syndrome region.

Hemizygous interstitial deletions in human chromosome 22q11 are associated with velocardiofacial syndrome and DiGeorge syndrome and lead to multiple congenital abnormalities, including cardiovascular defects. The gene(s) responsible for these disorders is thought to reside in a 1.5-Mb region of 22q11 in which 27 genes have been identified. We have used Cre-mediated recombination of LoxP sites in embryonic stem cells and mice to generate a 550-kb deletion encompassing 16 of these genes in the corresponding region on mouse chromosome 16. Mice heterozygous for this deletion are normal and do not exhibit cardiovascular abnormalities. Because mice with a larger deletion on mouse chromosome 16 do have heart defects, the results allow us to exclude these 16 genes as being solely, or in combination among themselves, responsible for the cardiovascular abnormalities in velocardiofacial/DiGeorge syndrome. We also generated mice with a duplication of the 16 genes that may help dissect the genetic basis of "cat eye" and derivative 22 syndromes that are characterized by extra copies of portions of 22q11, including these 16 genes. We also describe a strategy for selecting cell lines with defined chromosomal rearrangements. The method is based on reconstitution of a dominant selection marker after Cre-mediated recombination of LoxP sites. Therefore it should be widely applicable to many cell lines.

Abnormalities, Multiple↗

PubMed1999

Localization of Jacobsen syndrome breakpoints on a 40-Mb physical map of distal chromosome 11q.

Jacobsen syndrome is a haploinsufficiency disorder caused, most frequently by terminal deletion of part of the long arm of chromosome 11, with breakpoints in 11q23.3-11q24.2. Inheritance of an expanded p(CCG)n trinucleotide repeat at the folate-sensitive fragile site FRA11B has been implicated in the generation of the chromosome breakpoint in several Jacobsen syndrome patients. The majority of such breakpoints, however, map distal to this fragile site and are not linked with its expression. To characterize these distal breakpoints and ultimately to further investigate the mechanisms of chromosome breakage, a 40-Mb YAC contig covering the distal long arm of chromosome 11 was assembled. The utility of the YAC contig was demonstrated in three ways: (1) by rapidly mapping the breakpoints from two new Jacobsen syndrome patients using FISH; (2) by demonstrating conversion to high resolution PAC contigs after direct screening of PAC library filters with a YAC clone containing a Jacobsen syndrome breakpoint; and (3) by placing 23 Jacobsen syndrome breakpoints on the physical map. This analysis has suggested the existence of at least two new Jacobsen syndrome breakpoint cluster regions in distal chromosome 11.

Abnormalities, Multiple↗

PubMed1997

Isolation of monochromosomal hybrids for mouse chromosomes 3, 6, 10, 12, 14, and 18.

Mouse/human somatic cell hybrids constitute a valuable resource for both genetic and physical mapping. In this report, we describe the production and characterization of a series of six monochromosomal hybrids generated by fusion of murine micro-cells with intact human recipient cells. The presence of each mouse chromosome was characterized by PCR analysis and the integrity of the mouse chromosome retained in the hybrids confirmed by fluorescence in situ hybridization (FISH) analysis.

Animals↗

PubMed1996

Activation of the human homologue of the Drosophila sina gene in apoptosis and tumor suppression.

Developmentally regulated genes in Drosophila, which are conserved through evolution, are potential candidates for key functions in biological processes such as cell cycle, programmed cell death, and cancer. We report cloning and characterization of the human homologue of the Drosophila seven in absentia gene (HUMSIAH), which codes for a 282 amino acids putative zinc finger protein. HUMSIAH is localized on human chromosome 16q12-q13. This gene is activated during the physiological program of cell death in the intestinal epithelium. Moreover, human cancer-derived cells selected for suppression of their tumorigenic phenotype exhibit constitutively elevated levels of HUMSIAH mRNA. A similar pattern of expression is also displayed by the p21waf1. These results suggest that mammalian seven in absentia gene, which is a target for activation by p53, may play a role in apoptosis and tumor suppression.

Amino Acid Sequence↗

PubMed1995

A new congenital dysmegakaryopoietic thrombocytopenia (Paris-Trousseau) associated with giant platelet alpha-granules and chromosome 11 deletion at 11q23.

