Relative Abundance of Growth Hormone Receptor Isoforms in Rhesus Monkey Tissues and Human Transformed Lymphocytes

Abstract

The growth hormone receptor (GHR) is expressed as one active, full-sequence isoform and one truncated, inactive one that lacks the intracellular signaling domain. The aim of this study was to investigate the variation in the tissue expression of the full and truncated mRNA and protein. Epstein-Barr virus-transformed human B lymphocyte lines were established from 9 normal individuals with a height standard deviation score (SDS) of - 0.1 ± 1.1 (mean ± SD). Tissues were also collected from 3 Rhesus monkeys, whose GHR has 94.1 % homology with the human molecule. mRNA quantitation was determined by Real Time Quantitative PCR. Growth hormone receptor expression in transformed lymphocytes was also studied by fluorescence-activated cell sorter analysis. Both isoforms were expressed in transformed lymphocytes, but individual variation in the relative mRNA expression was small (truncated isoform percentage of total receptor mRNA: 17.1 ± 4.4, mean ± SD). There was no correlation between donors' height SDS and the expression of either isoform or the ratio between them. Protein expression by FACS analysis showed wider variation among the subjects; however, the relative ratio was similar in all the subjects. In monkey tissues, the truncated receptor showed a tissue-specific distribution. In conclusion, the expression of both isoforms in transformed lymphocytes from normal subjects shows small differences at the RNA or protein levels, and does not correlate with height SDS. Growth hormone splice isoforms show tissue specificity, suggesting local regulation of splicing. Tissues with relatively high expression of the truncated isoform are likely to be more resistant to the effects of GH due to the dominant negative effect of this isoform. In addition, the differential tissue expression might influence the levels of growth hormone binding protein in the immediate milieu of each tissue.

