Synthesis and Characterization of IGF-II Analogs: Applications in the Evaluation of IGF Receptor Function and IGF-Independent Actions of IGFBPS

Oh, Youngman; Müller, Hermann L.; Zhang, Heping; Ling, Nicholas; Rosenfeld, Ron G.

doi:10.1007/978-1-4615-2988-0_5

Cited by 14 publications

(4 citation statements)

References 33 publications

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“…Our studies on IGF-I R -Z give a stoichiometry of 1:1 (IGF-I:(␣-␤Ј-Z) 2 ) with high affinity, which could include two separate binding sites. The relative potency of binding to the produced IGF-I receptor for the different ligands is in accordance with previous investigations performed using competitive ligand methods (43). The des(1-3)-IGF-I exhibits a faster association rate than native IGF-I and thus a higher affinity.…”

Section: Discussionsupporting

confidence: 89%

Characterization of Ligand Binding of a Soluble Human Insulin-like Growth Factor I Receptor Variant Suggests a Ligand-induced Conformational Change

Jansson

Hallén²,

Koho³

et al. 1997

Journal of Biological Chemistry

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Section: Discussionsupporting

confidence: 89%

Characterization of Ligand Binding of a Soluble Human Insulin-like Growth Factor I Receptor Variant Suggests a Ligand-induced Conformational Change

Jansson

Hallén²,

Koho³

et al. 1997

Journal of Biological Chemistry

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“…The development of IGF analogs has aided immensely in the characterization of IGF receptor functions (41). Two IGF-II analogs, both of which were capable of binding to IGFR-II, but not IGFR-I, and one of which was unable to bind IGFBPs, were used in the present study.…”

Section: Discussionmentioning

confidence: 99%

Stimulation of Human Extravillous Trophoblast Migration by IGF-II Is Mediated by IGF Type 2 Receptor Involving Inhibitory G Protein(s) and Phosphorylation of MAPK

McKinnon¹,

Chakraborty²,

Gleeson³

et al. 2001

The Journal of Clinical Endocrinology & Metabolism

165

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We have earlier shown that migration and invasiveness of first trimester human extravillous trophoblast cells are stimulated by IGF-II, independently of IGF type 1 receptor and that migration stimulation is the primary reason for increased extravillous trophoblast cell invasiveness induced by IGF-II. In the present study we examined the functional role of IGF type II receptor in IGF-II stimulation of extravillous trophoblast cell migration and the underlying signal transduction pathways including the participation of inhibitory G protein(s) and MAPK. The migratory ability of a well characterized in vitro propagated human first trimester extravillous trophoblast cell line expressing the phenotype of extravillous trophoblast cells in situ was quantitated with a Transwell migration assay under different experimental conditions. We found that the extravillous trophoblast cells expressed an abundance of IGF type 2 receptor as detected by immunostaining and Western blots, and recombinant human IGF-II promoted their migration in a dose- and time-dependent manner. Both polyclonal and monoclonal IGF type 2 receptor-blocking antibodies blocked migration-stimulating effects of IGF-II. Two synthetic IGF-II analogs ([Leu27]IGF-II, which can bind to IGF type 2 receptor and IGF-binding proteins, but not IGF type 1 receptor, and [QAYL-Leu27]IGF-II, which can bind to IGFR-II, but neither IGFR-I nor IGF-binding proteins) both stimulated extravillous trophoblast cell migration to levels higher than those induced by wild-type IGF-II. These results reveal that IGF-II action was mediated by IGF type 2 receptor, independently of IGF type 1 receptor and IGF-binding proteins. Treatment of extravillous trophoblast cell membrane preparations with IGF-II decreased adenylyl cyclase activity in a concentration-dependant manner, indicating the participation of inhibitory G proteins in IGF-II action. This was substantiated further with the findings that increasing intracellular cAMP using forskolin or (Bu)2cAMP inhibited basal extravillous trophoblast cell migration and blocked IGF-II stimulation of migration. IGF-II treatment rapidly stimulated phosphorylation of MAPK (ERK-1 and -2), which was blocked by pretreatment of extravillous trophoblast cells with the MAPK kinase (MEK) inhibitor PD98059. Treatment with this inhibitor also blocked extravillous trophoblast cell migration in the presence or absence of IGF-II. These results, taken together, reveal that IGF-II stimulates extravillous trophoblast cell migration by signaling through IGF type 2 receptor, involving inhibitory G proteins and activating the MAPK pathway.

