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Rosengren L, Simko H, Aryan L, Axelsson-Lendin P, Chmielewska J, Mode A, Parrow V. Antisense and sense RNA probe hybridization to immobilized crude cellular lysates: a tool to screen growth hormone antagonists. ACTA ACUST UNITED AC 2005; 10:260-9. [PMID: 15809322 DOI: 10.1177/1087057104273802] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The growth-promoting effect of growth hormone (GH) is primarily mediated by insulin-like growth factor-1 (IGF-1). The liver is the main source of circulating IGF-I. The authors have used rodent primary hepatocytes for studies on pharmacological intervention of IGF-I mRNA expression. A 96-well nonradioactive IGF-1 mRNA quantification assay was developed, based on the hybridization of sense and antisense RNA probes, to replicate membranes with crude hepatocyte lysates. The sense hybridization was used as an internal standard. The antagonistic properties of a set of GH-receptor binding compounds were evaluated. Two compounds were found to down-regulate IGF-I mRNA. Effects due to metabolic inhibition or toxicity were excluded using a cell proliferation assay. To investigate potential unspecific transcriptional effects, the mRNA levels of the housekeeping genes, beta-actin and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), were determined. Two other GH-regulated genes, cytochrome P450 2C12 (CYP2C12) and a rat homologue to the human alpha1B-glycoprotein (A1BG), were quantified by RNase protection assays and found to be down-regulated, confirming the antagonistic property of 1 compound. In conclusion, a direct filter hybridization assay of hepatocyte lysates using nonradioactive sense and antisense probes can be used for quantitative mRNA measurements and could constitute a valuable tool in screening for pharmacologically active compounds.
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Affiliation(s)
- Linda Rosengren
- Department of Assay Development & Screening, Biovitrum AB, 17176 Stockholm, Sweden.
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Chen S, Wang HT, Yang B, Fu YR, Ou QJ. Protective effects of recombinant human growth hormone on cirrhotic rats. World J Gastroenterol 2004; 10:2894-7. [PMID: 15334695 PMCID: PMC4572127 DOI: 10.3748/wjg.v10.i19.2894] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
AIM: To investigate the effects and molecular mechanisms of recombinant human growth hormone (rhGH) on protecting liver function and alleviating portal hypertension of liver cirrhotic rats.
METHODS: Liver cirrhosis of male Sprague-Dawley rats was induced by administration of thioacetamide. The rats with or without liver cirrhosis were randomly divided into four groups. Group A consisted of the normal rats was treated with normal saline (NS), group B consisted of the normal rats was treated with rhGH, group C consisted of cirrhotic rats was treated with NS, and group D consisted of cirrhotic rats was treated with rhGH. The rats of different groups were subcutaneously injected with 0.5 mL of NS or 333 ng/kg of rhGH daily for 7 d. After treatments, the following parameters were examined, including GH-binding capacity (RT) by 125I-hGH binding, growth hormone receptor mRNA(GHR mRNA) expression by RT-PCR, relative content of collagen (RCC) by histomorphomertry, and level of malon-dialdehyde (MDA) and superoxide dismutase (SOD) in liver tissue by thiobarbituric acid reaction and pyrogallic acid self-oxidation, respectively. Serum albumin (ALB), alanine transaminase (ALT) and portal vein pressure (PVP) were also examined.
