bluuebunny/crossref_metadata_2025 huggingface dataset:
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

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

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

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

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

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

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

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

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

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

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

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.
In vitro evidence that LHRH stimulates the recruitment of prolactin mRNA-expressing cells during the postnatal period in the rat
Authors: Van Bael A , Huygen R , Himpens B , Denef C
Published: December 2008

We have studied the effect of LHRH and neuropeptide Y (NPY) on prolactin (PRL) mRNA levels in pituitary reaggregate cell cultures from 14-day-old female rats, by means of in situ hybridization and Northern blot analysis. As estimated by computer-image analysis, addition of LHRH on day 5 in culture for 40 h resulted in a 37% increase in the total cytoplasmic areas of cells containing PRL mRNA, visualized using a digoxigenin-labelled PRL cRNA. The size of individual PRL-expressing cells was not influenced, nor was the content of PRL mRNA per cell. A similar effect of LHRH was found by dot blot hybridization of extracted RNA. PRL mRNA levels were not affected by NPY. LHRH induced a 29% increase in the number of PRL mRNA-expressing cells processing through the S phase of the cell cycle, visualized by the incorporation of [3H]thymidine ([3H]T) into DNA over 16 h. The fraction of [3H]T-labelled cells was 10–12% of the total cell population. NPY did not influence the number of [3H]T-positive cells expressing PRL mRNA, but completely blocked the effect of LHRH on the latter population.

The present data suggest that LHRH, probably via a paracrine action of gonadotrophs, stimulates the recruitment of new lactotrophs, an action which is negatively modulated by NPY. Since the magnitude of this effect was the same in the total pituitary cell population as in cells processing through the S phase of the cell cycle and presumably mitosis, recruitment of lactotrophs seems to be based on differentiation of progenitor or immature cells into PRL-expressing cells, rather than on a mitogenic action on pre-existing lactotrophs alone.
Lack of effect of atrial natriuretic peptide and urodilatin on vasopressin-stimulated cyclic AMP production in microdissected rat inner medullary collecting ducts
Authors: Burgess W J , Perrott M N , Balment R J
Published: December 2008

It is unclear whether the diuretic effects of atrial natriuretic peptide (ANP) result, in part, from an inhibition of the renal actions of vasopressin. Moreover, accruing evidence suggests that the kidneys themselves may produce an ANP-like peptide, urodilatin, which shares many of the renal actions of ANP. The mechanism underlying the diuretic action of urodilatin has not yet been examined. Accordingly, we have investigated the potential modulatory actions of both ANP and urodilatin on vasopressin-stimulated cyclic AMP (cAMP) production in microdissected inner medullary collecting duct (IMCD) segments of rat kidney.

ANP and urodilatin alone (at 10−8 or 10−6 m) had no demonstrable effect on cAMP accumulation in IMCD segments. Moreover, neither ANP nor urodilatin (each at 10−6 m) significantly altered either the profile or the absolute magnitude of the cAMP response stimulated by vasopressin.

These findings indicate that neither ANP nor urodilatin interacts with the vasopressin-sensitive adenylate cyclase site in the rat IMCD to contribute to its diuretic actions.
Epitopic heterogeneity of human 3β-hydroxysteroid dehydrogenase in villous and extravillous human trophoblast
Authors: Hawes C S , McBride M W , Petropoulos A , Mueller U W , Sutcliffe R G
Published: December 2008

A new monoclonal antibody (FDO26G) is described which was raised against purified human 3β-hydroxysteroid dehydrogenase type I (3β-HSD type I). FDO26G reacted strongly with villous syncytiotrophoblast, weakly with some trophoblast cells in chorion laeve, and not at all with extravillous trophoblast in cytotrophoblast cell islands and decidual trophoblast. All these types of trophoblast reacted strongly with monoclonal antibody FDO161G, which has previously been shown to react with 3β-HSD type I and, like FDO26G, reacts strongly with adrenal cells.

