bims-polyam 2021-05-02 papers

bims-polyam

Biomed News

on Polyamines

Issue of 2021–05–02
seven papers selected by
Sebastian J. Hofer, University of Graz

The Emerging Clinical Role of Spermine in Prostate Cancer.
Increased polyamine levels and maintenance of γ-aminobutyric acid (Gaba) homeostasis in the gills is indicative of osmotic plasticity in killifish.
The Vibrio cholerae SpeG Spermidine/Spermine N-Acetyltransferase Allosteric Loop and β6-β7 Structural Elements Are Critical for Kinetic Activity.
Metformin Inhibits the Urea Cycle and Reduces Putrescine Generation in Colorectal Cancer Cell Lines.
Dual Role for Astroglial Copper-Assisted Polyamine Metabolism during Intense Network Activity.
Putrescine Depletion Affects Arabidopsis Root Meristem Size by Modulating Auxin and Cytokinin Signaling and ROS Accumulation.
A G316A Polymorphism in the Ornithine Decarboxylase Gene Promoter Modulates MYCN-Driven Childhood Neuroblastoma.

Int J Mol Sci. 2021 Apr 22. pii: 4382. [Epub ahead of print]22(9):

The Emerging Clinical Role of Spermine in Prostate Cancer.

Qiang Peng, Christine Yim-Ping Wong, Isabella Wai-Yin Cheuk, Jeremy Yuen-Chun Teoh, Peter Ka-Fung Chiu, Chi-Fai Ng.

  Spermine, a member of polyamines, exists in all organisms and is essential for normal cell growth and function. It is highly expressed in the prostate compared with other organs and is detectable in urine, tissue, expressed prostatic secretions, and erythrocyte. A significant reduction of spermine level was observed in prostate cancer (PCa) tissue compared with benign prostate tissue, and the level of urinary spermine was also significantly lower in men with PCa. Decreased spermine level may be used as an indicator of malignant phenotype transformation from normal to malignant tissue in prostate. Studies targeting polyamines and key rate-limiting enzymes associated with spermine metabolism as a tool for PCa therapy and chemoprevention have been conducted with various polyamine biosynthesis inhibitors and polyamine analogues. The mechanism between spermine and PCa development are possibly related to the regulation of polyamine metabolism, cancer-driving pathways, oxidative stress, anticancer immunosurveillance, and apoptosis regulation. Although the specific mechanism of spermine in PCa development is still unclear, ongoing research in spermine metabolism and its association with PCa pathophysiology opens up new opportunities in the diagnostic and therapeutic roles of spermine in PCa management.

Keywords:  biomarker; cancer metabolism; polyamine; prostate cancer; spermine

DOI:  https://doi.org/10.3390/ijms22094382
Comp Biochem Physiol A Mol Integr Physiol. 2021 Apr 26. pii: S1095-6433(21)00075-1. [Epub ahead of print] 110969

Increased polyamine levels and maintenance of γ-aminobutyric acid (Gaba) homeostasis in the gills is indicative of osmotic plasticity in killifish.

Kathleen M Munley, Dong Liu, Fernando Galvez.

  The Fundulus genus of killifish includes species that inhabit marshes along the U.S. Atlantic coast and the Gulf of Mexico, but differ in their ability to rapidly adjust to fluctuations in salinity. Previous work suggests that euryhaline killifish stimulate polyamine biosynthesis and accumulate putrescine in the gills during acute hypoosmotic challenge. Despite evidence that polyamines have an osmoregulatory role in euryhaline killifish species, their function in marine species is unknown. Furthermore, the consequences of hypoosmotic-induced changes in polyamine synthesis on downstream pathways, such as ƴ-aminobutyric acid (Gaba) production, have yet to be explored. Here, we examined the effects of acute hypoosmotic exposure on polyamine, glutamate, and Gaba levels in the gills of a marine (F. majalis) and two euryhaline killifish species (F. heteroclitus and F. grandis). Fish acclimated to 32 ppt- or 12 ppt water were transferred to fresh water, and concentrations of glutamate (Glu), Gaba, and the polyamines putrescine (Put), spermidine (Spd), and spermine (Spm) were measured in the gills using high-performance liquid chromatography. F. heteroclitus and F. grandis exhibited an increase in gill Put concentration, but showed no change in Glu or Gaba levels following freshwater transfer. F. heteroclitus also accumulated Spd in the gills, whereas F. grandis showed transient increases in Spd, and Spm levels. In contrast, gill Put, Spm, Glu, and Gaba levels decreased in F. majalis following freshwater transfer. Together, these findings suggest that increasing polyamine levels and maintaining Glu and Gaba levels in the gills may enable euryhaline teleosts to acclimate to shifts in environmental salinity.

