Cellular concentrations of glutamine synthetase in murine organs
| Autor: | Youji He, Marjan M van Duist, Paul van Dijk, Wil T. Labruyère, Henny W. M. van Straaten, Theodorus B. M. Hakvoort, Wouter H. Lamers, Jan M. Ruijter, Jacqueline L.M. Vermeulen |
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| Přispěvatelé: | Anatomie en Embryologie, RS: NUTRIM School of Nutrition and Translational Research in Metabolism, RS: GROW - School for Oncology and Reproduction, Medical Biology, Amsterdam Gastroenterology Endocrinology Metabolism |
| Jazyk: | angličtina |
| Rok vydání: | 2006 |
| Předmět: |
Male
Gs alpha subunit Transcription Genetic Adipose tissue Biology Kidney Biochemistry Mice Glutamate-Ammonia Ligase Glutamine synthetase Testis medicine Animals Post-translational regulation RNA Messenger RNA Processing Post-Transcriptional Molecular Biology Epididymis Base Sequence Stomach Uterus Glutamate receptor Cell Biology Immunohistochemistry Molecular biology Intestines Glutamine Convoluted tubule medicine.anatomical_structure Adipose Tissue Liver Organ Specificity Female |
| Zdroj: | Biochemistry and Cell Biology-Biochimie et Biologie Cellulaire, 84(2), 215-231. National Research Council of Canada Biochemistry and cell biology = Biochimie et biologie cellulaire, 84(2), 215-231. National Research Council of Canada |
| ISSN: | 0829-8211 |
| DOI: | 10.1139/o05-170 |
| Popis: | Glutamine synthetase (GS) is the only enzyme that can synthesize glutamine, but it also functions to detoxify glutamate and ammonia. Organs with high cellular concentrations of GS appear to function primarily to remove glutamate or ammonia, whereas those with a low cellular concentration appear to primarily produce glutamine. To validate this apparent dichotomy and to clarify its regulation, we determined the GS concentrations in 18 organs of the mouse. There was a >100-fold difference in GS mRNA, protein, and enzyme-activity levels among organs, whereas there was only a 20-fold difference in the GS protein:mRNA ratio, suggesting extensive transcriptional and posttranscriptional regulation. In contrast, only small differences in the GS enzyme activity : protein ratio were found, indicating that posttrans lational regulation is of minor importance. The cellular concentration of GS was determined by relating the relative differences in cellular GS concentration, detected using image analysis of immunohistochemically stained tissue sections, to the biochemical data. There was a >1000-fold difference in cellular concentrations of GS between GS-positive cells in different organs, and cellular concentrations were up to 20× higher in subpopulations of cells within organs than in whole organs. GS activity was highest in pericentral hepatocytes (~485 µmol·g–1·min–1), followed in descending order by epithelial cells in the epididymal head, Leydig cells in the testicular interstitium, epithelial cells of the uterine tube, acid-producing parietal cells in the stomach, epithelial cells of the S3 segment of the proximal convoluted tubule of the kidney, astrocytes of the central nervous tissue, and adipose tissue. GS activity in muscle amounted to only 0.4 µmol·g–1·min–1. Our findings confirmed the postulated dichotomy between cellular concentration and GS function.Key words: mRNA, protein, enzyme activity, posttranscriptional regulation, quantitative immunohistochemistry. |
| Databáze: | OpenAIRE |
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