Transgenic Manipulation of Polyamine Metabolism

Enhanced oxidative stress is closely related to aging and impaired metabolic health and is influenced by diet-derived nutrients and energy. Recent studies have shown that methionine restriction (MetR) is related to longevity and metabolic health in organisms from yeast to rodents. The effect of MetR on lifespan extension and metabolic health is mediated partially through a reduction in oxidative stress. Methionine metabolism is involved in the supply of methyl donors such as S-adenosyl-methionine (SAM), glutathione synthesis and polyamine metabolism. SAM, a methionine metabolite, activates mechanistic target of rapamycin complex 1 and suppresses autophagy; therefore, MetR can induce autophagy. In the process of glutathione synthesis in methionine metabolism, hydrogen sulfide (H2S) is produced through cystathionine-β-synthase and cystathionine-γ-lyase; however, MetR can induce increased H2S production through this pathway. Similarly, MetR can increase the production of polyamines such as spermidine, which are involved in autophagy. In addition, MetR decreases oxidative stress by inhibiting reactive oxygen species production in mitochondria. Thus, MetR can attenuate oxidative stress through multiple mechanisms, consequently associating with lifespan extension and metabolic health. In this review, we summarize the current understanding of the effects of MetR on lifespan extension and metabolic health, focusing on the reduction in oxidative stress.

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A MYC-Driven Plasma Polyamine Signature for Early Detection of Ovarian Cancer

Cancers ◽

10.3390/cancers13040913 ◽

2021 ◽

Vol 13 (4) ◽

pp. 913

Author(s):

Johannes Fahrmann ◽

Ehsan Irajizad ◽

Makoto Kobayashi ◽

Jody Vykoukal ◽

Jennifer Dennison ◽

...

Keyword(s):

Ovarian Cancer ◽

Early Stage ◽

Area Under The Curve ◽

Polyamine Metabolism ◽

Healthy Controls ◽

Test Set ◽

Exact Test ◽

Oncogenic Driver ◽

Characteristic Area ◽

Validation Set

MYC is an oncogenic driver in the pathogenesis of ovarian cancer. We previously demonstrated that MYC regulates polyamine metabolism in triple-negative breast cancer (TNBC) and that a plasma polyamine signature is associated with TNBC development and progression. We hypothesized that a similar plasma polyamine signature may associate with ovarian cancer (OvCa) development. Using mass spectrometry, four polyamines were quantified in plasma from 116 OvCa cases and 143 controls (71 healthy controls + 72 subjects with benign pelvic masses) (Test Set). Findings were validated in an independent plasma set from 61 early-stage OvCa cases and 71 healthy controls (Validation Set). Complementarity of polyamines with CA125 was also evaluated. Receiver operating characteristic area under the curve (AUC) of individual polyamines for distinguishing cases from healthy controls ranged from 0.74–0.88. A polyamine signature consisting of diacetylspermine + N-(3-acetamidopropyl)pyrrolidin-2-one in combination with CA125 developed in the Test Set yielded improvement in sensitivity at >99% specificity relative to CA125 alone (73.7% vs 62.2%; McNemar exact test 2-sided P: 0.019) in the validation set and captured 30.4% of cases that were missed with CA125 alone. Our findings reveal a MYC-driven plasma polyamine signature associated with OvCa that complemented CA125 in detecting early-stage ovarian cancer.

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Polyamine Metabolism in Scots Pine Embryogenic Cells under Potassium Deficiency

Cells ◽

10.3390/cells10051244 ◽

2021 ◽

Vol 10 (5) ◽

pp. 1244

Author(s):

Riina Muilu-Mäkelä ◽

Jaana Vuosku ◽

Hely Häggman ◽

Tytti Sarjala

Keyword(s):

Scots Pine ◽

Culture Medium ◽

Developmental Regulation ◽

Cell Mass ◽

Arginine Decarboxylase ◽

Protective Role ◽

Potassium Deficiency ◽

Polyamine Metabolism ◽

Embryogenic Cells ◽

Embryogenic Cell

Polyamines (PA) have a protective role in maintaining growth and development in Scots pine during abiotic stresses. In the present study, a controlled liquid Scots pine embryogenic cell culture was used for studying the responses of PA metabolism related to potassium deficiency. The transcription level regulation of PA metabolism led to the accumulation of putrescine (Put). Arginine decarboxylase (ADC) had an increased expression trend under potassium deficiency, whereas spermidine synthase (SPDS) expression decreased. Generally, free spermidine (Spd) and spermine (Spm)/ thermospermine (t-Spm) contents were kept relatively stable, mostly by the downregulation of polyamine oxidase (PAO) expression. The low potassium contents in the culture medium decreased the potassium content of the cells, which inhibited cell mass growth, but did not affect cell viability. The reduced growth was probably caused by repressed metabolic activity and cell division, whereas there were no signs of H2O2-induced oxidative stress or increased cell death. The low intracellular content of K+ decreased the content of Na+. The decrease in the pH of the culture medium indicated that H+ ions were pumped out of the cells. Altogether, our findings emphasize the specific role(s) of Put under potassium deficiency and strict developmental regulation of PA metabolism in Scots pine.