Mapping experiments using a combination of lacZ fusion polypeptides and synthetic peptides located the FDO26G epitope to residues 354–366 at the C-terminal end of the molecule, a sequence that is identical in the type I and type II forms of the enzyme. The epitope contains a consensus for a casein kinase-II site with serine 359 as the candidate phosphorylation site. This suggested that the lack of reactivity of FDO26G to 3β-HSD in extravillous trophoblast might be due to phosphorylation at serine 359. Peptide 354–366 was synthesized with phosphoserine at residue 359 and its binding to FDO26G was compared with that of the unphosphorylated peptide. FDO26G bound the phosphopeptide at least as strongly as the unphosphorylated peptide. It is concluded that the lack of staining of extravillous trophoblast by FDO26G is due to the presence of a different sequence at residues 354–366 and that a hitherto unidentified third isoform of human 3β-HSD is expressed in these cells.
Identification of the horse epidermal growth factor (EGF) coding sequence and its use in monitoring EGF gene expression in the endometrium of the pregnant mare
Authors: Stewart F , Power C A , Lennard S N , Allen W R , Amet L , Edwards R M
Published: December 2008

The PCR technique and highly degenerate oligonucleotide primers were used to amplify a 282 bp fragment of the horse (Equus caballus) epidermal growth factor (EGF) cDNA. The clone corresponded to 94 amino acids of the EGF precursor molecule. The deduced amino acid sequence of the 53 residue EGF mitogenic peptide within the precursor sequence showed 60–70% identity with five other published EGF sequences. The PCR cDNA fragment hybridized to a 4·9 kb transcript in horse kidney and endometrial RNA which was of a similar size to the mature EGF transcript found in other mammalian species.

The horse cDNA clone was used in Northern blots to monitor EGF expression in the endometrium of pregnant mares up to day 83 of gestation (term=330–340 days). The level of expression increased from day 33 and showed a further dramatic increase between days 35 and 45, which coincides with the onset of implantation and placentation in this species. Levels remained elevated up to day 83. The horse DNA sequence was used to design sense and antisense oligonucleotide probes (45-mers) for in situ hybridization studies. The antisense probe showed specific hybridization to the glandular, but not lumenal, epithelial cells of the endometrium and there was no signal in fetal membranes. The in situ hybridization signal increased between days 35 and 45 to a similar degree to that observed in the Northern blot analysis. This dramatic increase in EGF expression in the glandular epithelium of the mare's endometrium during pregnancy may provide a mitogenic stimulus to the endometrium and/or trophoblast to facilitate placental differentiation and attachment. Alternatively, the precursor could be involved in the endometrial gland secretory process which is necessary to produce uterine milk for fetal sustenance.

The PCR cloning methods used in this study should be generally applicable to the cloning of EGF cDNAs from other species.
Transcripts and CpG islands associated with the pro-opiomelanocortin gene and other neurally expressed genes
Authors: Gardiner-Garden M , Frommer M
Published: December 2008

DNA sequences of vertebrate genes which code for neural or neuroendocrine peptides were analysed in terms of CpG dinucleotide distribution and G+C content. The vast majority of the genes were found to contain a region with the sequence characteristics of a CpG island surrounding the 5′ end. In mammalian species, the gene which codes for the neuroendocrine polypeptide pro-opiomelanocortin (POMC) was shown to be associated with two separate CpG islands: a 5′ CpG island which surrounds the POMC transcription start site and a 3′ CpG island which lies approximately 5 kb downstream, encompassing the third exon of POMC. Short POMC-related transcripts, known to be transcribed in the germline, were found to initiate from a promoter within the 3′ CpG island. The start sites of the short POMC-related transcripts in mouse testis were mapped to the region coding for γMSH in exon 3, in a similar location to transcription start sites identified in other mammalian POMC genes. Similar short POMC-related transcripts were identified in both the mouse F9 embryonal carcinoma cell line and mouse embryonic stem cells, suggesting that transcription initiating within the third exon may occur very early in development. No short transcripts were detected by Northern blot hybridization in either Xenopus laevis testis or oocyte poly(A)+ RNA extracts. The Xenopus laevis POMC genes, A and B, were associated with neither a 5′ nor a 3′ CpG island. Hence, the presence of a 5′ CpG island is not required for production of full-length transcripts from the Xenopus laevis POMC gene, but the presence of a 3′ CpG island may be required for transcription to occur from the third exon.
Follistatin but not α or βA inhibin subunit mRNA is expressed in ovine fetal ovaries in late gestation
Authors: Braw-Tal R , Tisdall D J , Hudson N L , Smith P , McNatty K P
Published: December 2008

