scholarly journals Hyperphosphorylation of fetal liver IGFBP-1 precedes slowing of fetal growth in nutrient-restricted baboons and may be a mechanism underlying IUGR

2020 ◽  
Vol 319 (3) ◽  
pp. E614-E628
Author(s):  
Jenica H. Kakadia ◽  
Bhawani B. Jain ◽  
Kyle Biggar ◽  
Austen Sutherland ◽  
Karen Nygard ◽  
...  
Keyword(s):  
Amino Acid ◽  
Fetal Liver ◽  
Control Diet ◽  
Nutrient Restriction ◽  
Mtor Inhibition ◽  
Group 13 ◽  
Umbilical Blood ◽  
Parallel Reaction Monitoring ◽  
Igf Binding ◽  
Igf Binding Protein

In cultured fetal liver cells, insulin-like growth factor (IGF) binding protein (IGFBP)-1 hyperphosphorylation in response to hypoxia and amino acid deprivation is mediated by inhibition of mechanistic target of rapamycin (mTOR) and activation of amino acid response (AAR) signaling and casein kinase (CK)2. We hypothesized that fetal liver mTOR inhibition, activation of AAR and CK2, and IGFBP-1 hyperphosphorylation occur before development of intrauterine growth restriction (IUGR). Pregnant baboons were fed a control (C) or a maternal nutrient restriction (MNR; 70% calories of control) diet starting at gestational day (GD) 30 (term GD 185). Umbilical blood and fetal liver tissue were obtained at GD 120 (C, n = 7; MNR, n = 10) and 165 (C, n = 7; MNR, n = 8). Fetal weights were unchanged at GD 120 but decreased at GD 165 in the MNR group (−13%, P = 0.03). IGFBP-1 phosphorylation, as determined by parallel reaction monitoring mass spectrometry (PRM-MS), immunohistochemistry, and/or Western blot, was enhanced in MNR fetal liver and umbilical plasma at GD 120 and 165. IGF-I receptor autophosphorylationTyr1135 (−64%, P = 0.05) was reduced in MNR fetal liver at GD 120. Furthermore, fetal liver CK2 (α/α′/β) expression, CK2β colocalization, proximity with IGFBP-1, and CK2 autophosphorylationTyr182 were greater at GD 120 and 165 in MNR vs. C. Additionally, mTOR complex (mTORC)1 (p-P70S6KThr389, −52%, P = 0.05) and mTORC2 (p-AktSer473, −56%, P < 0.001) activity were decreased and AAR was activated (p-GCN2Thr898, +117%, P = 0.02; p-eIF2αSer51, +294%, P = 0.002; p-ERKThr202, +111%, P = 0.03) in MNR liver at GD 120. Our data suggest that fetal liver IGFBP-1 hyperphosphorylation, mediated by mTOR inhibition and both AAR and CK2 activation, is a key link between restricted nutrient and oxygen availability and the development of IUGR.

scholarly journals Hypoxia Increases IGFBP-1 Phosphorylation Mediated by mTOR Inhibition

2016 ◽  
Vol 30 (2) ◽  
pp. 201-216 ◽  
Author(s):  
Ian Damerill ◽  
Kyle K. Biggar ◽  
Majida Abu Shehab ◽  
Shawn Shun-Cheng Li ◽  
Thomas Jansson ◽  
...  
Keyword(s):  
Fetal Growth ◽  
Fetal Liver ◽  
Multiple Reaction Monitoring ◽  
Mtor Inhibitors ◽  
Immunoblot Analysis ◽  
Primate Model ◽  
Mtor Inhibition ◽  
Interacting Protein ◽  
Igf I ◽  
Igf Binding

