Successful Combination of Sequential Gene Therapy and Rescue Allo-HSCT in Two Children with X-CGD - Importance of Timing

We report on a series of sequential events leading to long-term survival and cure of pediatric X-linked chronic granulomatous disease (X-CGD) patients after gamma-retroviral gene therapy (GT) and rescue HSCT. Due to therapyrefractory life-threatening infections requiring hematopoietic stem cell transplantation (HSCT) but absence of HLAidentical donors, we treated 2 boys with X-CGD by GT. Following GT both children completely resolved invasive Aspergillus nidulans infections. However, one child developed dual insertional activation of ecotropic viral integration site 1 (EVI1) and signal transducer and activator of transcription 3 (STAT3) genes, leading to myelodysplastic syndrome (MDS) with monosomy 7. Despite resistance to mismatched allo-HSCT with standard myeloablative conditioning, secondary intensified rescue allo-HSCT resulted in 100 % donor chimerism and disappearance of MDS. The other child did not develop MDS despite expansion of a clone with a single insertion in the myelodysplasia syndrome 1 (MDS1) gene and was cured by early standard allo-HSCT. The slowly developing dominance of clones harboring integrations in MDS1-EVI1 may guide clinical intervention strategies, i.e. early rescue allo-HSCT, prior to malignant transformation. GT was essential for both children to survive and to clear therapy-refractory infections, and future GT with safer lentiviral self-inactivated (SIN) vectors may offer a therapeutic alternative for X-CGD patients suffering from life-threatening infections and lacking HLA-identical HSC donors.

Telomere disruption results in non-random formation of de novo dicentric chromosomes involving acrocentric human chromosomes

Genome rearrangement often produces chromosomes with two centromeres (dicentrics) that are inherently unstable because of bridge formation and breakage during cell division. However, mammalian dicentrics, and particularly those in humans, can be quite stable, usually because one centromere is functionally silenced. Molecular mechanisms of centromere inactivation are poorly understood since there are few systems to experimentally create dicentric human chromosomes. Here, we describe a human cell culture model that enriches for de novo dicentrics. We demonstrate that transient disruption of human telomere structure non-randomly produces dicentric fusions involving acrocentric chromosomes. The induced dicentrics vary in structure near fusion breakpoints and like naturally-occurring dicentrics, exhibit various inter-centromeric distances. Many functional dicentrics persist for months after formation. Even those with distantly spaced centromeres remain functionally dicentric for 20 cell generations. Other dicentrics within the population reflect centromere inactivation. In some cases, centromere inactivation occurs by an apparently epigenetic mechanism. In other dicentrics, the size of the α-satellite DNA array associated with CENP-A is reduced compared to the same array before dicentric formation. Extra-chromosomal fragments that contained CENP-A often appear in the same cells as dicentrics. Some of these fragments are derived from the same α-satellite DNA array as inactivated centromeres. Our results indicate that dicentric human chromosomes undergo alternative fates after formation. Many retain two active centromeres and are stable through multiple cell divisions. Others undergo centromere inactivation. This event occurs within a broad temporal window and can involve deletion of chromatin that marks the locus as a site for CENP-A maintenance/replenishment.

Endogenous human centromeres are defined by large arrays of α-satellite DNA. A portion of each α-satellite array is assembled into CENP-A chromatin, the structural and functional platform for kinetochore formation. Most chromosomes are monocentric, meaning they have a single centromere. However, genome rearrangement can produce chromosomes with two centromeres (dicentrics). In most organisms, dicentrics typically break during cell division; however, dicentric human chromosomes can be stable in mitosis and meiosis. This stability reflects centromere inactivation, a poorly understood phenomenon in which one centromere is functionally silenced. To explore molecular and genomic events that occur at the time of dicentric formation, we describe a cell-based system to create dicentric human chromosomes and monitor their behavior after formation. Such dicentrics can experience several fates, including centromere inactivation, breakage, or maintaining two functional centromeres. Unexpectedly, we also find that dicentrics with large (>20Mb) inter-centromeric distances are stable through at least 20 cell divisions. Our results highlight similarities and differences in dicentric behavior between humans and model organisms, and they provide evidence for one mechanism of centromere inactivation by centromeric deletion in some dicentrics. The ability to create dicentric human chromosomes provides a system to test other mechanisms of centromere disassembly and dicentric chromosome stability.