The aim of this study was to investigate the sites of follistatin and α and βA inhibin mRNA expression in the ovaries of female sheep fetuses at 90, 100, 120 and 135 days of gestation (term=day 147). At 90 and 100 days primordial follicles were formed, followed by the appearance of primary follicles at 100 days of gestation. At days 120 and 135, primordial, primary and preantral (i.e. secondary) follicles were present in the ovaries, but antral (i.e. tertiary) follicles were not observed at any of these gestational ages. Two Booroola genotypes were studied: homozygous carriers (BB) and non-carriers (++) of the fecundity gene (FecB). Irrespective of genotype no specific hybridization of the α and βA inhibin riboprobes was detected in any ovarian cells at days 90, 100, 120 or 135 of gestation. In control mature ovaries, on the other hand, strong hybridization in the granulosa cells of antral follicles was observed. In contrast to α and βA inhibin, follistatin antisense (but not sense) riboprobes hybridized specifically to the granulosa cells of preantral follicles with two or more layers of cells at days 120 and 135 of gestation. Moreover, hybridization was also evident in the cells of the ovarian rete at days 120 and 135, but not at 90 or 100 days. No follistatin mRNA expression was observed in the granulosa cells of primordial or primary follicles or in any other ovarian cell type at any of the gestational ages examined. No FecB-specific differences in follistatin expression were noted with respect to stage of preantral follicular development and there were no obvious differences in the intensity of expression.

These results show that follistatin mRNA is expressed specifically in the granulosa cells and intraovarian rete. Expression of follistatin in rete cells was coincident with the increasing numbers of growing follicles within the fetal ovary, indicating that rete cell function may have a role in the ontogeny of early follicular growth. Our results suggest that follistatin and α and βA inhibin may not be important for the initiation of follicle growth in the sheep ovary, since these genes are not expressed during the transformation of a primordial follicle to a primary structure. However, the evidence for follistatin mRNA expression in the ovine fetal ovary implies that this hormone is likely to play a role during the early stages of follicle growth.
Growth hormone induces tyrosine phosphorylation but does not alter insulin-like growth factor-I gene expression in human IM9 lymphocytes
Authors: Clayton P E , Day R N , Silva C M , Hellmann P , Day K H , Thorner M O
Published: December 2008

GH induces hepatic IGF-I synthesis by increasing transcription of its gene. IGF-I is synthesized, however, in many other tissues where the effect of GH on its gene expression is less well characterized. IGF-I and GH are produced by human lymphocytes and may function as autocrine regulators of lymphoproliferation. We have therefore used the human IM9 lymphocyte cell line to (A) define the IGF-I gene transcripts expressed and (B) investigate the effect of GH on early (protein tyrosine phosphorylation) and late (changes in IGF-I mRNA levels) events in intracellular signal transduction. Multiple IGF-I mRNA species, ranging in size from 0·9 to 5·8 kb, were detected by Northern hybridization of poly(A)+ mRNA from IM9 cells. The human IGF-I gene contains at least six exons and alternative splicing produces a number of transcripts. Solution hybridization with exon-specific riboprobes and amplification by PCR using exon-specific primers revealed that multiple transcripts were expressed in IM9 cells, and that exon 2 was the dominant leader exon.

Treatment of IM9 cells with 200 ng recombinant human (rh)GH/ml led to the specific tyrosine phosphorylation of three intracellular proteins (93, 120 and 134 kDa), which are involved in the initial signalling of the GH transduction pathway. However a solution hybridization assay using the IGF-IA specific riboprobe on IM9 cell RNA from similar experiments revealed that GH treatment did not change IGF-I gene expression.

