Percorrer por autor "Danks, J. A."
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- Cloning of the cDNA for sea bream (Sparus aurata) parathyroid hormone-related proteinPublication . Flanagan, J. A.; Power, Deborah; Bendell, L. A.; Guerreiro, P. M.; Fuentes, J.; Clark, M. S.; Canario, Adelino V. M.; Danks, J. A.; Brown, B. L.; Ingleton, P. M.This paper reports cloning of the cDNA for sea bream (Sparus aurata) parathyroid hormone-related protein (PTHrP). The gene codes for a 125-amino acid mature protein with a 35-residue prepeptide. The total gene sequence is 1.8 kb with approximately 75% noncoding. The N-terminus of the protein resembles mammalian and chicken PTHrP peptides with 12 of the first 21 amino acids identical and for which there is homology with mammalian parathyroid hormone. Toward the C-terminus, the nuclear transporter region between residues 79 and 93 in sea bream is 73% homologous to tetrapod PTHrP, and the RNA binding domain, 96–117, is 50% homologous, moreover starting with the conserved lysine and terminating with the lysine/arginine sequence. Sea bream PTHrP differs significantly from mammalian and chicken PTHrP, having a novel 16-amino acid segment between residues 38 and 54 and completely lacking the terminal domain associated in mammals with inhibition of bone matrix lysis. RT-PCR and in situ hybridization of sea bream tissues show that the gene is expressed widely and the results confirm observations of a PTHrP-like factor in sea bream detected with antisera to human PTHrP.
- Genomic structure and expression of parathyroid hormone-related protein gene (PTHrP) in a teleost, Fugu rubripesPublication . Power, Deborah; Ingleton, P. M.; Flanagan, J. A.; Canario, Adelino V. M.; Danks, J. A.; Elgar, Greg; Clark, M. S.In this study we describe the isolation and characterisation of the parathyroid hormone-related protein (PTHrP) gene from the teleost Fugu rubripes. The gene has a relatively simple structure, compared with tetrapod PTHrP genes, composed of three exons and two introns, encompassing 2.25 kb of genomic DNA. The gene encodes a protein of 163 amino acids, with a putative signal peptide of 37 amino acids and a mature peptide of 126 amino acids. The overall homology with known tetrapod PTHrP proteins is low (36%), with a novel sequence inserted between positions 38 and 65, the absence of the conserved pentapeptide (TRSAW) and shortened C-terminal domain. The N-terminus shows greater conservation (62%), suggesting that it may have a hypercalcaemic function similar to that of tetrapod PTHrP. In situ localisation and RT–PCR have demonstrated the presence of PTHrP in a wide range of tissues with varying levels of expression. Sequence scanning of overlapping cosmids has identified three additional genes, TMPO, LDHB and KCNA1, which map to human chromosome 12, with the latter two mapping to 12p12-11.2. PTHrP in human also maps to this chromosome 12 sub-region, thus demonstrating conservation of synteny between human and Fugu.
- Immunochemical detection of parathyroid hormone-related protein in the saccus vasculosus of a teleost fishPublication . Devlin, A. J.; Danks, J. A.; Faulkner, M. K.; Power, Deborah; Canario, Adelino V. M.; Martin, T. J.; Ingleton, P. M.Using antisera to regions of human parathyroid hormone- related protein (PTHrP) the saccus vasculosus (SV) of the sea bream (Sparus aurata) has been shown to contain immunoreactive PTHrP. By immunohistochemistry (IHC) the epithelial coronet cells in fixed and waxembedded SV tissue reacted with antisera to the prepro region of human PTHrP (−13 to +2), the N-terminus PTHrP (1–16), and the midmolecule PTHrP (50–69). Sodium dodecyl sulfate–polyacrylamide gel electrophoresis of saccus extracts and incubation media contained two major proteins of 14.3 and 15 kDa. By Western blotting these two proteins both reacted with the three antisera used for IHC, suggesting that they are immunochemically similar to human PTHrP (1–84). Ultrastructurally the coronet cells of Sparus saccus vasculosus resembled coronet cells described for other teleosts, with an abundant smooth endoplasmic reticulum (SER) which was more highly organized in the coronets. IHC at EM level showed reaction mainly with the membranes of the SER. These results suggest that S. aurata saccus vasculosus may produce a PTHrP-like molecule similar to human PTHrP.
- Parathyroid hormone-related protein and somatolactin in sea bream (Sparus aurata) brain and pituitaryPublication . Ingleton, P. M.; Power, Deborah; Canario, Adelino V. M.; Martin, T. J.; Danks, J. A.Parathyroid hormone-related protein (PTHrP) and somatolactin (SL) are both peptides that have been located in PAS+ve pars intermedia (PI) cells of teleost fishes. In mammals and the chick PTHrP is a hypercalcaemic factor causing lysis of bone calcified matrix and inhibiting phosphate excretion via the kidney. Functions of PTHrP in fishes are unknown but SL stimulates phosphate re-absorption by flounder kidney tubule cells1 and low ambient calcium activates PI cells of trout pituitaries.2 It appears possible that both peptides have some similar functions. They only share incidental amino acid homologies, so we have examined brain and pituitaries of sea bream for their distribution using specific antiserum to chum salmon SL (generous gift of H. Kawauchi) and to two regions of human PTHrP (1–16 ) and (50–69).
- Parathyroid hormone-related protein in lower vertebratesPublication . Danks, J. A.; Trivett, M. K.; Power, Deborah; Canario, Adelino V. M.; Martin, T. J.; Ingleton, P. M.1. Parathyroid hormone-related protein (PTHrP) is an important mediator of humoral hypercalcaemia of malignancy in humans. Normal human subjects have very low levels of PTHrP in their circulation. 2. Parathyroid hormone-related protein has recently been demonstrated in high levels in the circulation and tissues of the sea bream and the dogfish, leading to the hypothesis that PTHrP may be a 'classical' hormone in fish. 3. Immunohistochemistry and in situ hybridization were performed to investigate the evolutionary history of PTHrP. Tissues were examined from a number of lower vertebrates, including lungfish, lamprey and several species of bony and cartilaginous fish. Parathyroid hormone-related protein was localized to the skin and to kidney tubules in all animals studied. In the developing lungfish, PTHrP was observed in the notochord, developing brain and skeletal muscle layers. These results suggest that PTHrP is of ancient origin and has a basic and fundamental function in vertebrates.