{"title":"Calcitonin gene related peptide stimulates differentiation of neonatal rat myogenic cultures.","authors":"B S Noble, D N McMillan, C A Maltin","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The effect of the nerve derived peptide, calcitonin gene related peptide (CGRP) on myoblast fusion/differentiation was studied in rat myogenic cell cultures, using creatine kinase activity as an index of fusion. Addition of CGRP at 10(-7) M to myoblast cultures resulted in an enhancement of kinase activity after 11 days of treatment. This response was not accompanied by increased protein content of cultures implying an effect primarily on fusion rather than on myotube growth/size. Neither was it a direct effect on enzyme activity alone since no increase in creatine kinase activity occurred when CGRP was added to mature myotube cultures. These data suggest a role for CGRP in the myoblast fusion process itself and raise questions as to its importance in the growth and development of muscle in vivo.</p>","PeriodicalId":77148,"journal":{"name":"Growth regulation","volume":"3 4","pages":"245-8"},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19122928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P J Fielder, J P Tauber, K F Wilson, H M Pham, R G Rosenfeld
{"title":"Insulin-like growth factors (IGFs) stimulate and dexamethasone inhibits IGF binding protein (BP)-5 expression in a mouse pituitary cell line.","authors":"P J Fielder, J P Tauber, K F Wilson, H M Pham, R G Rosenfeld","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The mouse pituitary cell line AtT-20 was found to secrete two low MW IGFBPs into conditioned medium (CM). The major IGFBP migrated at approximately 29 kDa and a minor IGFBP of 24 kDa was also present on western ligand blots (WLB). Both IGFBPs were purified from CM by IGF-affinity chromatography followed by reverse phase-FPLC. N-terminal analysis revealed that the first 10 amino acids of the 29 kDa and the 24 kDa IGFBPs were homologous to corresponding sequences of both human and rat IGFBP-5 and IGFBP-4, respectively. The 24 kDa IGFBP also crossreacted with a new antiserum specific for rodent IGFBP-4. The concentrations of both IGFBPs were increased by the addition of IGF-I, IGF-II, or insulin to the cell cultures, with IGFBP-5 demonstrating the greatest hormonal stimulation. The effects of IGF-I on IGFBP-5 expression were both time and dose dependent, with IGF-I being more potent than IGF-II, and IGF-II more potent than insulin. The relative potencies of these hormones in stimulating IGFBP-5 production were consistent with the peptides acting through the type-I IGF receptor. Similarly, the IGF-II analog [Leu 27]-IGF-II, which has very low affinity for the type-I receptor, only slightly stimulated an increase in IGFBP-5. Addition of dexamethasone to the cultures decreased both basal and IGF-stimulated IGFBP-5 production. Northern blotting demonstrated that IGF-I increased the expression of the mRNA for IGFBP-5, whereas dexamethasone decreased it. Together, these data suggest that the IGFs can increase IGFBP-5 production at both the protein and mRNA level.</p>","PeriodicalId":77148,"journal":{"name":"Growth regulation","volume":"3 4","pages":"226-34"},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"18518928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F Nieves-Rivera, J R Kerrigan, R J Krieg, J Egan, L J Hwang, E Truumees, J D Veldhuis, W S Evans, A D Rogol
{"title":"Altered growth hormone (GH) secretion in vivo and in vitro in the diabetes-prone BB/Worcester rat.","authors":"F Nieves-Rivera, J R Kerrigan, R J Krieg, J Egan, L J Hwang, E Truumees, J D Veldhuis, W S Evans, A D Rogol","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Diminished concentrations of growth hormone (GH) have been observed in the male BB/Wor rat with diabetes mellitus (DM). The precise mechanism(s) responsible for the altered GH levels is not entirely understood. We have therefore employed independent techniques to investigate potential alterations in: 1) the peripheral metabolism of the hormone; 2) GH release by somatotropes; and 3) hypothalamic regulation of GH secretion. An extra group of insulin-untreated animals was included for the studies of acute DM. The results demonstrate diminished circulating mean concentrations of GH (35 +/- 4 vs. 16 +/- 4 micrograms/l; mean +/- SEM; control vs. animal with DM; P = 0.006) due to impaired GH secretion. In particular, there was a decrease in the mass of GH secreted per burst (230 +/- 22 vs. 136 +/- 34 micrograms/l; P = 0.04) and in the GH secretory rate (24 +/- 4 vs. 9 +/- 3 micrograms/l/min; P < 0.01). No differences in the secretory burst frequency, (5.3 +/- 0.3 vs. 5.2 +/- 0.5 #/8-h; P = 0.68), secretory half-duration (10 +/- 2 vs. 17 +/- 2 min; P = 0.09), or serum GH half-life (8 +/- 1 vs. 6 +/- 1 min; P = 0.13) were observed. In vitro studies of acutely dispersed somatotropes obtained from rats with DM demonstrated increased sensitivity to GHRH (1 nM), as detected by a greater mean hemolytic plaque area following exposure to an EC50 dose of the secretagogue (14.3 +/- 3.3 vs. 17.4 +/- 3.5 microns 2 x 10(3); P = 0.049), and diminished sensitivity to SRIH (1 nM) inhibition of GH release following exposure to an EC50 dose of the secretagogue (10.0 +/- 1.2 vs. 14.9 +/- 2.3 microns2 x 10(3); P = 0.026). The number of the pituitary cells (18.0 +/- 2.8 vs. 15.3 +/- 1.0 x 10(5) cells; P = 0.38) as well as the number of somatotropes (7.3 +/- 1.4 vs. 7.6 +/- 0.9 x 10(5) cells; P = 0.87) were indistinguishable between experimental groups. Hypothalamic gene transcript levels for GH-releasing hormone (GHRH) and somatotropin release-inhibiting hormone (SRIH) were evaluated by in situ hybridization histochemistry to assess cellular synthetic activity.(ABSTRACT TRUNCATED AT 400 WORDS)</p>","PeriodicalId":77148,"journal":{"name":"Growth regulation","volume":"3 4","pages":"235-44"},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"18905579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The plasminogen activator and inhibitor system in bone remodelling.","authors":"T J Martin, E H Allan, S Fukumoto","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The neutral protease, plasmin, is generated by plasminogen activators, and is ascribed an important role in several physiological and pathological circumstances characterized by tissue remodelling and cell motility. The two types of plasminogen activator, tissue-type (tPA) and urokinase-type (uPA), are produced by osteoblasts, as is the specific PA inhibitor, PAI-1. Some hormones which activate bone resorption increase PA activity produced by osteoblasts, by decreasing the production of PAI-1. The increased PA activity has been suggested to facilitate bone resorption by activating latent collagenase, thus preparing the bone surface for osteoclastic resorption. Targeted and regulated production of plasmin might also contribute to the coupling of bone formation to resorption, by activating latent TGF beta in bone, and activating IGF-1 by freeing it from association with inhibitory binding protein. TGF beta itself is a powerful inhibitor of PA activity, an effect achieved by enhancing mRNA and protein for PAI-1. Thus the PA system is a potentially important regulatory system in bone remodelling, whose local activity is controlled through concerted actions of hormones and locally generated growth factors and cytokines.</p>","PeriodicalId":77148,"journal":{"name":"Growth regulation","volume":"3 4","pages":"209-14"},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19122927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D C Claffey, M E Yateman, P A Lane, P A Ealey, J A Wass, N J Marshall, J M Holly
{"title":"The development and characterization of an eluted stain assay (ESTA) for the insulin-like growth factors.","authors":"D C Claffey, M E Yateman, P A Lane, P A Ealey, J A Wass, N J Marshall, J M Holly","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>An Eluted Stain Assay System (ESTA) has been adapted for the bioassay of the insulin-like growth factors, IGF-I and IGF-II. This ESTA is based on the Fischer Rat Thyroid cell line FRTL-5 which was grown as uniform, adherent microcultures on 96-well microtitre plates. The cells were stimulated with the growth factors for 48 h in hormone and serum free conditions. Responses were determined by the addition of the tetrazolium salt MTT which was reduced to a purple formazan product in a dose related manner. This was directly eluted from the cells and measured with a microtitre plate reader. The signal generated was solely dependent on metabolic activation of the cells, since no increase in cell numbers was detected during the bioassay. The advantages of using this method are its sensitivity, precision, specificity, rapidity and high sample throughout. This bioassay, which is based on a colorimetric method, is technically convenient compared with other systems including the earlier cytochemical bioassays and the radioisotopic methods. We have demonstrated that this MTT ESTA provides a useful method for the study of complex interactions between IGF-I and IGF-II and their related binding proteins and that IGF bioactivity in serum may also be investigated using this ESTA bioassay.