This study has demonstrated (A) that the IGF-I gene is expressed in human IM9 lymphocytes, (B) that in contrast to other human tissue, exon 2 is the major leader exon, and (C) that rhGH induces tyrosine phosphorylation of 93, 120 and 134 kDa proteins but does not alter IGF-I gene expression. The IM9 cell may form an important model to investigate a GH transduction pathway not coupled to the IGF-I gene.
Evidence that a calmodulin-like calcium-binding domain of the FSH β-subunit is involved in FSH-induced calcium uptake by Sertoli cells
Authors: Grasso P , Reichert L E
Published: December 2008

We have previously shown that a synthetic peptide amide corresponding to residues 1–15 of the human FSH β-subunit (hFSH-β-(1–15)) possesses structural characteristics and calcium-binding properties similar to the calcium-binding loops of calmodulin (CaM). The calcium-binding property of hFSH-β-(1–15) correlated well with its ability to stimulate uptake of calcium (as45 Ca2+) by cultured rat Sertoli cells and proteoliposomes enriched with bovine calf testis FSH receptors. A sequence found in the calcium-binding loops of CaM and a number of other calcium-binding proteins can be represented by the motif +−+−+−+−+−−+, where + represents a calcium-binding residue and − represents a non-binding residue. A sequence containing a similar motif appears in hFSHβ-(1–15) between residues 4 and 15: +−++−+−−−+−+. Using a synthetic peptide strategy, we undertook to determine whether the first three residues of hFSH-β-(1–15) were required to induce uptake of calcium by cultured rat Sertoli cells and FSH receptor-enriched proteoliposomes, and to assess whether rearrangement of the putative calcium-binding ligands (+) of hFSH-β-(1–15) to correspond to their linear sequence in CaM would enhance the ability of hFSH-β-(1–15) to induce calcium uptake in these two model systems. Our results indicate that (1) the amino terminal tripeptide of hFSH-β-(1–15), NSC, is not required for its effects on calcium influx and (2), although the putative calcium-binding loop of hFSH-β-(1–15) does not strictly adhere to the structural motif present in the calcium-binding loops of CaM, this does not adversely affect the potency of hFSH-β-(1–15) in the systems studied. In addition to providing a structural basis for understanding the affinity of hFSH-β-(1–15) for calcium, these studies suggest that the effects of FSH on calcium flux in Sertoli cells may involve a CaM-like region of its β-subunit.
Restricted expression of a zinc finger protein in male germ cells
Authors: Hosseini R , Marsh P , Pizzey J , Leonard L , Ruddy S , Bains S , Dudley K
Published: December 2008

Zfp-37 is a zinc finger protein gene expressed in male germ cells. The cDNA detected two transcripts on Northern blots of testis RNA, with expression first detected at around day 19. To establish the pattern of expression of the protein we have raised antibodies to ZFP-37 and used them on thin sections of testis and on Western blots. On Western blots the antibody detected two proteins exclusively in testis extracts, confirming the previous mRNA expression data. A time-course study revealed that the larger of the two proteins appears at about day 22 but the smaller one is not detected until day 34. Analysis of the expression of these two proteins in purified germ cell preparations revealed that the smaller protein is only detectable in the elongating spermatids or residual bodies. Data from thin sections showed that most, but not all, of the protein recognized by the antibody is in the nucleus, a result further confirmed by Western blotting. These results are discussed in the light of the possible role of this protein in regulating spermatogenesis.
'Liver-type' 11β-hydroxysteroid dehydrogenase cDNA encodes reductase but not dehydrogenase activity in intact mammalian COS-7 cells
Authors: Low S C , Chapman K E , Edwards C R W , Seckl J R
Published: December 2008

