Activation of hepatic glutaminase by spermine

Kovačević, Zoran; Day, Stephen H.; Collett, Vaughn M.; Brosnan, John T.; Brosnan, Margaret E.

doi:10.1042/bj3050837

Cited by 12 publications

(4 citation statements)

References 34 publications

(25 reference statements)

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“…An elevation in [Mg 2ϩ ] m from 44 M to 1.69 mM also induced a stimulation in the rate of citrulline synthesis in rat liver mitochondria (12). Modulation of mitochondrial glutaminase by 0 -2 mM Mg 2ϩ has also been observed (13). All of these reports describing an active movement of Mg 2ϩ in cells and mitochondria of different tissues and in response to different agonists suggest that Mg 2ϩ may play a role as a second messenger in the cell.…”

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confidence: 79%

Modulation of Oxidative Phosphorylation by Mg2+ in Rat Heart Mitochondria

Rodríguez‐Zavala

Moreno‐Sánchez

1998

Journal of Biological Chemistry

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The effect of varying the Mg 2؉ concentration on the 2-oxoglutarate dehydrogenase (2-OGDH) activity and the rate of oxidative phosphorylation of rat heart mitochondria was studied. The ionophore A23187 was used to modify the mitochondrial free Mg 2؉ concentration. Half-maximal stimulation (K 0.5 ) of ATP synthesis by Mg 2؉ was obtained with 0.13 ؎ 0.02 mM (n ‫؍‬ 7) with succinate (؉rotenone) and 0.48 ؎ 0.13 mM (n ‫؍‬ 6) with 2-oxoglutarate (2-OG) as substrates. Similar K 0.5 values were found for NAD(P)H formation, generation of membrane potential, and state 4 respiration with 2-OG. In the presence of ADP, an increase in P i concentration promoted a decrease in the K ] c has been determined, after stimulation with the muscarinic agonist carbachol, and a 10% increase was observed, after addition of forskolin in rat sublingual mucous acini (3). In acinar pancreatic cells, addition of acetylcholine or cholecystokinin-octapeptide promoted a significant diminution in [Mg 2ϩ ] c (4). Arginine-vasopressin and endothelin-1 induced an increment in [Mg 2ϩ ] c in muscle cells, probably through a Ca 2ϩ -mediated mechanism (5). Depletion of inositol 1,4,5-trisphosphate-sensitive Ca 2ϩ stores, induced by ␣-adrenergic agonists, activated the uptake of Mg 2ϩ by these organelles (6). Extracellular ATP stimulated the release of 40% of cellular Mg 2ϩ in ascites cells (7); it was proposed that cAMP promoted Mg 2ϩ release through the activation of a plasma membrane Na ϩ /Mg 2ϩ antiporter (8). However, a report indicating that addition of cAMP also induced a net release of 20 -25% of total Mg 2ϩ in rat liver mitochondria (9) was not confirmed (10). In beef heart mitochondria, the transition from basal (state 4) to active (state 3) respiration led to a small, but significant elevation in the mitochondrial matrix free ] m , can modulate the activities of the 2-OGDH and the ATP synthase and, in consequence, Mg 2ϩ may affect the rate of oxidative phosphorylation in isolated rat heart mitochondria. MATERIALS AND METHODSRat heart mitochondria were isolated from male Wistar rats of 250 -300-g weight according to a previously described method using the protease type XXVII (Nagarse) from Sigma (14).Dye Loading-Heart mitochondria were loaded with Mag-Fura-2 or BCECF (Molecular Probes) by incubating 30 -40 mg of mitochondrial protein in 2 ml of a medium composed of 250 mM sucrose, 10 mM HEPES, 1 mM EGTA (SHE medium), 1 mM MgCl 2 , 1 mM ADP, 0.2% fatty acid-free bovine serum albumin, pH 7.4, and 5 M Mag-Fura-2/AM or BCECF/AM at 25°C for 20 min. At the end of this incubation period, mitochondria were diluted 10 -15 times with ice-cold SHE medium ϩ 0.2% bovine serum albumin, centrifuged, resuspended in 1 ml of SHE medium, and kept on ice until use. Mitochondria loaded by following this procedure showed higher respiratory control values than nonloaded mitochondria, 8.6 and 4.3 (n ϭ 2), respectively, with 10 mM 2-oxoglutarate as a substrate.Determination of [Mg 2ϩ ] m -Mag-Fura-2-loaded mitochondria (0.5 mg protein/ml) were incubated in 120...

