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Insulin-like growth factor-II and transforming growth factor-alpha in developing human fetal pancreatic islets.

To understand the development of the human pancreas better, we studied the expression and regulation of insulin, insulin-like growth factor-II (IGF-II) and transforming growth factor-alpha (TGF-alpha) genes in the human fetal pancreas and islet-like cell clusters (ICC) from the second trimester human fetuses. Northern blot analysis revealed an abundant expression of IGF-II, insulin and TGF-alpha mRNAs in the intact pancreas and the cultured ICCs. Furthermore, transcripts for insulin receptor, type-1 and -2 IGF receptors, and GH receptor could be amplified by polymerase chain reaction analysis from the pancreas and the ICCs. With in-situ hybridization, IGF-II mRNA was found in abundance in both the exocrine and endocrine pancreas, exceeding the amount of insulin mRNA. In ICCs, insulin mRNA-containing cells were present as small clusters in the periphery and in the centre of the clusters corresponding to the immunolocation of insulin. The ICCs also contained many epidermal growth factor-, insulin- and type-1 IGF receptor- and TGF-alpha-positive cells. When the ICCs were cultured in the presence of various secretagogues, only dibutyryl cyclic AMP was found to up-regulate insulin mRNA (39%; P < 0.05). IGF-II mRNA was also under cyclic AMP-dependent regulation (threefold increase; P = 0.025). Furthermore, blocking the type-1 IGF receptor with a monoclonal receptor antibody drastically reduced insulin expression (87%; P = 0.005) and additionally down-regulated IGF-II mRNA (49%; P = 0.005). IGF-1, IGF-II, TGF-alpha or epidermal growth factor-receptor antibody had no significant effect on either insulin or IGF-II mRNA. Exogenous TGF-alpha inhibited the release of insulin by the ICCs. It was concluded that IGF-II and TGF-alpha may be involved in the regulation of islet growth and differentiation.

Base Sequence↗

Insulin-like growth factor-II as a paracrine growth factor in human neuroblastoma cells.

The human neuroblastoma line, SK-N-SH, has been subcloned into SH-SY5Y, a neuroblast N cell line, and SH-EP, an epithelial Schwann S cell line. We have previously shown that SH-SY5Y neuroblastoma cells produce insulin-like growth factor II (IGF-II), which acts by an autocrine mechanism to stimulate cell growth. In the current study, we examined the effect of IGF-II on SH-EP neuroblastoma cells. Northern blot and reverse transcriptase-polymerase chain reaction analyses indicate that SH-EP cells do not produce IGF-I or IGF-II but express the type I and type II IGF receptors (IGF-IR and IGF-IIR). Cell surface expression of IGF-IR, assessed by fluorescence-activated sorting, was lower in SH-EP cells than in SH-SY5Y cells. Immunoprecipitation of IGF-IR, followed by anti-phosphotyrosine or anti-IGF-IR immunoblotting, demonstrated functional expression of these receptors in both cell types and confirmed the lower level of IGF-IR expression in SH-EP cells. IGF-II promoted SH-EP cell growth in the presence of low concentrations of calf serum (0.1-0.3%) or 10 ng/ml epidermal growth factor (EGF). IGF-II stimulation of SH-EP growth was eliminated by the IGF-IR blocking antibody (alpha IR-3) but not by an IGF-IIR blocking antibody. Stimulation of cell growth via this receptor was also indicated by the ligand specificity for IGF analogs and insulin (IGF-II approximately IGF-I approximately des(1-3)IGF-I >> insulin). These results indicate that in the presence of a permissive factor such as calf serum or EGF, IGF-II stimulates SH-EP cell growth via the IGF-IR. Collectively, these data suggest that within primary neuroblastomas, IGF-II may act as a paracrine factor to contribute to the promotion of S cell growth.

Base Sequence↗

Respective roles of factors II, VII, IX, and X in the procoagulant activity of FEIBA.