Abstract In fetal growth restriction (FGR), fetal growth is limited by reduced nutrient and oxygen supply. Insulin-like growth factor I (IGF-I) is a key regulator of fetal growth and IGF binding protein -1(IGFBP-1) is the principal regulator of fetal IGF-I bioavailability. Phosphorylation enhances IGFBP-1's affinity for IGF-I. Hypoxia induces IGFBP-1 hyperphosphorylation, markedly decreasing IGF-I bioavailability. We recently reported that fetal liver IGFBP-1 hyperphosphorylation is associated with inhibition of the mechanistic target of rapamycin (mTOR) in a nonhuman primate model of FGR. Here, we test the hypothesis that IGFBP-1 hyperphosphorylation in response to hypoxia is mediated by mTOR inhibition. We inhibited mTOR either by rapamycin or small interfering RNA (siRNA) targeting raptor (mTOR complex [mTORC]1) and/or rictor (mTORC2) in HepG2 cells cultured under hypoxia (1% O2) or basal (20% O2) conditions. Conversely, we activated mTORC1 or mTORC1+mTORC2 by silencing endogenous mTOR inhibitors (tuberous sclerosis complex 2/DEP-domain-containing and mTOR-interacting protein). Immunoblot analysis demonstrated that both hypoxia and inhibition of mTORC1 and/or mTORC2 induced similar degrees of IGFBP-1 phosphorylation at Ser101/119/169 and reduced IGF-I receptor autophosphorylation. Activation of mTORC1+mTORC2 or mTORC1 alone prevented IGFBP-1 hyperphosphorylation in response to hypoxia. Multiple reaction monitoring-mass spectrometry showed that rapamycin and/or hypoxia increased phosphorylation also at Ser98 and at a novel site Ser174. In silico structural analysis indicated that Ser174 was in close proximity to the IGF-binding site. Together, we demonstrate that signaling through the mTORC1 or mTORC2 pathway is sufficient to induce IGFBP-1 hyperphosphorylation in response to hypoxia. This study provides novel understanding of the cellular mechanism that controls fetal IGFBP-1 phosphorylation in hypoxia, and we propose that mTOR inhibition constitutes a mechanistic link between hypoxia, reduced IGF-I bioavailability and FGR.

scholarly journals Reduced placental amino acid transport in response to maternal nutrient restriction in the baboon

2015 ◽  
Vol 309 (7) ◽  
pp. R740-R746 ◽  
Author(s):  
Priyadarshini Pantham ◽  
Fredrick J. Rosario ◽  
Mark Nijland ◽  
Alex Cheung ◽  
Peter W. Nathanielsz ◽  
...  
Keyword(s):  
Amino Acid ◽  
Fetal Growth ◽  
Control Diet ◽  
Later Life ◽  
Nutrient Restriction ◽  
Mole Percent ◽  
Maternal Undernutrition ◽  
System A ◽  
System L

Intrauterine growth restriction increases the risk of perinatal complications and predisposes the infant to diabetes and cardiovascular disease in later life. Mechanisms by which maternal nutrient restriction (MNR) reduces fetal growth are poorly understood. We hypothesized that MNR decreases placental amino acid (AA) transporter activity, leading to reduced transplacental transfer of AAs. Pregnant baboons were fed either a control (ad libitum, n = 7), or MNR diet (70% of control diet, n = 7) from gestational day (GD) 30. At GD 165 (0.9 gestation), placentas ( n = 7 in each group) were collected, and microvillous plasma membrane vesicles (MVM) isolated. MVM system A and system L AA transport was determined in vitro using radiolabeled substrates and rapid filtration techniques. In vivo transplacental AA transport was assessed by infusing nine 13C- or 2H-labeled essential AA as a bolus into the maternal circulation ( n = 5 control, n = 4 MNR) at cesarean section. A fetal vein-to-maternal artery mole percent excess ratio for each essential AA was calculated. Fetal and placental weights were significantly reduced in the MNR group compared with controls ( P < 0.01). The activity of system A and system L was markedly reduced by 73 and 84%, respectively, in MVM isolated from baboon placentas at GD 165 following MNR ( P < 0.01). In vivo, the fetal vein-to-maternal artery mole percent excess ratio was significantly reduced for leucine, isoleucine, methionine, phenylalanine, threonine, and tryptophan in MNR baboons ( P < 0.05). This is the first study to investigate placental AA transport in a nonhuman primate model of MNR. We demonstrate that the downregulation of system A and system L activity in syncytiotrophoblast MVM in MNR leads to decreased transplacental AA transport and, consequently, reduced circulating fetal AA concentrations, a potential mechanism linking maternal undernutrition to reduced fetal growth.

scholarly journals Chorionic somatomammotropin RNA interference alters fetal liver glucose utilization

2020 ◽  
Vol 247 (3) ◽  
pp. 251-262
Author(s):  
Asghar Ali ◽  
Callie M Swanepoel ◽  
Quinton A Winger ◽  
Paul J Rozance ◽  
Russell V Anthony
Keyword(s):  
Glucose Utilization ◽  
Glycogen Synthase ◽  
Fetal Liver ◽  
Liver Glycogen ◽  
Control Shrna ◽  
Maternal Metabolism ◽  
Igf Binding ◽  
Chorionic Somatomammotropin ◽  
Igf Binding Protein ◽  
Receptor Beta