RESULTS: rhGH up-regulated both the GH-binding capacity (RT) and the expression of GHR mRNA in vivo. RT in group A (72 ± 12 fmol/mg protein) was significantly higher than that in group C (31 ± 4 fmol/mg protein) (P < 0.05). RT in group B (80 ± 9 fmol/mg protein) increased markedly compared to group A (P < 0.05). RT in group D (40 ± 7 fmol/mg protein) raised remarkably compared with group C (P < 0.05), but less than that in group A, and there was no significant GH binding affinity contrast (Kd) change. The GHR mRNA level (iOD, pixel) in group A (29 ± 3) was significantly higher than that in group C (23 ± 3) (P < 0.05). GHR mRNA levels were significantly raised in group B (56 ± 4) and group D (42 ± 8) compared with groups A and C (29 ± 3 and 23 ± 3, respectively) (P < 0.05). Compared with the normal liver, MDA level was higher and SOD level was lower in cirrhotic livers. After rhGH treatment, MDA level was significantly declined to 12.0 ± 2.2 nmol/mg protein and SOD was raised to 1029 ± 76 U/mg protein in group D (P < 0.05). ALB levels in groups B and D (42 ± 7 g/L and 37 ± 7 g/L, respectively) were significantly raised compared with those in groups A and C (35 ± 5 g/L and 29 ± 4 g/L, respectively) (P < 0.05). ALT level was markedly lower in group D (69 ± 7 U/L) compared to group C (89 ± 15 U/L) (P < 0.05), and close to group A (61 ± 10 U/L). RCC in group C (22.30% ± 3.86%) was significantly higher than that in group A (1.14% ± 0.21%) and group D (14.70% ± 2.07%) (P < 0.05). In addition, rhGH markedly alleviated portal hypertension in liver cirrhotic rats (group D vs C, 9.3 ± 1.5 cmH2O vs 14.4 ± 2.0 cmH2O) (P < 0.05).
CONCLUSION: Pharmacological doses of rhGH can increase RT and GHR mRNA expression, ameliorate liver functions, repress fibrosis and decline portal hypertension, suggesting it has potentially clinical usage as a hepatotropic factor.
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Affiliation(s)
- Shuang Chen
- Department of General Surgery, Sun Yat-Sen Memorial Hospital, the Second Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510120, Guangdong Province, China.
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Wang HT, Chen S, Wang J, Ou QJ, Liu C, Zheng SS, Deng MH, Liu XP. Expression of growth hormone receptor and its mRNA in hepatic cirrhosis. World J Gastroenterol 2003; 9:765-70. [PMID: 12679928 PMCID: PMC4611446 DOI: 10.3748/wjg.v9.i4.765] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the expression of growth hormone receptor (GHR) and mRNA of GHR in cirrhotic livers of rats with the intension to find the basis for application of recombinant human growth hormone (rhGH) to patients with liver cirrhosis.
METHODS: Hepatic cirrhosis was induced in Sprague-Dawley rats by administration of thioacetamide intraperitoneally for 9-12 weeks. Collagenase IV was perfused in situ for isolation of hepatocytes. The expression of GHR and its mRNA in cirrhotic livers was studied with radio-ligand binding assay, RT-PCR and digital image analysis.
RESULTS: One class of specific growth hormone-binding site, GHR, was detected in hepatocytes and hepatic tissue of cirrhotic livers. The binding capacity of GHR (RT, fmol/mg protein) in rat cirrhotic liver tissue (30.8 ± 1.9) was significantly lower than that in normal control (74.9 ± 3.9) at the time point of the ninth week after initiation of induction of cirrhosis (n = 10, P < 0.05), and it decreased gradually along with the accumulation of collagen in the process of formation and development of liver cirrhosis (P < 0.05). The number of binding sites (× 104/cell) of GHR on rat cirrhotic hepatocytes (0.86 ± 0.16) was significantly lower than that (1.28 ± 0.24) in control (n = 10, P < 0.05). The binding affinity of GHR among liver tissue, hepatocytes of various groups had no significant difference (P > 0.05). The expression of GHR mRNA (riOD, pixel) in rat cirrhotic hepatic tissues (23.3 ± 3.1) was also significantly lower than that (29.3 ± 3.4) in normal control (n = 10, P < 0.05).
CONCLUSION: The growth hormone receptor was expressed in a reduced level in liver tissue of cirrhotic rats, and lesser expression of growth hormone receptors was found in a later stage of cirrhosis. The reduced expression of growth hormone receptor was partly due to its decreased expression on cirrhotic hepatocytes and the reduced expression of its mRNA in cirrhotic liver tissue.
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Affiliation(s)
- Hong-Tao Wang
- Department of Hepato-biliary Surgery, Sun Yat-Sen Memorial Hospital, the Second Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510120, Guangdong Province, China.