Topoisomerase I suppresses genomic instability by preventing interference between replication and transcription

Topoisomerase I (Top1) is a key enzyme in functioning at the interface between DNA replication, transcription and mRNA maturation. Here, we show that Top1 suppresses genomic instability in mammalian cells by preventing a conflict between transcription and DNA replication. Using DNA combing and ChIP (chromatin immunoprecipitation)-on-chip, we found that Top1-deficient cells accumulate stalled replication forks and chromosome breaks in S phase, and that breaks occur preferentially at gene-rich regions of the genome. Notably, these phenotypes were suppressed by preventing the formation of RNA-DNA hybrids (R-loops) during transcription. Moreover, these defects could be mimicked by depletion of the splicing factor ASF/SF2 (alternative splicing factor/splicing factor 2), which interacts functionally with Top1. Taken together, these data indicate that Top1 prevents replication fork collapse by suppressing the formation of R-loops in an ASF/SF2-dependent manner. We propose that interference between replication and transcription represents a major source of spontaneous replication stress, which could drive genomic instability during the early stages of tumorigenesis.

Telomere dysfunction as a cause of genomic instability in Werner syndrome

Werner syndrome (WS) is a rare human premature aging disease caused by mutations in the gene encoding the RecQ helicase WRN. In addition to the aging features, this disorder is marked by genomic instability, associated with an elevated incidence of cancer. Several lines of evidence suggest that telomere dysfunction is associated with the aging phenotype of the syndrome; however, the origin of the genomic instability observed in WS cells and the reason for the high incidence of cancer in WS have not been established. We previously proposed that WRN helicase activity was necessary to prevent dramatic telomere loss during DNA replication. Here we demonstrate that replication-associated telomere loss is responsible for the chromosome fusions found in WS fibroblasts. Moreover, using metaphase analysis we show that telomere elongation by telomerase can significantly reduce the appearance of new chromosomal aberrations in cells lacking WRN, similar to complementation of WS cells with WRN. Our results suggest that the genome instability in WS cells depends directly on telomere dysfunction, linking chromosome end maintenance to chromosomal aberrations in this disease.

Genetics of neuroendocrine and carcinoid tumours

Neuroendocrine tumours (NETs) originate in tissues that contain cells derived from the embryonic neural crest, neuroectoderm and endoderm. Thus, NETs occur at many sites in the body, although the majority occur within the gastro-entero-pancreatic axis and can be subdivided into those of foregut, midgut and hindgut origin. Amongst these, only those of midgut origin are generally argentaffin positive and secrete serotonin, and hence only these should be referred to as carcinoid tumours. NETs may occur as part of complex familial endocrine cancer syndromes, such as multiple endocrine neoplasia type 1 (MEN1), although the majority occur as non-familial (i.e. sporadic) isolated tumours. Molecular genetic studies have revealed that the development of NETs may involve different genes, each of which may be associated with several different abnormalities that include point mutations, gene deletions, DNA methylation, chromosomal losses and chromosomal gains. Indeed, the foregut, midgut and hindgut NETs develop via different molecular pathways. For example, foregut NETs have frequent deletions and mutations of the MEN1 gene, whereas midgut NETs have losses of chromosome 18, 11q and 16q and hindgut NETs express transforming growth factor-alpha and the epidermal growth factor receptor. Furthermore, in lung NETs, a loss of chromosome 3p is the most frequent change and p53 mutations and chromosomal loss of 5q21 are associated with more aggressive tumours and poor survival. In addition, methylation frequencies of retinoic acid receptor-beta, E-cadherin and RAS-associated domain family genes increase with the severity of lung NETs. Thus the development and progression of NETs is associated with specific genetic abnormalities that indicate the likely involvement of different molecular pathways.

