• Asian-Australasian Journal of Animal Sciences
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• v.19 no.10
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• pp.1508-1513
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• 2006

Myostatin (MSTN) and insulin-like growth factors (IGFs) are a known inhibitor and stimulators of proliferation and differentiation of muscle cells, respectively. The present study was performed to investigate the relationship of MSTN-induced growth inhibition to expression of the IGF system components and myogenin, a muscle cell-specific transcription factor, in rat L6 myoblasts. The L6 cells transfected with a green fluorescent protein-MSTN plasmid expression construct had a 47% less cell number than mock-transfected cells after 3-d serum-free culture, accompanied by delayed differentiation which was suggested by inhibited aggregation of cells. Moreover, cells transfected with the expression construct had decreased expression of IGF-II and myogenin genes, but not IGF-I or its receptor genes, as examined by reverse transcription-polymerase chain reaction. The reduced mitosis of the L6 cells transfected with the MSTN-expression construct increased following an addition of either IGF-I or IGF-II to the culture medium, but not to the level of mock-transfected cells. By contrast, myogenin gene expression in these cells increased after the addition of either IGF to the level of mock-transfected cells. Collectively, these results suggest that the inhibitory effect of MSTN on L6 cell proliferation and differentiation is likely to be partly mediated by serially suppressed expression of IGF-II and myogenin genes, not IGF-I gene.

• Journal of Nutrition and Health
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• v.34 no.8
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• pp.905-911
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• 2001

Phytoestrogens, especially soy-derived isoflavones, are receiving great scrutiny as a food supplement for preventing hormone dependent diseases such as cardiovascular diseases, cancer, and osteoporosis. These beneficial effects of phytoestrogens are caused by functioning as partial agonists or antagonists of estrogens. In contrast to the common usage of soy bean, Yak-kong(Rhynchosia Molubilis ; ) has been used as supplements of estrogen fir preventing postmenopausal osteoporosis in Oriental medicine. To investigate estrogenic effects of Yak-kong and soy bean on the proliferation of MG-63 osteoblastic cells, each bean was extracted with 70% methanol and dried by freeze-drying. Yak-kong treatment of MG-63 cells resulted in an increase of cell proliferation to a maximum of 76% compared to 68% of soy bean treatment. Treatment of MG-63 cells with Yak-kong extract also resulted in an increase of transactivation of an ERE(estrogen response element)-luciferase reporter plasmid and IGF-I expression selectively. Despite increased effects of both bean treatments on the expression of estrogen receptor $\alpha$(ER$\alpha$) and $\beta$(ER$\beta$), soy bean treatment decreased transactivation of an ERE-luciferase reporter plasmid and did not further enhance IGF-I expression. Together, our data demonstrates that the greater estrogenic response of Yak-kong extract for MG-63 cell proliferation is mediated by ER derived transactivation of ERE and selective induction of IGF-I expression.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.8
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• pp.1069-1077
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• 2009

Castration of male pig produces significant negative effects on skeletal muscle development. The androgen receptor (AR), two splice variants of insulin-like growth factor-I (IGF-I Ea and MGF) and the myostatin gene may play important roles in this process. In the present study, the expression of AR, IGF-I Ea, MGF and myostatin genes in three skeletal muscles, the brachialis, longissimus and semitendinosus, were studied using real-time quantitative RT-PCR. Our experimental design used 14 pairs of male Landrace sire${\times}$Yorkshire dam piglets. The two piglets in each pair were full sibs, one of which was castrated at 21 d of age; the other remained intact. The study group was divided into subgroups of equal size. Animals in the first subgroup were slaughtered at 147 d and those of the second at 210 d of age. Carcass weight and lean meat yield were similar between boars and barrows at 147 d of age (p>0.05), whereas barrows had lower carcass weight and less lean meat yield at 210 d of age (p<0.05). Castration caused down-regulation of AR gene expression at both 147 and 210 d of age (p<0.05). The two splice variants of the IGF-I gene from porcine skeletal muscle were cloned using RT-PCR, and it was found that MGF differs from IGF-I Ea in having a 52-base insert in the last coding exon of the mRNA. Both splice variants were down-regulated by castration only at 210 d of age (p<0.05). No differences in expression of the myostatin gene were observed between boars and barrows at either 147 or 210 d of age (p>0.05). These results suggest that the downregulation of AR, IGF-I Ea and MGF gene expression following castration helps to explain the negative effect of castration on skeletal muscle development.