This study characterizes a new congenital thrombocytopenia with mild hemorrhagic tendency occurring in a woman and her child with the following features. We found a deletion of the distal part of one chromosome 11 [del(11)q23.3-->qter] that was detected by cytogenetic analysis and confirmed by chromosome painting in the two patients and also an increased number of bone marrow megakaryocytes (MKs), including numerous micromegakaryocytes (mMKs) associated with a normal platelet life span. A normal number of MK colonies in culture was observed with one third of them containing a few large MKs; however, these were always associated with mMKs identified by immunologic staining. A massive cell lysis was observed at the end of the maturation. Fifteen percent of the platelets in the peripheral blood showed giant alpha-granules resulting from the fusion of alpha-granules. These giant granules, which appeared in red on giemsa stain, had a mean diameter of 1.5 microns and showed all markers (detected at electron microscopy by immunogold method) of matrix and alpha-granule membrane, ie, von Willebrand factor, fibrinogen, CD41, CD62P (P-selectin); however, they differed from lysosomes because acid phosphatases were not present. These giant alpha-granules were unable to release their contents after stimulation by thrombin, in contrast to platelets with normal morphology. Abnormalities in bone marrow MK maturation that were detected at the electron microscopic level and that led to lysis of numerous MKs were responsible for thrombocytopenia and were similar in both patients. MK abnormalities are probably the consequence of the chromosome aberration. ETS 1 and FLI, two proto-oncogenes that appear to be essential with GATA1 for the normal expression of MK-specific genes, map to 11q23-q24 and are, thus, deleted in this thrombocytopenia. In conclusion, the association of all these abnormalities constitutes a new familial platelet disorder and may present a valuable model for exploring the role of some genes involved in the regulation of thrombopoiesis.

Adult↗

PubMed1995

Organization of the human immunoglobulin lambda light-chain locus on chromosome 22q11.2.

The maps of the human immunoglobulin heavy-chain and kappa light-chain loci have recently been completed. We have now completed a map of the human lambda locus (IGL) located on chromosome 22q11.2. We mapped 52 V lambda genes from 10 V lambda families and 7 J lambda and C lambda genes on a 1140 kb contig constructed from eight YACs and 129 cosmid clones. The V lambda genes are arranged within 800 kb. Genes of the different V lambda families are organized in three clusters, V lambda II and III families (cluster A); V lambda I, V, VII and IX families (cluster B); V lambda IV, VI, VIII and X families (cluster C), in contrast to the dispersed organization of the different VH and V kappa families within the human VH and V kappa loci. We note that the most frequently used V lambda families (V lambda II and III) are proximal to the J lambda and C lambda genes. The VpreB gene, encoding part of the surrogate light chain, the GGT2 gene and the BCRL4 pseudogene were also mapped within the lambda locus.

Base Sequence↗

PubMed1995

Cloning, functional expression, and chromosomal localization of the human pancreatic islet glucose-dependent insulinotropic polypeptide receptor.

Glucose-dependent insulinotropic polypeptide (GIP) is a hormone secreted by the endocrine K-cells from the duodenum that stimulates glucose-induced insulin secretion. Here, we present the molecular characterization of the human pancreatic islet GIP receptor. cDNA clones for the GIP receptor were isolated from a human pancreatic islet cDNA library. They encoded two different forms of the receptor, which differed by a 27-amino acid insertion in the COOH-terminal cytoplasmic tail. The receptor protein sequence was 81% identical to that of the rat GIP receptor. When expressed in Chinese hamster lung fibroblasts, both forms of the receptor displayed high-affinity binding for GIP (180 and 600 pmol/l). GIP binding was displaced by < 20% by 1 mumol/l glucagon, glucagon-like peptide (GLP-I)(7-36) amide, vasoactive intestinal peptide, and secretin. However exendin-4 and exendin-(9-39) at 1 mumol/l displaced binding by approximately 70 and approximately 100% at 10 mumol/l. GIP binding to both forms of the receptor induced a dose-dependent increase in intracellular cAMP levels (EC50 values of 0.6-0.8 nmol/l) but no elevation of cytoplasmic calcium concentrations. Interestingly, both exendin-4 and exendin-(9-39) were antagonists of the receptor, inhibiting GIP-induced cAMP formation by up to 60% when present at a concentration of 10 mumol/l. Finally, the physical and genetic chromosomal localization of the receptor gene was determined to be on 19q13.3, close to the ApoC2 gene. These data will help study the physiology and pathophysiology of the human GIP receptor.

