Novel Ghrelin Assays Provide Evidence for Independent Regulation of Ghrelin Acylation and Secretion in Healthy Young Men

Liu, Jianhua; Prudom, Catherine E.; Nass, Ralf; Pezzoli, Suzan S.; Oliveri, Mary C.; Johnson, Michael L.; Veldhuis, Paula P.; Gordon, David; Howard, Andrew D.; Witcher, Derrick R.; Geysen, H. Mario; Gaylinn, Bruce D.; Thorner, Michael O.

doi:10.1210/jc.2007-2235

Cited by 224 publications

(232 citation statements)

References 41 publications

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“…Each 50-l reaction mixture contained 50 M palmitoyl CoA, 1 M [ 3 H]octanoyl CoA (11 dpm/fmol), and (where indicated) 50 g membrane protein, 500 M of the indicated peptide, or 8 M proghrelin-His8. After incubation at 37°C for 10 min, each reaction mixture was subjected to either TLC analysis (tubes [1][2][3][4] or nickel chromatography assay (tubes 5 and 6) as described in SI Experimental Procedures. The complete TLC profile for Exp.…”

Section: Discussionmentioning

confidence: 99%

“…After secretion into plasma, octanoylated ghrelin travels to the pituitary where it binds to a G protein-coupled receptor that triggers the release of growth hormone (3). The plasma concentration of ghrelin rises immediately before meals (4), and the octanoylated peptide enhances food intake when administered to rats (5) and humans (6)(7)(8)(9). Inactivation of the gene encoding ghrelin or its receptor produces a modest resistance to obesity in mice that are presented with a high-fat diet (10,11).…”

Section: G Hrelin O-acyltransferase (Goat) Is the Membrane-boundmentioning

confidence: 99%

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Inhibition of ghrelin O -acyltransferase (GOAT) by octanoylated pentapeptides

Yang

Zhao

Goldstein

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

179

234

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The discovery of ghrelin O-acyltransferase (GOAT) opens the way to the design of drugs that block the attachment of an octanoyl group to the appetite-stimulating peptide hormone ghrelin, potentially preventing obesity. Here, we develop a biochemical assay that uses membranes from insect cells infected with baculovirus encoding mouse GOAT. The GOAT-containing membranes transferred the [ 3 H]octanoyl group from [ 3 H]octanoyl CoA to recombinant proghrelin in vitro. Transfer depended on the serine at residue 3 of proghrelin, which is the known site of acylation. GOAT also transferred [ 3 H]octanoyl to a pentapeptide containing only the N-terminal five amino acids of proghrelin. GOAT activity could be inhibited by an octanoylated ghrelin pentapeptide, and its potency was enhanced 45-fold when the octanoylated serine-3 was replaced by octanoylated diaminopropionic acid. The data suggest that GOAT is subjected to end-product inhibition and this inhibition is better achieved with substrates having the octanoyl group attached through an amide linkage rather than the corresponding ester. These insights may facilitate the future design of useful inhibitors of GOAT.appetite control ͉ in vitro ͉ inhibitors ͉ obesity ͉ octanoylation of proghrelin

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Section: Discussionmentioning

confidence: 99%

Section: G Hrelin O-acyltransferase (Goat) Is the Membrane-boundmentioning

confidence: 99%

Inhibition of ghrelin O -acyltransferase (GOAT) by octanoylated pentapeptides

Yang

Zhao

Goldstein

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

179

234

View full text Add to dashboard Cite

show abstract

“…These findings and the observations that circulating ghrelin levels are increased prior to a meal and during food deprivation and caloric restriction, as well as in disease states such as anorexia and cachexia, but reduced after a meal and in obesity (Ikezaki et al 2002;Liu et al 2008;Shiiya et al 2002;Tschop et al 2001aTschop et al , 2001bVan der Lely et al 2004;Yang et al 2007), strongly implicate ghrelin being involved in the regulatory processes controlling meal initiation, priming metabolic pathways and leading to more efficient calorie storage.…”

Section: Page 5 Of 37mentioning

confidence: 93%

Ghrelin neutralization during fasting-refeeding cycle impairs the recuperation of body weight and alters hepatic energy metabolism