Activated prothrombin complex concentrates (APCCs) are effective in the therapy of bleeding episodes in hemophilic patients with inhibitors. We investigated the respective roles of factor II, factor VII, factor IX, and factor X in the procoagulant activity of the APCC FEIBA. Factor II, factor VII, factor IX, and factor X were reduced in platelet-poor plasma, and the thrombin potential (TP) was determined using a chromogenic substrate in the absence or presence of FEIBA. Reduction of factor II resulted in a significant decrease of the TP without influencing the lag phase until the onset of thrombin generation. The reduction of factor VII showed no effect on the TP, but resulted in a prolongation of the lag phase. Changes of factor IX or factor X concentrations showed neither an effect on the TP nor on lag phases. Our study demonstrates that thrombin generation in the presence of FEIBA mainly depends on prothrombin.

Blood Coagulation Factors↗

Functional study of the E276Q mutant hepatocyte nuclear factor-4alpha found in type 1 maturity-onset diabetes of the young: impaired synergy with chicken ovalbumin upstream promoter transcription factor II on the hepatocyte nuclear factor-1 promoter.

Seven mutations in the hepatocyte nuclear factor (HNF)-4alpha gene have been shown to correlate with type 1 maturity-onset diabetes of the young (MODY 1), a monogenic form of type 2 diabetes. Up to now, only the functional properties of two MODY 1 HNF-4alpha mutants, Q268X and V393I, have been investigated to address how the mutations in the HNF-4alpha gene, found by genetic studies, can give rise to impaired activities of mutated HNF-4alpha proteins and can cause this disease. The E276Q mutation results in a nonconservative substitution occurring in the HNF-4alpha E domain, which is involved in dimerization and transactivation activities as well as in protein-protein interactions with other transcription factors or coactivators. Using the mutated human HNF-4alpha2, we have found that, in the absence of chicken ovalbumin upstream promoter transcription factor II (COUP TFII), the E276Q substitution does not significantly affect the dimerization and transactivating activities of HNF-4alpha, at least on the promoters studied herein. On the other hand, in the presence of COUP TFII, the substitution impairs the enhancement of HNF-4-mediated activation of HNF-1 promoter. The impaired synergy between COUP TFII and HNF-4 on the HNF-1 promoter results from an alteration of their interaction. HNF-1 expression plays a crucial role in transactivation of insulin promoter and of numerous genes coding for enzymes involved in glucose homeostasis. Therefore, its downregulation resulting from the E276Q mutation in HNF-4alpha gene most probably impairs the function of pancreatic beta-cells.

Animals↗

Biospecific interactions of vitamin K-dependent factors with phospholipid-like polystyrene derivatives. Part II: factor IX.

We previously demonstrated that phosphorylated polystyrene derivatives exhibit phospholipid-like behaviour and therefore are able to interact with factor II, one of the vitamin K-dependent coagulation factors. Under the same conditions as for factor II, we examined the interactions of factor IX with phosphorylated resins of various compositions in phosphate groups: these studies were carried out with or without albumin precoating of the polymers and either in the presence or absence of calcium ions. Adsorption experiments show that, in the absence of calcium ions, only one class of adsorption sites of factor IX can be evidenced with the interactions taking place through the formation of binary complexes, whereas in the presence of calcium ions, the affinity of factor IX for phosphorylated resins becomes very high and two types of adsorption sites have been evidenced with biospecific ternary complexes being formed. The domains of predominance of these complexes were determined. Moreover, the only functional groups borne by the phosphorylated polystyrene resins involved in factor IX-polymer interactions are phosphodiester groups. Comparison between factor II and factor IX adsorption onto the same polymers leads to the conclusion that the observed differences probably reflect the differences in the Gla domains of the vitamin K-dependent factors. Finally, this study demonstrates that phosphorylated polystyrene derivatives can be used as stationary phases for purification of factor IX by highly specific liquid biochromatography.

Adsorption↗

Insulin-like growth factor-II (IGF-II): a potential autocrine/paracrine growth factor for human breast cancer acting via the IGF-I receptor.