Chorionic somatomammotropin (CSH) is a placenta-specific hormone associated with fetal growth, and fetal and maternal metabolism in both humans and sheep. We hypothesized that CSH deficiency could impact sheep fetal liver glucose utilization. To generate CSH-deficient pregnancies, day 9 hatched blastocysts were infected with lentiviral particles expressing CSH-specific shRNA (RNAi) or scramble control shRNA (SC) and transferred to synchronized recipients. CSH RNAi generated two distinct phenotypes at 135 days of gestational age (dGA); pregnancies with IUGR (RNAi-IUGR) or with normal fetal weight (RNAi-NW). Fetal body, fetal liver and placental weights were reduced (P < 0.05) only in RNAi-IUGR pregnancies compared to SC. Umbilical artery plasma insulin and insulin-like growth factor 1 (IGF1) concentrations were decreased, whereas insulin receptor beta (INSR) concentration in fetal liver was increased (P < 0.05) in both RNAi phenotypes. The mRNA concentrations of IGF1, IGF2, IGF binding protein 2 (IGFBP2) and IGFBP3 were decreased (P < 0.05) in fetal livers from both RNAi phenotypes. Fetal liver glycogen concentration and glycogen synthase 1 (GYS1) concentration were increased (P < 0.05), whereas fetal liver phosphorylated-GYS (inactive GYS) concentration was reduced (P < 0.05) in both RNAi phenotypes. Lactate dehydrogenase B (LDHB) concentration was increased (P < 0.05) and IGF2 concentration was decreased (P < 0.05) in RNAi-IUGR fetal livers only. Our findings suggest that fetal liver glucose utilization is impacted by CSH RNAi, independent of IUGR, and is likely tied to enhanced fetal liver insulin sensitivity in both RNAi phenotypes. Determining the physiological ramifications of both phenotypes, may help to differentiate direct effect of CSH deficiency or its indirect effect through IUGR.

PSV-2 Maternal nutrient restriction and re-alimentation influences liver and muscle tissue development and gene expression

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 307-307
Author(s):  
Brandon I Smith ◽  
Manuel A Vasquez-Hidalgo ◽  
Kimberly A Vonnahme ◽  
Anna T Grazul-Bilska ◽  
Kendall C Swanson ◽  
...  
Keyword(s):  
Gene Expression ◽  
Lipid Content ◽  
Muscle Development ◽  
Glycogen Synthase ◽  
Fetal Liver ◽  
Control Diet ◽  
National Research Council ◽  
Pyruvate Dehydrogenase Kinase ◽  
Nutrient Restriction ◽  
Metabolic Factors

Abstract To determine the effects of maternal nutrient restriction and re-alimentation on fetal liver and muscle development, 48 pregnant ewes with singletons, were fed a control diet [100% National Research Council (NRC) requirements (CON)] starting at the beginning of gestation. On day 50 of gestation, ewes (n = 7) were euthanized and fetal liver and skeletal muscle samples were collected. The remaining animals were fed either CON or 60% NRC requirements (RES), a subset were euthanized at day 90 of gestation (n = 7/treatment), and fetal samples obtained. Remaining ewes were maintained on the current diet (CON-CON, n = 6; RES-RES, n = 7) or switched to alternative diet (CON-RES, RES-CON; n = 7/treatment). On day 130 of gestation, remaining ewes were euthanized, and fetal samples collected. Fetal liver was analyzed for general tissue morphology, and fetal skeletal muscles were analyzed for lipid accumulation. mRNA expression of growth and metabolic factors were quantified in liver and muscle tissues. Hepatocellular vacuolation was increased in RES-CON and RES-RES compared with CON-CON and CON-RES (P &lt; 0.01). In semitendinosus and triceps brachii, intramyocellular lipid content increased 19% and 15%, respectively, in RES-CON and RES-RES compared with CON-CON and CON-RES (P£0.02) and in longissimus dorsi, lipid content was decreased 7% in CON-RES and RES-RES compared with CON-CON and RES-CON (P=0.01). In liver, insulin-like growth factor binding protein-1, glycogen synthase 2, and pyruvate dehydrogenase kinase 1 expression increased 1.92-fold, 1.45-fold, and 1.47-fold, respectively (P£0.03) in CON-RES and RES-RES compared with RES-CON and CON-CON. In LD, IGF1-R expression increased 3.19-fold in CON-RES and RES-RES compared with RES-CON and CON-CON (P = 0.05). These results demonstrate that maternal nutrient restriction followed by re-alimentation restores liver and muscle gene expression of growth and metabolic factors while negatively impacting liver composition and muscle lipid content potentially leading to altered tissue function and metabolism later in life. Supported by USDA-AFRI grants 2016-67016-24884 and 2017-67016-26568.