11β-Hydroxysteroid dehydrogenase (11β-HSD) catalyses the metabolism of corticosterone to inert 11-dehydrocorticosterone, thus preventing glucocorticoid access to otherwise non-selective renal mineralocorticoid receptors (MRs), producing aldosterone selectivity in vivo. At least two isoforms of 11β-HSD exist. One isoform (11β-HSD1) has been purified from rat liver and an encoding cDNA cloned from a rat liver library. Transfection of rat 11β-HSD1 cDNA into amphibian cells with a mineralocorticoid phenotype encodes 11 β-reductase activity (activation of inert 11-dehydrocorticosterone) suggesting that 11β-HSD1 does not have the necessary properties to protect renal MRs from exposure to glucocorticoids. This function is likely to reside in a second 11β-HSD isoform. 11β-HSD1 is co-localized with glucocorticoid receptors (GRs) and may modulate glucocorticoid access to this receptor type. To examine the predominant direction of 11β-HSD1 activity in intact mammalian cells, and the possible role of 11β-HSD in regulating glucocorticoid access to GRs, we transfected rat 11β-HSD1 cDNA into a mammalian kidney-derived cell system (COS-7) which has little endogenous 11β-HSD activity or mRNA expression.

Homogenates of COS-7 cells transfected with increasing amounts of 11β-HSD cDNA exhibited a dose-related increase in 11 β-dehydrogenase activity. In contrast, intact cells did not convert corticosterone to 11-dehydrocorticosterone over 24 h, but showed a clear dose-related 11β-reductase activity, apparent within 4 h of addition of 11-dehydrocorticosterone to the medium. To demonstrate that this reflected a change in functional intracellular glucocorticoids, COS-7 cells were co-transfected with an expression vector encoding GR and a glucocorticoid-inducible MMTV-LTR luciferase reporter construct, with or without 11β-HSD. Corticosterone induced MMTV-LTR luciferase expression in the presence or absence of 11β-HSD. 11-Dehydrocorticosterone was without activity in the absence of 11β-HSD, but induced MMTV-LTR luciferase activity in the presence of 11β-HSD. These results indicate that rat 11β-HSD1 can behave exclusively as a reductase in intact mammalian cells. Thus in some tissues in vivo, 11β-HSD1 may regulate ligand access to GRs by reactivating inert glucocorticoids.
Localization of the response elements of a gene induced by intermittent growth hormone stimulation
Authors: Johnson D , Harrison S , Pineda N , Heinlein C , Al-Shawi R , Bishop J O
Published: December 2008

Three regions required for the expression of a mouse major urinary protein (MUP) transgene were identified by a deletion analysis. One of these was located upstream of the cap site between −2139 and −1800, another was the proximal promoter region downstream of −324 and the third lay within the 338 nucleotide intron 1. Both the proximal promoter and intron 1 are involved in sexually dimorphic expression of the transgene (male/female ratio 20), which is dictated by the different temporal profiles of circulating GH in the two sexes. The data also indicated that the region between exons 3 and 7 may contribute to full expression in males and that a region between −718 and −324 may contribute towards the low expression level that obtains in females, but compared with the three principal regions the effects of these regions are relatively minor. We propose (1) that full expression of the transgene requires the co-operation of transcription factors binding to the three principal regions and (2) that the difference in expression between the sexes relates to interactions between transcription factors bound to the proximal promoter and to sites in intron 1. Our results complement earlier in vitro footprinting and gel-retardation studies of the homologous rat α2u-globulin genes. These identified a number of response elements, including putative C/EBP and AP1 sites in the proximal promoter and intron 1 respectively and three putative ΨNF-1 sites, two in the proximal promoter and one in intron 1, but proof of the functionality of these sites in regulating transcription was lacking. The proximal promoter also contained a 34 nucleotide sequence that has 70% identity with the SPI GH response element.
Interaction of LHRH with growth hormone-releasing factor-dependent and -independent postnatal development of somatotrophs in rat pituitary cell aggregates
Authors: Van Bael A , Proesmans M , Tilemans D , Denef C
Published: December 2008