• Animal Bioscience
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• v.36 no.9
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• pp.1350-1356
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• 2023

Objective: This study was conducted to investigate polymorphisms of the melanocortin-4 receptor (MC4R) and insulin like growth factor 2 (IGF2) genes and to evaluate the growth traits affected by such polymorphisms in Thai native (Kradon) pigs. Methods: Blood samples and productive data from 91 Kradon pigs were collected. DNA was extracted and quantified, the IGF2 and MC4R genes were amplified, and the polymerase chain reaction (PCR) produces were digested using the PCR-restriction fragment length polymorphism (PCR-RFLP) technique. Genotyping was performed, and the association between genotypes and growth traits on the birth and weaning weights were evaluated. Results: The IGF2 intron7 g.162G>C variations in Kradon pigs were found in three genotypes: i) GG, ii) GC, and iii) CC. The GG genotype frequency was the highest followed by the GC and CC genotypes. The frequencies of the G and C alleles were 0.703 and 0.297, respectively. The MC4R genotype was found in only one genotype (GG). The IGF2 gene pattern was not associated with birth weight traits, whereas the IGF2 gene pattern was related to the weaning weight trait in Kradon pigs. Pigs with the CC and GC genotypes had higher weaning weights than ones with the GG genotype (p<0.001). Conclusion: Thai native Kradon pigs with the CC and GC genotypes of the IGF2 gene have higher weaning weights than pigs with the GG genotype.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.2
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• pp.285-290
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• 1997

The insulin-like growth factors(IGFs) are bound to several binding proteins(IGFBPs) that appear to regulate IGF transport, receptor binding, and its action. The concentration of these peptides are altered by catabolic conditions. To determine IGF-I and IGFBP levels in noninsulin-dependent diabetes mellitus (NIDDM), sera was obtained from 5 patients and 7 controls. Serum levels of IGF-I in NIDDM were lower than those in either of the controls. By western immunoblot analysis, especially IGFBP-1 levels are increased, whereas IGFBP-3 levels decreased and their fragments was increased in NIDDM serum. IGFBP-3 proteolytic activity in NIDDM sera was inhibited by phenylmethylsulfonylfluoride (PMSF), aprotinin, and ethylenediaminetetraacetic acid(EDTA). This pattern of inhibition was consistent with a metal-dependent serine protease. By gelatin zymography, these proteolytic enzymes were identified as the size of 97 and 69 kDa. IGFBP-1, which is primarily insulin regulated, was increased in NIDDM and may modulate circulating IGF-I levels by regulating capillary passage of IGF-I. IGFBP-3 proteolysis markedly reduces its affinity for the IGFs, particularly for IGF-I. This accelerates their kinetics of dissociation, thereby increasing the proportions of IGF-I in free form and its availability to the cells.

• Journal of Ginseng Research
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• v.46 no.4
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• pp.526-535
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• 2022

Background: During the pathogenesis of tendinopathy, the chronic inflammation caused by the injury and apoptosis leads to the generation of scars. Ginsenoside Rg1 (Rg1) is extracted from ginseng and has anti-inflammatory effects. Rg1 is a unique phytoestrogen that can activate the estrogen response element. This research aimed to explore whether Rg1 can function in the process of tendon repair through the estrogen receptor. Methods: In this research, the effects of Rg1 were evaluated in tenocytes and in a rat model of Achilles tendinitis (AT). Protein levels were shown by western blotting. qRT-PCR was employed for evaluating mRNA levels. Cell proliferation was evaluated through EdU assay and cell migration was evaluated by transwell assay and scratch test assay. Results: Rg1 up-regulated the expression of matrix-related factors and function of tendon in AT rat model. Rg1 reduced early inflammatory response and apoptosis in the tendon tissue of AT rat model. Rg1 promoted tenocyte migration and proliferation. The effects of Rg1 on tenocytes were inhibited by ICI182780. Rg1 activates the insulin-like growth factor-I receptor (IGF1R) and MAPK signaling pathway. Conclusion: Rg1 promotes injured tendon healing in AT rat model through IGF1R and MAPK signaling pathway activation.

