Mechanism of glucagon stimulation of fructose‐1,6‐bisphosphatase in rat hepatocytes

Casteleijn, Eric; Rooij, H. C. J. Van; Berkel, Theo J.C. Van; Koster, J.F.

doi:10.1016/0014-5793(86)80607-x

Cited by 32 publications

(21 citation statements)

References 29 publications

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“…While the exact regulatory sites causing altered flux through gluconeogenesis still await identification, the above distinction has been challenged by the recent description for hepatocytes of two-signal transduction systems for glucagon (adenylate cyclase and phosphodiesterase, [23,241). Also, a cAMP-independent activation of fructose-l,6-bisphosphatase has been noticed [25], possibly involving two membrane receptor populations. Our report on the potent physiological action of GLPs in conjunction with the alleged lack of GLP membrane receptors will make the sorting out of the control of gluconeogenesis and the interaction of hormones, receptors and their intracellular messengers an even more challenging task.…”

Section: Discussionmentioning

confidence: 99%

Glucagon‐like peptides activate hepatic gluconeogenesis

1987

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Piscine (anglerfish, catfish, coho salmon) glucagon-like peptides (GLPs), applied at 3.5 nM, stimulate (1.1-1.9-fold) flux through gluconeogenesis above control levels in isolated trout and salmon hepatocytes. Human GLP-1 and GLP-2 also activate gluconeogenesis, but to a lesser degree than their piscine counterparts. Minor increases of substrate oxidation are noticed at times of peak gluconeogenic activation through GLPs. These hormones, which are derived from the same precursor peptide as glucagon are more potent activators of gluconeogenesis than glucagon when applied at equimolar concentrations, and do not appear to employ cAMP or cGMP as the intraceilular messenger in hepatic tissue.

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Section: Discussionmentioning

confidence: 99%

Glucagon‐like peptides activate hepatic gluconeogenesis

1987

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“…Liver parenchymal cells were isolated by perfusion of the liver with 0.05% collagenase by the method of Seglen (1976) modified as previously described (Casteleijn et al, 1986). The parenchymal cells obtained were resuspended in Dulbecco's modified Eagle's medium containing 2% BSA, pH 7.4.…”

Section: Chemicalsmentioning

confidence: 99%

Blockade of the α₂‐Macroglobulin Receptor/Low‐Density‐Lipoprotein‐Receptor‐Related Protein on Rat Liver Parenchymal Cells by the 39‐kDa Receptor‐Associated Protein Leaves the Interaction of β‐Migrating very‐Low‐Density Lipoprotein with the Lipoprotein Remnant Receptor Unaffected

Ziere¹,

Kaaden²,

Vogelezang³

et al. 1996

European Journal of Biochemistry

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The nature of the liver binding site which is responsible for the initial recognition and clearance of chylomicron-remnants and P-migrating very-low-density lipoprotein (P-VLDL) is under active dispute. We have investigated the effect of the 39-kDa receptor-associated protein (RAP) on the recognition site for activated a,-macroglobulin and P-VLDL on rat liver parenchymal cells in vivo and in vitro in order to analyze whether both substrates are recognized and internalized by the same receptor system. Radiolabelled trypsin-activated a,-macroglobulin (a,M-T) was cleared rapidly by the liver (maximal uptake of 80.8 ? 1 .O% of the injected dose). Prior injection of 5, 15, or 50 mg gluthathione-S-transferase-linked RAP (GST-RAP)& rat reduced the liver uptake to 62.2 -+ 2.3 %, 59.3 2 1.1 %, or 2.9 ? 0.1 % of the injected dose, respectively. Concurrently the serum decay was strongly delayed after injection of 50 mg GST-RAP/kg rat but this did not affect the serum decay and liver uptake of '"I-P-VLDL. Binding studies with isolated liver parenchymal cells in vitru demonstrated that the binding of 'ZSI-a,M-T was 98% inhibited by GST-RAP with an IC,, of 0.3 pg/ml (4.2 nM), whereas the binding of '*'I-P-VLDL and "'7-p-VLDL + recombinant apolipoprotein E (rec-apoE) was unaffected by GST-RAP up to 50 pg/ml (700 nM). Also, the cell association and degradation of a,M-T was blocked by RAP, while the association and degradation of P-VLDL and P-VLDL + rec-apoE were not influenced. The inhibitory effect of RAP on the cell association and degradation of a,M-T lasted for 1-2 h of incubation at 37 "C. The binding of the radioiodinated RAP to isolated liver parenchymal cells was highly efficiently coupled to lysosomal degradation. Upon in vivo injection into rats, '*'I-labeled RAP is rapidly cleared from the serum and taken up by the liver, which is also coupled to efficient degradation. Since RAP blocks binding of all known ligands to the a,-macroglobulin receptor/low-density lipoprotein receptor-related protein (the a,Mr/LRP) and at high concentrations the binding to the LDL receptor, we conclude that the initial binding and internalization of P-VLDL by rat liver parenchymal cells is not mediated by the a,Mr/LRP. The properties of binding of P-VLDL to rat liver parenchymal cells points to an apoE-specific recognition site for lipoprotein remnants which differs from the a,Mr/LRP, proteoglycans and the LDL receptor and is tentatively called the lipoprotein remnant receptor.Keywords: lipoprotein remnants ; low-density-lipoprotein-receptor-related protein : liver; receptor-associated protein (39 kDa).Chylomicrons and very-low-density lipoprotein (VLDL) interact with lipoprotein lipase after entering the blood circulation. This interaction leads to hydrolysis of most of their triacylglycerols (Redgrave and Small, 1979). During this process, the apo-

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“…Liver endothelial cells and Kupffer cells were isolated after pronase perfusion of the organ, followed by centrifugation and counterflow centrifugal elutriation as described (15). Liver parenchymal cells were isolated after collagenase perfusion as described (16). The numbers of cells of the different fractions were determined microscopically.…”

Section: Methodsmentioning

confidence: 99%

Massive targeting of liposomes, surface-modified with anionized albumins, to hepatic endothelial cells

Kamps¹,

Morselt²,

Meijer³

et al. 1997

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

118

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Human serum albumin (HSA) derivatized with cis-aconitic anhydride was covalently coupled to liposomes with a size of approximately 100 nm [polyaconitylated HSA (Aco-HSA) liposomes]. Within 30 min after injection into a rat, Aco-HSA liposomes were completely cleared from the blood and almost exclusively taken up by the liver, whereas in control liposomes 80% was still present in the blood at that time. Endothelial cells were shown to account for almost two-thirds of the hepatic uptake of the Aco-HSA liposomes, the remainder being recovered mainly in the liver macrophages

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Mechanism of glucagon stimulation of fructose‐1,6‐bisphosphatase in rat hepatocytes

Cited by 32 publications

References 29 publications

Glucagon‐like peptides activate hepatic gluconeogenesis

Glucagon‐like peptides activate hepatic gluconeogenesis

Massive targeting of liposomes, surface-modified with anionized albumins, to hepatic endothelial cells

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