Sangiao‐Alvarellos

Helmling

Vázquez

et al. 2011

Molecular and Cellular Endocrinology

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Ghrelin neutralization during fasting-refeeding cycle impairs the recuperation of body weight and alters hepatic energy metabolism.. Molecular and Cellular Endocrinology, Elsevier, 2011, 335 (2) This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.Page 1 of 37A c c e p t e d M a n u s c r i p t A c c e p t e d M a n u s c r i p t 2 ABSTRACT Ghrelin, a hormone whose levels increase during food deprivation, plays a pivotal role in the regulation of food intake, energy metabolism and storage, as well as in insulin sensitivity. Here, we investigated the effects of acyl-ghrelin neutralization with the acyl-ghrelin-binding compound NOX-B11(2) during the fasting-refeeding cycle. Our data demonstrate that ghrelin neutralization with NOX-B11(2) impairs recuperation of lost body weight after food deprivation. Analysis of enzymes involved in glucose and lipid metabolism in liver of fed, fasted and refed rats revealed that neutralization of acyl-ghrelin resulted in minor decreases in the enzymes of glycolytic and lipogenic pathways during fasting. However, during refeeding these enzymes as well as glycogen levels recovered more slowly when acyl-ghrelin was blocked. The high levels of ghrelin in response to food deprivation may contribute to an adequate decrease in hepatic glycolytic and lipogenic enzymes and aid in the recovery of body weight and energetic reserves once food becomes available after the fasting period.

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“…1999; Liu et al. 2008). Ghrelin can be posttranslationally acylated by ghrelin‐ O ‐acyl‐transferase (GOAT) and unacylated by serum esterases (Gutierrez et al.…”

Section: Introductionmentioning

confidence: 99%

“…2005; Liu et al. 2008). Acylated ghrelin (AG) acts through GHS‐R1a in nonmuscle peripheral tissues, and potentially the corticotropin‐releasing factor (CRF‐2) receptor in muscle (Filigheddu et al.…”

Section: Introductionmentioning

confidence: 99%

Acylated and unacylated ghrelin do not directly stimulate glucose transport in isolated rodent skeletal muscle

Cervone

Dyck

2017

Physiol Rep

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Emerging evidence implicates ghrelin, a gut‐derived, orexigenic hormone, as a potential mediator of insulin‐responsive peripheral tissue metabolism. However, in vitro and in vivo studies assessing ghrelin's direct influence on metabolism have been controversial, particularly due to confounding factors such as the secondary rise in growth hormone (GH) after ghrelin injection. Skeletal muscle is important in the insulin‐stimulated clearance of glucose, and ghrelin's exponential rise prior to a meal could potentially facilitate this. This study was aimed at elucidating any direct stimulatory action that ghrelin may have on glucose transport and insulin signaling in isolated rat skeletal muscle, in the absence of confounding secondary factors. Oxidative soleus and glycolytic extensor digitorum longus skeletal muscles were isolated from male Sprague Dawley rats in the fed state and incubated with various concentrations of acylated and unacylated ghrelin in the presence or absence of insulin. Ghrelin did not stimulate glucose transport in either muscle type, with or without insulin. Moreover, GH had no acute, direct stimulatory effect on either basal or insulin‐stimulated muscle glucose transport. In agreement with the lack of observed effect on glucose transport, ghrelin and GH also had no stimulatory effect on Ser473 AKT or Thr172 AMPK phosphorylation, two key signaling proteins involved in glucose transport. Furthermore, to our knowledge, we are among the first to show that ghrelin can act independent of its receptor and cause an increase in calmodulin‐dependent protein kinase 2 (CaMKII) phosphorylation in glycolytic muscle, although this was not associated with an increase in glucose transport. We conclude that both acylated and unacylated ghrelin have no direct, acute influence on skeletal muscle glucose transport. Furthermore, the immediate rise in GH in response to ghrelin also does not appear to directly stimulate glucose transport in muscle.

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Novel Ghrelin Assays Provide Evidence for Independent Regulation of Ghrelin Acylation and Secretion in Healthy Young Men

Cited by 224 publications

References 41 publications

Inhibition of ghrelin O -acyltransferase (GOAT) by octanoylated pentapeptides

Inhibition of ghrelin O -acyltransferase (GOAT) by octanoylated pentapeptides

Ghrelin neutralization during fasting-refeeding cycle impairs the recuperation of body weight and alters hepatic energy metabolism

Acylated and unacylated ghrelin do not directly stimulate glucose transport in isolated rodent skeletal muscle

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