• Journal of Life Science
• /
• v.17 no.5 s.85
• /
• pp.687-693
• /
• 2007

Insulin-like growth factor-I(IGF-I) has significant insulin-like anabolic effects which include the stimulation of glucose and amino acid uptake, as well as protein and glycogen synthesis. IGFs exist in serum and other biological fluids as complexes bound to a family of structurally related insulin-like growth factor binding proteins(IGFBPs). Six human IGFBPs can modulate the effects of IGFs on target tissues by several mechanisms, including altering the serum's half-life and the transcapillary transport of IGFs, as well as changing the availability of IGFs to specific cell surface receptors. Human fibroblasts secrete IGFBPs that can modify IGF-I action. Previous to our study using either Northern blotting, and Western blotting have shown that fibroblasts express mRNA IGFBP-3, -4, and -5, and synthesize these proteins. In addition, fibroblast cell lysates revealed that the IGFBP-3 was most abundant. For these reasons, we undertook to gain further insight into the effects of high and low glucose incubation condition on metabolism and IGFBP-3 expression. In results of metabolites and IGFBP-3 expression in GM10 cells cultivated with various glucose concentration, the consumption of glucose and accumulation of triglyceride were increased in condition of high glucose, and total protein level was decreased. in the course of time. After 5 days incubation, levels of free amino acid in medium containing glucose of high concentration glucose were higher than in conditions of low glucose. Although the levels of IGFBP-3 protein and mRNA levels were increased in low glucose, and IGFBP-3 was not affected by any pretense. Taken together, we suggest that the study of growth factors, like IGFs, might be a possible model of diabetes militus in cell, although the results in cell models were not in accord with in vivo.

• Journal of Nutrition and Health
• /
• v.35 no.2
• /
• pp.192-200
• /
• 2002

Conjugated linoleic acid (CLA) is a collective term for positional and geometric isomers of octadecadienoic acid in which the double bonds are conjugated. CLA has anticancer activity in a variety of animal cancer models, and cis-9, trans-11 (c9t11) and trans-10, cis-12(t10c12) CLA are the most predominant isomers present in the synthetic preparations utilized in these animal studies. To compare the ability of c9t11, t10c12 and an isomeric mixture of CLA to inhibit TSU-Prl cell growth, cells were incubated in a serum-free medium with various concentrations of these fatty acids. The isomeric mixture inhibited cell growth in a dose-dependent manner (1-3 $\mu$M) with a 41 $\pm$ 1% inhibition observed at 3 $\mu$M concentration after 48 hours. T10c12 also inhibited cell proliferation in a dote-dependent manner, However, the efficacy and potency of this isomer was much greater than that of the isomeric mixture with a 49 $\pm$ 2% inhibition observed at 0.3 $\mu$M concentration after 48 hours. By contrast, c9t11 slightly increased cell proliferation. To determine whether the growth-inhibiting effect of CLA is related to the changes in production of insulin-like growth factors (IGF) and IGF-binding proteins (IGFBP) by these cells, serum-free conditioned media were collected. Immunoblot analysis of conditioned media using a monoclonal anti-IGF-II antibody showed that both the isomeric mixture and t10c12 inhibited secretion of both mature 7,500 Mr and higher Mr forms of pro IGF-II, whereas c9t11 had no effect. Ligand blot analysis with 125I-IGF-II revealed the presence of two types of IGFBPs : 24,000 Mr IGFBP-4 and 30,000 Mr IGFBP-6. The production of IGFBP-4 slightly decreased at the highest concentrations of the isomeric mixture and t10c12. These results indicate that CLA inhibits human prostate cancer cell growth, an effect largely due to the action of t10c12. The growth inhibition may result, at least in part, from decreased production of IGF-II and IGFBP-4 by these cells.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.45 no.5
• /
• pp.423-429
• /
• 2012