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“…After 3 days recovery from surgery, fetuses were randomly assigned to different treatment groups: vehicle (100 m m of acetic acid (Sigma‐Aldrich, Australia; n = 4) or Leu 27 IGF‐2 (an analogue of IGF‐2 that binds to the IGF‐2R but not to the IGF‐1R (Sakano et al 1991; Oh et al 1993); Novozymes GroPep, Adelaide, SA, Australia; 0.4 μg h −1 , n = 8; 0.8 μg h −1 , n = 2) and infused via the left circumflex coronary artery for 4 days. This effect was expected to be specific to the left ventricle because the left circumflex coronary artery directly perfuses the left ventricle and a posterior portion of the interventricular septum, but not the right ventricle (Rudolph et al 1999).…”

Section: Methodsmentioning

confidence: 99%

“…Serum‐free medium was replaced with either 2 ml of fresh serum‐free medium, or 2 ml of medium with serum (to increase cardiomyocyte size), or 2 ml of serum‐free medium containing an analogue of IGF‐2 which binds to the IGF‐2R but not IGF‐1R (1 n m Leu 27 IGF‐2; Novozymes, GroPep) (Sakano et al 1991; Oh et al 1993) and/or a PKA inhibitor (2.5 μ m H‐89; Cell Signaling Technology) (Chijiwa et al 1990; Zou et al 1999). For cardiomyocytes that were exposed to both inhibitor and agonist, the inhibitor was added 30 min prior to the addition of the agonist.…”

Section: Methodsmentioning

confidence: 99%

Activation of IGF‐2R stimulates cardiomyocyte hypertrophy in the late gestation sheep fetus

Wang¹,

Brooks²,

Thornburg³

et al. 2012

The Journal of Physiology

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Key points• This study investigates the impact that insulin-like growth factor 2 receptor (IGF-2R) activation has on the fetal heart, by infusing Leu 27 IGF-2 into the left circumflex coronary artery of the sheep fetus, to specifically activate IGF-2R and it's downstream signalling pathway.• Activation of cardiac IGF-2R resulted in cardiomyocyte hypertrophy, but with no changes in heart weight, cardiomyocyte proliferation, binucleation or apoptosis. This hypertrophy was mediated via protein kinase A activation.• Infusion of Leu 27 IGF-2 increases atrial natriuretic peptide abundance, a marker of cardiac pathological hypertrophy.• Cardiac IGF-2R activation may alter important regulators of cardiac contractility and relaxation by decreasing sarcoplasmic reticulum Ca 2+ -ATPase and phospho-troponin I abundance.• This study places the interaction between the IGF-2R and Gαs signalling pathway as a potential mechanism that can contribute to cardiomyocyte growth in fetal life, but which may result in pathological cardiac hypertrophy in postnatal life.Abstract In vitro studies using rat and fetal sheep cardiomyocytes indicate that, in addition to its role as a clearance receptor, the insulin-like growth factor 2 receptor (IGF-2R) can induce cardiomyocyte hypertrophy. In the present study, we have determined the effect of specific activation of the IGF-2R in the heart of the late gestation fetus on cardiomyocyte development. Leu 27 IGF-2, an IGF-2R agonist, was infused into the fetal left circumflex coronary artery for 4 days beginning at 128.1 ± 0.4 days gestation. Ewes were humanely killed at 132.2 ± 1.2 days gestation (term, 150 days). Fetuses were delivered and hearts dissected to isolate the cardiomyocytes and to collect and snap-freeze tissue. Leu 27 IGF-2 infusion into the left circumflex coronary artery of fetal sheep increased the area of binucleated cardiomyocytes in the left, but not the right, ventricle. However, this infusion of Leu 27 IGF-2 did not change fetal weight, heart weight, blood pressure, blood gases or cardiomyocyte proliferation/binucleation. The increase in cardiomyocyte size in the Leu 27 IGF-2-infused group was associated with increased expression of proteins in the Gαs, but not the Gαq, signalling pathway. We concluded that infusion of Leu 27 IGF-2 into the left circumflex coronary artery causes cardiac IGF-2R activation in the left ventricle of the heart, and this stimulates cardiomyocyte hypertrophy in a Gαs-dependent manner.

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Synthesis and Characterization of IGF-II Analogs: Applications in the Evaluation of IGF Receptor Function and IGF-Independent Actions of IGFBPS

Cited by 14 publications

References 33 publications

Characterization of Ligand Binding of a Soluble Human Insulin-like Growth Factor I Receptor Variant Suggests a Ligand-induced Conformational Change

Characterization of Ligand Binding of a Soluble Human Insulin-like Growth Factor I Receptor Variant Suggests a Ligand-induced Conformational Change

Stimulation of Human Extravillous Trophoblast Migration by IGF-II Is Mediated by IGF Type 2 Receptor Involving Inhibitory G Protein(s) and Phosphorylation of MAPK

Activation of IGF‐2R stimulates cardiomyocyte hypertrophy in the late gestation sheep fetus

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