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Biomedical subjects

G Wistow

Publications and source records attributed to G Wistow.

At least 37 records · Page 2Linked to original sources
PubMed1998

Cloning and tissue expression of the mouse ortholog of AIM1, a betagamma-crystallin superfamily member.

We report the isolation of the murine ortholog of AIM1, a human gene whose expression is associated with the reversal of tumorigenicity in an experimental model of melanoma. Mouse and human AIM1 are more than 90% identical in amino acid sequence in the betagamma-crystallin repeats and the C-terminal domain, and more than 75% identical in the extended N-terminal domain. Consistent with the isolated cDNA representing the authentic AIM1 ortholog, linkage analysis localized mouse Aim1 to proximal mouse Chromosome (Chr) 10 in a conserved linkage group with genes localized to human Chr band 6q21. Searches of EST databases identified a second AIM1-like gene in both mouse and human, suggesting the existence of a gene family. Northern analysis demonstrates Aim1 is expressed most abundantly in adult skin, lung, heart, liver, and kidney and is temporally regulated during embryogenesis. Aim1 is expressed highly in the shaft region of the hair follicles and the presumptive ectoderm, but not at detectable levels in melanocytes or melanocyte precursor cells.

Amino Acid Sequence↗
PubMed1998

Conserved gene structure and genomic linkage for D-dopachrome tautomerase (DDT) and MIF.

Macrophage migration inhibitory factor (MIF) and D-dopachrome tautomerase (DDT) are small proteins, which are related both by sequence and by in vitro enzyme activity. Here we show that the gene for DDT in human and mouse is identical in exon structure to MIF. Both genes have two introns that are located at equivalent positions, relative to a twofold repeat in protein structure. Although in similar positions, the introns are in different phases relative to the open reading frame. Other members of this superfamily exist in nematodes and a plant, and a related gene in C. elegans shares an intron position with MIF and DDT. In addition to similarities in structure, the genes for DDT and MIF are closely linked on human Chromosome (Chr) 22 and mouse Chr 10.

3T3 Cells↗
PubMed1998

Lens-specific gene recruitment of zeta-crystallin through Pax6, Nrl-Maf, and brain suppressor sites.

Zeta-Crystallin is a taxon-specific crystallin, an enzyme which has undergone direct gene recruitment as a structural component of the guinea pig lens through a Pax6-dependent mechanism. Tissue specificity arises through a combination of effects involving three sites in the lens promoter. The Pax6 site (ZPE) itself shows specificity for an isoform of Pax6 preferentially expressed in lens cells. High-level expression of the promoter requires a second site, identical to an alphaCE2 site or half Maf response element (MARE), adjacent to the Pax6 site. A promoter fragment containing Pax6 and MARE sites gives lens-preferred induction of a heterologous promoter. Complexes binding the MARE in lens nuclear extracts are antigenically related to Nrl, and cotransfection with Nrl elevates zeta-crystallin promoter activity in lens cells. A truncated zeta promoter containing Nrl-MARE and Pax6 sites has a high level of expression in lens cells in transgenic mice but is also active in the brain. Suppression of the promoter in the brain requires sequences between -498 and -385, and a site in this region forms specific complexes in brain extract. A three-level model for lens-specific Pax6-dependent expression and gene recruitment is suggested: (i) binding of a specific isoform of Pax6; (ii) augmentation of expression through binding of Nrl or a related factor; and (iii) suppression of promoter activity in the central nervous system by an upstream negative element in the brain but not in the lens.

Animals↗
PubMed1997

Alternative splicing of Pax6 in bovine eye and evolutionary conservation of intron sequences.

Pax-6 is essential for eye development and for tissue-specific gene expression within the eye. Splicing of an alternative exon (5a) leads to variant DNA binding specificity in Pax6. Here we show that in the mature bovine eye the relative abundance of the alternative Pax6-5a mRNA varies markedly, particularly between the lens and iris. Additional alternative splicing products were identified which may lead to "domain swapping" or truncation of Pax6 proteins. Comparison of amphibian (Xenopus) and mammalian (bovine) Pax-6 genes revealed highly conserved intronic sequences flanking exon 5a, including potential lariat sites which may have a role in the mechanism of alternative splicing.

Alternative Splicing↗
PubMed1997

Two roles for mu-crystallin: a lens structural protein in diurnal marsupials and a possible enzyme in mammalian retinas.