Hodgkin's lymphoma cell lines are characterized by frequent aberrations on chromosomes 2p and 9p including REL and JAK2

Four Hodgkin's lymphoma cell lines (KM-H2, HDLM-2, L428, L1236) were analyzed for cytogenetic aberrations, applying multiplex fluorescence in situ hybridization, chromosome banding and comparative genomic hybridization. Each line was characterized by a highly heterogeneous pattern of karyotypic changes with a large spectrum of different translocated chromosomes (range 22-57). A recurrent finding in all cell lines was the presence of chromosomal rearrangements of the short arm of chromosome 2 involving the REL oncogene locus. Furthermore, multiple translocated copies of telomeric chromosomal segments were frequently detected. This resulted in a copy number increase of putative oncogenes, e.g., JAK2 (9p24) in 3 cell lines, FGFR3 (4p16) and CCND2 (12p13) in 2 cell lines as well as MYC (8q24) in 1 cell line. Our data confirm previous cytogenetic results from primary Hodgkin's tumors suggesting an important pathogenic role of REL and JAK2 in this disease. In addition, they provide evidence for a novel cytogenetic pathomechanism leading to increased copy numbers of putative oncogenes from terminal chromosomal regions, most probably in the course of chromosomal stabilization by telomeric capture.

DNA ligase IV-dependent NHEJ of deprotected mammalian telomeres in G1 and G2

BACKGROUND

Telomeres are required to prevent end-to-end chromosome fusions. End-to-end fusions of metaphase chromosomes are observed in mammalian cells with dysfunctional telomeres due to diminished function of telomere-associated proteins and in cells experiencing extensive attrition of telomeric DNA. However, the molecular nature of these fusions and the mechanism by which they occur have not been elucidated.

RESULTS

We document that telomere fusions resulting from inhibition of the telomere-protective factor TRF2 are generated by DNA ligase IV-dependent nonhomologous end joining (NHEJ). NHEJ gives rise to covalent ligation of the C strand of one telomere to the G strand of another. Breakage of the resulting dicentric chromosomes results in nonreciprocal translocations, a hallmark of human cancer. Telomere NHEJ took place before and after DNA replication, and both sister telomeres participated in the reaction. Telomere fusions were accompanied by active degradation of the 3' telomeric overhangs.

CONCLUSIONS

The main threat to dysfunctional mammalian telomeres is degradation of the 3' overhang and subsequent telomere end-joining by DNA ligase IV. The involvement of NHEJ in telomere fusions is paradoxical since the NHEJ factors Ku70/80 and DNA-PKcs are present at telomeres and protect chromosome ends from fusion.

Study of 30 patients with unexplained developmental delay and dysmorphic features or congenital abnormalities using conventional cytogenetics and multiplex FISH telomere (M-TEL) integrity assay

Cryptic subtelomeric chromosome rearrangements are a major cause of mild to severe mental retardation pointing out the necessity of sensitive screening techniques to detect such aberrations among affected patients. In this prospective study a group of 30 patients with unexplained developmental retardation and dysmorphic features or congenital abnormalities were analysed using the recently published multiplex FISH telomere (M-TEL) integrity assay in combination with conventional G-banding analysis. The patients were selected by one or more of the following criteria defined by de Vries et al.: (a) family history with two or more affected individuals, (b) prenatal onset growth retardation, (c) postnatal growth abnormalities, (d) facial dysmorphic features, (e) non-facial dysmorphism and congenital abnormalities. In addition, we included two patients who met these criteria and revealed questionable chromosome regions requiring further clarification. In four patients (13.3%) cryptic chromosome aberrations were successfully determined by the M-TEL integrity assay and in two patients with abnormal chromosome regions intrachromosomal aberrations were characterized by targetted FISH experiments. Our results accentuate the requirement of strict selection criteria prior to patient testing with the M-TEL integrity assay. Another essential precondition is high-quality banding analysis to identify structural abnormal chromosomes. The detection of familial balanced translocation carriers in 50% of the cases emphasizes the significance of such an integrated approach for genetic counselling and prenatal diagnosis.