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confidence: 79%

Modulation of Oxidative Phosphorylation by Mg2+ in Rat Heart Mitochondria

Rodríguez‐Zavala

Moreno‐Sánchez

1998

Journal of Biological Chemistry

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“…into -HEPATIC GLUTAMINE METABOLISM 45 the cells. This chapter summarizes some basic concepts on hepatic glutamine transport and metabolism; for detailed analysis, the reader is referred to recent reviews and monographs (Haussinger and Sies 1984a;Haussinger, , 1990aKovacevic and McGivan, 1983;Kvamme, 1988;Meijer, et al 1990; Lang and Haussinger, 1993;Curthoys and Watford, 1995;Kilberg and Haussinger, 1992;Souba, 1991). A.…”

Section: Introductionmentioning

confidence: 99%

Hepatic Glutamine Transport and Metabolism

Häussinger

1998

Advances in Enzymology - And Related Areas of Molecular Biology

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“…This may suggest increased glutamine degradation for urea synthesis. Of note, it has been shown [16] that spermine activates hepatic glutaminase, leading to an increase in glutamine uptake by the liver and an increase flux of ammonia in the liver, activating in turn carbamyl-phosphate synthase [16], the first enzyme of the urea cycle. However, in our experiment the increase in liver spermine did not reach statistical significance.…”

Section: Discussionmentioning

confidence: 99%

Is N-Carbamoyl Putrescine, the Decarboxylation Derivative of Citrulline, a Regulator of Muscle Protein Metabolism in Rats?

et al. 2019

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N-carbamoyl putrescine (NCP), the decarboxylation derivative of citrulline, metabolically related to polyamines, may exert biological effects in mammals. The aim of this study was (i) to evaluate the nutritional properties of NCP in healthy rats and (ii) to determine the effect of NCP administration on muscle metabolism in malnourished old rats. The nutritional properties of NCP were first evaluated in 20 8-week-old male rats randomized to receive for two weeks a standard diet either alone (C group) or supplemented with NCP, 5 or 50 mg/kg/d. In a second study, 29 malnourished 18-month-old male rats were studied either before or after a 4-day refeeding with a standard diet either alone (REN group) or supplemented with NCP, 1 or 10 mg/kg/d. NCP had no effect on weight gain and body composition in either of the two studies. In healthy rats, muscle protein content was significantly increased in the soleus with NCP 5 mg/kg/d. A decrease in plasma glutamine and kidney spermine was observed at the 50 mg/kg/d dose; otherwise, no significant changes in plasma chemistry and tissue polyamines were observed. In malnutrition-induced sarcopenic old rats, refeeding with NCP 10 mg/kg/d was associated with higher tibialis weight and a trend for increased protein content in extensor digitorum longus (EDL). While the muscle protein synthesis rate was similar between groups, ribosomal protein S6 kinase was increased in tibialis and higher in the EDL in NCP-treated rats. The muscle RING-finger protein-1 expression was decreased in tibialis and urinary 3-methyl-histidine to creatinine ratio slightly lower with the supply of NCP. However, this initial period of refeeding was also associated with elevated fasted plasma triglycerides and glucose, significant in NCP groups, suggesting glucose intolerance and possibly insulin resistance. NCP was well-tolerated in healthy young-adults and in malnourished old rats. In healthy adults, NCP at 5 mg/kg/d induced a significant increase in protein content in the soleus, a type I fiber-rich muscle. In malnourished old rats, NCP supply during refeeding, may help to preserve lean mass by limiting protein breakdown; however, these effects may be limited in our model by a possible immediate refeeding-associated glucose intolerance.

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Activation of hepatic glutaminase by spermine

Cited by 12 publications

References 34 publications

Modulation of Oxidative Phosphorylation by Mg2+ in Rat Heart Mitochondria

Modulation of Oxidative Phosphorylation by Mg2+ in Rat Heart Mitochondria

Hepatic Glutamine Transport and Metabolism

Is N-Carbamoyl Putrescine, the Decarboxylation Derivative of Citrulline, a Regulator of Muscle Protein Metabolism in Rats?

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