bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulation of the growth hormone receptor during liver regeneration in the rat
Authors: Husman B , Andersson G 
Published: December 2008

ABSTRACT
The GH receptor (GHR) in regenerating rat liver following partial hepatectomy has been characterized in terms of mRNA levels, size of receptor variants, ligand binding, endocytosis and degradation. The GHR mRNA level, quantitated by solution hybridization, was found to be unchanged during the first 3 days of regeneration. The specific binding of 125I-labelled bovine GH to a GHR-enriched low density membrane fraction was, in contrast to the mRNA level, reduced to 10–35% between 12 and 24 h after partial hepatectomy, and remained low until 48 h. Removal of endogenous GH by MgCl2 treatment did not further increase the binding of 125I-labelled bovine GH. Affinity cross-linking experiments revealed reduced labelling of a specific receptor binder at 95 kDa, assuming a 1:1 stoichiometric binding of the ligand, in regenerating liver. Additional evidence for a decrease in the amount of functional GHR was provided by the finding of decreased levels of IGF-I mRNA in the liver remnant, with a nadir at 50% between 24 and 48 h after hepatectomy. GH binding was reduced to a similar extent in hypophysectomized animals subjected to partial hepatectomy, implying that pituitary GH is not involved in the mechanism of GHR down-regulation.
The in-vivo uptake of 125I-labelled bovine GH, which is correlated with the number of GHRs available for binding in the plasma membrane, was decreased to 23% in an endosome-enriched membrane fraction from regenerating liver at 24 h. No qualitative differences in the size distribution of endocytosed receptor-ligand complexes in normal and regenerating liver were noted. The degradation of internalized 125I-labelled bovine GH, analysed as trichloroacetic acid solubility, was unaffected during regeneration.
It is concluded that the reduced number of GHRs available for binding in regenerating liver cells is caused by an alteration exerted at a post-translational level during receptor biosynthesis.
Partial characterization of a novel oestrogen-induced protein in the rat adenohypophysis
Authors: Casabiell X , Zugaza J L , Pombo C M , Bokser L , Mulet N , Casanueva F F 
Published: December 2008

ABSTRACT
In order to detect putative markers of prolactin-secreting pituitary tumours, adult rats were subjected to long-term oestrogenization with oestradiol benzoate (OE2) on a monthly basis. At 6 months, anterior pituitaries were dissected and incubated either as tissue fragments or as dispersed cells with a S]methionine mix for labelling. Proteins released into the incubation medium and from tissue extracts were further analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and fluorography.
Oestrogen induced the appearance in the incubation medium of a protein (OE2 band) with an Mr of 38 000 under reducing conditions, and high specific activity. Surprisingly, such a protein was not detected in tissue extracts. The OE2 band was detectable by 7 days after the first dose of oestrogen, and remained throughout 1 year of treatment. The tumour cell line GH3 showed a similar OE2 band which was further enhanced by oestrogens. The protein was observed similarly in both female and male pituitary donors, either intact or gonadectomized, and also in rats of different strains, suggesting that its appearance was independent of the strain of rat and gonadal status. Furthermore, the OE2 band was specific for pituitary cells and not produced by other oestrogenized tissues.
No alteration in the rate of generation or the electrophoretic pattern of the OE2 band was observed when pituitary cells from oestrogenized rats were metabolically labelled while being incubated with tunicamycin. Furthermore, a system for glycan detection, adsorption to Concanavalin A or incubation with endoglycosidase F also failed to show a clear amount of glycosylation of the oestrogen-induced protein. Both immunoprecipitation experiments and time-limited proteolysis with V8 protease ruled out the possibility that the OE2 band could be structurally related to either GH or prolactin.
In conclusion, oestrogens induce the generation of a new monocatenary protein with an apparent Mr of 38 000, which has at least one intramolecular disulphide loop and is not glycosylated. The OE2 band was detected only in incubation medium and never in tissue extracts.
ISOLATION AND STRUCTURE OF A PARTIAL SHEEP OXYTOCIN RECEPTOR cDNA AND ITS USE AS A PROBE FOR NORTHERN ANALYSIS OF ENDOMETRIAL RNA
Authors: Stewart H J , Stevenson K R , Flint A P F 
Published: December 2008