• Journal of Embryo Transfer
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• v.12 no.3
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• pp.229-246
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• 1997

Implantation is a most important biological process during pregnancy whereby conceptus establishes its survival as well as maintenance of pregnancy. During the periimplantation period, both uterine endometriurn and conceptus synthesize and secrete a host of growth factors and cytokines which mediate the actions of estrogen and /or progesterone and also exert their steroid-independent actions. Growth factors expressed by the materno-conceptal unit en masse have important roles in cell migration, stimulation or inhibition of cell proliferation, cellular differentiation, maintenance of pregnancy and materno-conceptal communications in an autorcrine /paracrine manner. The present review focuses on the role of the intrauterine IGF system during periimplantation conceptus development. The IGF system comprises of IGF- I and IGF- II ligands, types I and II IGF receptors and six or more IGF-binding proteins(IGFBPs). IGFs and IGFBPs are expressed and secreted by uterine endometrium with tissue, pregnancy stage and species specificities under the influence of estrogen, progesterone and other growth factor(s). Conceptus also synthesizes components of the IGF system beginning from a period between 2-cell and blastocyst stages. Maternal IGFs are utilized by both maternal and conceptal tissues; conceptus-derived growth factors are believed to be taken up primarily by conceptus. IGFs enhance the development of both maternal and conceptal compartments in a wide range of biological processes. They stimulate proliferation and differentiation of endometrial cells and placental precursor cells including decidual transformation from stromal cells, placental formation and the synthesis of some steroid and protein hormones by differentiated endometrial cells or placenta. It is also well-documented in a number of experimental settings that both IGFs stimulate preimplantation embryo development. In slight contrast to these, prenatal mice carrying a null mutation of IGF and /or IGF receptor gene do not exhibit any apparent growth retardation until after implantation. Reason (s) for this discrepancy between the knock-out result and the in vitro ones, however, is not known. IGFBPs, in general, are believed to inhibit IGF action within the materno-conceptal unit, thereby allowing endometrial stromal cell differentiation as well as dampening ex cessive placental invasion into maternal tissue. There is evidence, however, indicating that IGFBP can enhance IGF action depending on environrnental conditions perhaps by directioning IGF ligand to the target cell. There is also a third possibility that certain IGFBPs and their proteolytic fragments may have their own biological activities independent of the IGF. In addition to IGFBPs, IGFBP proteases including those found within the uterine tissue or lumen are thought to enhance IGF bioavailability by degrading their substrates without affecting their bound ligand. In this regard, preliminary results in early pregnant pigs suggest that a partially characterized IGFBP protease activity in uterine luminal fluid enhances intrauterine IGF bioavailability during conceptus morphological development. In summary, a number of in vitro results indicate that IGFs stimulates the development of the rnaterno-conceptal unit during the periimplantation period. IGFBPs appear to inhibit IGF action by sequestering their ligands, whereas IGFBP proteases are thought to enhance intrauterine bioavailability of IGFs. Much is remaining to be clarified, however, regarding the roles of the individual IGF system components. These include in vivo evidence for the role of IGFs in early conceptus development, identification of IGF-regulated genes and their functions, specific roles for individual IGFBPs, identification and characterization of IGFBP proteases. The intrauterine IGF club house thus will be paying a lot of attention to forthcoming results in above and other areas, with its door wide-open!

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.11
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• pp.1542-1547
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• 2005

The Melanocortin-4 Receptor (MC4R) and Insulin-like Growth Factor 2 (IGF2) are two important candidate genes related to fat deposition and carcass traits. MC4R was found on study on human obesity and then was studied as candidate gene affecting food intake and fat deposition traits in mice and pigs. Insulin-like Growth Factor 2 (IGF2) gene plays an important role on tumor cell proliferation and muscle growth. It also affects fat traits and live weight in pigs. In this paper, MC4R and IGF2 were studied as two candidate genes associated with important economic traits such as fat deposition and carcass traits in five different pig populations. Taq I-PCR-RFLP and Bcn I-PCR-RFLP were respectively used to detect the polymorphism of genotypes of MC4R and IGF2 genes. Different MC4R genotype frequencies were observed in four populations. IGF2 genotype frequencies were also different in two populations. The results of association analysis show both MC4R and IGF2 genes were significantly associated with fat deposition and carcass traits in about 300 pigs. This work will add new evidence of MC4R and IGF2 affecting fat deposition and carcass traits in pigs and show that two genes can be used as important candidate genes for marker assistant selection (MAS) of growth and lean meat percentage in pigs.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.4
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• pp.493-501
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• 1998