Amino Acid Sequence↗

PubMed1994

Refined mapping of a gene (NPH1) causing familial juvenile nephronophthisis and evidence for genetic heterogeneity.

Familial juvenile nephronophthisis (NPH) is an autosomal recessive progressive tubulo-interstitial kidney disorder, responsible for 6-10% of end-stage renal failure in children, and is frequently associated with Leber amaurosis (termed Senior-Løken syndrome). The biochemical basis of NPH is unknown. We recently reported linkage of the purely renal form of NPH to three markers on chromosome 2. Our results also suggested the existence of genetic heterogeneity between NPH and SLS. To map this NPH gene more precisely, we have now tested the segregation of six new microsatellite markers and five additional families. Haplotype analyses show unequivocally that four NPH families are not linked to the chromosome 2 markers, although there are no clinical or pathological features discernible in these families that could separate them from the families linked to the chromosome 2 NPH locus (NPH1). This reveals genetic heterogeneity in the purely renal form of NPH. In situ hybridization of YAC clones isolated with two closely linked markers assigned the NPH1 region to 2q13. Furthermore, based on haplotype analysis and specific recombination events, the NPH1 gene has been placed between D2S293/D2S340 and D2S121, a genetic interval of about 5-7 cM.

Chromosomes, Human, Pair 2↗

PubMed1994

A YAC contig in 6p23 based on sequence tagged sites.

A yeast artificial chromosome (YAC) contig located in 6p23 and spanning roughly 2.5 Mb has been constructed from the content of 10 sequence tagged sites (STSs) for YAC clones in 66 yeast colonies. Nine of the STSs have been genetically mapped in CEPH families. The order of STSs mapped with the contig is consistent with that of the genetic map. The order of loci that did not recombine with each other on the genetic map was inferred from the contig. Various regions of the contig are covered by multiple YAC clones that complement observed STS deletions. The STS for the CAG repeat sequence contained in the gene for spinal cerebellar ataxia 1 (gene symbol SCA1) is localized in the contig. It is likely that this gene is located in 6p23. The frequency of chimeric YAC clones in this contig is 35%. Eleven yeast colonies were found to carry two or more YACs. YAC subclones from some of these colonies showed size variation, and for several subclones, evidence consistent with deletion of a sequence tagged site.

Base Sequence↗

PubMed1994

Molecular characterization of a human tyrosinase-related-protein-2 cDNA. Patterns of expression in melanocytic cells.

Pigmentation in mammals is under complex genetic control. Amongst the genes involved in this process, those encoding tyrosinase and the tyrosinase-related-proteins 1 and 2 have been well characterized and share a number of features. Recently, the murine tyrosinase-related-protein-2 gene was shown to encode dopachrome-tautomerase activity and was mapped to the slaty locus. Human tyrosinase and tyrosinase-related-protein-1 genes have been isolated and demonstrate a high degree of similarity with their murine counterparts. However, there has been limited data regarding the existence of a human homologue for tyrosinase-related-protein-2 and its relationship to the other tyrosinase-related proteins. In this study, we report the molecular isolation of a cDNA encoding a human homologue of the murine tyrosinase-related-protein-2/dopachrome tautomerase. We have characterized its expression in human melanocytic cells and have analyzed the relationship between dopachrome tautomerase and tyrosinase activities with the level of visible pigmentation in these cells. TYRP2 has been mapped to the chromosomal region 13q32, thus extending a region of synteny with mouse-chromosome 14.

Animals↗

PubMed1994

Large human YACs constructed in a rad52 strain show a reduced rate of chimerism.

Current YAC libraries are plagued by a high frequency of chimeras--that is, clones containing fragments from multiple genomic regions. Chimeras are thought to arise largely through recombination in the yeast host cell. If so, the use of recombination-deficient yeast strains, such as rad52 mutants, might be expected to alleviate the problem. Here, we report the construction of megabase-sized human YACs in the rad52 strain MHY5201 and the determination of their rate of chimerism by fluorescence in situ hybridization analysis. Examination of 48 YACs showed a rate of chimerism of at most 8%, whereas YACs constructed in the wildtype host AB1380 showed a rate of about 50%. These results show that it is possible to significantly decrease the rate of YAC chimerism through the use of appropriate yeast host strains.

Base Sequence↗

PubMed1994

Ordering markers in the region of the ataxia-telangiectasia gene (11q22-q23) by fluorescence in situ hybridization (FISH) to interphase nuclei.