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4
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Phillips LS, Pao CI, Villafuerte BC. Molecular regulation of insulin-like growth factor-I and its principal binding protein, IGFBP-3. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1998; 60:195-265. [PMID: 9594576 DOI: 10.1016/s0079-6603(08)60894-6] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The insulin-like growth factors (IGFs) have diverse anabolic cellular functions, and structure similar to that of proinsulin. The distribution of IGFs and their receptors in a wide variety of organs and tissues enables the IGFs to exert endocrine, paracrine, and autocrine effects on cell proliferation and differentiation, caloric storage, and skeletal elongation. IGF-I exhibits particular metabolic responsiveness, and circulating IGF-I originates predominantly in the liver. Hepatic IGF-I production is controlled at the level of gene transcription, and transcripts are initiated largely in exon 1. Hepatic IGF-I gene transcription is reduced in conditions of protein malnutrition and diabetes mellitus, and our laboratory has used in vitro transcription to study mechanisms related to diabetes. We find that the presence of sequences downstream from the major transcription initiation sites in exon 1 is necessary for the diabetes-induced decrease in IGF-I transcription. Six nuclear factor binding sites have been identified within the exon 1 downstream region, and footprint sites III and V appear to be necessary for metabolic regulation; region V probes exhibit a decrease in nuclear factor binding with hepatic nuclear extracts from diabetic animals. IGFs in biological fluids are associated with IGF binding proteins, and IGFs circulate as a 150-kDa complex that consists of an IGF, an IGFBP-3, and an acid-labile subunit. Circulating IGFBP-3 originates mainly in hepatic nonparenchymal cells, where IGF-I increases IGFBP-3 mRNA stability, but insulin increases IGFBP-3 gene transcription. Regulation of IGFBP-3 gene transcription by insulin appears to be mediated by an insulin-responsive element, which recognizes insulin-responsive nuclear factors in both gel mobility shift assays and southwestern blots. Studies of mechanisms underlying the modulation of IGF-I and IGFBP-3 gene transcription, and identification of critical nuclear proteins involved, should lead to new understanding of the role and regulation of these important growth factors in diabetes mellitus and other metabolic disorders.
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Affiliation(s)
- L S Phillips
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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Skrtic S, Wallenius V, Ekberg S, Brenzel A, Gressner AM, Jansson JO. Insulin-like growth factors stimulate expression of hepatocyte growth factor but not transforming growth factor beta1 in cultured hepatic stellate cells. Endocrinology 1997; 138:4683-9. [PMID: 9348194 DOI: 10.1210/endo.138.11.5540] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Hepatic stellate cells (HSC) are located adjacent to hepatocytes and produce hepatocyte growth factor (HGF) in the normal liver, whereas transformed HSC in fibrotic livers produce transforming growth factor beta1 (TGFbeta1), an inhibitor ofhepatocyte proliferation. In addition to the endocrine actions of hepatic insulin-like growth factor-I (IGF-I), it also stimulates the proliferation of HSC. In this study we found that addition of IGF-1 (20-500 ng/ml) for 48 h to 2- to 7-day-old primary cultures of rat HSC resulted in a time- and dose-dependent increase by 50-190% of the concentrations of immunoreactive HGF in the medium. The levels of HGF as well as DNA synthesis measured as thymidine incorporation were also enhanced by IGF-II and des(1-3)IGF-I, which has reduced binding to IGF binding proteins. There was no consistent effect of the IGFs on the levels of immunoreactive TGFbeta1 or on the total DNA content of the cultures. There was no effect of human GH on medium levels of HGF or TGFbeta1, thymidine incorporation, or total DNA content. IGF-I increased the abundance of HGF messenger RNA, as measured by the RNase protection/solution hybridization technique, whereas there was no effect on TGFbeta1 or glyceraldehyde phosphate dehydrogenase messenger RNA. The results suggest that IGFs stimulate the production of HGF but not TGFbeta1 by HSC in vitro.