ABSTRACT
The polymerase chain reaction (PCR) was used to generate a 131 bp cDNA encoding part of the sheep endometrial oxytocin receptor. The nucleotide sequence of this cDNA was 93.8% identical to the human oxytocin receptor sequence in this region. When used to probe Northern blots of sheep endometrial RNA the PCR product identified a 6.7 kb mRNA which appeared and disappeared during the oestrous cycle in parallel with the oxytocin receptor molecule as measured by ligand binding. The sheep endometrial receptor mRNA was significantly larger than the human myometrial mRNA (4.7 kb). It is suggested that the cloned cDNA described here is an appropriate probe for use where it is required to measure sheep oxytocin receptor mRNA.
Characterization of rabbit κ-casein cDNA: control of κ-casein gene expression in vivo and in vitro
Authors: Bösze Zs , Devinoy E , Puissant C , Fontaine M L , Houdebine L M 
Published: December 2008

ABSTRACT
The rabbit κ-casein cDNA was cloned and sequenced. One of the isolated clones included almost the entire 5′ end, while another clone corresponded to the 3′ end of the cDNA. No polyadenylation site was found and therefore this clone did not harbour the complete cDNA. The amino acid sequence of a full-length protein was deduced from the nucleotide sequence obtained for this partial cDNA. It revealed the presence of a chymosin cleavage site and five potential phosphorylation sites. Rabbit κ-casein was compared with those already described in other species. The rabbit sequence is closer to the ovine than to the mouse sequence. This result supports the idea that Lagomorpha are not closer to Rodentia than to Artiodactyla. The cDNA described above was used to study κ-casein gene expression in the rabbit mammary gland. This expression was induced primarily by prolactin in mammary gland organoids and was similar to αs1-casein gene expression in vivo. The κ-casein gene present in the casein gene locus is thus subject to the same regulation as the αs1-casein gene, although it has evolved from a fibrinogen gene.
Evolutionary conservation of the insulin gene structure in invertebrates: cloning of the gene encoding molluscan insulin-related peptide III from Lymnaea stagnalis
Authors: Smit A B , van Marle A , van Elk R , Bogerd J , van Heerikhuizen H , Geraerts W P M 
Published: December 2008

ABSTRACT
Although insulins and structurally related peptides are found in vertebrates as well as in invertebrates, it is not clear whether the genes encoding these hormones have emerged from a single ancestral (insulin)-type of gene or, alternatively, have arisen independently through convergent evolution from different types of gene. To investigate this issue, we cloned the gene encoding the molluscan insulin-related peptide III (MIP III) from the freshwater snail, Lymnaea stagnalis. The predicted MIP III preprohormone had the overall organization of preproinsulin, with a signal peptide and A and B chains, connected by two putative C peptides. Although MIP III was found to share key features with vertebrate insulins, it also had unique structural characteristics in common with the previously identified MIPs I and II, thus forming a distinct class of MIP peptides within the insulin superfamily. MIP III is synthesized in neurones in the brain. It is encoded by a gene with the overall organization of the vertebrate insulin genes, with three exons and two introns, of which the second intron interrupts the coding region of the C peptides. Our data therefore demonstrate that in the Archaemetazoa, the common ancestor of the vertebrates and invertebrates, a primordial peptide with a two-chain insulin configuration encoded by a primordial insulin-type gene must have been present.
Modulation of human DNA methyltransferase activity and mRNA levels in the monoblast cell line U937 induced to differentiate with dibutyryl cyclic AMP and phorbol ester
Authors: Soultanas P , Andrews P D , Burton D R , Hornby D P 
Published: December 2008