Isochromosome 1q as an early genetic event in a child with intracranial ependymoma characterized by molecular cytogenetics

Data concerning cytogenetic features of childhood ependymoma are rare. In this article, a gain of 1q was identified as the sole alteration in a primary childhood infratentorial ependymoma by comparative genomic hybridization (CGH). A recurrence of this brain tumor was studied using multiplex-fluorescence in situ hybridization (M-FISH) in addition to CGH and G-banding analysis. In accordance with the primary tumor, a gain of 1q corresponding to an isochromosome 1q was observed indicating an early event in the tumor development. Furthermore, M-FISH classified several other rearranged chromosomes including 6q and 17p that have previously been found to be involved in the development and progression of childhood ependymoma.

Comparative genomic hybridization in childhood acute lymphoblastic leukemia: correlation with interphase cytogenetics and loss of heterozygosity analysis

We used comparative genomic hybridization (CGH) to study DNA copy number changes in 71 children with acute lymphoblastic leukemia (ALL) including 50 B-lineage and 21 T-ALLs. Forty-two patients (59%) showed genomic imbalances whereby gains were more frequently observed than losses (127 vs. 29). Gains most commonly affected the entire chromosomes 21 and 10 (19.7% each), 6, 14, 18, X (15.5% each), 17 (14.1%) and 4 (11.3%). Highly hyperdiploid karyotypes (chromosome number >50) occurred more frequently in B-lineage than in T-lineage ALL (24% vs. 4.8%). In both cell lineages deletions were mainly detected on 9p (14.1%) and 12p (8.4%), and on 6q in T-lineage ALL (4.2%). These findings were compared with loss of heterozygosity (LOH) of 6q, 9p, 11q, and 12p previously performed in 56 of the 71 patients. Among 54 sites of LOH, CGH revealed losses of the respective chromosome arms in 17 LOH-positive regions (31.5%). G-banding analysis and interphase cytogenetics with subregional probes for 14 loci confirmed the presence of genomic imbalances as detected by CGH. We, therefore, conclude that, in the absence of cytogenetic data, CGH represents a suitable method for identifying hyperdiploid karyotypes as well as prognostically relevant deletions in ALL patients.

Genetic characterization of a human skin carcinoma progression model: from primary tumor to metastasis

The type and number of genetic aberrations required for a fully malignant tumor are still unclear. This study describes the genetic analysis of a series of skin squamous cell carcinomas, representing the primary tumor, two recurrences, and a metastatic lesion from a single patient and cell lines established therefrom (MET-1 to MET-4). Comparative genomic hybridization demonstrated that: (i) most of the gains and losses were common for tumors and cell lines and affected chromosomes 3 (3p loss, 3q gain), 5 (5p gain, 5q loss), 7 (7p gain), 8 (8p loss, 8q gain), 11 (11q gain), and 17 (17p loss), and (ii) only one aberration was present in a tumor but not in the cell line (10 loss in tumor 4); and only few aberrations were cell line specific. From these, 10p loss and 17q gain were shared by all lines and tumor 4, suggesting that they were already present in all tumors, although in only a subpopulation of cells, whereas 20q gain (shared by all lines), 4q loss (MET-2), and 18p gain/18q loss (MET-3) seem to be culture derived. In agreement, multiplex fluorescence in situ hybridization demonstrated a set of common translocations for all lines thereby further confirming their common origin. In addition, each cell line, exhibited one or more individual translocation chromosomes, which suggested that MET-1 was a precursor of MET-4, whereas MET-2 and MET-3 developed in parallel. Whereas MET-1 to MET-3 were hypodiploid or hyperdiploid, MET-4 was characterized by polyploidization, a set of specific aberrations (t(3;7), t(X;2), i(10q)), and increased heterogeneity (varying translocations in individual metaphases). Using sequencing and expression studies, cells from all lines were wild type for p53, did not exhibit mutations in any of the ras genes (Harvey, Kirsten, or N-ras), and expressed wild-type fragile histidine triad gene (FHIT; mapped to 3p14.2, a locus underrepresented in all cells) transcripts. Thus, with the MET cell lines we present an in vivo skin carcinoma progression model that was genetically well defined, and which, despite originating from a sun-exposed site, is wild type for p53.