Key words

Growth Hormone Receptor Isoforms - R. Monkey Tissues - Human Lymphocytes

References

• 1 Bazan J F. Structural design and molecular evolution of a cytokine receptor superfamily.  Proc Natl Acad Sci U S A. 1990;  87 6934-6938
• 2 Leung D W, Spencer S A, Cachianes G, Hammonds R G, Collins C, Henzel W S, Barnard R, Waters M J, Wood W I. Growth hormone receptor and serum binding protein: purification, cloning and expression.  Nature. 1987;  330 537-543
• 3 Urbanek M, Russell J E, Cooke N E, Liebhaber S A. Functional characterization of the alternatively spliced, placental human growth hormone receptor.  J Biol Chem. 1993;  268 19 025-19 032
• 4 Sobrier M L, Duquesnoy P, Duriez B, Amselem S, Goossens M. Expression and binding properties of two isoforms of the human growth hormone receptor.  FEBS. 1993;  319 16-20
• 5 Esposito N, Paterlini P, Kelly P A, Postel-Vinay M C, Finidori J. Expression of two isoforms of the human growth hormone receptor in normal liver and hepatocarcinoma.  Mol Cell Endocrinol. 1994;  103 13-20
• 6 Dastot F, Sobrier M L, Duquesnoy P, Duriez B, Goossens M, Amselem S. Alternatively spliced forms in the cytoplasmic domain of the human growth hormone (GH) receptor regulate its ability to generate a soluble GH-binding protein.  Proc Natl Acad Sci USA. 1996;  93 10 723-10 728
• 7 Smith W C, Kuniyoshi J, Talamantes F. Mouse serum growth hormone (GH) binding protein has GH receptor extracellular and substituted transmembrane domains.  Mol Endocrinol. 1989;  3 984-990
• 8 Baumbach W R, Horner D L, Logan J S. The growth hormone-binding protein in rat serum is an alternatively spliced form of the rat growth hormone receptor.  Genes Dev. 1989;  3 1199-1205
• 9 Amit T, Bergman T, Dastot F, Youdim M B, Amselem S, Hochberg Z. A membrane-fixed, truncated isoform of the human growth hormone receptor.  J Clin Endocrinol Metab. 1997;  82 3813-3817
• 10 Ballesteros M, Leung K C, Ross R J, Iismaa T P, Ho K K. Distribution and abundance of messenger ribonucleic acid for growth hormone receptor isoforms in human tissues.  J Clin Endocrinol Metab. 2000;  85 2865-2871
• 11 Ross R J, Esposito N, Shen X Y, von Laue S, Chew S L, Dobson P R, Postel-Vinay M C, Finidori J. A short isoform of the human growth hormone receptor functions as a dominant negative inhibitor of the full-length receptor and generates large amounts of binding protein.  Mol Endocrinol. 1997;  11 265-273
• 12 Amit T, Barkey R J, Youdim M B, Hochberg Z. Effect of human growth hormone (GH)-binding protein in human serum on GH binding to rabbit liver membranes.  Metabolism. 1992;  41 732-737
• 13 Martini J F, Pezet A, Guezennec C Y, Edery M, Postel-Vinay M C, Kelly P A. Monkey growth hormone (GH) receptor gene expression. Evidence for two mechanisms for the generation of the GH binding protein.  J Biol Chem. 1997;  272 18 951-18 958
• 14 Vottero A, Kirschner L S, Yue W, Brodie A, Stratakis C A. P450arom gene expression in peripheral blood lymphocytes: identification of a cryptic splice site for exon-1 after Epstein-Barr virus transformation.  J Steroid Biochem Mol Biol. 1998;  64 245-250
• 15 Heid C A, Stevens J, Livak K J, Williams P M. Real time quantitative PCR.  Genome Res. 1996;  6 986-994
• 16 Shifrin V I, Neel B G. Growth factor-inducible alternative splicing of nontransmembrane phosphotyrosine phosphatase PTP-1B pre-mRNA.  J Biol Chem. 1993;  268 25 376-25 384
• 17 Metheny L J, Skuse G R. NF1 mRNA isoform expression in PC12 cells: modulation by extrinsic factors.  Exp Cell Res. 1996;  228 44-49
• 18 McKay N G, Hunter D J, Haites N E, Power D A. Regulation of alternative splicing of the fibronectin IIICS domain by cytokines.  Biochem Biophys Res Commun. 1994;  199 1005-1011
• 19 Kosaki A, Webster N J. Effect of dexamethasone on the alternative splicing of the insulin receptor mRNA and insulin action in HepG2 hepatoma cells.  J Biol Chem. 1993;  268 21 990-21 996
• 20 Chalfant C E, Mischak H, Watson J E, Winkler B C, Goodnight J, Farese R V, Cooper D R. Regulation of alternative splicing of protein kinase C beta by insulin.  J Biol Chem. 1995;  270 13 326-13 332
• 21 Konig H, Ponta H, Herrlich P. Coupling of signal transduction to alternative pre-mRNA splicing by a composite splice regulator.  EMBO J. 1998;  17 2904-2913
• 22 Xiao S H, Manley J L. Phosphorylation of the ASF/SF2 RS domain affects both protein-protein and protein-RNA interactions and is necessary for splicing.  Genes Dev. 1997;  11 334-344
• 23 Holmberg J, Clarke D L, Frisen J. Regulation of repulsion versus adhesion by different splice forms of an Eph receptor.  Nature. 2000;  408 203-206
• 24 Vottero A, Kimchi-Sarfaty C, Kratzsch J, Chrousos G P, Hochberg Z. Transcriptional and translational regulation of the splicing isoforms of the growth hormone receptor by glucocorticoids. Companion paper 2000
• 25 Hochberg Z, Youdim M B, Amit T. A mathematical model for appraisal of the impact of GH binding protein on GH receptor binding.  Growth Regul. 1994;  4 8-13
• 26 Hochberg Z, Hertz P, Colin V, Ish-Shalom S, Yeshurun D, Youdim M B, Amit T. The distal axis of growth hormone (GH) in nutritional disorders: GH-binding protein, insulin-like growth factor-I (IGF-I), and IGF-I receptors in obesity and anorexia nervosa.  Metabolism. 1992;  41 106-112
• 27 Rasmussen M H, Ho K K, Kjems L, Hilsted J. Serum growth hormone-binding protein in obesity: effect of a short-term, very low calorie diet and diet-induced weight loss.  J Clin Endocrinol Metab. 1996;  81 1519-1524
• 28 Valerio G, Bond H M, Badolato R, Petrella A, Dimaio S, Salerno M, Waters M J, Venuta S, Tenore A. Expression of growth hormone receptor by peripheral blood lymphocytes in children: evaluation in clinical conditions of impaired growth.  Clin Endocrinol (Oxf). 1997;  47 329-335