Addition of LHRH for 40 h to aggregate cell cultures of 14-day-old rat pituitary significantly decreased the number of [3H]thymidine ([3H]T)-incorporating cells which immunostained for GH protein as well as the number of [3H]T-labelled cells expressing GH mRNA detectable by in situ hybridization with a digoxigenin-labelled riboprobe. The effect at the level of GH protein was seen at a dose of 1 nm LHRH. However, the effect at the GH mRNA level required a higher dose of LHRH (10 nm) or a longer incubation time (64 h). Treatment of the cultures for 40 h with 0·1 nm GH-releasing factor (GRF) provoked a 54% increase in the number of [3H]T-labelled cells containing GH mRNA and a 30% increase in the number of cells immunostained for GH protein. The latter effects of GRF were completely blocked by simultaneous addition of LHRH (1 nm) to the cultures. In the absence of GRF, LHRH (1 nM) also had an inhibitory effect on the total number of cells containing GH mRNA and a comparable effect on the total number of cells stained for GH protein. The present data show that LHRH is capable of inhibiting the GRF-independent as well as the GRF-dependent development of somatotrophs in postnatal rat pituitary in culture.
Sequence analysis of the turkey LH β subunit and its regulation by gonadotrophin-releasing hormone and prolactin in cultured pituitary cells
Authors: You S , Foster L K , Silsby J L , El Halawani M E , Foster D N
Published: December 2008

cDNAs encoding the precursor molecule of the turkey LH β subunit (tLHβ) were cloned from a turkey pituitary cDNA library. The nucleotide sequence of the longest of two different tLHβ cDNA clones contained 592 bp, and included 23 bp of the 5′ untranslated region (UTR) and 92 bp of the 3′ UTR in addition to a 477 bp open reading frame that encoded a 39 amino acid leader polypeptide and a 120 amino acid mature apoprotein. Turkey and chicken LHβ sequences shared approximately 92 and 93% nucleotide and amino acid sequence similarities respectively. Northern blot analysis of total cellular anterior pituitary RNA showed that an approximate 800 base transcript hybridized to a 32P-labelled tLHβ cDNA probe.

The gonadotrophin-releasing hormone (GnRH)-and prolactin (PRL)-regulated expression of LH and PRL in dispersed pituitary cells was determined by Northern blot analysis of tLHβ and PRL steady-state mRNA levels and by RIA analysis of secreted LH and PRL. GnRH-treated cells showed increased levels of both tLHβ mRNA and secreted LH, whereas mRNA and secreted levels of PRL did not change significantly. Cells treated with PRL showed lower levels of tLHβ and PRL mRNA as well as decreased release of LH and PRL. When cells were treated with both PRL and GnRH, increases in tLHβ mRNA and secreted levels of LH observed with GnRH alone were negated, whereas the decreases in mRNA and secreted levels of PRL observed with PRL alone were abrogated.

These findings suggest that PRL can down-regulate tLHβ gene expression and spontaneous release of LH as well as autoregulate PRL gene expression and spontaneous release of PRL, while GnRH appears capable of modulating the effects of PRL-regulated LH and PRL gene expression and spontaneous release.
Thyroid hormone receptor β mRNA expression in Sertoli cells isolated from prepubertal testis
Authors: Palmero S , De Marco P , Fugassa E
Published: December 2008

A polymerase chain reaction (PCR)-based assay was used to evaluate the expression of thyroid hormone receptor β mRNA in Sertoli cells isolated from both prepubertal rat and piglet testes. The expression of an mRNA coding for the functional thyroid hormone receptor β isoform, as established by the PCR assay, agrees with the presence of specific tri-iodothyronine (T3)-binding sites in the Sertoli cell nuclei of both species, as previously evaluated by displacement analysis. The results ratify the existence of a functional T3 receptor in the prepubertal testis and confirm the Sertoli cell as a specific target for thyroid hormone action on the developing testis. On the other hand, in both peripubertal rat (Palmero et al. 1988; Jannini et al. 1990) and piglet (Palmero et al. 1992) testes, high-affinity, low-capacity T3 binding sites have been specifically localised at the Sertoli cell level and TRal mRNA expression has been detected very recently in immature Sertoli cells (Jannini et al. 1994).