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Affiliation(s)
- S Skrtic
- Research Center for Endocrinology and Metabolism, Sahlgrenska University Hospital, Göteborg, Sweden
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6
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Brameld JM. Molecular mechanisms involved in the nutritional and hormonal regulation of growth in pigs. Proc Nutr Soc 1997; 56:607-19. [PMID: 9264111 DOI: 10.1079/pns19970061] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- J M Brameld
- Department of Applied Biochemistry and Food Science, University of Nottingham, Loughborough
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7
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Brenzel A, Gressner AM. Characterization of insulin-like growth factor (IGF)-I-receptor binding sites during in vitro transformation of rat hepatic stellate cells to myofibroblasts. EUROPEAN JOURNAL OF CLINICAL CHEMISTRY AND CLINICAL BIOCHEMISTRY : JOURNAL OF THE FORUM OF EUROPEAN CLINICAL CHEMISTRY SOCIETIES 1996; 34:401-9. [PMID: 8790975 DOI: 10.1515/cclm.1996.34.5.401] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Insulin-like growth factors are growth-promoting peptides structurally related to insulin which possess autocrine and paracrine activities. IGF-I is mainly synthesized in hepatocytes, but little is known about its paracrine action on hepatocyte-adjacent perisinusoidal hepatic stellate cells, the principal matrix producing precursor cell type in the liver. IGF-I might stimulate proliferation and phenotypical transformation of hepatic stellate cells into myofibroblasts, the cell type responsible for the excessive production of connective tissue elements during fibrogenesis. In this study we investigated the expression and function of the IGF-I receptor during transformation of isolated and cultured hepatic stellate cells. The respective stages of transformation of hepatic stellate cells were defined by determination of cellular smooth muscle iso-alpha-actin and retinyl-palmitate content, respectively. IGF-I receptor protein decreased stage-dependently down to 0.5 at the 4th day and about 0.17 at the 8th day. The number of IGF-I receptors was determined to be initially 1.3 x 10(5)/cell. Their quantity decreased to 0.8 x 10(5) sites/cell (4th day) down to 0.5 x 10(5) sites/cell at the 7th day and remained constant thereafter at 0.7 x 10(5) sites/cell. Dissociation constants (KD) for IGF-I range from 0.32-0.57 nmol/l showing constantly high receptor affinity. Northern blot analyses revealed distinct upregulation of IGF-I receptor mRNA level during culture. It is concluded that hepatocyte-generated IGF-I and/or IGF-I binding proteins are candidate mediators of hepatic stellate cell activation during the initial period of transformation to myofibroblasts. After completion of transformation the cell becomes relatively refractory to the action of IGF-I as judged from receptor density.
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Affiliation(s)
- A Brenzel
- Department of Clinical Chemistry, Philipps University, Marburg, Germany
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9
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Bourinbaiar AS, Lee-Huang S. Anti-HIV effect of beta subunit of human chorionic gonadotropin (beta hCG) in vitro. Immunol Lett 1995; 44:13-8. [PMID: 7536708 DOI: 10.1016/0165-2478(94)00191-s] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Human chorionic gonadotropin (hCG)--a pregnancy-associated immunomodulating hormone--has been recently shown in vitro to suppress reverse transcriptase activity in chronically HIV-infected lymphocytes and monocytes and to block viral transmission resulting from cell-cell contact between virus-carrying lymphocytes and placental trophoblasts. In further pursuit of the query into the mechanism of action, purified alpha and beta subunits of hCG were tested for the inhibition of p24 gag protein synthesis in virus-producing ACH-2 lymphocytes and U1 monocytes. Unlike the alpha subunit, beta-hCG displayed a distinct U-shaped dose response, characteristic of the effect of dimer hCG. Maximum inhibition of viral expression has been achieved at 10-100 ng/ml, the concentration corresponding to blood levels of beta-hCG in pregnant women. The doses that were several logs higher of normal levels seemed to increase viral production in monocytes. The data presented supports our original observations regarding the effect of intact hCG on HIV replication. While the mechanism of action remains to be established, the results suggest that the virus-interfering activity of hCG is determined by hormone-specific beta chain but not by the alpha subunit--shared with the family of glycoprotein hormones from the pituitary--follicle-stimulating hormone, luteinizing hormone and thyrotropin.