Insulin-like growth factor-II (IGF-II) is a potent mitogen for several types of cultured cells and tissues. We have studied the interaction of IGF-II with a panel of cultured human breast cancer cell lines, examining the possibility that these cells synthesize and secrete IGF-II activity which could have autocrine/paracrine functions. Synthetic IGF-II was mitogenic in five of seven cell lines tested, including the estrogen receptor-positive lines MCF-7L, ZR75-1, and T47D and the estrogen receptor (ER)-negative lines Hs578T and MDA-231. IGF-II was slightly less potent than IGF-I in stimulating DNA synthesis in MCF-71 cells, an effect that paralleled its ability to compete for [125I]IGF-I binding in these cells. Affinity labeling studies revealed that IGF-II could also compete for binding to the 130,000 mol wt alpha-subunit of the IGF-I receptor. A monoclonal antibody to the IGF-I receptor inhibited the mitogenic effects of IGF-II in MCF-7L and MDA-231 cells, suggesting that this receptor mediates the growth effects of IGF-II in these breast cancer cells. Using a RIA and a RRA, IGF-II-like activity was detected in conditioned medium extracts processed to remove IGF-binding proteins from several breast cancer cell lines, with the highest levels found in conditioned medium from MCF-7L and T47D cell lines. IGF-II mRNA transcripts in MCF-7L and T47D cells were identified by Northern blot analysis and were confirmed by RNase protection assay. IGF-II mRNA was increased by estrogen in MCF-7L cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding, Competitive↗

Design of a prospective neonatal cohort study of homozygous and double heterozygous factor V Leiden and factor II G20210A.

BACKGROUND: Factor V Leiden (FVL) and Factor II (FII) G20210A represent common risk factors for thromboembolic (TE) events. In children, both venous and arterial TE-events have been associated with the presence of FVL and FII G20210A. In most heterozygous children with TE-events other prothrombotic factors can usually be identified. Case reports of children with homozygous FVL, including 3 patients described here, suggest that this genotype may convey a particulary high risk. However, prospective data about the type and frequency of TE-events in such children are lacking. STUDY DESIGN: We have initiated a prospective neonatal cohort study for the homozygous and double heterozygous genotypes for FVL and FII G20210A. The probands and the heterozygous controls are identified by neonatal screening that involves > 98% of the children born in Berlin and are followed up in a special out-patient clinic to document details of the clinical history, developmental parameters and the occurrence of TE-events. CONCLUSIONS: This study will provide controlled and unbiased information about the clinical significance of the homozygous and double heterozygous genotypes of these mutations.

Blood Coagulation Disorders↗

Insulin-like growth factor II and transforming growth factor beta 1 regulate insulin-like growth factor I secretion in mouse bone cells.

Bone cells in culture produce and respond to growth factors, suggesting that local as well as systemic factors regulate bone volume. Previous studies have shown that IGF-I is the major mitogen produced by mouse bone cells and that its production is regulated by systemic agents such as PTH and estrogen. Because IGF-II and transforming growth factor beta 1 have been shown, respectively, to increase and decrease MC3T3-E1 cell proliferation, we tested the hypothesis that these two growth factors modulate the production of IGF-I in this cell line. In order to eliminate artifacts owing to IGF binding proteins, conditioned media samples were pretreated with IGF-II before measurement of IGF-I by RIA. After 24 h treatment at a density of 2.5 x 10(4) cells/cm2, IGF-II (10 micrograms/l) induced a 2.2-fold increase compared with untreated control (9.5 +/- 1.5 vs 4.2 +/- 0.44 pg/micrograms protein, p less than 0.001), whereas transforming growth factor beta 1 (1 microgram/l) caused a 66% decrease in IGF-I production (1.5 +/- 0.3 vs 4.2 +/- 0.44 pg/micrograms protein, p less than 0.001). Both IGF-II and transforming growth factor beta 1 regulated IGF-I production in a dose-, time- and cell density-dependent manner. The lowest effective doses for IGF-II and transforming growth factor beta 1 were 1 and 0.01 microgram/l, respectively. These results support a role for IGF-II and transforming growth factor beta 1 as potent modulators of IGF-I secretion in mouse bone cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Insulin-like growth factor II receptor, transforming growth factor-beta, and Cdk4 expression and the developmental epigenetics of mouse palate morphogenesis and dysmorphogenesis.

