Reciprocal regulation of glutamine synthetase and carbamoylphosphate synthetase levels in rat liver

Groot, C. J. De; Voorde, G.H.J. ten; Andel, R.E. van; Kortschot, A. te; Janzen, J. W. Gaasbeek; Wilson, Richard H.; Moorman, Antoon F.M.; Charles, R.; Lamers, Wouter H.

doi:10.1016/0167-4781(87)90103-5

Cited by 66 publications

(46 citation statements)

References 57 publications

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“…15,36,37 Only the observed increase in GS expression upon fasting appears to distinguish the mouse from the rat, in which GS activity decreases after 24 hours of starvation. 38,39 Even though the parameters describing the porto-central gradient in PEPCK are similar in fed and fasted animals, the response of PEPCK to fasting differs qualitatively from the other enzymes in that the absolute increase in mRNA concentration is similar in all hepatocytes. The response of CPS, OAT, and GS to fasting, however, is largely confined to cells that already express the gene at a high level.…”

Section: Discussionmentioning

confidence: 99%

Stereological measurement of porto-central gradients in gene expression in mouse liver

et al. 2004

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The liver is thought to consist of lobules, numerous repeating, randomly oriented units. Within these lobules, genes are expressed in gradients along the porto-central axis, which spans the distance between portal and central veins. We have developed a robust stereological method to map all points in an image to their position on this porto-central axis. This approach is based on the distribution of well-characterized periportal and pericentral enzymes, which are visualized on sections preceding and following the section of interest. Because expression of the model genes phosphoenolpyruvate carboxykinase and ornithine aminotransferase declines gradually with increasing distance from the portal vein and central vein, respectively, these genes can be used to prepare images with topographical information without any assumption about the shape of the hepatic unit, or about the direction or shape of the gradient to be determined. The "relative distance" image is a 2-dimensional image that accurately maps the relative position of hepatocytes on the porto-central axis in 3-dimensional space. It is superimposed on the serial section under investigation to relate local staining density to position on the porto-central axis and obtain the gene expression gradient. The method was used to determine the expression gradient of 2 periportal and 2 pericentral enzymes and their response to fasting. The "total distance" image was used to measure the length of the porto-central axis, which was approximately 210 m in mice and found to decrease 13% after 1 day of starvation. The method can be applied to any tissue component that can be stained quantitatively. (HEPATOLOGY 2004;39:343-352.)

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Section: Discussionmentioning

confidence: 99%

Stereological measurement of porto-central gradients in gene expression in mouse liver

et al. 2004

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“…The glutamine synthetase probe used was the 1.5 kb cDNA insert isolated from clone pBR-GS2 [1,5]. It was labeled with [35S]dCTP and [32p]dCTP (all from Amersham/Buchler, Braunschweig) to a specific activity of 107-108 and 108 cpm/,ag, respectively, using the multi-prime DNA labeling kit (Amersham/Buchler, Braunschweig).…”

Section: Hybridization Probesmentioning

confidence: 99%

“…The unique restriction of this enzyme to small rings of hepatocytes encircling the terminal hepatic venules has now been convincingly demonstrated for the rat [2][3][4][5][6] as well as for other mammalian species [7,8] including man [9]. In addition, the localization of GS is distinct from that of other hepatic enzymes by its apparent inflexibility preventing an adaptive shift or an enlargement of the enzyme-positive zone under a variety Of physiological as well as experimental conditions [3,6,10].…”

Section: Introductionmentioning

confidence: 98%

Heterogeneous expression of glutamine synthetase mRNA in rat liver parenchyma revealed by in situ hybridization and Northern blot analysis of RNA from periportal and perivenous hepatocytes

1988

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Using radiolabeled specific cDNA glutamine synthetase mRNA could be detected by in situ hybridization exclusively within those few perivenous hepatocytes which stained immunocytochemically for glutamine synthetase. This localization of glutamine synthetase mRNA was recently reported by Moorman et al. [(1988) J. Histochem. Cytochem. 36, 751-755]. Biotinylated cDNA was not suitable for mRNA detection because of a very high background staining under the conditions of in situ hybridization. Dot blot and Northern blot analysis of RNA isolated from periportal and perivenous subfractions of hepatocytes also demonstrated the exclusive perivenous localization of two hybridizable glutamine synthetase mRNAs of length 2.8 and 1.6 kilobases. These results indicate that the unique heterogeneity of glutamine synthetase in rat liver parenchyma is controlled at the pretranslational level.

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“…The RNA was irreversibly bound to the membranes by air-drying and heating at 80 C for 1 h. CPS and GS mRNAs were identi®ed by hybridization with their respective cDNA probes. 7 DNA fragments were labelled with (a-32 P)dCTP by using the Multiprime labelling kit (Amersham International). The mRNA was quanti®ed by densitometry using an EPSON-8000 scanner with GELIMAGE software (Pharmacia, Sweden).…”

Section: Rna Isolation and Northern Blot Analysismentioning

confidence: 99%

“…6 This hepatic complementary distribution of the rate-determining enzyme of urea synthesis, carbamoylphosphate synthetase I (EC 6.3.4.16), and glutamine synthetase (EC 6.3.1.2) is highly suggestive of a reciprocal regulation of gene expression. 7 Here we investigate whether this relationship persists under conditions of N-retention (nutritionally obese animals) and without N-retention (genetically obese rats).…”

Section: Introductionmentioning

confidence: 99%

Regulation of ammonia-metabolizing enzymes expression in the liver of obese rats: Differences between genetic and nutritional obesities

et al. 1997

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OBJECTIVE: To determine the expression of carbamoylphosphate synthetase (CPS) and glutamine synthetase (GS) in two different models of obese rats: genetically obese rats and diet obese rats. SUBJECTS: Lean and genetically obese (fa/fa) Zucker rats were used. DESIGN: Lean animals (30±60 d old) were fed for 30 d with standard chow pellets or with a hypercaloric cafeteria diet. Genetically obese rats were fed with standard chow pellets. MEASUREMENTS: Enzyme activity, protein (Western blot) and mRNA (Northern blot) contents of CPS and GS were measured in liver homogenates. RESULTS: In genetically obese animals CPS mRNA content was higher, and GS mRNA content was lower than in control animals; CPS protein content did not change and CPS activity was lower than in control rats. Diet-obese rats had higher levels of CPS and GS mRNAs than control animals; GS protein content and activity was higher than in the control group and at the same time, CPS activity was very low. CONCLUSIONS: In the genetically obese animals the expression of CPS and GS is mainly regulated at the pretranslational level, whereas in the diet obese rats there is a noticeable post-translational component. A reciprocal regulation between CPS and GS can be established at pre-translational levels, whereas at post-transcriptional levels it cannot. It can be concluded that in diet-obese animals the mechanisms involved in retaining nitrogen (low CPS activity) are modulated at the post-translational level.

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Reciprocal regulation of glutamine synthetase and carbamoylphosphate synthetase levels in rat liver

Cited by 66 publications

References 57 publications

Stereological measurement of porto-central gradients in gene expression in mouse liver

Stereological measurement of porto-central gradients in gene expression in mouse liver

Heterogeneous expression of glutamine synthetase mRNA in rat liver parenchyma revealed by in situ hybridization and Northern blot analysis of RNA from periportal and perivenous hepatocytes

Regulation of ammonia-metabolizing enzymes expression in the liver of obese rats: Differences between genetic and nutritional obesities

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