ABSTRACT
The regulation of DNA (cytosine-5) methyltransferase (DNA MeTase) enzyme activity and gene expression was examined in the monoblastoid U937 cell line induced to differentiate with either dibutyryl cyclic AMP (dbcAMP) or phorbol ester. dbcAMP treatment was found to cause the rapid (<4 h) suppression of DNA MeTase specific activity, with no DNA MeTase activity detectable after 10 h. Equally, no DNA MeTase activity was detectable in nuclear extracts of fresh peripheral blood monocytes. Using both a U937 DNA MeTase cDNA and a mouse DNA MeTase cDNA as probes, steady-state levels of DNA MeTase mRNA were found to decline sharply between 4 and 15 h after dbcAMP treatment. No DNA MeTase mRNA was detectable after 20 h of dbcAMP treatment. Nuclear run-on analysis showed there to be only a small (40%) suppression of DNA MeTase gene transcription in cells treated with dbcAMP for 24 h, implying a role for post-transcriptional processes in the regulation of DNA MeTase mRNA levels. The observed decline in DNA MeTase activity/mRNA levels appeared to precede the dbcAMP-induced arrest in DNA replication, as judged by the incorporation of tritiated thymidine into DNA.
In contrast to the effect of dbcAMP, treatment of U937 cells with the phorbol ester 12-O-tetradecanoyl phorbol-13-acetate (TPA) led to an overall stimulation of DNA MeTase specific activity. The TPA response was found to be complex and broadly consisted of an early (0–15 h) burst of DNA MeTase activity followed by a more gradual sustained increase in DNA MeTase activity after prolonged (16–40 h) TPA treatment. The early phase of high DNA MeTase activity was not mirrored by an increase in steady-state levels of DNA MeTase mRNA, as judged by Northern blot analysis. However, a substantial induction of DNA MeTase mRNA levels was observed after 20–24 h of TPA treatment. Nuclear run-on analysis showed this not to be due to any significant increase in DNA MeTase gene transcription. The observed increases in DNA MeTase activity/mRNA levels were observed whilst cells were undergoing deproliferation. Interestingly, the addition of TPA and more physiological protein kinase C (PKC) activators, such as diacylglycerol and phosphatidylserine, to DNA MeTase-enriched nuclear extracts generated a 4·5-fold and a 1·5-fold increase in DNA MeTase specific activity respectively. The TPA-induced stimulation of DNA MeTase activity could be inhibited by the PKC inhibitor H-9, implicating a role for PKC in the regulation of DNA MeTase activity in vivo.
Distribution of insulin-like growth factor-I receptor mRNA in rat brain. Regulation in the hypothalamo-neurohypophysial system
Authors: Aguado F , Rodrigo J , Cacicedo L , Mellström B 
Published: December 2008

ABSTRACT
The distribution and regulation of mRNA for the IGF-I receptor (IGF-I-R) in the adult rat brain were studied by in-situ hybridization with a 35S-labelled cRNA probe. The pituitary gland showed a strong hybridization signal in the pars tuberalis (the surface of the median eminence), pars distalis and pars intermedia. Within the brain, a strong hybridization signal was found in the circumventricular organs, olfactory bulb, hippocampus, cerebellum and hypothalamus.
IGF-I-R mRNA was consistently found in cell bodies of the hypothalamo-neurohypophysial systern. Six days of intermittent salt-loading resulted in an increase in IGF-I-R gene expression in the supraoptic nucleus. The increase in IGF-I-R mRNA was accompanied by a high expression of c-Fos immunoreactivity in the same cells. The presence and regulation of IGF-I-R mRNA in the hypothalamus suggest that IGF-I may affect the local plasticity or modulation of activated magnocellular neurones by an autocrine or paracrine action through specific receptors in the hypothalamo-neurohypophysial system.
Prothymosin α mRNA is expressed in competent and proliferating rat thyroid cells (FRTL-5) but is not sufficient to elicit cell progression through the cell cycle
Authors: Alvarez C V , Zalvide J B , Cancio E , Dieguez C , Regueiro B J , Vega F V , Dominguez F 
Published: December 2008

ABSTRACT
Using flow cytometry we observed the effects that different hormonal treatments had on the progression of rat thyroid (FRTL-5) cells through the cell cycle. The absence of hormones or the addition of TSH (6 mU/ml) did not induce DNA synthesis; however, the addition of IGF-I (30 ng/ml) promoted cell proliferation. The number of cells recruited by IGF-I was lower than when IGF-I and TSH were used. We therefore concluded that we had a model with three different types of cells: (1) quiescent cells, cells cultured in the absence of hormones, considered to be G0-arrested cells, (2) competent cells, TSH-treated cells that did not proliferate (being arrested in a cycle phase different from G0) and (3) actively proliferating cells, cells treated with TSH plus IGF-I.
Prothymosin α (PTA) mRNA levels were almost undetectable in cells cultured without hormones at all times studied, i.e. 8, 14 and 24 h. On the contrary, TSH and/or IGF-I greatly increased PTA mRNA. These data indicate that G0-arrested quiescent cells do not express PTA mRNA and that PTA mRNA is induced when FRTL-5 cells are committed to proliferate by the addition of TSH, in spite of being arrested by the lack of IGF-I. We therefore conclude that PTA mRNA expression may be an event that is necessary for cells to proliferate, but that it is not sufficient for the promotion of cell progression through the cell cycle.
Molecular cloning of cDNAs encoding two types of gonadotrophin α subunit from the masu salmon, Oncorhynchus masou: construction of specific oligonucleotides for the α1 and α2 subunits
Authors: Gen K , Maruyama O , Kato T , Tomizawa K , Wakabayashi K , Kato Y 
Published: December 2008