scholarly journals 345 The effects of maternal nutrient restriction followed by re-alimentation on offspring growth and metabolism in sheep

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 98-98
Author(s):  
Brandon I Smith ◽  
Manuel A Vásquez-Hidalgo ◽  
Kimberly A Vonnahme ◽  
Kendall C Swanson ◽  
Anna T Grazul-Bilska ◽  
...  
Keyword(s):  
Maternal Nutrition ◽  
Management Practice ◽  
Fetal Liver ◽  
Control Diet ◽  
Liver Lipid ◽  
Nutrient Restriction ◽  
Triceps Brachii ◽  
Liver Growth ◽  
Offspring Growth ◽  
Negative Impacts

Abstract The duration and timing of inadequate maternal nutrition can have detrimental effects on metabolism and organogenesis in the offspring. Re-alimentation, a common management practice that involves feeding full nutrient requirements following a period of nutrient restriction, may reduce the negative impacts of maternal nutrient restriction. To determine the effects of maternal nutrient restriction and re-alimentation on offspring growth,48 primiparous ewes, confirmed pregnant with singletons, were fed a control diet consisting of100% NRC requirements (CON) starting on day25 of gestation. On day50 of gestation, ewes (n = 7) were euthanized and fetal liver, muscle, and blood samples were collected. The remaining animals were fed either CON or60% NRC requirements (RES). On day90 of gestation, a portion of ewes were euthanized (n = 7 per treatment) and fetal samples and weights were collected. Remaining ewes were maintained on the current diet (CON-CON, n = 6; RES-RES, n = 7) or switched to the alternative diet (CON-RES, RES-CON; n = 7/treatment). On day130 of gestation, all remaining ewes were euthanized. All fetal BW, liver, longissimus muscle, semitendinosus, and triceps brachii weights were determined for each day of gestation. Fetal BW’s were not different between treatment groups (P = 0.29; P = 0.83). Fetal liver weights decreased12.89% in RES-RES compared with CON-CON at day130 (P = 0.049), but were not different at day90 (P = 0.69). There was a tendency for decreased semitendinosus weight in RES group compared with CON at day90 (P = 0.055). Liver lipid droplet accumulation was analyzed for day90 and130 using histochemistry and an effect of maternal nutrition was not observed (P = 0.562). In summary, maternal nutrient restriction reduces offspring muscle and liver growth. To gain insight into the effects of maternal nutrient restriction and re-alimentation on liver development and metabolism, analysis of liver morphology, gene expression, and global metabolomics are needed. Supported by USDA-AFRI grant2016-67016-24884

Cloning and characterization of a chick embryo cDNA and gene for IGF-binding protein-2

1995 ◽  
Vol 15 (1) ◽  
pp. 49-59 ◽  
Author(s):  
T J Schoen ◽  
K Mazuruk ◽  
R J Waldbillig ◽  
J Potts ◽  
D C Beebe ◽  
...  
Keyword(s):  
Amino Acid ◽  
Chick Embryo ◽  
Binding Protein ◽  
Single Gene ◽  
Binding Motif ◽  
Sequence Information ◽  
Reading Frame ◽  
Chick Retina ◽  
Igf Binding ◽  
Igf Binding Protein

ABSTRACT We have isolated and characterized a cDNA for IGF-binding protein-2 (IGFBP-2) and its gene from the chick embryo. Using primers from a conserved region of the mammalian IGFBP-2 sequence, a cDNA clone (1·6 kb) was isolated from an embryonic day-18 chick retina cDNA library. Although the clone was truncated at the 5′ end, the complete coding sequence was obtained from 5′ rapid amplification of cDNA ends and genomic sequencing. The open reading frame encoded a 311 amino acid precursor protein which contains a putative 36 residue signal peptide. The mature 275 amino acid protein had a predicted Mr of 33 500 and exhibited 71, 68, 68 and 66% identity to rat, bovine, ovine and human IGFBP-2 cDNA respectively, with conservation of all 18 cysteines. The cDNA contained an RGD peptide but lacked a putative ATP-binding motif. A single transcript of approximately 2·3 kb was present in embryonic day-15 eye, brain, skeletal muscle, heart and intestine, but was virtually absent from embryonic day-15 liver. The chicken IGFBP-2 gene spanned approximately 38 kb, consisted of four exons, and was similarly organized to that of the rat and human. Southern blot analysis of chicken genomic DNA suggested that it is encoded by a single gene. The sequence information from the avian IGFBP-2 should be of value in examining the role of IGFBP-2 in vertebrate development.

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