Multiplex FISH telomere integrity assay identifies an unbalanced cryptic translocation der(5)t(3;5)(q27;p15.3) in a family with three mentally retarded individuals

Cryptic rearrangements involving the terminal regions of chromosomes are suspected to be the cause of idiopathic mental retardation in a significant number of cases. This finding highlights the necessity of a primary screening test for such chromosome aberrations. Here we present a multiplex fluorescence in situ hybridization telomere integrity assay which allows the detection of submicroscopic aberrations in the telomeric regions of all chromosomes. This novel approach identified an unbalanced cryptic translocation der(5)t(3;5)(q27;p15.3) in a family with three cases of unexplained mental retardation and dysmorphic features. The symptoms of the patients represent neither the classical dup(3q)- nor cri du chat syndrome, although all affected individuals demonstrate several features of both syndromes. The identification of two balanced translocation carriers emphasizes the significance of the telomere integrity assay for genetic counseling and prenatal diagnosis.

Molecular evidence for derivation of metastatic cells from minor subclones of primary clear renal cell carcinomas

The production of metastases depends on changes in a large number of genes. It is also connected with the interaction of tumor cells with the environment. It has been reported that primary tumor clone domination is also an important factor in metastasizing, and in many neoplasms dominating clones are the metastatic forerunners. Up to now it is unknown whether domination of a given clone in a primary renal cell carcinoma is a crucial factor in forming metastases or rather presence or absence of specific genes imposes the major advantage in the metastatic process. To study the presence or absence of the duplication and mitotic nondisjunction event as one of the phenomenon in the creation of metastases, as well as possible derivation of metastatic cells from the minor subclone of primary tumor, we examined three metastatic renal clear-cell carcinomas in which by comparative genomic hybridization we detected the loss of 3p in the primary tumor and two copies of 3p in the corresponding metastasis. Loss of heterozygosity analyses using markers for 3p25 (D3S1038), 3p21.1 (D3S1295), and 3p14.2 (D3S1481) proved heterozygosity of at least two 3p loci in all metastatic tumors, which indicates the absence of mitotic nondisjunction event as a cause of occurrence of two copies of 3p in metastases. Our results suggest that in some of the clear-cell renal carcinomas metastatic cells may derive from minor subclones of primary tumors.

Mapping the gene causing hereditary primary hyperparathyroidism in a Portuguese kindred to chromosome 1q22-q31

A Portuguese kindred with autosomal dominant isolated primary hyperparathyroidism (HPT) that was associated with parathyroid adenomas and carcinomas was investigated with the aim of determining the chromosomal location of this gene, designated HPTPort. Leukocyte DNA from 9 affected and 16 unaffected members and 7 parathyroid tumors from 4 patients was used in comparative genomic hybridization (CGH), tumor loss of heterozygosity (LOH), and family linkage studies. The CGH studies revealed abnormalities of chromosomes 1 and 13, and the results of LOH studies were consistent with the involvements of tumor suppressor genes from these regions. Family segregation studies mapped HPTPort to chromosome 1q22-q31 by establishing linkage with eight loci (D1S254, D1S222, D1S202, D1S238, D1S428, D1S2877, D1S422, and D1S412) (peak two-point LOD scores = 3. 46-5.14 at 0% recombination), and defined the location of HPT Port to a 21 cM region flanked centromerically by D1S215 and telomerically by D1S306. Thus, HPTPort has been mapped to chromosome 1q22-q31, and a characterization of this gene will help to elucidate further the mechanisms that are involved in the development of parathyroid tumors.

Chromosomal abnormalities in renal cell neoplasms associated with acquired renal cystic disease. A series studied by comparative genomic hybridization and fluorescence in situ hybridization