The most significant direct role of estrogen in vivo is its ability to elicit receptor-mediated cellular proliferation in mammalian target tissues. However, the mechanism by which exogenously added estrogen causes the neoplastic transformation of renal cortical cells is yet to be uncovered. The present study was designed to evaluate interaction of $17{\beta}-estradiol\;(E_2)$ with epidermal growth factor (EGF) and insulin-like growth factor-I (IGF-I) on proliferation and $P_i$ uptake in primary cultured rabbit renal proximal tubular cells in phenol red-free, hormonally defined-medium. $[^3H]-thymidine$ incorporation increased markedly by about 133% and 141% more in the presence of $10^{-9}\;and\;10^{-6}\;M\;E_2$, respectively, than that of control. Cell count was 162% and 143% greater in the presence of $10^{-9}\;and\;10^{-6}\;M\;E_2$ , respectively, compared with control. Among all time points examined, there was an increase in $[^3H]-thymidine$ incorporation in the presence of $10^{-9}\;M\;E_2$ at day 9 or 13, respectively. However, $E_2$ ($10^{-9}\;M$) significantly drove up cell count to 160% of that of control at day 13, while it had a slight but statistically insignificant effect at day 9. $E_2-induced$ stimulation of $[^3H]-thymidine$ incorporation was completely reversed by $E_2$ antagonists (progesterone or tamoxifen). $E_2$ ($10^{-9}\;M$) or EGF ($10^{-8}\;M$) significantly stimulated $[^3H]-thymidine$ incorporation by 144% and 154% of control. $E_2$ plus EGF was synergistic on $[^3H]-thymidine$ incorporation (204% of control), while $E_2$ plus IGF-I showed a slight but no significant synergistic effect. Cell number also displayed similar pattern. $E_2$ ($10^{-9}\;M$) significantly stimulated $P_i$ uptake to 134% of control. $E_2$-induced stimulation of $P_i$ uptake was partially reversed by $E_2$ antagonists. EGF or IGF-I ($10^{-8}\;M$) significantly also increased $P_i$ uptake to 132% or 129% of control. $E_2$ plus EGF had synergistic effect on $P_i$ uptake, while $E_2$ plus IGF-I did not. In conclusion, $E_2$ may act not only directly interaction with its receptors but also indirectly as a modulator of EGF in proliferation and $P_i$ uptake of primary cultured rabbit renal proximal tubular cells.

• Journal of Nutrition and Health
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• v.38 no.7
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• pp.512-520
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• 2005

Phytoestrogens, especially Yak-kong or soybean-derived isoflavones have been traditionally used as a supplement of estrogen for preventing postmenopausal osteoporosis in oriental folk medicine. In a previous study, we demonstrated that as Yak-kong and soybean increased MG-63 human osteoblastic cell proliferation, the expression of estrogen receptor $\alpha\;and\;beta\;(ER\;\alpha:\;ER\;\beta$) both were increased. However, the increased level of ER $\alpha$ is much higher than that of ER$\beta$. To determine whether the altered level of ER $\alpha$ expression affects Yak-kong or soybean induced MG-63 cell proliferation, we established cell lines stably expressing either ER $\alpha$ or antisense ER $\alpha$ RNAs. Increased expression of ER a in MG- 63 cells (ER $\alpha$-MG63) enhanced Yak-kong or soybean induced proliferation which paralleled with the enhanced expression of IGF-I. Inhibition of ER $\alpha$ expression by antisense $ER\;\alpha\;RNAs\;(As-ER\;\alpha-MG63$) caused these cells to insensitize Yak- kong or soybean induced proliferation and IGF-I expression. Furthermore, the comparable effects between Yak-kong and the combined treatment of genistein and daidzein at $0.5\;{\times}\;10^{-8}M$, which is a concentration of these two isoflavones similar to Yak-kong at 0.001 mg/ml, on cell proliferation and IGF-I expression in $ER\;\alpha-MG63\;or\;As-ER\;\alpha-MG63$ cells demonstrate that ER $\alpha$ plays an important, active role in MG-63 cell proliferation induced by phytoestrogens, especially Yak-kong or soybean derived isoflavones.