Nobel Lecture: Prions

Approximately 70 percent of the mutations in cystic fibrosis patients correspond to a specific deletion of three base pairs, which results in the loss of a phenylalanine residue at amino acid position 508 of the putative product of the cystic fibrosis gene. Extended haplotype data based on DNA markers closely linked to the putative disease gene locus suggest that the remainder of the cystic fibrosis mutant gene pool consists of multiple, different mutations. A small set of these latter mutant alleles (about 8 percent) may confer residual pancreatic exocrine function in a subgroup of patients who are pancreatic sufficient. The ability to detect mutations in the cystic fibrosis gene at the DNA level has important implications for genetic diagnosis.

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Identification of the cystic fibrosis gene: genetic analysis.

The invention relates to transgenic non-human animals capable of producing heterologous antibodies and methods for producing human sequence antibodies which bind to human antigens with substantial affinity.

Transgenic non-human animals capable of producing heterologous antibodies

Metal ions are essential cofactors for a wealth of biological processes, including oxidative phosphorylation, gene regulation and free-radical homeostasis. Failure to maintain appropriate levels of metal ions in humans is a feature of hereditary haemochromatosis, disorders of metal-ion deficiency, and certain neurodegenerative diseases. Despite their pivotal physiological roles, however, there is no molecular information on how metal ions are actively absorbed by mammalian cells. We have now identified a new metal-ion transporter in the rat, DCT1, which has an unusually broad substrate range that includes Fe2+, Zn2+, Mn2+, Co2+, Cd2+, Cu2+, Ni2+ and Pb2+. DCT1 mediates active transport that is proton-coupled and depends on the cell membrane potential. It is a 561-amino-acid protein with 12 putative membrane-spanning domains and is ubiquitously expressed, most notably in the proximal duodenum. DCT1 is upregulated by dietary iron deficiency, and may represent a key mediator of intestinal iron absorption. DCT1 is a member of the 'natural-resistance-associated macrophage protein' (Nramp) family and thus its properties provide insight into how these proteins confer resistance to pathogens.

Cloning and characterization of a mammalian proton-coupled metal-ion transporter

The invention relates to transgenic non-human animals capable of producing heterologous antibodies and transgenic non-human animals having inactivated endogenous immunoglobulin genes. In one aspect of the invention, endogenous immunoglobulin genes are suppressed by antisense polynucleotides and/or by antiserum directed against endogenous immunoglobulins. Heterologous antibodies are encoded by immunoglobulin genes not normally found in the genome of that species of non-human animal. In one aspect of the invention, one or more transgenes containing sequences of unrearranged heterologous human immunoglobulin heavy chains are introduced into a non-human animal thereby forming a transgenic animal capable of functionally rearranging transgenic immunoglobulin sequences and producing a repertoire of antibodies of various isotypes encoded by human immunoglobulin genes. Such heterologous human antibodies are produced in B-cells which are thereafter immortalized, e.g., by fusing with an immortalizing cell line such as a myeloma or by manipulating such B-cells by other techniques to perpetuate a cell line capable of producing a monoclonal heterologous antibody. The invention also relates to heavy and light chain immunoglobulin transgenes for making such transgenic non-human animals as well as methods and vectors for disrupting endogenous immunoglobulin loci in the transgenic animal.

Transgenic non-human animals for producing heterologous antibodies

Wilson disease (WD) is an autosomal recessive disorder of copper transport, resulting in copper accumulation and toxicity to the liver and brain. The gene (WD) has been mapped to chromosome 13 q14.3. On yeast artificial chromosomes from this region we have identified a sequence, similar to that coding for the proposed copper binding regions of the putative ATPase gene (MNK) defective in Menkes disease. We show that this sequence forms part of a P-type ATPase gene (referred to here as Wc1) that is very similar to MNK, with six putative metal binding regions similar to those found in prokaryotic heavy metal transporters. The gene, expressed in liver and kidney, lies within a 300 kb region likely to include the WD locus. Two WD patients were found to be homozygous for a seven base deletion within the coding region of Wc1. Wc1 is proposed as the gene for WD.

The Wilson disease gene is a putative copper transporting P–type ATPase similar to the Menkes gene

We have previously reported the cloning of a gene that encodes a copper transporting P-type ATPase (ATP7B) which is defective in Wilson disease. We have now identified in 58 WND patients, 20 new mutations as well as three of five previously published mutations: 11 small insertions and deletions, seven missense, two nonsense and three splice site mutations. Two of the mutations are relatively frequent, representing 38% of the mutations in patients of European origin. Our findings suggest a wider spectrum of age of onset than is considered typical of Wilson disease: mutations that completely disrupt the gene can produce liver disease in early childhood when Wilson disease may not typically considered in the differential diagnosis. The mutations identified provide an explanation for at least part of the wide phenotypic variation observed in Wilson disease.

The Wilson disease gene: spectrum of mutations and their consequences

The Long-Evans Cinnamon (LEC) rat shows similarity to Wilson disease in many clinical and biochemical features. We have cloned cDNAs for the rat gene (Atp7b) homologous to the human Wilson disease gene (ATP7B) and have used them to identify a partial deletion in the Atp7b gene in the LEC rat. The deletion removes at least 900 bp of the coding region at the 3' end, includes the crucial ATP binding domain and extends downstream of the gene. Our results provide convincing evidence for defining the LEC rat as an animal model for Wilson disease. This model will be important for studying liver pathophysiology, for developing therapy for Wilson disease and for studying the pathway of copper transport and its possible interaction with other heavy metals.

The LEC rat has a deletion in the copper transporting ATPase gene homologous to the Wilson disease gene

Wilson disease and Menkes disease: new handles on heavy-metal transport

The α1-protease inhibitor, or α-antitrypsin (AAT), a major plasma inhibitor of leukocyte elastase and bacterial proteases, is encoded at the PI locus on chromosome 14 (14q24.3–q32.1)1. A deficiency of AAT in individuals homozygous for the PI Z allele occurs in about 1 in 2,000–8,000 Caucasians2 and is associated with an increased risk of early adult onset emphysema3 and liver disease in childhood4. We have now used DNA polymorphisms associated with the AAT gene to investigate the origin of the PI Z allele. Using two genomic probes5 extending into the 5′ and 3′ flanking regions, respectively, we have identified eight polymorphic restriction sites. Extensive linkage disequilibrium occurs throughout the probed region with the PI Z allele, but not with normal PI M alleles. The Z allele occurs mainly with one haplotype, indicating a single, relatively recent, origin in Caucasians.

Diane W. Cox

Papers

The Wilson disease gene is a putative copper transporting P–type ATPase similar to the Menkes gene

The Wilson disease gene: spectrum of mutations and their consequences

The LEC rat has a deletion in the copper transporting ATPase gene homologous to the Wilson disease gene

Wilson disease and Menkes disease: new handles on heavy-metal transport

DNA restriction fragments associated with α 1 -antitrypsin indicate a single origin for deficiency allele PI Z