This study evaluated the effects of adding sea mustard Undaria pinnatifida glycoprotein to the diet of juvenile olive flounder Paralichthys olivaceus on its growth, and levels of insulin-like growth factor I (IGF-I), IGF binding proteins (IGFBPs), and interleukins. Three experimental diets (U0, U0.5, and U1.0) were formulated that contained different amounts of an extract of U. pinnatifida (0, 0.5, and 1.0%, respectively). Experimental groups were established in triplicate (30 fish/group) and fed for 12 weeks. The experimental group fed 1.0% added U. pinnatifida glycoprotein had the greatest rate of weight gain, which differed significantly from the other experimental groups. SDS-PAGE of the plasma IGF-I and muscle protein showed that the experimental groups taking U. pinnatifida glycoprotein had significantly more IGF-I and a ca. 200 kDa protein, as compared to the control group. In addition, the amount of IGFBP-3 at ca. 43 kDa increased in the group given the U. pinnatifida extract, as compared to the control group. The interluekin-2, -4, -6, and -12 levels paralleled the level of growth factor in the groups given the U. pinnatifida extract. In conclusion, supplementing the diet of olive flounder with U. pinnatifida glycroprotein improved its growth and immunity.

• Tuberculosis and Respiratory Diseases
• /
• v.50 no.5
• /
• pp.549-556
• /
• 2001

Background : IGF-I is an important mitogen in many types of malignancies. Tumors also express many IGF binding proteins, which modulate IGF action. The propose of this study was to evaluate the effect of IGF-I and IGFBP on cell proliferation in mouse lung cancer cells (3LL). Methods : The cellular proliferation of 3LL with the treatment of growth factors was evaluated using MTT assay. Western ligand blot was performed in order to determine whether 3LL cells secrete IGFBPs and we evaluated the effect of IGFBP on cellular proliferation. Results : The treatment of 3LL cells with IGF-I increased cellular proliferation in a serum free media. Western ligand blot of conditioned medium of 3LL with $^{125}I$-IGF-I demonstrated one single major band with an estimated molecular mass of 24 kDa. This band was identified as IGFBP-4 with immunoblot analysis using antisera. The addition of anti-IGFBP-4 antibody to abrogate the effect of IGFBP-4 resulted in increased cellular proliferation suggesting that IGFBP-4 inhibits cell growth. Conclusion : IGF-I increases cellular proliferation, however the secreted IGFBP-4 has an inhibitory function on cell growth in 3LL. These findings suggest that IGF-I and IGFBP are involved in the cell proliferation.

• The Korean Journal of Physiology and Pharmacology
• /
• v.17 no.2
• /
• pp.157-162
• /
• 2013

Insulin-like growth factor binding proteins (IGFBPs) are important components of insulin growth factor (IGF) signaling pathways. One of the binding proteins, IGFBP-5, enhances the actions of IGF-1, which include the enhanced proliferation of smooth muscle cells. In the present study, we examined the expression and the biological effects of IGFBP-5 in vascular smooth muscle cells (VSMCs) from spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). The levels of IGFBP-5 mRNA and protein were found to be higher in the VSMC from SHR than in those from WKY. Treatment with recombinant IGFBP-5-stimulated VSMC proliferation in WKY to the levels observed in SHR. In the VSMCs of WKY, incubation with angiotensin (Ang) II or IGF-1 dose dependently increased IGFBP-5 protein levels. Transfection with IGFBP-5 siRNA reduced VSMC proliferation in SHR to the levels exhibited in WKY. In addition, recombinant IGFBP-5 significantly up-regulated ERK1/2 phosphorylation in the VSMCs of WKY as much as those of SHR. Concurrent treatment with the MEK1/2 inhibitors, PD98059 or U0126 completely inhibited recombinant IGFBP-5-induced VSMC proliferation in WKY, while concurrent treatment with the phosphatidylinositol-3 kinase inhibitor, LY294002, had no effect. Furthermore, knockdown with IGFBP-5 siRNA inhibited ERK1/2 phosphorylation in VSMC of SHR. These results suggest that IGFBP-5 plays a role in the regulation of VSMC proliferation via ERK1/2 MAPK signaling in hypertensive rats.