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Affiliation(s)
- A S Bourinbaiar
- Department of Biochemistry, New York University Medical Center, NY 10016, USA
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10
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Gressner AM, Brenzel A, Vossmeyer T. Hepatocyte-conditioned medium potentiates insulin-like growth factor (IGF) 1 and 2 stimulated DNA synthesis of cultured fat storing cells. LIVER 1993; 13:86-94. [PMID: 8510491 DOI: 10.1111/j.1600-0676.1993.tb00612.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
IGF-1 and IGF-2 stimulate dose-dependently DNA synthesis of nonconfluent cultures of rat fat storing cells, a nonparenchymal type of liver cells pathogenetically involved in the generation of liver fibrosis. Maximum stimulation of [3H] thymidine incorporation of about 2.6-fold above control was reached with 100 ng/ml IGF-1 and 500 ng/ml IGF-2, respectively. The DNA synthesis promoting action of both IGF-1 and IGF-2 was most efficiently potentiated by hepatocyte-conditioned medium raising the stimulatory effect up to 21-fold above control cultures. Lysate of hepatocytes (up to 15 micrograms protein/ml) was not effective in potentiating the effect of IGF-1. IGF-1 is bound to free carrier protein(s) present in the medium of hepatocytes, but obviously absent in cell lysate. Three molecular weight fractions in the ranges of 67 kd, 35 kd, and 25 kd could be identified in the medium, which potentiate the growth-promoting effect of IGF-1. Applying Western ligand blot analysis, three molecular size classes of IGF-1 binding proteins in the conditioned media of rat hepatocytes were determined. The major binding protein had a M(r) of 28-34 kd, a minor portion was localized at M(r) 24 kd, whereas trace binding affinities were found at M(r) of about 95 kd. It is suggested that IGF-1, IGF-2 and the complex array of IGF-binding proteins secreted by hepatocytes might be involved in the paracrine regulation of growth of fat storing cells.
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Affiliation(s)
- A M Gressner
- Department of Clinical Chemistry, Philipps University, Marburg, Germany
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Bestetti GE, Blum JW, Rossi GL. Immunohistochemistry of hepatic IGF-I in calf, pig, and rat. ZENTRALBLATT FUR VETERINARMEDIZIN. REIHE A 1992; 39:747-51. [PMID: 1492507 DOI: 10.1111/j.1439-0442.1992.tb00239.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The liver appears to be the major site of synthesis of somatomedin C or insulin-like growth factor I (IGF-I), yet, the intrahepatic histological localization of this polypeptide is not well known. For this reason we investigated immunohistochemically the liver of calves, pigs, and rats, fixed by perfusion or immersion with Karnovsky solution. In all three animal species the layer of hepatocytes bordering the liver capsule was labeled by anti-IGF-I. In the pig and rats all perivenous hepatocytes were intensively labeled whereas in calves only the periportal hepatocytes contained immunoreactive IGF-I. While preabsorption of the anti-IGF-I antiserum with the antigen abolished the immunoreaction, preabsorption with insulin or IGF-II did not. No labeling occurred when immersion-fixed liver tissue was used.
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Affiliation(s)
- G E Bestetti
- Institute of Animal Pathology, University of Berne, Switzerland
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Abstract
The successful treatment of pediatric surgical disease requires an understanding of the acute metabolic stress response. Poor clinical outcome can result when the metabolic demands of acute injury exceed the ability of endogenous host mechanisms to compensate. Appropriate exogenous supplementation may provide the metabolic and nutritional support crucial to recovery. As knowledge in this area grows, more effective treatment strategies are evolving. The potential for further advances, especially in the infant critical care population, offers the hope for substantial progress in the near future.
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Affiliation(s)
- W J Chwals
- Department of General Surgery, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina
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Ma L, Burton K, Saunders J, Dauncey M. Thermal and nutritional influences on tissue levels of insulin-like growth factor-I mRNA and peptide. J Therm Biol 1992. [DOI: 10.1016/0306-4565(92)90004-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Abstract
Biochemical membrane alterations appearing during the process of chemical carcinogenesis are described. Emphasis is put on membrane composition, structure, and biogenesis. In this presentation the knowledge gained from experimental studies of liver and skin in the process of cancer development is acknowledged. Important biochemical changes have been reported in lipid composition, fatty acid saturation, constitutional enzyme expression, receptor turnover and oligomerization. Functional consequences of the altered membrane structure is discussed within the concepts of regulation of cell proliferation, regulation of membrane receptor expression, redox control, signal transduction, drug metabolism, and multidrug resistance. Data from malignant tumours and normal tissue are addressed to evaluate the importance of the alterations for the process and for the eventual malignant transformation.
