• Asian-Australasian Journal of Animal Sciences
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• v.13 no.12
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• pp.1653-1658
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• 2000

Insulin-like growth factor-I (IGF-I) mRNA levels in the eyes, heart, liver and breast muscle removed from dwarf egg-type, normal egg-type and normal meat-type chicken embryos at 7, 14 and 20 days of incubation were measured. There was no influence of chicken strain on IGF-I gene expression in the eyes and liver. The IGF-I gene expression in eyes increased significantly along with the incubation period. In the liver, IGF-I gene expression at 20 days of incubation was significantly higher than that at 14 days of incubation. In the muscle, the lowest value for IGF-I gene expression was observed in meat-type chicken embryos. Regression analysis revealed that IGF-I gene expression was significantly correlated to the weights of the eyes and liver, but not the muscle. We conclude that there is little influence of strain on tissue IGF-I gene expression in chicken embryos during incubation but that tissue development in chicken embryos is nevertheless at least partly regulated by the change in IGF-I gene expression.

• Journal of Periodontal and Implant Science
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• v.30 no.2
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• pp.375-390
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• 2000

The purpose of this study is to evaluate the expression ofIGF-I, considered as the mediator of action of estrogen, and IGF-IA and IGF-IB, alternative slicing form of IGF-I, using $17{\beta}-estradiol$ in MC3T3-E1 cells. We observed the effect on type I collagen and osteopontin gene expression and DNA synthetic activity of MC3T3-E1 cells, added by estrogen, IGF-I and combination and the interactionon proliferation and differentiation of MC3T3-E1 cells. The results were as follows :RT-PCR experiment for observing timedependantIGF-I gene expression patternshowed IGF-IA and IB gene expression in both of control and test group. In these IGF-IA gene expression was appeared predominantly. In control, IGF-I geneexpression level was maintained until 24hr and then decreased gradually. In testgroup, IGF-I gene expression level increased as time goes by. Experiment measuring DNA synthetic activity, as it is added by $17{\beta}-estradiol$, IGF-I and combination, showed that first day , there was the tendency of more increase of synthetic activity in all test group than control but no statical significance(P>0.05), and third day, there was more increase of DNA synthetic activity in $17{\beta}-estradiol$ group and combination group and it was statically significant. (P<0.005) Experiment for observing type I collagen gene expression pattern showed more increase of expression in $17{\beta}-estradiol$ group than control and no significant difference in IGF-I group and combination group. Experiment for observing osteopontin gene expression pattern showed no significant difference in control and test group. In conclusion, $17{\beta}-estradiol$ in MC3T3- E1 cells increased IGF-I gene and DNA synthetic activity simultaneously, therefore it appeared that IGF-I is related to the action of estrogen. Combination treatment of IGF-I and $17{\beta}-estradiol$ has effect on cell proliferation but this effect is lower than IGF-I or $17{\beta}-estradiol$ alone. However, combination treatment has not great effect on type I collagen or osteopontin gene expression thus little effect of cell differentiation.

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

• Clinical and Experimental Pediatrics
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• v.52 no.3
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• pp.356-363
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• 2009

Purpose : A polymorphism in the IGF-I gene promoter region is known to be associated with serum IGF-I levels, birth weight, and body length, suggesting that IGF-I gene polymorphism might influence postnatal growth. The present study aimed to investigate the role of this polymorphic cytosine-adenine (CA) repeat of the IGF-I gene in children with idiopathic short stature. Methods : The study involved 131 children (72 boys and 59 girls) diagnosed with idiopathic short stature, aged 715 years. Genomic DNA was extracted from anticoagulated peripheral whole blood. The primers were designed to cover the promoter region containing the polymorphic CA repeat. Data were analyzed using GeneMapper software. The correlations between age and serum IGF-I levels were analyzed using Spearmans correlation coefficient. Results : The CA repeat sequences ranged from 15 to 22, with 19 CA repeats the most common with an allele frequency of 40.6%. Homozygous for 19 CA repeat was 13.0%, heterozygous for 19 CA repeat was 56.5%, and 19 CA non-carrier was 30.5%. The three different genotype groups showed no significant differences in height, body weight and body mass index, and serum IGF-I levels. The serum IGF-I level and age according to the IGF-I genotypes were significantly correlated in the entire group, 19 CA repeat carrier group, and the non-carrier group. The three groups also showed no significant differences in the first year responsiveness to GH treatment. Conclusion : There were no significant different correlations between 19 CA repeat polymorphism and serum IGF-I levels according to genotype. Our results suggest that the IGF-I 19 CA repeat gene polymorphism is not functional in children with idiopathic short stature.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.3
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• pp.245-248
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• 1998