• Proceedings of the Korean Nutrition Society Conference
• /
• 1995.11b
• /
• pp.11-34
• /
• 1995

Growth hormone (GH) plays a key role in regulating postnatal growth and can stimulate growth of animals by acting directly on specific receptors on the plasma membrane of tissues or indirectly through stimulating insulin-like growth factor (IGF)-I synthesis and secretion by the liver and other tissues. IGF-I and IGF-Ⅱ are polypeptides with structural similarity with proinsulin that stimulate cell proliferation by endocrine, paracrine and autocrine mechanisms. The initial event in the metabolic action of IGFs on target cells appears to be their binding to specific receptors on the plasma membrane. Current evidence indicates that the mitogenic actions of both IGFs are mediated primarily by binding to the type I IGF receptors, and that IGF action is also mediated by interactions with IGF-binding proteins (IGFBPs). Six distinct IGFBPs have been identified that are characterized by cell-specific interaction, transcriptional and post-translational regulation by many different effectors, and the ability to either potentiate or inhibit IGF actions. Nutritional deficiencies can have their devastating consequence during growth. Although IGF-I is the major mediator of GH's action on somatic growth, nutritional status of an organism is a critical regulator of IGF-I and IGFBPs. Various nutrient deficiencies result in decreased serum IGF-I levels and altered IGFBP levels, but the blood levels of GH are generally unchanged or elevated in malnutrition. Effects of protein, energy, vitamin C and D, and zinc on serum IGF and IGFBP levels and tissue mRNA levels were reviewed in the text. Multiple factors are involved in the regulation of intestinal epithelial cell growth and differentiation. Among these factors the nutritional status of individuals is the most important. The intestinal epithelium is an important site for mitogenic action of the IGFs in vivo, with exogenous IGF-I stimulating mucosal hyperplasia. Therefore, the IGF system appears to provide and important mechanism linking nutrition and the proliferation of intestinal epithelial cells. In order to study the detailed mechanisms by which intestinal mucosa is regulated, we have utilized IEC-6 cells, an intestinal epithelial cell line and Caco-2 cells, a human colon adenocarcinoma cell line. Like intestinal crypt cells analyzed in vivo or freshly isolated intestinal epithelial cells, IEC-6 cells and Caco-2 cells possess abundant quatities of both type Ⅰ and type Ⅱ IGF receptors. Exogenous IGFs stimulate, whereas addition of IGFBP-2 inhibits IEC-6 cell proliferation. To investigate whether endogenously secreted IGFBP-2 inhibit proliferation, IEC-6 cells were transfected with a full-length rat IGFBP-2 cDNA anti-sense expression construct. IEC-6 cells transfected with anti-sense IGFBP-2 protein in medium. These cells grew at a rate faster than the control cells indicating that endogenous IGFBP-2 inhibits proliferation of IEC-6 cells, probably by sequestering IGFs. IEC-6 cells express many characteristics of enterocyte, but do not undergo differentiation. On the other hand, Caco-2 cells undergo a spontaneous enterocyte differentiation. On the other hand, Caco-2 cells undergo a spontaneous enterocyte differentiation after reaching confluency. We have demonstrated that Caco-2 cells produce IGF-Ⅱ, IGFBP-2, IGFBP-3, and an as yet unidentified 31,000 Mr IGFBP, and that both mRNA and peptide secretion of IGFBP-2 and IGFBP-3 increased, but IGFBP-4 mRNA and protein secretion decreased after the cells reached confluency. These changes occurred in parallel to and were coincident with differentiation of the cells, as measured by expression of sucrase-isomaltase. In addition, Caco-2 cell clones forced to overexpress IGFBP-4 by transfection with a rat IGFBP-4 cDNA construct exhibited a significantly slower growth rate under serum-free conditions and had increased expression of sucrase-isomaltase compared with vector control cells. These results indicate that IGFBP-4 inhibits proliferation and stimulates differentiation of Caco-2 cells, probably by inhibiting the mitogenic actions of IGFs.

