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Title: Parathyroid hormone blocks the stimulatory effect of insulin-like growth factor-I on collagen synthesis in cultured 21-day fetal rat calvariae

Abstract

We examined the interaction of parathyroid hormone (PTH) and recombinant human insulin-like growth factor I (IGF-I) on collagen synthesis in 21-day fetal rat calvariae as assessed by measuring the incorporation of ({sup 3}H)proline into collagenase-digestible protein. After 96 hours of culture, 10 nM PTH antagonized the stimulation of collagen synthesis and partially blocked the increase in dry weight produced by 10 nM IGF-I. The effect of PTH to block IGF-I stimulated collagen synthesis was observed in the central bone of calvariae and was mimicked by forskolin and phorbol 12-myristate 13-acetate, but not by 1,25-dihydroxyvitamin D3, transforming growth factor-alpha or dexamethasone. Our data are consistent with the concept that the direct effect of PTH is to inhibit basal CDP labeling and fully oppose IGF-I stimulated CDP labeling. The finding that this effect of PTH is mimicked by forskolin and PMA suggests that this block in IGF-I stimulation of CDP labeling involves both cAMP and protein kinase C mediated pathways.

Authors:
; ;  [1]
  1. (Univ. of Connecticut Health Center, Farmington (USA))
Publication Date:
OSTI Identifier:
5803013
Resource Type:
Journal Article
Resource Relation:
Journal Name: Bone; (USA); Journal Volume: 11:6
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; 63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; COLLAGEN; BIOSYNTHESIS; GROWTH FACTORS; BIOCHEMICAL REACTION KINETICS; PARATHORMONE; PHORBOL ESTERS; BIOLOGICAL EFFECTS; AMP; BIOLOGICAL PATHWAYS; DEXAMETHASONE; FETUSES; PHOSPHOLIPIDS; PHOSPHOTRANSFERASES; PROLINE; RATS; SKULL; TRACER TECHNIQUES; TRITIUM COMPOUNDS; ADRENAL HORMONES; AMINES; AMINO ACIDS; ANIMALS; AZOLES; BODY; CARBOXYLIC ACIDS; CARCINOGENS; CORTICOSTEROIDS; ENZYMES; ESTERS; GLUCOCORTICOIDS; HETEROCYCLIC ACIDS; HETEROCYCLIC COMPOUNDS; HORMONES; HYDROGEN COMPOUNDS; HYDROXY COMPOUNDS; ISOTOPE APPLICATIONS; KETONES; KINETICS; LIPIDS; MAMMALS; MITOGENS; NUCLEOTIDES; ORGANIC ACIDS; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; ORGANIC PHOSPHORUS COMPOUNDS; ORGANS; PEPTIDE HORMONES; PHOSPHORUS-GROUP TRANSFERASES; PREGNANES; PROTEINS; PYRROLES; PYRROLIDINES; REACTION KINETICS; RODENTS; SCLEROPROTEINS; SKELETON; STEROIDS; SYNTHESIS; TRANSFERASES; VERTEBRATES; 550201* - Biochemistry- Tracer Techniques; 560300 - Chemicals Metabolism & Toxicology