The influence of refeeding either protein, carbohydrate or fat on hepatic insulin-like growth factor-I (IGF-I) mRNA level in chicks which had been fasted for 2 days was examined. The hepatic IGF-I mRNA was measured by ribonuclease protection assay. Fasting reduced hepatic IGF-I mRNA levels to less than half of those in the fed control. When chicks were refed either a control, protein or carbohydrate diet, IGF-I mRNA levels significantly increased to those in the fed control until 2 hours of refeeding. Refeeding of fat did not alter hepatic IGF-I mRNA levels. The significant correlation between liver weight and hepatic IGF-I gene expression suggests that when chicks are refed after 2-d fasting, the acute increase in hepatic IGF-I gene expression brought about after refeeding may be partly regulated by the increase in liver protein metabolism.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.8
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• pp.1061-1065
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• 2005

Growth rate is one of the economically important quantitative traits that affect carcass quantity in beef cattle. Two genes, bovine insulin-like growth factor I (IGF-I) and myogenic factor 5 (MYF5), were chosen as candidate genes for growth traits due to their important role in growth and development of mammals. The objectives of this study were to determine gene-specific single nucleotide polymorphism (SNP) markers of the IGF-I and MYF5 positional candidate genes and to investigate their associations with growth traits in Korean cattle. Genotyping of the SNP markers in these candidate genes was carried out using the single strand conformation polymorphism (SSCP) analysis. The frequencies of A and B alleles were 0.72 and 0.28 for IGF-I gene and 0.39 and 0.61 for MYF5 gene, respectively, in Korean cattle population examined. The gene-specific SNP marker association analysis indicated that the SNP genotype in IGF-I gene showed a significant association (p<0.05) with weight at 3 months (W3), and cows with AB genotype had higher W3 than BB genotype cows. The SNP genotype of MYF5 gene was found to have a significant effect (p<0.05) on the weight at 12 months (W12) and average daily gain (ADG), and cows with BB and AB genotypes had higher W12 and ADG compared with cows with AA genotype, respectively. However, no significant association between the SNP genotypes and any other growth traits was detected. The gene-specific SNP markers in the IGF-I and MYF5 candidate genes may be useful for selection on growth traits in Korean cattle.

• Clinical and Experimental Pediatrics
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• v.49 no.12
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• pp.1340-1347
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• 2006

Purpose : The aim of the present study was to investigate the role of polymorphic cytosine adenine (CA) repeat of the IGF-I gene in the age-related alterations of serum IGF-I levels in healthy children. Methods : Two hundred and forty three normal healthy children (136 boys; 107 girls) aged between 7 and 15 years were enrolled in the present study. The primers were designed to cover the promoter regions containing the polymorphic CA repeat. Data were analyzed using GeneMapper software, version 3.7. All analyses were performed using MEDCALC software packages. Results: Deletion of 2 bp (G, A) following 3' of CA repeat were observed in all Korean children. The CA repeat sequences ranged from 17 to 23, and 19 CA repeat were the most common with an alleles frequency of 39.3 percent. Considering genotypes, 63.8 percent of subjects were homozygote or heterozygote for 19 CA repeat (192 bp allele), suggesting that this is wild type allele from which all other alleles originated in Korean children. Homozygote for 19 CA repeat were 14.7 percent, heterozygote for 19 CA repeat was 49.1 percent and 19 CA noncarriers totalled 36.2 percent. In 19 CA repeat noncarriers, the mean height, weight and serum IGF-I level were lower compared with those of 19 CA homozygous carriers, but statistically not significant. Correlations between serum IGF-I level and age according to the IGF-I genotypes revealed statistically significant relationships in the all groups, in the 19 CA repeat carrier group and, even in the noncarrier group. Conclusions : There were no significant differences of the mean height, weight and serum IGF-I levels among three different genotype groups. Also, there were no significantly different correlations between 19 CA repeat polymorphisms and serum IGF-I levels, according to genotype. Our results suggest that the IGF-I 19 CA repeat gene polymorphism is not associated with circulating IGF-I levels in healthy children.