The B10/B10.A congenic mouse pair serves as a model for identifying specific genes related to morphogenesis and dysmorphogenesis of the embryonic palate and other organs. The present report describes our initial investigation of the Fraser-Juriloff paradigm, which proposes that susceptibility to malformation results from genetically determined differences in normal developmental patterns. Specifically, we evaluated the relationship between Igf2r gene expression, transforming growth factor-beta (TGF-beta) activation, and cdk4 gene expression. By using in situ hybridization, RNase protection assays, indirect immunofluorescence, Western blots, and bioassays, we show 1) the presence of insulin-like growth factor II (IGF-II), IGF-II receptor (IGF-IIR), IGF-IR, TGF-beta, plasminogen, plasminogen activators [urokinase plasminogen activator (uPA) and tissue plasminogen activator (tPA)], and Cdk4 in developing palates; 2) on embryonic day 14 (E14), which is a critical day for palatal growth, B10.A embryos have 82% greater IGF-IIR mRNA than B10; 3) on E14, B10.A embryonic palates have a 57% greater level of active TGF-beta2 than B10, although the total TGF-beta2 is nearly identical; and 4) on E14, B10 embryonic palates have a 52% greater level of Cdk4 mRNA than B10.A palates, a measure of cell cycle progression. Because cellular activation of latent TGF-beta appears to require binding to the mannose-6-phosphate (M6P) binding site of the IGF-IIR and is plasmin and plasminogen activator dependent, the positive correlation of IGF-IIR levels and active TGF-beta2 levels seems to be key. Thus, the strain variation of TGF-beta2/IGF-IIR-mediated growth inhibition in late G1 phase would appear to account for the slower growth and development of B10.A palates relative to B10. Elevated corticosteroid (CORT) exposure in E14 B10.A embryos significantly increases TGF-beta levels, 87% of which is TGF-beta2, as well as the levels of active TGF-beta, 64% of which is TGF-beta2. Without exogenous CORT, B10.A embryos do not have clefts; hence, we present an outline of pathogenesis: slower growing B10.A embryos have an up-regulation of IGF-IIR, which serves to sequester IGF-II from the growth-promoting IGF-IR and to bind more CORT-up-regulated, latent TGF-beta2 for subsequent plasmin-dependent activation; higher levels of TGF-beta2 signaling down-regulate Cdk4 and result in greater palatal growth inhibition at a critical stage of palatogenesis and, thus, cleft palate. We present an epigenetic model of information processing related to cell proliferation. The model is a dynamical network that uses continuous logic to learn its rules from changing conditions.

Animals↗

Regulation of mannose 6-phosphate/insulin-like growth factor-II receptors and transforming growth factor beta during liver tumor promotion with phenobarbital.

Chronic exposure of rats to the liver tumor promoter phenobarbital (PB) significantly reduces the ability of normal hepatocytes, but not of initiated hepatocytes, to respond to mitogenic stimuli. This reduced proliferative ability of normal hepatocytes was correlated with a marked elevation in hepatic concentration of the potent mito-inhibitory factor, transforming growth factor-beta 1 (TGF-beta 1). PB also increased the mannose 6-phosphate/insulin-like growth factor-II (M6P/IGF-II) receptor concentration in hepatocytes, with a concomitant up-regulation in gene expression. Since the M6P/IGF-II receptor facilitates the proteolytic activation of TGF-beta 1, this suggests that PB increases the capacity of normal hepatocytes to activate TGF-beta 1. In contrast, a subset of preneoplastic lesions induced with N-nitrosodiethylamine did not demonstrate elevated levels of the M6P/IGF-II receptor or TGF-beta 1 in response to PB. These findings emphasize the potential importance of TGF-beta 1 during liver tumor promotion with PB and suggest that reduction of M6P/IGF-II receptor levels in liver tumors may provide the tumor cells with an important selective growth advantage.

Animals↗

Effects of insulin, insulin-like growth factor-II, and nerve growth factor on neurite formation and survival in cultured sympathetic and sensory neurons.