Citation Formats

Kream, B.E., Petersen, D.N., and Raisz, L.G.. Parathyroid hormone blocks the stimulatory effect of insulin-like growth factor-I on collagen synthesis in cultured 21-day fetal rat calvariae. United States: N. p., 1990. Web. doi:10.1016/8756-3282(90)90136-M.
Kream, B.E., Petersen, D.N., & Raisz, L.G.. Parathyroid hormone blocks the stimulatory effect of insulin-like growth factor-I on collagen synthesis in cultured 21-day fetal rat calvariae. United States. doi:10.1016/8756-3282(90)90136-M.
Kream, B.E., Petersen, D.N., and Raisz, L.G.. 1990. "Parathyroid hormone blocks the stimulatory effect of insulin-like growth factor-I on collagen synthesis in cultured 21-day fetal rat calvariae". United States. doi:10.1016/8756-3282(90)90136-M.
@article{osti_5803013,
title = {Parathyroid hormone blocks the stimulatory effect of insulin-like growth factor-I on collagen synthesis in cultured 21-day fetal rat calvariae},
author = {Kream, B.E. and Petersen, D.N. and Raisz, L.G.},
abstractNote = {We examined the interaction of parathyroid hormone (PTH) and recombinant human insulin-like growth factor I (IGF-I) on collagen synthesis in 21-day fetal rat calvariae as assessed by measuring the incorporation of ({sup 3}H)proline into collagenase-digestible protein. After 96 hours of culture, 10 nM PTH antagonized the stimulation of collagen synthesis and partially blocked the increase in dry weight produced by 10 nM IGF-I. The effect of PTH to block IGF-I stimulated collagen synthesis was observed in the central bone of calvariae and was mimicked by forskolin and phorbol 12-myristate 13-acetate, but not by 1,25-dihydroxyvitamin D3, transforming growth factor-alpha or dexamethasone. Our data are consistent with the concept that the direct effect of PTH is to inhibit basal CDP labeling and fully oppose IGF-I stimulated CDP labeling. The finding that this effect of PTH is mimicked by forskolin and PMA suggests that this block in IGF-I stimulation of CDP labeling involves both cAMP and protein kinase C mediated pathways.},
doi = {10.1016/8756-3282(90)90136-M},
journal = {Bone; (USA)},
number = ,
volume = 11:6,
place = {United States},
year = 1990,
month = 1
}
  • Insulin and insulin-like growth factor type I (IGF-I) stimulate an overlapping spectrum of biological responses in human skin fibroblasts. Although insulin and IGF-I are known to stimulate the incorporation of (/sup 3/H)thymidine into DNA in these cells, the identify of the receptor(s) that mediates this effect has not been fully clarified. The mouse anti-human IGF-I receptor antibody ..cap alpha..IR-3 binds with specificity to IGF-I but not to insulin receptors in human placental membranes; it also specifically inhibits the binding of /sup 125/I-labeled IGF-I but not /sup 125/I-labeled insulin to suspensions of human skin fibroblasts in a dose-dependent manner. ..cap alpha..IR-3more » competitively inhibits IGF-I-mediated stimulation of (/sup 3/H)thymidine incorporation into DNA. This inhibition is dependent on the concentration of ..cap alpha..IR-3 and in the presence of a fixed antibody concentration can be partially overcome by high concentrations of IGF-I. In contrast, at concentrations of < 1 ..mu..g/ml, the effect of insulin to stimulate (/sup 3/H)thymidine incorporation is not inhibited by ..cap alpha..IR-3. However, the incremental effects of higher concentrations (> 1 ..mu..g/ml) of insulin on (/sup 3/H)thymidine incorporation are inhibited by ..cap alpha..IR-3. ..cap alpha..IR-3 is a highly specific antagonist of IGF-I receptor-mediated mitogenesis in human skin fibroblasts. By using this antibody, it is shown directly that insulin can act through the IGF-I receptor to stimulate DNA synthesis but can also activate this effect through the insulin receptor itself.« less
  • The authors studied the GH-insulin-like growth factor-I (IGF-I) axis serially over 24-36 months in six patients with medulloblastoma who underwent surgical removal of the tumor followed by craniospinal irradiation therapy for 6 weeks and then chemotherapy for 42 weeks. Eighteen and 24 months after beginning irradiation there was a decline in the peak GH secretory response to acute stimulation with arginine/insulin hypoglycemia. Six months after irradiation and during chemotherapy there was a transient decline in IGF-I, IGF binding protein-3 (IGFBP-3), and GH-BP values (respective mean values of 56.1 {+-} 9.0 ng/mL, 1.1 {+-} 0.2 {mu}g/mL, and 7.6 {+-} 3.3% ofmore » radioactivity as compared to time 0 values: 139 {+-} 15 ng/mL, 2.2 {+-} 0.2 {mu}g/mL, and 20.0 {+-} 4.0%, P < 0.001), although provoked GH secretion was normal at this time. The IGF-I, IGFBP-3, and GH-BP returned to pretreatment ranges by 12-36 months after initiation of the study. There was also a decline in body mass index and serum protein values at 6 months after irradiation in ligand and immunoblot analysis there was a decline in IGFBP-3 and an abnormal electrophoretic mobility of IGFBP-2 that were both normalized at 36 months. In one patient they observed a high level of IGFBP-3 proteolysis at this time. This study demonstrates that before the decrease of GH secretion in patients receiving cranial irradiation there is a transient phase of GH insensitivity that may be characteristic of the acute therapeutic phase including the chemotherapy. This partial insensitivity may explain the early growth retardation observed in these patients. 28 refs., 4 figs., 1 tab.« less