Sporadic renal cell carcinomas (RCCs) display different chromosomal abnormalities according to their morphology; gains of chromosomes 7 and 17 and loss of Y are commonly observed in papillary lesions, whereas loss of 3p sequences and multiple losses of specific chromosomes are found in non-papillary and chromophobe cell carcinomas, respectively. Acquired renal cystic disease (ARCD) is associated with an increased incidence of renal cell tumours, especially papillary lesions. The aim of this study was to examine a series of ARCD-related tumours for chromosomal abnormalities and to compare the findings with those abnormalities commonly observed in sporadic RCCs. Nine tumours from four patients with ARCD were examined using comparative genomic hybridization (CGH) and interphase cytogenetics. Gain of chromosomes 7 and 17 was observed in all four papillary lesions and loss of Y in three. In addition, gain of chromosome 16 was observed in three papillary tumours. Three chromophobe RCCs originating from the same kidney showed different genomic profiles; two had no abnormalities, whereas one showed loss of chromosome 17p. Two non-papillary RCCs failed to show chromosome 3p alterations. In conclusion, renal cell tumours developing in ARCD may show chromosomal abnormalities both similar to and different from those seen in sporadic tumours.

The human small conductance calcium-regulated potassium channel gene (hSKCa3) contains two CAG repeats in exon 1, is on chromosome 1q21.3, and shows a possible association with schizophrenia

Mutations in various ion channel genes are responsible for neuromuscular and other neurological disorders. We have previously identified the human small conductance calcium-activated potassium channel gene (hSKCa3) which has two tandemly arranged CAG repeats in its 5' region. Here we have isolated the first genomic clones containing the gene and have shown that both repeats are in exon 1. Homology to the previously localized sequence tagged site G16005 indicated that the gene may be on chromosome 22q, however using polymerase chain reaction amplification of somatic cell hybrid DNA and fluorescence in situ hybridization of two P1 artificial chromosome clones, we physically localized the gene to chromosome 1q21.3. We previously found an association between the highly polymorphic second (more 3') CAG repeat and schizophrenia in 98 patients and 117 controls. We have now genotyped an additional 19 patients with schizophrenia and have performed statistical analyses on the entire group of patients and controls to investigate the possible effect of age of onset, family history, and gender of the patients on the observed association. None of these factors were found to influence the results. Both CAG repeats have been typed in 86 bipolar I disorder patients, and no significant difference in allele distribution was observed between our bipolar disorder patients and controls.

Separate and variably shaped chromosome arm domains are disclosed by chromosome arm painting in human cell nuclei

Fluorescence in situ hybridization (FISH) with microdissection probes from human chromosomes 3 and 6 was applied to visualize arm and subregional band domains in human amniotic fluid cell nuclei. Confocal laser scanning microscopy and quantitative three-dimensional image analysis showed a pronounced variability of p- and q-arm domain arrangements and shapes. Apparent intermingling of neighbouring arm domains was limited to the domain surface. Three-dimensional distance measurements with pter and qter probes supported a high variability of chromosome territory folding.

Comparison of DNA gains and losses in primary renal clear cell carcinomas and metastatic sites: importance of 1q and 3p copy number changes in metastatic events

Archival material from primary and metastatic renal clear cell carcinomas of 25 patients was studied by comparative genomic hybridization. Copy number changes of entire chromosomes or chromosomal subregions were detected in 22 primary and 21 metastatic tumors. Copy number changes affected the following chromosomes in at least 20% of the 25 primary tumors (minimal common region given in parentheses): gains were noted for chromosomes 1 (1q21-->q23), 5 (5q31-->q34), 7 (7p), 8 (8q), 16 (16p), 17 (17q12-->qter), 19, and 22 (22q12-->qter); losses were revealed for chromosomes 3 (3p21-->pter), 8 (8p23-->pter), 14(14q21-->qter), and Y. The same chromosomal regions that were involved in primary renal clear cell carcinomas were also found in the respective metastatic tumors but with strikingly different frequencies for a few regions. Metastatic tumors showed a significantly higher frequency of complete or partial gains of the long arm of chromosome 1, in particular at 1q21-->q23 than primary tumors (16 cases versus 6 cases; P < 0.005). These data suggest a correlation of metastatic events in renal clear cell carcinomas with an increase in the copy number of genes located at 1q, in particular at 1q21-->q23. In contrast, the entire or partial loss of the short arm of chromosome 3 was significantly less frequent in metastatic tumors (8 cases versus 15 cases; P < 0.025). The validity of 1q and 3p copy number changes detected by comparative genomic hybridization was confirmed by interphase cytogenetics with region-specific yeast artificial chromosomes to paraffin-embedded tumor tissue sections.