• Journal of Life Science
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• v.19 no.5
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• pp.593-597
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• 2009

The uterus plays a critical role in pregnancy and steroid hormones, and both estrogen (E2) and progesterone (P4) especially play important roles in the cross-talk between embryos and uterus to support the pregnancy. E2 stimulates uterine growth during early pregnancy to prepare for implantation of embryos. This cross-talk during the implantation period involves hormones (E2 and P4) and growth factors, including insulin-like growth factor-I (IGF-I). In the uterus of a pregnant pig, the action of E2 is mediated by estrogen receptor-${\beta}$ (ER-${\beta}$). The expression of ER-a was much higher in early pregnancy than in mid- and late- pregnancy, suggesting E2 secretion from embryos enhances transcription of ER-a during early pregnancy. In order to prove whether IGF-I is an E2 target gene, quantitative real-time PCR was performed on ovariectomized murine uterus with E2 and/or P4 treatment(s). Increased IGF-I mRNA expression was observed with E2 treatment, however, it was not significantly induced by P4 treatment, which clearly demonstrates that, in mice, E2 depends on the activation of uterine IGF-I gene expression. The expression of IGF-I in the uterus of pigs was much higher in early pregnancy than in mid- and late- pregnancy and these data exhibited the same expression pattern with the ER-${\beta}$ gene expression in the uterus. It suggests that a positive co-relationship between IGF-I and ER-${\beta}$ expression exists in the uterus, and that both gene expressions of IGF-I and ER-${\beta}$ are regulated by E2. It further suggests that uterine the IGF-I gene expression might be initiated by E2 secreted from embryos to increase ER-${\beta}$ gene expression, and that this increased ER-${\beta}$ further stimulates the expression of IGF-I in the uterus during early pregnancy.

• KSBB Journal
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• v.17 no.3
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• pp.283-289
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• 2002

The present study was aimed at investigating the metabolic regulation of insulin-like growth factor-I(IGF-I) expression in fasting animals. The expression of IGF-I gene was determined by a solution hybridization/RNase protection assay using total RNA from control, 4d-fasting, and 2d-fasting-refed rats. The levels of IGF-I transcripts were reduced in 4d-fasting than in control by decreasing its transcriptional rate, which was measured through nuclear nun-on assay. DNase I footprinting, which was performed using nuclear extracts from fasting rat, demonstrated protein binding to a sequence that extended from +179 to +210 (termed region B). These data suggest that the expression of IGF-I is transcriptionally regulated through DNA-liver enriched protein binding in a sequence which is located downstream from major transcription initiation site of IGF-I gene.

• KSBB Journal
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• v.18 no.4
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• pp.329-334
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• 2003

The present study was aimed at investigating the regulatory mechanism in tissue-specific expression of insulin-like growth factor-I (IGF-I) gene. The expression of IGF-I gene was determined by a solution hybridization/RNase protection assay using total RNA prepared from rat liver or brain of various ages. The levels of IGF-I transcripts were increased in liver gradually after birth, but decreased in brain. By using an oligonucleotide (FRE) corresponding to the C/EBP binding site of the rat IGF-I exon 1, multiple forms of C/EBP${\alpha}$ and C/EBP${\beta}$ proteins, which have DNA-binding activity, were detected in the rat liver or brain. Western immunoblot and southwestern analyses show that p42$\^$C/EBP${\alpha}$/, p38$\^$C/EBP${\alpha}$/, p35$\^$C/EBP${\alpha}$/, p38$\^$C/EBP${\beta}$/, and p35$\^$C/EBP${\beta}$ form specific complexes with the IGF-I exon 1 oligonucleotide in liver nuclear extract and that p42$\^$C/EBP${\alpha}$/ and p38$\^$C/EBP${\beta}$/ form complexes in brain. These data suggest that the formation of FRE-C/EBP isoform complexes may play important roles in the tissue-specific regulation of IGF-I gene expression.