  • Somatomedin-C or insulin-like growth factor I (Sm-C/IGF-I) and insulin-like growth factor II (IGF-II) have been implicated in the regulation of fetal growth and development. In the present study /sup 32/P-labeled complementary DNA probes encoding human and mouse Sm-C/IGF-I and human IGF-II were used in Northern blot hybridizations to analyze rat Sm-C/IGF-I and IGF-II mRNAs in poly(A/sup +/) RNAs from intestine, liver, lung, and brain of adult rats and fetal rats between day 14 and 17 of gestation. In fetal rats, all four tissues contained a major mRNA of 1.7 kilobase (kb) that hybridized with the human Sm-C/IGF-I cDNA and mRNAsmore » of 7.5, 4.7, 1.7, and 1.2 kb that hybridized with the mouse Sm-C/IGF-I cDNA. Adult rat intestine, liver, and lung also contained these mRNAs but Sm-C/IGF-I mRNAs were not detected in adult rat brain. These findings provide direct support for prior observations that multiple tissues in the fetus synthesize immunoreactive Sm-C/IGF-I and imply a role for Sm-C/IGF-I in fetal development as well as postnatally. Multiple IGF-II mRNAs of estimated sizes 4.7, 3.9, 2.2, 1.75, and 1.2 kb were observed in fetal rat intestine, liver, lung, and brain. The 4.7- and 3.9-kb mRNAs were the major hybridizing IGF-II mRNAs in all fetal tissues. Higher abundance of IGF-II mRNAs in rat fetal tissues compared with adult tissues supports prior hypotheses, based on serum IGF-II concentrations, that IGF-II is predominantly a fetal somatomedin. IGF-II mRNAs are present, however, in some poly(A/sup +/) RNAs from adult rat tissues. The brain was the only tissue in the adult rat where the 4.7- and 3.9-kb IGF-II mRNAs were consistently detected. These findings suggest that a role for IGF-II in the adult rat, particularly in the central nervous system, cannot be excluded.« less
  • The acute and long-term effects of growth hormone (GH) on the binding of insulin-like growth factor II (IGF-II) were evaluated in adipose cells from hypophysectomized rats given replacement therapy with thyroxine and hydrocortisone and in cells from their sham-operated littermates. After the cells were incubated with insulin and/or GH, the recycling of /sup 125/I-labeled IGF-II receptors was metabolically inhibited by treating the cells with KCN. IGF-II binding was 100 +/- 20% higher in cells from GH-deficient animals when compared with sham-operated controls. These GH-deficient cells also showed an increased sensitivity for insulin as compared with control cells (the EC/sub 50/more » for insulin was 0.06 ng/ml in GH-deficient cells and 0.3 ng/ml in control cells.). However, the maximal incremental effect of insulin on IGH-II binding was reduced approx. = 27% by hypophysectomy. GH added to the incubation medium increased the number of IGF-II binding sites by 100 +/- 18% in cells from hypophysectomized animals. This increase was rapidly induced, but the time course was slower than that for the stimulatory effect of insulin. Half-maximal effect of GH on IGF-II binding was obtained at approx. = 30 ng/ml. Thus, GH added in vitro exerted a rapid insulin-like effect on the number of IGH-II receptors. GH also appears to play a regulating role for maintaining the cellular number of IGH-II receptors and, in addition, modulates the stimulatory effect of insulin on IGF-II binding.« less
  • We have characterized insulin-like growth factor I (IGF-I) and insulin receptors in cultured bovine adrenal cells by binding and cross-linking affinity experiments. At equilibrium the dissociation constant and the number of binding sites per cell for IGF-I were 1.4 +/- (SE) 0.3 x 10(-9) M and 19,200 +/- 2,100, respectively. Under reduction conditions, disuccinimidyl suberate cross-linked (/sup 125/I)iodo-IGF-I to one receptor complex with an Mr of 125,000. Adrenal cells also contain specific insulin receptors with an apparent dissociation constant (Kd) of 10(-9) M. Under reduction conditions (/sup 125/I)iodo-insulin binds to one band with an approximate Mr of 125,000. IGF-I andmore » insulin at micromolar concentrations, but not at nanomolar concentrations, slightly stimulated DNA synthesis, but markedly potentiated the mitogenic action of fibroblast growth factor. Adrenal cells cultured in a serum-free medium containing transferrin, ascorbic acid, and insulin (5 micrograms/ml) maintained fairly constant angiotensin-II (A-II) receptor concentration per cell and increased cAMP release on response to ACTH and their steroidogenic response to both ACTH and A-II. When the cells were cultured in the same medium without insulin, the number of A-II receptors significantly decreased to 65% and the increased responsiveness was blunted. Treatment of such cells for 3 days with increasing concentrations of IGF-I (1-100 ng/ml) produced a 2- to 3-fold increase in A-II receptors and enhanced the cAMP response (3- to 4-fold) to ACTH and the steroidogenic response (4- to 6-fold) to ACTH and A-II. These effects were time and dose dependent (ED50 approximately equal to 10(-9) M). Insulin at micromolar concentrations produced an effect similar to that of IGF-I, but at nanomolar concentrations the effect was far less.« less