PURPOSE: micro-Crystallin is a major taxon-specific lens protein in some marsupials. Like other taxon-specific crystallins, it probably has another, non-crystallin role. Here we examine the distribution of mu-crystallin among species and its localization in the eye in placental mammals. We also compare its sequence and ligand binding characteristics with those of known enzymes. METHODS: An antibody (Mup1) was raised against a conserved 21 residue peptide of tammar wallaby mu-crystallin. This was used to detect mu-crystallin immunoreactivity in lens extracts of several species and in the tissues of rat and bovine eyes. PCR methods were used to complete the cDNA sequence of human mu-crystallin. The ability of kangaroo mu-crystallin to bind enzymatic cofactors was tested by blue-sepharose chromatography. RESULTS: Using Mup1, abundant mu-crystallin was observed in soluble whole lens extracts of diurnal Australian marsupials. Although abundant micro-crystallin was not detectable in whole lens of nocturnal marsupials, other mammals or a bird, lower levels of immunoreactivity were detectable in lens epithelium, retinal pigment epithelium and, particularly, retina of bovine eye. In rat eye the highest levels of Mup1 reactivity were found in retinal photoreceptors. Sequence comparisons of human and kangaroo mu-crystallin reveal a superfamily relationship with enzymes of glutamate and ornithine metabolism. Co-factor binding studies indicate that mu-crystallin, like related glutamyl-tRNA reductases, binds NADPH. CONCLUSIONS: These results suggest that mu-crystallin is a normal component of retina and other tissues which underwent gene recruitment to gain an additional structural role in the lens during the evolution of diurnal marsupial species. mu-crystallin may be an enzyme, possibly of amino acid metabolism, with particular importance for photoreceptors.

Amino Acid Sequence↗
PubMed1997

AIM1, a novel non-lens member of the betagamma-crystallin superfamily, is associated with the control of tumorigenicity in human malignant melanoma.

AIM1 is a novel gene whose expression is associated with the experimental reversal of tumorigenicity of human malignant melanoma. The predicted protein product of the major 4.1-kb transcript shows striking similarity to the betagamma-crystallin superfamily. All known members of this superfamily contain two or four characteristic motifs arranged as one or two symmetrical domains. AIM1, in contrast, contains 12 betagamma motifs, suggesting a 6-domain structure resembling a trimer of beta- or gamma-crystallin subunits. The structure of the AIM1 gene shows remarkable similarity to beta-crystallin genes, with homologous introns delineating equivalent protein structural units. AIM1 is the first mammalian member of the betagamma superfamily with a primarily non-lens role. Other parts of the predicted AIM1 protein sequence have weak similarity with filament or actin-binding proteins. AIM1 is a good candidate for the putative suppressor of malignant melanoma on chromosome 6, possibly exerting its effects through interactions with the cytoskeleton.

Amino Acid Sequence↗
PubMed1997

Decentralisation from acute to home care settings in England.

The impact of technology and resource constraints on acute care, the concept of a 'primary-care led National Health Service' (NHS), and the emphasis on developing community-based alternatives to institutional care have contributed to a reshaping of the respective roles of acute and home care services over the past 10-15 years in the United Kingdom. In England, recent reforms are allowing GP Fundholders, District Health Authorities representing a specific geographic area, and local government social services departments to purchase both acute and community-based care. In addition, new constraints on further expansion of institutional long-term care are encouraging the substitution of home care for the elderly needing long term care services. The result has been a dramatic increase in use of home care services. However, resource and supply constraints impede further home care expansion. Other forces within the NHS continue to foster unnecessary post-acute institutionalization. The successful decentralization of acute services from hospitals to home care requires an integrated program across the continuum of health and social services. In practice, no such concerted program exists.

Ambulatory Care↗
PubMed1997

For debate. Local government and the National Health Service: the new agenda.

There are some interesting paradoxes in the relationship between local government and the National Health Service (NHS). Local government is responsible for a range of major services, many of which relate to health broadly defined. The NHS provides many services which are often popularly thought to be part of local government (and, indeed, in many countries are). Local government prides itself on its 'localness'; the NHS, with its services delivered in a very local fashion for the most part, cannot quite decide whether it is a national service or a local one. Yet these two major agencies of governance and public service provision often seem unable to work very well together. In the interests of good government, both agencies need to work together where their interests coincide or abut one another. Differences of perspective, priority, culture and style need to be recognized but resolved. Opportunities for joint working need to be grasped and the experience built on. The paper looks at a series of issues and opportunities which bring local government and the NHS together. They create an incentive to improve working relationships; at the same time they suggest an agenda of future possibilities.

Humans↗
PubMed1996

LP2, a differentiation-associated lipid-binding protein expressed in bovine lens.

A 13 kDa protein from bovine lens was identified and characterized by protein microsequencing and by rapid amplification of cDNA ends (RACE) PCR. Its complete sequence shows that this protein belongs to a family of fatty acid-binding proteins (FABPs), including myelin and adipocyte P2, that are associated with cellular differentiation. The bovine lens protein, designated LP2, shows very close similarity to human epidermal FABP (eFABP) and human eFABP was detected in human lens, suggesting that the two proteins might be orthologous. Reverse transcriptase-PCR (RT-PCR) was used to compare expression patterns of LP2 with those for actin and for the differentiation markers gamma B-crystallin and gamma s-crystallin in lens. Actin was most abundant in the relatively undifferentiated epithelial cells and decreased with lens cell differentiation. In contrast gamma B-crystallin and gamma s-crystallin were detected only in fibres (nuclear and cortical respectively). LP2 transcripts were detected most abundantly in fibre cells and apparently increased with cellular differentiation. Molecular modelling confirms that the sequence of LP2 fits the tertiary template of adipocyte P2 but reveals the presence of two close pairs of cysteine residues that might be susceptible to intramolecular disulphide bond formation under appropriate oxidizing conditions. LP2 is thus another potential target for oxidative stress during cataract formation in lens.

