Construction of a genetic map of human chromosome 17 by use of chromosome-mediated gene transfer

Mutation Analysis in the Coding Sequence of Thymidine Kinase 1 in Breast and Colorectal Cancer

We report the first mutational study of thymidine kinase 1 (TK1) performed in human solid tumors. We sequenced cDNAs representing the complete coding region of TK1 in human breast (n=22) and colorectal (n=26) cancer. Codon 106 near the ATP binding site constantly differed (ATG → GTG; Met → Val) from the one deposited by Bradshaw and Deininger in the Genbank database (Accession number NM_003258). Silent polymorphisms at codon 11 (CCC → CCT; Pro → Pro) and codon 75 (GCG → GCA; Ala → Ala) were frequently detected in tumors as well as in normal tissues. In breast cancer the two polymorphisms were observed in 63.6% of the samples analyzed. No significant association could be found between polymorphisms and TK activity. In colorectal cancer the incidence of the two changes was 73.1% and 69.2%, respectively. Interestingly, one colon cancer with high cytosolic TK activity displayed two missense mutations located in and near the putative phosphorylation site by tyrosine kinase (s) (TAT → CAT; Tyr → His) and by cAMP-, cGMP-dependent protein kinase (TAC → TGC; Tyr → Cys), respectively; adjacent normal mucosa showed no mutation. This may open new avenues that imply TK1 activity in tumor cell proliferation.

The role of thymidine kinase in cancer diseases

Thymidine kinase 1 (TK 1-fetal) is a cell cycle-dependent marker that increases dramatically during the S-phase of the cell cycle. In this review, the authors discuss serum levels of thymidine kinase in a variety of neoplasias. Determination of thymidine kinase helps to monitor the follow-up of solid tumours and haematological malignancies as well as indicating the efficacy of adjuvant and palliative chemotherapy. Elevated levels of thymidine kinase must always be interpreted together with a detailed knowledge of the patient's condition because nonspecific elevations of serum levels (inflammatory and autoimmune diseases) must be excluded.

Expression of human growth hormone in the milk of transgenic rabbits with transgene mapped to the telomere region of chromosome 7q

The advent of transgenic technology has provided methods for the production of pharmaceuticals by the isolation of these proteins from transgenic animals. The mammary gland has been focused on as a bioreactor, since milk is easily collected from lactating animals and protein production can be expressed at very high levels, including hormones and enzymes. We demonstrate here the expression pattern of recombinant human growth hormone (rhGH) in transgenic rabbits carrying hGH genomic sequences driven by the rat whey acidic protein (WAP) promoter. The transgene was mapped to the q26-27 telomere region of chromosome 7q by fluorescence in situ hybridization (FISH). Nearly 30 % of the F1 generation demonstrated the presence of transgene. The recombinant growth hormone was detected in the milk of the transgenic rabbit females, but not in serum, up to the level of 10 μg/ml. Ectopic expression of the transgene in the brain, heart, kidney, liver, and salivary gland was not observed, indicating that a short sequence of rat WAP promoter (969 bp) contained essential sequences directing expression exclusively to the mammary gland. The biological activity of recombinant growth hormone was measured by immunoreactivity and the capability to stimulate growth of the hormone-dependent Nb211 cell line.

Short stature and metabolic abnormalities in two sisters with a 7.6-kb GH1 gene deletion

Growth hormone 1 (GH1) gene deletions occur in approximately 10-15% of patients with severe isolated, GH deficiency (GHD). The standard treatment for GHD is GH replacement. Individuals with GH gene defects, however, may form GH antibodies that interfere with the efficacy of exogenous recombinant GH (rhGH) therapy.

OBJECTIVE

We describe the growth measures and metabolic studies of two Hispanic sisters with the same 7.6-kb GH1 gene deletion who presented with short stature and increased body fat, and who developed neutralizing GH antibodies secondary to rhGH exposure.