The aim of the present work was to test if, in prepubertal Sertoli cells isolated from both immature rat and piglet testes, the expression of an erbAβ mRNA specifically coding for the TR protein could be detected employing an highly sensitive polymerase chain reaction (PCR)-based assay.
Actions of 3,5,3′-tri-iodothyronine on the synthesis and secretion of major plasma proteins by a human hepatoblastoma cell line (Hep G2)
Authors: Kobayashi M , Horiuchi R
Published: December 2008

We have elucidated the action of tri-iodothyronine (T3) on the synthesis and secretion of seven major plasma proteins in a human hepatoblastoma cell line, Hep G2, and established an in vitro experimental model of human liver cells for the study of the mechanism of the action of thyroid hormone.

Hep G2 cells cultured in serum-free medium were treated with various concentrations of T3. During the first 24 h of T3 treatment, accumulation of α-fetoprotein in the medium was decreased in a dose-dependent manner (10−11-10−8 m), and the inhibitory effect was enhanced during the second 24 h of T3 treatment. On the other hand, α1-antitrypsin accumulation in the medium during the second 24 h of hormone treatment was decreased by T3 (10−9–10−8 m), although no change in accumulation was observed during the first 24 h of T3 treatment.

The newly synthesized [35S]Met-labelled α1-acid glycoprotein was increased by T3 and reached 3·4-fold within 37 h of 10−8 m T3 treatment. The stimulatory effect increased time-dependently (4·6fold after 61 h). In contrast, the synthesis of α-fetoprotein was reduced to half of that of the control after T3 treatment for 37 h.

Although the content of newly synthesized [35S]α1-antitrypsin was not affected by 10−8m T3 treatment during 3 days of hormone treatment, the accumulation of α1-antitrypsin in the medium decreased to 87%; in contrast, total cellular newly synthesized α1-antitrypsin increased to 105–130% of that of the control. From these results, it is suggested that α1-antitrypsin secretion might be suppressed by T3 treatment. However, T3 did not affect the accumulation of albumin, transferrin, fibronectin and α2-macroglobulin in the medium throughout the experiments.

It was shown that T3 has diverse control mechanisms on the synthesis and secretion of plasma proteins in Hep G2 cells: stimulation (α1-acid glycoprotein) or inhibition (α-fetoprotein) of plasma protein synthesis, and inhibition of protein secretion (α1-antitrypsin).
Retinoic acid induces activin receptor IIB mRNA in F9 embryonal carcinoma cells
Authors: Wan Y-J Y , Wang L , Wu T-C J
Published: December 2008

Mouse embryonal carcinoma F9 cells are pluripotent stem cells and differentiate into primitive endodermal cells upon treatment with retinoic acid (RA). We have recently shown that in F9 cells RA regulates gene expression of activin receptor type II (ActR-II), whose ligand is a potent differentiation agent. The present study examined the regulation of the newly cloned activin receptor type IIB (ActR-IIB) gene by RA. F9 cells expressed equal amounts of three ActR-IIB transcripts of 8·0, 7·5 and 4·0 kb. Both 9-cis-RA (c-RA) and all-trans-RA (t-RA) induced ActR-IIB gene expression in a dose-dependent manner. At 10−9m c-RA exerted no effect, while 10−5m c-RA increased the 8·0 kb ActR-IIB transcript about sevenfold. In contrast, t-RA induced the 8·0kb ActR-IIB transcript fivefold at 10−9m and up to eightfold at 10−5m. The inductive effect on the 8·0 kb transcript was greater than that on the 7·5 kb transcript, and was least effective on the 4·0 kb transcript, suggesting that these three mRNA isoforms may originate from different promoters. Both cycloheximide and actinomycin D inhibited the inductive effect of t-RA on ActR-IIB gene expression, in contrast to ActR-II whose gene expression was not suppressed by cycloheximide but abolished by actinomycin D. Thus, endodermal differentiation of F9 cells is associated with activation of ActR-IIB gene and the mechanisms involved in the regulation of ActR-II and IIB gene expression are different.