Insulin and the insulin-like growth factors (IGFs) may directly affect the development of the nervous system. NGF, IGF-II, and insulin's effects on neurite formation and neuronal survival were studied in peripheral ganglion cell cultures from chick embryos. Neurite outgrowth was enhanced in a dose-dependent manner by insulin and IGF-II in sympathetic cell cultures. The half-maximally effective concentration, ED50, was about 0.4-0.6 nM for both polypeptides, and concentrations as low as 10 pM were active. However, in sensory neurons the ED50 for neurite outgrowth was about 30 nM for insulin and 0.1 nM for IGF-II, suggesting that these factors may have selective effects in different neuronal tissues. Neither serum nor the presence of non-neuronal cells was required for the response in sympathetic neurons. The specific anti-NGF antiserum inhibited the neurite outgrowth response to NGF but not to insulin nor IGF-II. Insulin and IGF-II additionally supported survival of sensory and sympathetic neurons; however, insulin was not as efficacious as NGF. The combination of high concentrations of NGF and insulin was no better than NGF alone in supporting sympathetic cell survival, or neurite outgrowth. This indicates that insulin acts on the same, or a subpopulation, of NGF-responsive neurons. These results support the hypothesis that insulin and its homologs belong to a broad family of neuritogenic polypeptides.

Animals↗

Gene expression and secretion of insulin-like growth factor-II and insulin-like growth factor binding protein-2 from cultured sheep choroid plexus epithelial cells.

The gene expression of insulin-like growth factor II (IGF-II) and insulin-like growth factor binding protein-2 (IGFBP-2) has previously been demonstrated in rat and human choroid plexus by in situ hybridization analysis. In the present study we have characterized IGF-II and IGFBP-2 transcripts and proteins in primary cultures of epithelial cells from lateral choroid plexus of sheep brain. Northern blot analysis of total RNA showed one major IGF-II mRNA of 4.8 kb and four minor IGF-II transcripts of 1.5, 2.0, 3.0 and 6.0 kb as well as one IGFBP-2 transcript of 1.7 kb. Radioreceptor assay of conditioned medium from the cultured choroid plexus epithelial cells showed inhibition of [125I]IGF-I and [125I]IGF-II binding to mouse NIH 3T3 fibroblasts, the displacement curves being identical to that of unlabelled IGF-II. The conditioned medium was fractionated by gel filtration on a Bio-Gel P-60 column, and analysis by IGF-II radioreceptor assay showed two peaks of IGF-II-binding inhibitory activity of M(r) 7.5-10 and 25 kDa, suggesting the presence of both IGF-II, and an IGFBP. Western immunoblot analysis of conditioned medium with antibodies toward IGF-II and IGFBP-2 demonstrated proteins with M(r) 6 kDa and 32 kDa, respectively. Protein binding assays of the conditioned medium with [125I]IGF-I or [125]IGF-II demonstrated that the IGFBP present in the conditioned medium preferentially binds IGF-II. In conclusion, cultured sheep choroid plexus epithelial cells synthesize and secrete IGF-II and IGFBP-2, suggesting that the choroid plexus epithelium is the main source of these polypeptides in the cerebrospinal fluid.

3T3 Cells↗

Expression of insulin-like growth factor-II and insulin-like growth factor binding protein-1 in the placental basal plate from pre-eclamptic pregnancies.