DESIGN

The younger sister has now been treated with recombinant human insulin-like growth factor-I (rhIGF-I) for 4 years, and is continuing treatment. The older sister was not given rhIGF-I based on her normal height velocity and age. After the first 4 years of rhIGF-I treatment of the younger sister, we summarized the longitudinal anthropometric measures and serial laboratory studies, including GH surrogates, fasting lipid studies, oral glucose tolerance tests, and HbA1c, of both sisters. Body composition was quantified using DEXA analysis.

RESULTS

The older sister achieved an adult stature at the low end of her mid-parental target height range, having been treated only with rhGH for ~2.5 years (between 11 months and 3.5 years of age). Treatment of the younger sister with rhIGF-I for 4 years has led to persistent improvement in height velocity, but was associated with adverse short-term effects on all lipids. Her BMI increased modestly (+4.1 kg/m(2)) during rhIGF-I treatment, though her change in percent body fat was negligible by DEXA (Δ -0.7%).

CONCLUSIONS

In individuals with a GH gene deletion, rhIGF-I promotes increased height velocity, but may be associated with adverse effects on lipids and BMI. It is clear that the long-term effects of rhIGF-I on lipid metabolism and body composition require further monitoring and assessment with continued treatment.

A deletion mutation in the betaA1/A3 crystallin gene ( CRYBA1/A3) is associated with autosomal dominant congenital nuclear cataract in a Chinese family

Congenital cataracts are an important cause of blindness worldwide. In a family of Chinese descent, a dominant congenital nuclear cataract locus was mapped to chromosome 17q11.1-12. The maximum LOD score, 2.49, at recombination fraction 0, was obtained for marker D17S1294. The results of both linkage and haplotype analyses defined a disease-gene to an 11.78-cM region harboring the gene coding for betaA1/A3 crystallin ( CRYBA1/A3). Mutation analysis of the CRYBA1/A3 gene identified a 3-bp deletion in exon 4, which cosegregated with the disease risk in this family and was not observed in 100 normal chromosomes. This mutation resulted in the deletion of a highly conserved glycine at codon 91 (DeltaG91) and could be associated with an incorrect folding of betaA1/A3 crystallin. It highlights the physiological importance of crystallin and supports the role of CRYBA1/A3 in human cataracts formation.

Chronic non-spherocytic haemolytic anaemia due to congenital pyrimidine 5' nucleotidase deficiency: 25 years later

In 1972, Valentine et al described, under the name of 'non-spherocytic haemolytic anaemia, high red cell ATP and ribose phosphate pyrophosphokinase (RPK; EC 2.7.6.1) deficiency', an obscure congenital haemolytic anaemia with the characteristic feature of red blood cell basophilic stippling. The activity of Embden-Meyerhof pathway and hexose monophosphate shunt were normal, and the concentrations of reduced glutathione and of ATP were raised 2 SD above the normal mean. The low values of RPK also encountered were considered to be an epiphenomenon rather than a causative defect. One year later, further studies performed in two new kindreds with the same haemolytic disorder associated with persistent basophilic stippling were described under the name of 'haemolytic disorders associated with increased ATP'. In 1974, two new and important observations contributed to the final identification of the disease: the patients' red blood cells (RBCs) contained large amounts of nucleotides (pyrimidine nucleotides), and in all cases they were deficient in a hitherto unrecognized enzyme called pyrimidine 5' nucleotidase (P5N). In conclusion, all these cases were formerly referred to as 'high ATP syndromes' because of the erroneous assumption that the large number of nucleotides within deficient RBCs were adenine phosphate rather than pyrimidine phosphate. Twenty-five years after its description, P5N deficiency has been reported in about 35 unrelated families from different parts of the world, and it has become one commonly identified cause of hereditary non-spherocytic haemolytic anaemia due to RBC enzymopathy. Genetic transmission is via the autosomic recessive mode, and only homozygous or compound heterozygous are clinically affected. Family members who are biochemically heterozygous are haematologically normal and difficult to detect. Unfortunately, the precise gene mutation or mutations causing the disease remain unknown.