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Affiliation(s)
- L C Eriksson
- Karolinska Institute, Department of Pathology, Huddinge University Hospital, Sweden
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Kelly AC, Rodgers A, Dong KW, Barrezueta NX, Blum M, Roberts JL. Gonadotropin-releasing hormone and chorionic gonadotropin gene expression in human placental development. DNA Cell Biol 1991; 10:411-21. [PMID: 2069716 DOI: 10.1089/dna.1991.10.411] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Control of human chorionic gonadotropin (hCG) synthesis during pregnancy is poorly understood, although in vitro data suggest a role for placental gonadotropin releasing hormone (GnRH) in its regulation. To study GnRH regulation during placental development, placental tissue of different gestational ages was analyzed for GnRH and beta hCG mRNA content. cRNA probes to exonic/intronic sequences of GnRH and beta hCG transcripts were constructed and used to perform solution hybridization/nuclease protection and in situ hybridization assays. The levels of GnRH mRNA were approximately 0.1-1% of that of beta hCG mRNA, in agreement with its suggested paracrine, rather than endocrine, role. While beta hCG mRNA content decreased significantly from first trimester to term (643 to 21.6 pg/microgram RNA), there was no significant change in GnRH mRNA (0.179 to 0.155 pg/microgram RNA). While beta hCG mRNA was localized almost exclusively in syncytiotrophoblasts, GnRH mRNA was present in all cell types of the placenta, including the stroma. In the course of performing sense-strand controls in the in situ hybridization, we noted that the placenta appeared to express more antisense GnRH than sense GnRH mRNA, again, in all cell types. Solution hybridization/nuclease protection analysis with exon 1 and exon 3 probes confirmed this observation, showing that there is two to three times more antisense GnRH RNA than sense GnRH mRNA. These studies suggest that GnRH gene expression and its role in regulating hCG production in human placenta is complex and does not fit a simple model for paracrine regulation of hCG.
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Affiliation(s)
- A C Kelly
- Department of Obstetrics and Gynecology, Columbia University College of Physicians and Surgeons, New York, NY 10032
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Hill DJ, Hogg J. Growth factors and the regulation of pre- and postnatal growth. BAILLIERE'S CLINICAL ENDOCRINOLOGY AND METABOLISM 1989; 3:579-625. [PMID: 2698147 DOI: 10.1016/s0950-351x(89)80059-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Peptide growth factors represent a largely paracrine level of intercellular communication that is basic to the process of life. Growth factors are present in the ovum and are amongst the first products expressed by the embryonic genome. They function as both signals and progression factors for embryonic tissue growth, induction, differentiation, maturation and function. While a widespread tissue expression is demonstrable during fetal development, and in certain postnatal tissues such as the epiphyseal growth plate, growth factor presence in the adult is restricted to tissues sharing rapid cellular turnover such as ovary. However, a transient re-expression of peptide growth factors occurs during adult tissue repair. In addition to mitogenic peptides such as IGFs or EGF, the family of growth factors also includes physiological growth inhibitors such as TGF beta and certain neuropeptides. Insulin is mitogenic in the early embryo and evidence is presented to support a continuation of this role, under defined nutritional conditions, in late gestation. The importance of insulin to pre- and postnatal growth has prompted an expanding literature dealing with the interactions of nutrients, hormones and growth factors during the growth and functional maturation of the islets of Langerhans. While the expression of growth factors in the early embryo is apparently autonomous, some, such as IGFs, become increasingly dependent on nutrient, insulin and GH availability during fetal development and in childhood growth. This has resulted in circulating IGF I and II determinations becoming useful diagnostic markers of endocrine-based growth disorder and nitrogen balance.
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