Comparative genomic hybridization of formalin-fixed, paraffin-embedded breast tumors reveals different patterns of chromosomal gains and losses in fibroadenomas and diploid and aneuploid carcinomas

Comparative genomic hybridization serves as a screening test for regions of copy number changes in tumor genomes. We have applied the technique to map DNA gains and losses in 33 cases of formalin-fixed, paraffin-embedded primary breast tumors (13 fibroadenomas and 10 diploid and 10 aneuploid carcinomas). No genomic imbalances were found in fibroadenomas. Recurrent findings in adenocarcinomas include copy number increases for chromosomes 1q (14 of 20 samples), 8q (10 of 20), 17q (5 of 20), 6p (3 of 20), 13q (3 of 20), and 16p (3 of 20), and copy number decreases for chromosomes 22 (7 of 20), 17p (6 of 20), and 20 (3 of 20). Regional high level copy number increases were observed on chromosome bands 1q32, 8p11, 8q24, 10p, 11q13, 12p, 12q15, 17q11-12, and 17q22-24. The majority of the samples were studied for gene amplification of c-myc, c-erbB2, cycD1, and int-2 by means of Southern blot analysis. The comparison with DNA ploidy measurements revealed a different distribution and a significantly higher number of chromosomal aberrations in aneuploid tumors than in diploid tumors and in fibroadenomas.

Assignment of the gene encoding the 5-HT1E serotonin receptor (S31) (locus HTR1E) to human chromosome 6q14-q15

The human gene for the 5-HT1E serotonin receptor was recently cloned, but no chromosomal assignment has yet been given to this gene (locus HTR1E). In this work, we demonstrate by two independent polymerase chain reactions on a panel of human-hamster somatic cell hybrid genomic DNA that the 5-HT1E serotonin receptor gene is localized on human chromosome 6. Furthermore, by means of in situ hybridization to human metaphase chromosomes, using the cloned 5-HT1E receptor gene (phage clone lambda-S31; Levy et al., FEBS Lett. 296:201-206,1992) as was a probe, we demonstrate that this gene is localized to the q14-q15 region on chromosome 6. Screening of genomic DNA from 15 unrelated Caucasian individuals, using as a probe the open reading frame of the cloned 5-HT1E receptor gene, did not reveal any restriction fragment length polymorphisms with the enzymes BamHI, BanII, BglII, EcoRI, HincII, HindIII, HinfI, MspI, PstI, and PvuII. Since the 5-HT1E receptor is found mainly in the cerebral cortex and abnormal function of the serotonergic system has been implicated in a variety of neurologic and psychiatric diseases, the precise chromosomal assignment of the 5-HT1E receptor gene is the crucial first step toward the evaluation of this locus as a candidate for mutations in such syndromes.

Localization of the human FSH receptor to chromosome 2 p21 using a genomic probe comprising exon 10

Screening of a human genomic library with a cDNA probe corresponding to the transmembrane domain of the FSH receptor (FSHR) resulted in the identification of a positive clone with a DNA insert of approximately 17.5 kb. Part of the clone encoded exon 10 of the FSHR gene. Sequence analysis of this exon revealed an open reading frame corresponding to base positions 855-2085 of the FSHR cDNA, thereby coding for 410 amino acids. Exon 10 was found to comprise the seven transmembrane domains, the C-terminal intracellular domain and a fragment of 81 amino acids belonging to the extracellular N-terminal domain of the FSHR. The exon/intron boundary is in phase 2 and the amino acid which resides in this junction is isoleucine. The genomic clone was used to map the chromosomal localization of the human FSHR gene. In situ hybridization experiments allowed the allocation of the human gene to chromosome 2 p21. As this position is identical to that of the human LH receptor gene, these two receptor genes may have evolved from a common ancestor.