Amino Acid Sequence↗
PubMed1996

A retinaldehyde dehydrogenase as a structural protein in a mammalian eye lens. Gene recruitment of eta-crystallin.

eta-Crystallin is a taxon-specific crystallin, a major component of the eye lens in elephant shrews (Macroscelidea). Sequence analysis of eta-crystallin from two genera of elephant shrews and expression of recombinant eta-crystallin show that the protein is a cytoplasmic (class 1) aldehyde dehydrogenase (ALDH1, EC 1.2.1.3) with activity for the oxidation of retinaldehyde to retinoic acid. Unlike many other mammals, elephant shrews have two ALDH1 genes. One encodes ALDH1/eta-crystallin which, in addition to its very high expression in lens, is also the predominant form of ALDH1 expressed in other parts of the eye. The second gene encodes a "non-lens" ALDH1 (ALDH1-nl) which is the predominant form expressed in liver. This pattern of tissue preference contrasts with other mammals which make use of the same major ALDH1 transcript in both ocular and non-ocular tissues. Thus the gene recruitment of ALDH1/eta-crystallin as a structural protein in elephant shrew lenses is associated with its collateral recruitment as the major form of ALDH1 expressed in other parts of the eye.

Aldehyde Oxidoreductases↗
PubMed1995

The duck gene for alpha B-crystallin shows evolutionary conservation of discrete promoter elements but lacks heat and osmotic shock response.

The gene for alpha Beta-crystallin from a bird (the domestic duck, Anas platyrhynchos) has been cloned and sequenced to allow comparison with its mammalian homologues. The duck gene has the same general structure as those of humans and rodents although, unlike those of mammals, the duck gene has two polyadenylation signals at the 3' end. The most interesting comparisons are in the 5'flanking promoter regions. In contrast to the broad conservation of promoter sequence among mammals, only two significant blocks and a few smaller elements have been conserved during evolution in the more distantly related avian gene. Block 1 (-350/-308) corresponds to alpha BE-2, a functional element defined in the mouse gene. Further downstream, block 2 (-98/-65) shows 27/33 identity among all three species but does not correspond to any previously defined element. Other regions are less well-conserved. In particular, putative heat-shock response elements of the mammalian alpha B-crystallin genes are absent from the duck gene. In contrast to the heat and osmotic stress-inducibility of mouse alpha B-crystallin in NIH 3T3 cells, duck alpha B-crystallin showed no inducibility in duck cells in culture. Thus, although high expression in lens is common to alpha B-crystallin genes in birds and mammals, other modes of expression appear to be taxon-specific.

Amino Acid Sequence↗
PubMed1995

Genomic cloning of mouse MIF (macrophage inhibitory factor) and genetic mapping of the human and mouse expressed gene and nine mouse pseudogenes.

The single functional mouse gene for MIF (macrophage migration inhibitory factor) has been cloned from a P1 library, and its exon/intron structure determined and shown to resemble that of the human gene. The gene was mapped to chromosome 10 using two multilocus crosses between laboratory strains and either Mus musculus musculus or Mus spretus. Nine additional loci containing related sequences, apparently all processed pseudogenes, were also mapped to chromosomes 1, 2, 3, 7, 8, 9, 12, 17, and 19. While most of these pseudogenes were found in inbred mice and M. spretus, some are species specific. This suggests that there have been active phases of pseudogene formation in Mus both before and after the separation of musculus and spretus. The human genome contains no pseudogenes; we assigned the human gene to chromosome 19, consistent with the location of mouse and human functional genes for MIF in a region of conserved linkage.

Amino Acid Sequence↗
PubMed1995

Pax-6 is essential for lens-specific expression of zeta-crystallin.

Pax-6 is essential for normal eye development and has been implicated as a "master gene" for lens formation in embryogenesis. Guinea pig zeta-crystallin, a taxon-specific enzyme crystallin, achieves high expression specifically in lens through use of an alternative promoter. Here we show that Pax-6 binds a site in this promoter, which is essential for lens-specific expression. Lens and lens-derived cells exhibit a tissue-specific pattern of alternative splicing of Pax-6 transcripts and Pax-6 is expressed in adult lenses and cells that support zeta-crystallin expression. These results suggest that zeta-crystallin is a natural target gene for Pax-6 and that this Pax family member has a direct role in the continuing expression of tissue-specific genes.

Animals↗