Induction of L-lysine-2-oxoglutarate reductase by glucagon and glucocorticoid in developing and adult rats in vivo and in vitro studies

Shinno, Hideki; Noda, Chiseko; Tanaka, Keiji; Ichihara, Akira

doi:10.1016/0304-4165(80)90190-7

Cited by 20 publications

(13 citation statements)

References 24 publications

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“…In particular, the high expression level observed in the liver is consistent with the activity observed in this organ, not only in human but also in bovine, baboon and rat livers [14,18]. In the kidney, mRNA levels seem to be lower than in the liver ( Figure 3) ; this parallels the LOR enzymic activity observed in rat kidney, which is only 10 % lower than that found in liver [20].…”

Section: Discussionsupporting

confidence: 84%

“…Firstly, these enzyme activities are responsible for lysine catabolism in the liver, contributing not only to the general nitrogen balance in the organism but also to the controlled conversion of lysine into ketone bodies [6,7,9,19,20]. Secondly, lysine is an essential amino acid and its supply is therefore required during embryonic development and early childhood.…”

Section: Introductionmentioning

confidence: 99%

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Lysine degradation through the saccharopine pathway in mammals: involvement of both bifunctional and monofunctional lysine-degrading enzymes in mouse

Papes

Kemper

Cord-Neto

et al. 1999

Biochemical Journal

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Lysine-oxoglutarate reductase and saccharopine dehydrogenase are enzymic activities that catalyse the first two steps of lysine degradation through the saccharopine pathway in upper eukaryotes. This paper describes the isolation and characterization of a cDNA clone encoding a bifunctional enzyme bearing domains corresponding to these two enzymic activities. We partly purified those activities from mouse liver and showed for the first time that both a bifunctional lysine-oxoglutarate reductase/saccharopine dehydrogenase and a monofunctional saccharopine dehydrogenase are likely to be present in this organ. Northern analyses indicate the existence of two mRNA species in liver and kidney. The longest molecule, 3.4 kb in size, corresponds to the isolated cDNA and encodes the bifunctional enzyme. The 2.4 kb short transcript probably codes for the monofunctional dehydrogenase. Sequence analyses show that the bifunctional enzyme is likely to be a mitochondrial protein. Furthermore, enzymic and expression analyses suggest that lysine-oxoglutarate reductase/saccharopine dehydrogenase levels increase in livers of mice under starvation. Lysine-injected mice also show an increase in lysine-oxoglutarate reductase and saccharopine dehydrogenase levels.

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Section: Discussionsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Lysine degradation through the saccharopine pathway in mammals: involvement of both bifunctional and monofunctional lysine-degrading enzymes in mouse

Papes

Kemper

Cord-Neto

et al. 1999

Biochemical Journal

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“…The complexity of conditions in vivo makes it difficult to obtain clear cut results on the mech anisms of enzyme induction and metabolic regula tion caused by the nutritional state and hormones. However, we recently showed that primary cul tures of adult rat hepatocytes were a suitable in vitro system for studies on hormonal and nutri tional regulation of enzymes and metabolic activ ities in the liver (23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35).…”

Section: The Biosynthesismentioning

confidence: 99%

Hormonal Regulations of Glucose-6-Phosphate Dehydrogenase and Lipogenesis in Primary Cultures of Rat Hepatocytes1