Localization and ordering of acid alpha-glucosidase (GAA) and thymidine kinase (TK1) by fluorescence in situ hybridization

Genomic DNA clones of human acid alpha glucosidase (GAA) and thymidine kinase (TK1) were used to map the exact location and order of these genes on human chromosome 17. Both genes were localized to the 17q25-qter band (17q25.2-q25.3), with GAA distal to TK1. They were also shown to be, respectively, distal and proximal to an anonymous cosmid (cK17.71) previously mapped to this region.

A somatic cell hybrid map of the long arm of human chromosome 17, containing the familial breast cancer locus (BRCA1)

We describe a detailed somatic cell hybrid map of human chromosome 17q11.2-q23, containing the familial breast and ovarian cancer locus (BRCA1) and highly informative closely linked markers. An X-irradiation panel of 38 hamster/human and mouse/human hybrids with fragments of chromosome 17 was generated and characterized with 22 STS markers from this chromosome. A detailed map of 61 probes onto chromosome 17q, subdividing the chromosome arm into 25 regions, was done by using a panel of hybrids with well-defined breakpoints and nine chromosome-mediated gene transfectants. Our localization of RARA, TOP2, EDH17B1 and 2, and possibly WNT3, between THRA1 and D17S181, two markers known to flank BRCA1, suggests that any of these is a potential candidate for the BRCA1 locus. The marker D17S579 (Mfd188), which is believed to be very close to BRCA1, maps closest to the EDH17B genes.

Cloning of a human galactokinase gene (GK2) on chromosome 15 by complementation in yeast

A human cDNA encoding a galactokinase (EC 2.7.1.6) was isolated by complementation of a galactokinase-deficient (gal1-) strain of Saccharomyces cerevisiae. This cDNA encodes a predicted protein of 458 amino acids with 29% identity to galactokinase of Saccharomyces carlsbergensis. Previous studies have mapped a human galactokinase gene (GK1) to chromosome 17q23-25, closely linked to thymidine kinase. The galactokinase gene that we have isolated (GK2) is located on chromosome 15. The relationship between the disease locus for galactokinase deficiency galactosemia, which is responsible for cataracts in newborns and possibly presenile cataracts in adults, and the two galactokinase loci is unknown.

The NM23 gene maps to human chromosome band 17q22 and shows a restriction fragment length polymorphism with BglII

The NM23-Hl gene is a putative tumor suppressor gene that may be important in the metastasic process. Recent genetic and immunological data indicate that the NM23-Hl gene encodes a protein with nucleoside diphosphate (NDP) kinase activity. The mapping of NM23-Hl by panels of rodent-human somatic cell hybrids and in situ hybridization showed that the gene is located in human chromosome band 17q22. A two-allele polymorphism with BglII was demonstrated.

Somatic cell genetic analysis of the galactocerebrosidase gene: lack of complementation in human Krabbe disease/twitcher mouse cell hybrids

The inherited deficiency of galactosylceramide beta-galactosidase (E.C. 3.2.1.46: galactocerebrosidase) activity results in globoid cell leukodystrophy in humans (Krabbe disease) and in mice (twitcher mutant). To determine whether Krabbe patients' cells complement twitcher cells to produce, in hybrid combination, greater than deficient levels of galactocerebrosidase activity, five separate crosses were made between an established twitcher mouse cell line and five cell strains from unrelated Krabbe disease patients. A total of 57 twitcher mouse/Krabbe somatic cell hybrid lines developed from all of these crosses were deficient in galactocerebrosidase activity despite the presence of human chromosomes 14 or 17, which have been previously implicated as bearing the galactocerebrosidase gene. A control cross between twitcher mouse/positive control human fibroblasts resulted in 14 of 21 independent hybrid lines that expressed higher than deficient levels of galactocerebrosidase activity. The lack of complementation between Krabbe disease patient and twitcher mutant mouse cells provides further evidence that the twitcher mouse is an authentic murine model for Krabbe disease and supports the hypothesis that the mutations in both species are within the structural gene for the galactocerebrosidase enzyme.