• Asian-Australasian Journal of Animal Sciences
• /
• v.8 no.1
• /
• pp.51-58
• /
• 1995

To examine whether colostral growth factors are transferred to the general circulation, concentrations of plasma cortisol, insulin, prolactin, growth hormone, insulin-like growth factors(IGFs) -I and -II, IGF-binding proteins(IGFBPs) and total protein were measured in newborn calves fed colostrums, milk of milk replacer before and after feeding at 12 h intervals during the first two days after birth. Plasma protein concentrations increased with time after than in milk- or milk replacer-fed calves. The mean protein concentration was greater in colostrum-fed than in milk- or milk replacer-fed calves. Plasma cortisol levels transiently declined after each feeding regardless of the type of diet, while insulin levels tended to increase. Mean concentrations of these hormones did not differ between dietary groups, nor did they change with time after birth. Plasma concentrations of prolactin and growth hormone did not differ between dietary groups and also did not change with time after birth or after feeding. Concentrations of IGF-I and IGF-II transiently increased at the second feeding period, but these, as well as plasma IGFBP profiles, were not different between groups or before and after feeding. Results did not indicate significant transfer of colostral growth factors across the newborn ruminant small intestine.

• Journal of Animal Science and Technology
• /
• v.46 no.4
• /
• pp.563-570
• /
• 2004

The insulin-like growth factor(IGF) system, consisting of IGFs-I and -II ligands and their receptors and six IGF-binding proteins(IGFBPs), plays an important role in survival, proliferation and differentiation of a variety of cell types. Lithium is a known modulator of survival and proliferation of many cell types in vitro. The present study was undertaken to investigate the relationship between LiCI-induced changes in cell survival and growth and the expression of the IGF system components in C6 rat glioma cell line which, besides IGF-I and its receptor, is known to express IGFBP-3 as its major IGF carrier. When C6 cells were cultured for 24h in the absence or presence of 2mM or 5mM LiCl in a 10% serwn-containing medium, the viability and the number of cells were not affected by added lithium. In 72-h culture, however, C6 cells clearly exhibited a dose-dependent response to added LiCl. The cells cultured for 72h in the presence of 0, 2mM and 5mM LiCl exhibited a typical mitotic, a growth-arrested and an apoptotic appearances, respectively. Moreover, the apoptotic cells were accompanied by reduced expression of IGF-I, IGF-I receptor and IGFBP-3 as examined by semi-quantitative reverse transcription-polymerase chain reaction. Interestingly, blockade of IGFBP-3 mRNA translation by addition of 101${\mu}M$ IGFBP-3 anti-sense oligodeoxyribonucleotide in serum-free, 24-h culture resulted in a decrease in the number of cells as well as relative abundance of the target mRNA. In summary, results suggest that the cytotoxic effect of lithium in C6 cell is likely to be mediated, in part, by suppression by this agent of the expression of the IGF system components. In this regard, IGFBP-3 may play at least a 'permissive' role in normal proliferation of this cell.

• Asian-Australasian Journal of Animal Sciences
• /
• v.10 no.4
• /
• pp.335-356
• /
• 1997

Injection of bovine growth hormone (bGH) to lactating dairy cows increases milk yield and yields of milk components including fat. It is generally believed that most of the anabolic effects derived from bGH in animal tissues are primarily mediated by IGF-1. IGF-1 is a strong anabolic peptide in the plasma of animals and exerts mitogenic and metabolic effects on target cells. Contrary to most protein hormones, the majority of IGF-1 in circulation is bound to the binding proteins (IGFBPs) which are known to be responsible for modifying the biological actions of IGF-1, thus making determinations of IGF-1 actions more difficult. On the other hand, fat is a major milk component and the greatest energy source in milk. Currently, the fat content of milk is one of the major criteria used in determining milk prices. It has been known that flavor and texture of dairy products are mainly affected by milk fat and its composition. Acetyl-CoA carboxylase (ACC) is the rate limiting enzyme which catalyzes the conversion of acetyl-CoA to malonyl-CoA for fatty acid synthesis in 1ipogenic tissues of animals including bovine lactating mammary glands. In addition to the short-tenn hormonal regulation of ACC by changes in the catalytic efficiency per enzyme molecule brought about by phosphorylation and dephosphorylation of the enzyme, the long-term hormonal regulation of ACC by changes in the number of enzyme molecules plays an essential role in control of ACC and lipogenesis. Insulin, at supraphysiological concentrations, binds to IGF-1 receptors, thereby mimicking the biological effects of IGF-1. The receptors for insulin and IGF-1 share structural and functional homology. Furthermore, epidermal growth factor increased ACC activity in rat hepatocytes and adipocytes. Therefore, it can be assumed that IGF-1 mediating bGH action may increase milk fat production by stimulation ACC with phosphorylation (short term) and/or increasing amounts of the enzyme proteins (long term). Consequently, the main purpose of this paper is to give the readers not only the galactopoietic effects of bGH, but also the insight of bGH action with regard to stimulating milk fat synthesis from the whole body to the molecular levels.