OBJECTIVES: To determine whether expressions of insulin-like growth factor-II (IGF-II) and insulin-like growth factor binding protein-1 (IGFBP-1) are altered in pre-eclamptic placenta and to elucidate the possible relationship between their expressions and a mechanism for inadequate trophoblast invasion in pre-eclampsia. METHODS: Placental tissues were obtained at cesarean delivery from five normotensive, nine mild pre-eclamptic and five severe pre-eclamptic women at 33-39 completed weeks of gestation. After total ribonucleic acid was extracted, reverse transcriptase-polymerase chain reaction was performed to determine IGF-II and IGFBP-1 mRNA expression. Product bands were quantitated by scanning densitometry and results were expressed as ratio of cytokines/beta-actin. Western blot analysis was also done to determine IGF-II and IGFBP-1 protein expression. Statistical analysis was determined by Kruskal-Wallis analysis of variance with the Scheffe multiple post-hoc test. RESULTS: The IGF-II mRNA levels of mild and severe pre-eclamptic placenta were significantly lower than that of uncomplicated placenta (P<0.005, P<0.001, respectively), with the level of severe pre-eclamptic placenta being significantly lower than that of mild pre-eclamptic placenta (P<0.05). As for the IGF-II protein expression, a significant decrease was found among the three groups (P<0.001), correlating with the IGF-II mRNA results. However, the mean IGFBP-1 mRNA levels of mild and severe pre-eclamptic placenta were significantly higher than that of uncomplicated placenta (P<0.05, P<0.005, respectively), with the level of severe pre-eclamptic placenta being significantly raised compared with that of mild pre-eclamptic placenta (P<0.05). Finally, a significant increase of IGFBP-1 protein expression was noted among the three groups (P<0.001), correlating with the IGFBP-1 mRNA results. CONCLUSIONS: This study suggests that IGF-II and IGFBP-1 might be associated with the impaired trophoblastic invasion that may lead to pathogenesis of pre-eclampsia.

Actins↗

Effects of recombinant basic fibroblast growth factor, insulin-like growth factor-II and transforming growth factor-beta 1 on dog dental pulp cells in vivo.

The effects of recombinant basic fibroblast growth factor (bFGF), insulin-like growth factor (IGF)-II and transforming growth factor (TGF)-beta 1 on dental pulp cells were investigated by light and transmission electron microscopy after their implantation for 1 and 3 weeks at central sites of mechanically exposed pulps in dog molar and canine teeth. The implants were Millipore filters that have been soaked with solutions containing 100 or 500 ng/ml of bFGF or IGF-II or 100 ng/ml of TGF-beta 1. Control filters were soaked with dog albumin. No changes in cell organization or matrix synthesis were seen after implantation of control filters. Groups of columnar, polarized cells with numerous mitochondria and Golgi elements or elongated cells unassociated with any matrix deposition were demonstrated after 1 or 3 weeks, respectively, in close proximity to the filters that had been soaked with bFGF solution; at a distance from these implants enhanced formation of an osteotypic matrix was seen beneath the exposure site. No particular response was found in close proximity to the filters that had been soaked with IGF-II solution after 1 or 3 weeks implantation but thick zones of osteodentine were found beneath the exposure site and at adjacent circumferential dentine sites. Numerous elongated, polarized cells with long cytoplasmic extensions invading the filter pores were consistently seen after 1 week in close proximity to the filters that had been soaked with TGF-beta 1 solution. After 3 weeks implantation of these filters, deposition of a tubular matrix surrounding the implants was seen in association with the highly elongated odontoblast-like cells, while enhancement of circumferential dentine formation was also found at adjacent peripheral sites. These experiments demonstrate that TGF-beta 1 when implanted for short term periods at central pulp sites exerted dentine-specific effects, inducing differentiation of odontoblast-like cells and stimulating primary odontoblasts. Implantation of bFGF and IGF-II did not result in reparative dentine formation, but did stimulate osteotypical matrix deposition at a distance from the implants.

Animals↗

Synergistic effects of insulin-like growth factor II (IGF-II) with leukemia inhibiting factor (LIF) on establishment of rat pluripotential cell lines.

To examine effects of IGF-II on establishment of pluripotential diploid cells from rat embryos, we cultured blastocysts in medium containing mouse LIF with or without IGF-II. Combination of mouse LIF (5,000 units/ml) and rat IGF-II (100 ng/ml) promoted growth of inner cell mass (ICM) and was effective for establishment of pluripotential cell lines derived from the ICM. The cell lines indicated colony forms different from the rat ES cell lines. However, they showed morphological alteration to adult-like tissue cells, formed embryoid body in suspension culture, and thus, seemed to retain a pluripotent characteristics. The rat IGF-II is useful for establishing of pluripotential cells efficiently.

Animals↗