Homeobox gene expression plus autocrine growth factor production elicits myeloid leukemia

In the murine myelomonocytic leukemia WEHI-3B, proviral insertions have induced expression of the Hox-2.4 homeobox gene and the gene for the myeloid growth factor interleukin 3 (IL-3). To assess their potential oncogenic role, normal bone marrow cells were infected with retroviruses bearing the genes for IL-3 or IL-3 plus Hox-2.4. Unlike the IL-3 virus, the IL-3/Hox-2.4 virus was highly leukemogenic. Infected cells expressing both genes exhibited retarded differentiation in vitro, generated myelomonocytic cell lines, and provoked a rapid, transplantable myeloid leukemia in vivo. The oncogenic action of Hox-2.4 appears to derive from its ability to impede the IL-3-driven terminal differentiation of myeloid cells. The results suggest that homeobox genes can regulate key differentiation processes such as self-renewal capacity and that their inappropriate expression can be oncogenic.

Genetic and physical map of the von Recklinghausen neurofibromatosis (NF1) region on chromosome 17

The von Recklinghausen neurofibromatosis 1 (NF1) locus has been previously assigned to the proximal long arm of chromosome 17, and two NF1 patients have been identified who have constitutional balanced translocations involving 17q11.2. We have constructed a cosmid library from a chromosome-mediated gene transfectant, KLT8, that contains approximately 10% of chromosome 17, including 17q11.2. Cosmids isolated from this library have been mapped across a panel of somatic cell hybrids, including the hybrids from the two patients, and have been localized to seven small regions of proximal 17q. We have 5 cosmids that map directly above the two NF1 translocations, and 11 cosmids that map directly below. Of these, 2 cosmids in each region are linked to the disease locus and 3 of these cosmids show no recombination. One distal cosmid, 2B/B35, detects the two NF1 translocations by pulsed-field gel analysis and has been used to produce a long-range restriction map that covers the translocations.

SV40-mediated tumor selection and chromosome transfer to enrich for cystic fibrosis region

The somatic cell hybrid C121, with chromosome 7 as its sole human component, arose when mouse macrophages SV40 genomes are integrated at 7q31-7q35. We show that hybrids with a reduced chromosome 7 component, but which retain markers linked to the cystic fibrosis locus, can be generated by direct in vivo tumor selection or following chromosome-mediated gene transfer and SV40-mediated cellular transformation. Our methods for chromosome fragmentation and fine-structure mapping can now be applied to the substantial number of SV40-transformed human cell lines, with independent chromosomal integration sites, already available. Our results also suggest that expression of human epidermal growth factor receptor augments the tumorigenic potential of the SV40-transformed C121 hybrid.

Chromosome mapping of the human gene encoding the 68-kDa nuclear antigen (p68) by using the polymerase chain reaction

Chromosome mapping by Southern analysis of DNA from somatic cell hybrids is often unsuccessful when only cDNA probes are available. p68 is a putative RNA helicase that is antigenically related to the simian virus 40 large tumor antigen. By using the polymerase chain reaction and oligode-oxynucleotide primers based on the cDNA sequence, we have identified introns in the p68 gene. Comparison of human and mouse DNA fragments amplified with these primers revealed length differences that allowed us to identify the human gene. Application of this technique to DNA from human-mouse somatic cell hybrids and cell lines derived from them by chromosome-mediated gene transfer allowed us to map p68 to the distal part of the long arm of chromosome 17.

Human T cell leukemia viruses use a receptor determined by human chromosome 17

Human T cell leukemia viruses (HTLV-I and HTLV-II) can infect many cell types in vitro. HTLV-I and HTLV-II use the same cell surface receptor, as shown by interference with syncytium formation and with infection by vesicular stomatitis virus (VSV) pseudotypes bearing the HTLV envelope glycoproteins. Human-mouse somatic cell hybrids were used to determine which human chromosome was required to confer susceptibility to VSV(HTLV) infection. The only human chromosome common to all susceptible cell hybrids was chromosome 17, and the receptor gene was localized to 17cen-qter. Antibodies to surface antigens known to be determined by genes on 17q did not block the HTLV receptor.