• Asian-Australasian Journal of Animal Sciences
• /
• v.18 no.5
• /
• pp.747-754
• /
• 2005

Nutritional regulation of gene expression associated with growth and feeding behavior in avian species can become an important technique to improve poultry production according to the supply of nutrients in the diet. Insulin-like growth factor-I (IGF-I) found in chickens has been characterized to be a 70 amino acid polypeptide and plays an important role in growth and metabolism. Although it is been well known that IGF-I is highly associated with embryonic development and post-hatching growth, changes in the distribution of IGF-I gene expression throughout early- to late-embryogenesis have not been studied so far. We revealed that the developmental pattern of IGF-I gene expression during embryogenesis differed among various tissues. No bands of IGF-I mRNA were detected in embryonic liver at 7 days of incubation, and thereafter the amount of hepatic IGF-I mRNA was increased from 14 to 20 days of incubation. In eyes, a peak in IGF-I mRNA levels occurred at mid-embryogenesis, but by contrast, IGF-I mRNA was barely detectable in the heart throughout all incubation periods. In the muscle, no significant difference in IGF-I gene expression was observed during different stages of embryogenesis. After hatching, hepatic IGF-I gene expression as well as plasma IGF-I concentration increases rapidly with age, reaches a peak before sexual maturity, and then declines. The IGF-I gene expression is very sensitive to changes in nutritional conditions. Food-restriction and fasting decreased hepatic IGF-I gene expression and refeeding restored IGF-I gene expression to the level of fed chickens. Dietary protein is also a very strong factor in changing hepatic IGF-I gene expression. Refeeding with dietary protein alone successfully restored hepatic IGF-I gene expression of fasted chickens to the level of fed controls. In most circumstances, IGF-I makes a complex with specific high-affinity IGF-binding proteins (IGFBPs). So far, four different IGFBPs have been identified in avian species and the major IGFBP in chicken plasma has been reported to be IGFBP-2. We studied the relationship between nutritional status and IGFBP-2 gene expression in various tissues of young chickens. In the liver of fed chickens, almost no IGFBP-2 mRNA was detected. However, fasting markedly increased hepatic IGFBP-2 gene expression, and the level was reduced after refeeding. In the gizzard of well-fed young chickens, IGFBP-2 gene expression was detected and fasting significantly elevated gizzard IGFBP-2 mRNA levels to about double that of fed controls. After refeeding, gizzard IGFBP-2 gene expression decreased similar to hepatic IGFBP-2 gene expression. In the brain, IGFBP-2 mRNA was observed in fed chickens and had significantly decreased by fasting. In the kidney, IGFBP-2 gene expression was observed but not influenced by fasting and refeeding. Recently, we have demonstrated in vivo that gizzard and hepatic IGFBP-2 gene expression in fasted chickens was rapidly reduced by intravenous administration of insulin, as indicated that in young chickens the reduction in gizzard and hepatic IGFBP-2 gene expression in vivo stimulated by malnutrition may be, in part, regulated by means of the increase in plasma insulin concentration via an insulin-response element. The influence of dietary protein source (isolated soybean protein vs. casein) and the supplementation of essential amino acids on gizzard IGFBP-2 gene expression was examined. In both soybean protein and casein diet groups, the deficiency of essential amino acids stimulated chickens to increase gizzard IGFBP-2 gene expression. Although amino acid supplementation of a soybean protein diet significantly decreased gizzard IGFBP-2 mRNA levels, a similar reduction was not observed in chickens fed a casein diet supplemented with amino acids. This overview of nutritional regulation of IGF-I and IGFBP-2 gene expression in young chickens would serve for the establishment of the supply of nutrients to diets to improve poultry production.