ABSTRACT
Two types of cDNA (GTHα1 and -α2) encoding the α subunits of masu salmon (Oncorhynchus masou) gonadotrophin were cloned by the reverse transcription-polymerase chain reaction for pituitary mRNAs. The nucleotide sequences showed that the GTHα1 cDNA was 380 bp long, encoding 119 amino acids, and that GTHα2 cDNA was 365 bp long, encoding 114 amino acids. The masu salmon α subunit types had a few differences between the sequences, with homologies of 80% (nucleotide sequence) and 72% (amino acid sequence). The structural difference between the α1 and α2 subunits was predicted using hydropathic analysis. The evolutionary interval between masu and chum salmon was estimated to be 4·0 and 2·3 million years by comparing their GTHα1 and -α2 subunits respectively. These time values are roughly consistent with the evolutionary time interval (3·0 million years) estimated from fossil records and an isozyme study. Specific synthetic oligonucleotide probes were constructed and used for genomic Southern blot analyses. The restriction fragment sizes of the GTHα1 and -α2 genes were similar, and when their patterns were compared with those from four other teleosts, each species showed a different pattern from the others, but no difference between their respective α1 and α2 genes. Therefore, the structural features of the GTHα1 and -α2 genes may have diverged in a similar manner in these five teleosts.
Molecular cloning of cDNAs encoding two gonadotrophin β subunits (GTH-Iβ and -IIβ) from the masu salmon, Oncorhynchus masou: rapid divergence of the GTH-Iβ gene
Authors: Kato Y , Gen K , Maruyama O , Tomizawa K , Kato T 
Published: December 2008

ABSTRACT
Two types of cDNA (GTH-Iβ and -IIβ) encoding the β subunit of masu salmon (Oncorhynchus masou) gonadotrophin were cloned using the reverse transcription-polymerase chain reaction for pituitary mRNAs. The nucleotide sequence of GTH-Iβ cDNA was 469 bp long, encoding 137 amino acids, and GTH-IIβ cDNA was 476 bp long, encoding 142 amino acids. These two masu salmon β subunit types showed low homologies of 52% (nucleotide sequence) and 33% (amino acid sequence). The evolutionary interval between masu and chum salmon was estimated to be 5·65 and 1·43 million years by comparing GTH-Iβ and GTH-IIβ respectively. These time values are markedly inconsistent with the evolutionary time (30 million years) estimated from fossil records and an isozyme study. Southern blot analyses showed that the Iβ gene restriction fragment lengths differed among five teleosts, whereas, with one exception, the IIβ gene showed well conserved patterns. Therefore, the GTH-Iβ gene may have diverged at a faster rate than the GTH-IIβ gene.
Expression of Pit-1 and related proteins in diverse human pituitary adenomas
Authors: Hoggard N , Callaghan K , Levy A , Davis J R E 
Published: December 2008

ABSTRACT
Pit-1, a member of the POU family of homeodomain transcription factors, activates prolactin and GH gene expression but also has a role in pituitary cell differentiation and proliferation. Expression of Pit-1 may therefore be of central importance in the function and phenotype of human pituitary adenomas. We have found evidence that, in addition to Pit-1 mRNA, Pit-1-like immunoreactivity and DNA-binding activity are readily detectable in a series of human pituitary adenomas. Gel mobility shift assays using adenoma protein extracts with two Pit-1-binding sites from the human prolactin gene promoter demonstrated the formation of several DNA sequence-specific protein—DNA complexes; some of these could be accounted for by Oct-1-binding activity. Pit-1 activity was anticipated in prolactin- and GH-secreting adenomas, but was also detected in a proportion of endocrine-inactive (non-secreting) adenomas that did not express Pit-1 target genes.
The data demonstrate the presence of Pit-1 in a range of pituitary adenomas. Different adenomas generated slightly differing patterns of DNA-binding activity, though Pit-1 mRNA and protein size appeared normal in all tumours so far examined.
Insulin-like growth factor-I mRNA expression in the interstitial cells of the rat testis
Authors: Moore A , Chen C-L C , Davis J R E , Morris I D 
Published: December 2008