</p>","PeriodicalId":77148,"journal":{"name":"Growth regulation","volume":"3 4","pages":"215-25"},"PeriodicalIF":0.0,"publicationDate":"1993-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"18518927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Platelet derived growth factor/tyrosine kinase receptor mediated proliferation.","authors":"M Benito, M Lorenzo","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>PDGF heterodimer of A and B chains, a complete mitogen for 3T3 mouse fibroblasts, exemplifies those growth factors interacting with membrane associated tyrosine kinase receptors. Its binding to the PDGF-receptors results in receptor dimerization and subsequent activation of tyrosine kinase activity in the cytoplasmic protein domain, autophosphorylation of the receptor being the first event in the transduction cascade. Before the ligand-receptor complex is internalized and degraded, receptor stimulation is transmitted to the general transduction network, in which several tyrosine kinase substrates are activated by phosphorylation and changes the cytoplasmic biochemistry. These changes include cytoplasmic alkalinization, increases in the intracellular concentration of cyclic-AMP and Ca2+ and activation of protein kinase C through the degradation of phosphoinositides. The known substrates recruited by the PDGF-receptor association are phosphatidylinositol-3'-kinase, ras-GTPase-activating protein, phospholipase C-gamma, serine-threonine kinase Raf-1 and src and src-related tyrosine kinases. Upon binding of PDGF to its receptor, transactivation of transcriptional and nuclear factors such as c-fos and c-myc genes and dephosphorylation of c-jun occurs, V-sis, the oncogen of the simian sarcoma virus (SSV), is highly homologous to the c-sis/PDGF-B gene that encodes the homodimer of the B-chain of the PDGF receptor. Cells transformed by SSV have been studied as a model system for the autocrine stimulation of the PDGF receptor.</p>","PeriodicalId":77148,"journal":{"name":"Growth regulation","volume":"3 3","pages":"172-9"},"PeriodicalIF":0.0,"publicationDate":"1993-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19210050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E Kaicer, C Blat, J Imbenotte, F Troalen, O Cussenot, F Calvo, L Harel
{"title":"IGF binding protein-3 secreted by the prostate adenocarcinoma cells (PC-3): differential effect on PC-3 and normal prostate cell growth.","authors":"E Kaicer, C Blat, J Imbenotte, F Troalen, O Cussenot, F Calvo, L Harel","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Deregulation of growth in malignant cells has been suggested to be the result of increased secretion by these cells, of autocrine growth factors; alternatively, this deregulation has been assumed to be related to loss of sensitivity by malignant cells to secreted inhibitory molecules. The results of the present publication lend new support to both hypotheses. We recently showed that human prostate adenocarcinoma cells (PC-3 cells) secreted insulin-like growth factor binding proteins (IGFBP) of 45, 34 and 25 kDa. From medium conditioned by dense cultures of PC-3 cells, we have now purified two IGFBPs of M(r) 45 kDa and 34 kDa. The N-amino terminal sequences were determined, and it was shown that they are IGFBP-3. IGFBP-34 appeared to be a deglycosylated form of IGFBP-45. The two IGFBPs had more affinity for IGF-II than for IGF-I. IGFBP-45 and IGFBP-34 were growth-inhibitory factors of chick embryo fibroblasts (CEF): they totally inhibited DNA synthesis stimulated by serum in CEF. Our results point to a clear difference between the effects of these IGFBPs upon growth of normal prostate cells and malignant PC-3 cells. At a concentration of 150 ng/ml, they inhibited growth of normal prostate cells even in the presence of 1 microgram/ml insulin. This suggests that such inhibition was not simply the result of a decrease by the IGFBP of stimulation induced by serum IGF or IGF secreted by the cells. At a concentration of 150 ng/ml, IGFBP did not modify the growth of PC-3 cells. In contrast, it stimulated growth of PC-3 cells when added at a concentration lower than 50 ng/ml (about 1 nM). Our results thus provide new insight concerning the regulation of growth in PC-3 cells.</p>","PeriodicalId":77148,"journal":{"name":"Growth regulation","volume":"3 3","pages":"180-9"},"PeriodicalIF":0.0,"publicationDate":"1993-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"18695900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}