Increase in Glutaminase Activity during the Growth Cycle of
Cultured Human Diploid Fibroblasts

Da, Sevdalian; Pt, Ozand; Hr, Zielke

doi:10.1159/000459235

Cited by 18 publications

(4 citation statements)

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“…In stationary-phase cells, however, the activities were clearly decreased by 107% and 367% in both media. Sevdalian et al (1980) found similar results for cultured human diploid fibroblasts. The GLNase activity reached its maximum after 2 days of growth independently of the glutamine concentration (0.2-2.0 mM) and decreased once the cells reached confluency.…”

Section: Glutamine Metabolismsupporting

confidence: 67%

Metabolic adaptation of MDCK cells to different growth conditions: Effects on catalytic activities of central metabolic enzymes

Janke¹,

Genzel²,

Händel³

et al. 2011

Biotech & Bioengineering

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Lactate and ammonia are the most important waste products of central carbon metabolism in mammalian cell cultures. In particular during batch and fed-batch cultivations these toxic by-products are excreted into the medium in large amounts, and not only affect cell viability and productivity but often also prevent growth to high cell densities. The most promising approach to overcome such a metabolic imbalance is the replacement of one or several components in the culture medium. It has been previously shown that pyruvate can be substituted for glutamine in cultures of adherent Madin-Darby canine kidney (MDCK) cells. As a consequence, the cells not only released no ammonia but glucose consumption and lactate production were also reduced significantly. In this work, the impact of media changes on glucose and glutamine metabolism was further elucidated by using a high-throughput platform for enzyme activity measurements of mammalian cells. Adherent MDCK cells were grown to stationary and exponential phase in six-well plates in serum-containing GMEM supplemented with glutamine or pyruvate. A total number of 28 key metabolic enzyme activities of cell extracts were analyzed. The overall activity of the pentose phosphate pathway was up-regulated during exponential cell growth in pyruvate-containing medium suggesting that more glucose-6-phosphate was channeled into the oxidative branch. Furthermore, the anaplerotic enzymes pyruvate carboxylase and pyruvate dehydrogenase showed higher cell specific activities with pyruvate. An increase in cell specific activity was also found for NAD(+)-dependent isocitrate dehydrogenase, glutamate dehydrogenase, and glutamine synthetase in MDCK cells grown with pyruvate. It can be assumed that the increase in enzyme activities was required to compensate for the energy demand and to replenish the glutamine pool. On the other hand, the activities of glutaminolytic enzymes (e.g., alanine and aspartate transaminase) were decreased in cells grown with pyruvate, which seems to be related to a decreased glutamine metabolism.

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Section: Glutamine Metabolismsupporting

confidence: 67%

Metabolic adaptation of MDCK cells to different growth conditions: Effects on catalytic activities of central metabolic enzymes

Janke¹,

Genzel²,

Händel³

et al. 2011

Biotech & Bioengineering

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“…Active glutamine metabolism has been correlated with rapid cellular growth. For example, activity of glutaminase increases 3-fold during log phase growth in human diploid fibroblasts compared to confluent cultures (24). Moreover, glutaminase activity doubles between d 12 and 15 after birth (25).…”

Section: Discussionmentioning

confidence: 99%

Maturational Changes in Glutamine Transport by Rat Jejunal Brush Border Membrane Vesicles

et al. 1990

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ABSTRACT. The ontogeny of glutamine uptake by jejunal brush border membrane vesicles was studied in suckling and weanling rats and compared with the data obtained from previous studies done on adult rats in our laboratory. Glutamine uptake represented transport into the intravesicular space rather than mere binding into the membrane a s evident by osmolality study. The process of glutamine uptake was temperature dependent suggesting a carriermediated process with a p H optimum a t 7.0. Glutamine uptake was driven by Na+ and K+ gradient in both suckling and weanling rats. Both processes exhibited saturation kinetics and were inhibited by other neutral amino acids suggesting the presence of Na'-dependent neutral brush border system and Na+-independent (L)-like system. The V, , , of Na+-dependent and Na+-independent processes were significantly greater in suckling rats with V, . , of 4.9 f 0.36 nmol . mg protein-'. 7 s-' compared to weanling rats with V, , , of 2.4 f 0.2 nmol. mg protein-'. 7 s-' and adult rats with V, . , of 0.70 nmol . mg protein-'. 7 s-I. The greater V, , , in suckling rats is also evident when the kinetic parameters are analyzed by subtracting the sodium-dependent uptake values from the sodium-independent values. V,,, of 1.59 f 0.3 and 0.76 f 0.01 nmol. mg protein-'. 7 s-' in suckling and weanling rats, respectively, p < 0.01. Km values were not different a t 2.5 + 0.6 and 3.5 f 0.6 mM, respectively). The data suggest that the activity and/ or the number of transporters are greater during the period of active growth and development. W e conclude that glutamine transport in brush border membrane vesicles undergoes age-dependent changes with greater maximal capacity to transport glutamine in the suckling period. (Pediatr Res 27: 519-524,1990) Abbreviations BBMV, brush border membrane vesicles NBB, neutral brush border system HEPES, N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid BCH, (P-2 amino bicyclo (2,2,1) heptane-2-carboxylic acid)The developing intestine is characterized by very rapid growth with a daily protein turnover that exceeds 100% (I). The maturational process in the gastrointestinal tract includes morpho-

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“…1, Step1a). The presence and level of simple glutaminase activity, glutamine ~ glutamate + NHt, are strongly correlated with tissues and cells that exhibit high rates of glutamine oxidation (Williams and Manson, 1958;Knox et al, 1967Knox et al, , 1969Linder-Horowitz et al, 1969;Kovacevic, 1974;Pinkus and Windmueller, 1977;Sevdalian et al, 1980;Blitz et al, 1982). Detailed studies on the reaction kinetics and physicochemical properties…”

Section: Glutamine To Glutamate (Fig 1 Step 1)mentioning

confidence: 99%

Glutaminolysis in Animal Cells

McKeehan

1986

Carbohydrate Metabolism in Cultured Cells

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Increase in Glutaminase Activity during the Growth Cycle of Cultured Human Diploid Fibroblasts

Cited by 18 publications

References 0 publications

Metabolic adaptation of MDCK cells to different growth conditions: Effects on catalytic activities of central metabolic enzymes

Metabolic adaptation of MDCK cells to different growth conditions: Effects on catalytic activities of central metabolic enzymes

Maturational Changes in Glutamine Transport by Rat Jejunal Brush Border Membrane Vesicles

Glutaminolysis in Animal Cells

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