Nakamura

Yoshimoto

Aoyama

et al. 1982

The Journal of Biochemistry

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In primary cultured monolayer hepatocytes of adult rats, insulin (1 x 10(-8) M) induced glucose-6-phosphate dehydrogenase [EC 1.1.1.49, G6PDH] several fold in 48 h. It also induced lipogenesis, measured as [1-14C]acetate incorporation in 2 h, in these cells. Of the various lipids, triglycerides and phospholipids were induced markedly, while cholesterol and its esters were not induced. The increase of G6PDH and lipogenesis were parallel. Glucagon, dibutyryl cyclic AMP, triiodothyronine, dexamethasone, epinephrine, isoproterenol, and dibutyryl cyclic GMP were also tested under similar conditions, but none of them caused significant induction of G6PDH or lipogenesis. Use of anti-G6PDH serum showed that induction of G6PDH by insulin was due to increase in the amount of enzyme protein. Insulin was found to increase the rate of synthesis of G6PDH about 3-fold. SDS-polyacrylamide gel electrophoresis of the immunoprecipitable protein revealed that besides G6PDH another radioactive fraction (Mr 37,000) was increased by insulin. This suggests that complete synthesis of G6PDH protein is slowed down in primary cultured hepatocytes and that an apparent nascent peptide of the enzyme accumulates. Although on long-term treatment (48 h), glucagon and dibutyryl cyclic AMP had no effect on lipogenesis, when added with [14C]acetate for 2 h they strongly inhibited lipogenesis. Significant inhibition of lipogenesis by short-term treatment with glucagon was seen even in cells with a high capacity for lipogenesis induced by long-term treatment with insulin. Insulin again stimulated lipogenesis in short-term treatment, but its effect was slight. It is concluded from these results that insulin exerts long-term stimulation of lipogenesis by inducing enzymes related to lipogenesis including G6PDH as well as causing slight stimulation by enhancing supply of substrate for lipogenesis. Glucagon seems to play a minor role in long-term control, but it causes short-term inhibition of lipogenesis.

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“…In particular, high-lysine or high-protein diets promote increases in LKR and SDH activities in the rat liver [11], [40]. Also, LKR and SDH activities as well as LKR/SDH mRNA increase in mice receiving lysine or saccharopine injections or diets containing excess lysine [12], [39]. To investigate the role of this gene in tick physiology and the impacts of lysine levels, we injected lysine or saccharopine into ticks.…”

Section: Discussionmentioning

confidence: 99%

“…The Lys catabolic pathway is an important route for balancing Lys levels, mostly, because high levels of Lys are toxic to organisms [8]. LKR/SDH enzyme activities are important for Lys catabolism in the mammalian liver and kidney [9], [10], contributing not only to the general nitrogen balance but also the controlled conversion of lysine into ketone bodies [9]–[12]. In plants, the LKR level was shown to be significantly up-regulated in inflorescence tissues and developing seeds, as well as in response to osmotic stress [3], [4], [13], [14].…”

Section: Introductionmentioning

confidence: 99%

LKR/SDH Plays Important Roles throughout the Tick Life Cycle Including a Long Starvation Period

et al. 2009

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BackgroundLysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH) is a bifunctional enzyme catalyzing the first two steps of lysine catabolism in plants and mammals. However, to date, the properties of the lysine degradation pathway and biological functions of LKR/SDH have been very little described in arthropods such as ticks.Methodology/Principal FindingsWe isolated and characterized the gene encoding lysine-ketoglutarate reductase (LKR, EC 1.5.1.8) and saccharopine dehydrogenase (SDH, EC 1.5.1.9) from a tick, Haemaphysalis longicornis, cDNA library that encodes a bifunctional polypeptide bearing domains similar to the plant and mammalian LKR/SDH enzymes. Expression of LKR/SDH was detected in all developmental stages, indicating an important role throughout the tick life cycle, including a long period of starvation after detachment from the host. The LKR/SDH mRNA transcripts were more abundant in unfed and starved ticks than in fed and engorged ticks, suggesting that tick LKR/SDH are important for the starved tick. Gene silencing of LKR/SDH by RNAi indicated that the tick LKR/SDH plays an integral role in the osmotic regulation of water balance and development of eggs in ovary of engorged females.Conclusions/SignificanceTranscription analysis and gene silencing of LKR/SDH indicated that tick LKR/SDH enzyme plays not only important roles in egg production, reproduction and development of the tick, but also in carbon, nitrogen and water balance, crucial physiological processes for the survival of ticks. This is the first report on the role of LKR/SDH in osmotic regulation in animals including vertebrate and arthropods.

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Induction of L-lysine-2-oxoglutarate reductase by glucagon and glucocorticoid in developing and adult rats in vivo and in vitro studies

Cited by 20 publications

References 24 publications

Lysine degradation through the saccharopine pathway in mammals: involvement of both bifunctional and monofunctional lysine-degrading enzymes in mouse

Lysine degradation through the saccharopine pathway in mammals: involvement of both bifunctional and monofunctional lysine-degrading enzymes in mouse

Hormonal Regulations of Glucose-6-Phosphate Dehydrogenase and Lipogenesis in Primary Cultures of Rat Hepatocytes1

LKR/SDH Plays Important Roles throughout the Tick Life Cycle Including a Long Starvation Period

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