Mapping of multiple DNA gains and losses in primary small cell lung carcinomas by comparative genomic hybridization

Comparative genomic hybridization was applied for a comprehensive screening of under- and overrepresentation of genetic material in 13 autoptic small cell lung cancer specimens. The most abundant genetic changes include DNA losses of chromosome arms 3p, 5q, 10q, 13q, and 17p and DNA gains of 3q, 5p, 8q, and 17q. Amplification sites in these tumors were mapped to 22 chromosome bands. The most frequently involved band was 19q13.1 (4 cases). Bands 1p32, 2p23, 7q11.2, 8q24, and 13q33-34 were involved in two cases each.

Molecular cytogenetic analysis of formalin-fixed, paraffin-embedded solid tumors by comparative genomic hybridization after universal DNA-amplification

We present a technique which allows the detection and chromosomal localization of DNA sequence copy number changes in solid tumor genomes from frozen sections and paraffin embedded, formalin fixed specimens. Based on comparative genomic hybridization and on universal DNA amplification procedures this technique is possible even if only a few tumor cells are available. We demonstrate the feasibility of this method to visualize complete and partial chromosome gains and losses and gene amplifications in archived solid tumor samples.

Possible role for salivary gland protein in taste reception indicated by homology to lipophilic-ligand carrier proteins

Sensory transduction in taste and olfaction, the principal chemical senses, seems to be mediated by membrane-associated proteins on the apical surfaces of the respective receptor cells. The recent isolation and characterization of soluble 'odorant-binding proteins' secreted from the nasal glands of rat, cow and frog, led to the hypothesis that these proteins function as necessary cofactors in olfactory transduction by concentrating and delivering odorants to the receptors. The primary reception of taste stimuli occurs in specialized neuroepithelial receptor cells bundled in taste buds that are clustered in various types of papillae in the lingual epithelium of the tongue. Small tubulo-alveolar salivary glands, the von Ebner's glands, are located beneath the circumvallate and the foliate papillae. Their ducts open exclusively into the trough at the base of the papillae. Taste buds located in the medial and lateral walls of the papillae open with their taste pores into the trough and consequently are in direct contact with the secretions of von Ebner's glands. Here we report the molecular cloning and characterization of a protein of relative molecular mass 18,000 that is highly expressed in von Ebner's glands. Like the odorant-binding proteins, this protein shows similarity to members of a protein superfamily of hydrophobic molecule transporters, indicating that pre-receptor events could also be necessary for the concentration and delivery of sapid molecules in the gustatory system, and emphasizing the close relationship of taste and olfaction.

Impact of altered protein structures on the intracellular traffic of a mutated vasopressin precursor from Brattleboro rats

The rat vasopressin precursor, synthesized in the reticulocyte lysate system under the direction of in vitro transcribed mRNA, is processed and correctly delivered to the lumen of added microsomal vesicles. Translation of mRNA for the mutant (Brattleboro) vasopressin precursor which lacks a translational stop codon as a consequence of a frame-shift mutation, gives rise to a mutated protein (B-mutant precursor) with a C-terminal poly(lysine) sequence encoded by the poly(A) tail. Upon addition of microsomal membranes, the mutated precursor has access to the lumen of the vesicles as indicated by removal of the signal peptide; however, the C-terminal part with the poly(lysine) tail remains outside the vesicles as shown by its sensitivity to proteinase K. When a modified RNA, including a stop codon located similarly to that found in the cDNA encoding the normal precursor, is translated in the presence of microsomal membranes, the resulting product (S-mutant precursor) is refractory to proteolysis by exogenously added proteinase K. Analysis of the microsomal membranes indicates, however, that the C-terminus of the S-mutant precursor is still anchored within membranes. For studying the intracellular transport of the mutated precursor Xenopus laevis oocytes were injected with various RNA constructs. To monitor the transport steps from the endoplasmic reticulum to the Golgi compartment an RNA encoding a glycosylation site within the S-mutant precursor sequence was constructed. The resulting GS-mutant precursor is synthesized in the oocyte but not secreted into the incubation medium, completely in contrast to the normal vasopressin precursor which can be detected in the incubation bath 4 h after injection of the respective RNA. The sensitivity of the GS-mutant precursor carbohydrate side chain to endoglycosidase H treatment suggests that the mutated precursor does not reach the Golgi apparatus.