Fluorescence in situ hybridization (FISH) to interphase nuclei was performed to order probes corresponding to bands 11q22-q23 where the ataxia-telangiectasia (AT) gene(s) have been located. Cosmid probes and one phage probe previously localized to this chromosome 11 region by FISH to metaphase chromosomes, were hybridized to interphase nuclei of the somatic cell hybrid J1a, which contains chromosome 11 as the only human chromosome. Two-color FISH was used with a centromeric reference probe marker. The following order was obtained: cen-D11S385 (CJ52.75)-CJ52.3-D11S384 (CJ52.193)-CJ52.114-D11S424 (CJ52.77)-D11S132-NCAM-D11S351 (CJ52.208)-tel. The validity of using the centromeric probe was illustrated by showing that a probe corresponding to 11p13 hybridized more closely to the centromere than a probe corresponding to 11q22-q23, and by using cosmids hybridized three by three.

Ataxia Telangiectasia↗

PubMed1994

Hunting 11q23 deletions with fluorescence in situ hybridization (FISH).

Seven patients with acute leukemia and translocation involving band 11q23 have been studied by fluorescence in situ hybridization (FISH) using YAC probes spanning the HRX gene. While hybridization signal was split by translocation between the rearranged 11 and the partner chromosomes in five patients, only one signal on the derivative 11 was observed in two patients, one with t(9;11)(p21-22;q23) and the other with t(6;11)(q27;q23). Having shown that HRX was rearranged in these two cases, the distal part of 11q23 was investigated using other YACs containing markers for this region. This showed that a 600-700 kb deletion, distal to the HRX breakpoint cluster region, had occurred in the two cases. This study supports the notion that the 5' end of HRX is the important part in the chimeric genes resulting from 11q23 translocations and suggests that deletions of the 3' part are not uncommon.

Adult↗

PubMed1993

Molecular cloning of a novel human hsp70 from a B cell line and its assignment to chromosome 5.

A 2391-bp cDNA encoding a novel human hsp70, named hsp70 RY, is described. It was cloned from a cDNA library constructed using mRNA derived from an established EBV-transformed B cell line from a patient with leukocyte adhesion molecule deficiency. hsp70 RY is 701 amino acids long, has the characteristic N-terminal ATP-binding domain and the C-terminal peptide binding domain, and contains four potential N-glycosylation sites. Northern blotting revealed a single mRNA species of 3.0 kb in total RNA prepared from the patient's EBV cell line. In situ hybridization localized the single copy hsp70 RY gene to the long arm of chromosome 5 at 5 q31.1-5 q31.2.

Amino Acid Sequence↗

PubMed1993

Chromosome painting in acute monocytic leukemia.

An Alu polymerase chain reaction (PCR) probe specific for chromosome 11 prepared from the somatic cell hybrid J1 was used to analyze karyotypes of eight patients with acute monocytic leukemia (AML-M5). Chromosome painting confirmed the t(9;11) in one patient and a der(1)t(1;6)t(6;11) in another and allowed the identification of a complex rearrangement involving chromosomes 9, 11, and 17, previously classified as del(11)(q23), in a third patient. An analysis of five patients with AML-M5 and a normal karyotype did not detect abnormalities of chromosome 11. The usefulness of chromosome painting combined with in situ hybridization with probes previously located on particular chromosomes is emphasized.

Adult↗

PubMed1993

In situ hybridization to interphase nuclei in acute leukemia.

Numerical chromosome abnormalities were studied in 17 acute lymphoblastic leukemias and one hyperdiploid acute myeloblastic leukemia by fluorescence in situ hybridization (FISH) using YAC clones specific to chromosomes 21 and 6. The results agreed well with cytogenetic findings. Hyperdiploid leukemias with more than 50 chromosomes usually had 4 copies of chromosome 21 and three of chromosome 6, while diploid and pseudodiploid cases were confirmed to have two copies of the two chromosomes. Interesting discrepancies were also observed. In one patient, trisomy 6 was detected by FISH but not by cytogenetics because of the probable inclusion of a chromosome 6 segment within a marker chromosome. The percentages of nuclei with 3 or 4 spots (chromosome 21) and three spots (chromosome 6) in hyperdiploid cells were significantly different in some patients, whereas they might be identical from cytogenetic data.

Adolescent↗