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Overexpression of arginine decarboxylase in transgenic plants

Biochemical Journal ◽

10.1042/bj3250331 ◽

1997 ◽

Vol 325 (2) ◽

pp. 331-337 ◽

Cited By ~ 46

Author(s):

Daniel BURTIN ◽

Anthony J. MICHAEL

Keyword(s):

Transgenic Plants ◽

Arginine Decarboxylase ◽

Polyamine Metabolism ◽

Morphological Development ◽

Polyamine Biosynthesis ◽

Adenosylmethionine Decarboxylase ◽

Two Generations ◽

Key Enzyme ◽

Polyamine Conjugate ◽

And Control

The activity of arginine decarboxylase (ADC), a key enzyme in plant polyamine biosynthesis, was manipulated in two generations of transgenic tobacco plants. Second-generation transgenic plants overexpressing an oat ADC cDNA contained high levels of oat ADC transcript relative to tobacco ADC, possessed elevated ADC enzyme activity and accumulated 10–20-fold more agmatine, the direct product of ADC. In the presence of high levels of the precursor agmatine, no increase in the levels of the polyamines putrescine, spermidine and spermine was detected in the transgenic plants. Similarly, the activities of ornithine decarboxylase and S-adenosylmethionine decarboxylase were unchanged. No diversion of polyamine metabolism into the hydroxycinnamic acid–polyamine conjugate pool or into the tobacco alkaloid nicotine was detected. Activity of the catabolic enzyme diamine oxidase was the same in transgenic and control plants. The elevated ADC activity and agmatine production were subjected to a metabolic/physical block preventing increased, i.e. deregulated, polyamine accumulation. Overaccumulation of agmatine in the transgenic plants did not affect morphological development.

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Nicotinamide Nucleotide Transhydrogenase as a Novel Treatment Target in Adrenocortical Carcinoma

Endocrinology ◽

10.1210/en.2018-00014 ◽

2018 ◽

Vol 159 (8) ◽

pp. 2836-2849 ◽

Cited By ~ 8

Author(s):

Vasileios Chortis ◽

Angela E Taylor ◽

Craig L Doig ◽

Mark D Walsh ◽

Eirini Meimaridou ◽

...

Keyword(s):

Oxidative Stress ◽

Adrenocortical Carcinoma ◽

Reduced Form ◽

Polyamine Metabolism ◽

Metabolome Analysis ◽

Nucleotide Synthesis ◽

Treatment Target ◽

Nicotinamide Nucleotide Transhydrogenase ◽

Response To Chemotherapy

Abstract Adrenocortical carcinoma (ACC) is an aggressive malignancy with poor response to chemotherapy. In this study, we evaluated a potential new treatment target for ACC, focusing on the mitochondrial reduced form of NAD phosphate (NADPH) generator nicotinamide nucleotide transhydrogenase (NNT). NNT has a central role within mitochondrial antioxidant pathways, protecting cells from oxidative stress. Inactivating human NNT mutations result in congenital adrenal insufficiency. We hypothesized that NNT silencing in ACC cells will induce toxic levels of oxidative stress. To explore this, we transiently knocked down NNT in NCI-H295R ACC cells. As predicted, this manipulation increased intracellular levels of oxidative stress; this resulted in a pronounced suppression of cell proliferation and higher apoptotic rates, as well as sensitization of cells to chemically induced oxidative stress. Steroidogenesis was paradoxically stimulated by NNT loss, as demonstrated by mass spectrometry–based steroid profiling. Next, we generated a stable NNT knockdown model in the same cell line to investigate the longer lasting effects of NNT silencing. After long-term culture, cells adapted metabolically to chronic NNT knockdown, restoring their redox balance and resilience to oxidative stress, although their proliferation remained suppressed. This was associated with higher rates of oxygen consumption. The molecular pathways underpinning these responses were explored in detail by RNA sequencing and nontargeted metabolome analysis, revealing major alterations in nucleotide synthesis, protein folding, and polyamine metabolism. This study provides preclinical evidence of the therapeutic merit of antioxidant targeting in ACC as well as illuminating the long-term adaptive response of cells to oxidative stress.

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