ABSTRACT
IGF-I mRNA has been demonstrated in testicular tissue and, more recently, localized specifically to Leydig cells. This study investigated the expression of IGF-I and side-chain cleavage enzyme (SCC) mRNA in two preparations of rat interstitial testicular cells which were separated by buoyant density into Leydig cell-enriched and -depleted fractions. RNA was prepared from interstitial cells obtained from the testes of untreated adult and immature rats and adult rats treated with human chorionic gonadotrophin (hCG) or ethane dimethanesulphonate (EDS; to destroy Leydig cells). IGF-I mRNA was detected in all samples, with five major transcripts ranging from 7·5 to 0·6 kb. Leydig cells (3β-hydroxysteroid dehydrogenase-positive and sensitive to EDS) expressed abundant IGF-I and SCC mRNAs, and levels of both were increased following hCG treatment. However, in addition, IGF-I mRNA which was derived from non-Leydig interstitial cells was detected, in the complete absence of SCC message, either in the more buoyant interstitial cells or in both interstitial cell fractions following the destruction of Leydig cells by EDS treatment. IGF-I expression in the Leydig cell-depleted cell fraction was also increased by hCG treatment, and it is therefore suggested that at least part of this non-Leydig interstitial cell IGF-I mRNA originates in Leydig cell precursors. In conclusion, Leydig cells are not the sole origin of IGF-I mRNA in the testis, and the non-Leydig cell expression may be an important component of testicular IGF-I production.
Angiotensin II receptor subtypes in eel (Anguilla anguilla)
Authors: Marsigliante S , Verri T , Barker S , Jimenez E , Vinson G P , Storelli C 
Published: December 2008

ABSTRACT
Previous studies have shown the effects of angiotensin II (Ang II) in teleosts, and Ang II-binding sites have also been localized in tissues from rainbow trout. The purpose of this study was to extend these findings and to provide an analysis of Ang II receptor (Ang II-R) isoforms in three tissues obtained from European eel (Anguilla anguilla).
Ang II-Rs were identified in eel liver, kidney and intestine membranes by the binding of either 0·5 nmol human 125I-labelled Tyr4-lle5-Ang II/l or increasing concentrations (1–120 nmol/l) of [3,5-3H]Tyr4-Ile5-Ang II. Using an isoelectric focusing technique, two Ang II-binding sites were identified in liver membranes. These migrated to isoelectric points (pI values) 6·5 and 6·7. Seventy per cent of binding to both sites was displaced by a 10 000-fold excess of unlabelled human Ang II. In both whole plasma membranes and brush border membranes from intestine, only one form of the Ang II-R was found, with pI 6·5 and high affinity (Kd=3·4 nmol/l) for the [3,5-3H]Tyr4-Ile5-Ang II. Similarly, only the isoform focusing at pI 6·5 was observed in renal tubular epithelial brush border membranes. Reduction of disulphide bridges with dithiothreitol significantly enhanced Ang II binding to the isoform at pI 6·5 in liver (P<0·05) and kidney (P<0·01), while in liver the binding to the isoform of pI 6·7 was significantly reduced (P<0·001).
The data suggest the existence in eel liver of multiple forms of Ang II-R, which may have different functions, while one single form appeared to be present in enterocyte plasma membrane and in renal brush border membrane.
Isolation of a cDNA whose expression is markedly increased in malignantly transformed FRTL cells and neoplastic human thyroid tissues
Authors: Ohta K , Endo T , Gunji K , Onaya T 
Published: December 2008

ABSTRACT
We have cloned a cDNA whose mRNA levels are increased in malignantly transformed rat thyroid FRTL cells (FRTL-Tc cells). We constructed a cDNA library from FRTL-Tc cells in λgt10 and screened the cDNAs by differential plaque filter hybridization. Twenty-five thousand clones were screened and one cDNA (C140) was selected which corresponded to a mRNA whose expression was 5·8 times higher in FRTL-Tc cells than in FRTL cells. A 0·8 kb specific C140 mRNA was detected by Northern blot analysis of FRTL-Tc and FRTL mRNAs. The C140 cDNA was sequenced and found to encode a protein of 227 amino acids.
We have found that C140 mRNA is conserved in human thyroid cells, but it is encoded by a smaller 0·7 kb transcript. C140 mRNA was highly expressed in neoplastic thyroid tissues and weakly in normal thyroid tissues in the same patients. Additionally, we found that C140 mRNA was also increased in the thyroid tissue of a patient with Graves' disease. These results suggest that C140 expression might be higher in rapidly growing thyroid cells than in normal cells, and might provide a new aspect for the study of thyroid tumours.