Keywords:  Comparative physiology; Euryhaline; GABA; Osmotic stress tolerance; Plasticity; Polyamines

DOI:  https://doi.org/10.1016/j.cbpa.2021.110969
Front Mol Biosci. 2021 ;8 645768

The Vibrio cholerae SpeG Spermidine/Spermine N-Acetyltransferase Allosteric Loop and β6-β7 Structural Elements Are Critical for Kinetic Activity.

Van Thi Bich Le, Sofiya Tsimbalyuk, Ee Qi Lim, Allan Solis, Darwin Gawat, Paloma Boeck, Ee Qing Lim, Rosselini Renolo, Jade K Forwood, Misty L Kuhn.

  Polyamines regulate many important biological processes including gene expression, intracellular signaling, and biofilm formation. Their intracellular concentrations are tightly regulated by polyamine transport systems and biosynthetic and catabolic pathways. Spermidine/spermine N-acetyltransferases (SSATs) are catabolic enzymes that acetylate polyamines and are critical for maintaining intracellular polyamine homeostasis. These enzymes belong to the Gcn5-related N-acetyltransferase (GNAT) superfamily and adopt a highly conserved fold found across all kingdoms of life. SpeG is an SSAT protein found in a variety of bacteria, including the human pathogen Vibrio cholerae. This protein adopts a dodecameric structure and contains an allosteric site, making it unique compared to other SSATs. Currently, we have a limited understanding of the critical structural components of this protein that are required for its allosteric behavior. Therefore, we explored the importance of two key regions of the SpeG protein on its kinetic activity. To achieve this, we created various constructs of the V. cholerae SpeG protein, including point mutations, a deletion, and chimeras with residues from the structurally distinct and non-allosteric human SSAT protein. We measured enzyme kinetic activity toward spermine for ten constructs and crystallized six of them. Ultimately, we identified specific portions of the allosteric loop and the β6-β7 structural elements that were critical for enzyme kinetic activity. These results provide a framework for further study of the structure/function relationship of SpeG enzymes from other organisms and clues toward the structural evolution of members of the GNAT family across domains of life.

Keywords:  Gcn5-related N-acetyltransferase; acetylation; allosteric regulation; chimeric; polyamine; spermidine; spermidine/spermine N-acetyltransferase; spermine

DOI:  https://doi.org/10.3389/fmolb.2021.645768
Molecules. 2021 Apr 01. pii: 1990. [Epub ahead of print]26(7):

Metformin Inhibits the Urea Cycle and Reduces Putrescine Generation in Colorectal Cancer Cell Lines.

Tao Zhang, Ling Hu, Jia-Feng Tang, Hang Xu, Kuan Tian, Meng-Na Wu, Shi-Ying Huang, Yu-Mei Du, Peng Zhou, Rui-Jin Lu, Shuang He, Jia-Mei Xu, Jian-Jun Si, Jing Li, Di-Long Chen, Jian-Hua Ran.

  The urea cycle (UC) removes the excess nitrogen and ammonia generated by nitrogen-containing compound composites or protein breakdown in the human body. Research has shown that changes in UC enzymes are not only related to tumorigenesis and tumor development but also associated with poor survival in hepatocellular, breast, and colorectal cancers (CRC), etc. Cytoplasmic ornithine, the intermediate product of the urea cycle, is a specific substrate for ornithine decarboxylase (ODC, also known as ODC1) for the production of putrescine and is required for tumor growth. Polyamines (spermidine, spermine, and their precursor putrescine) play central roles in more than half of the steps of colorectal tumorigenesis. Given the close connection between polyamines and cancer, the regulation of polyamine metabolic pathways has attracted attention regarding the mechanisms of action of chemical drugs used to prevent CRC, as the drug most widely used for treating type 2 diabetes (T2D), metformin (Met) exhibits antitumor activity against a variety of cancer cells, with a vaguely defined mechanism. In addition, the influence of metformin on the UC and putrescine generation in colorectal cancer has remained unclear. In our study, we investigated the effect of metformin on the UC and putrescine generation of CRC in vivo and in vitro and elucidated the underlying mechanisms. In nude mice bearing HCT116 tumor xenografts, the administration of metformin inhibited tumor growth without affecting body weight. In addition, metformin treatment increased the expression of monophosphate (AMP)-activated protein kinase (AMPK) and p53 in both HCT116 xenografts and colorectal cancer cell lines and decreased the expression of the urea cycle enzymes, including carbamoyl phosphate synthase 1 (CPS1), arginase 1 (ARG1), ornithine trans-carbamylase (OTC), and ODC. The putrescine levels in both HCT116 xenografts and HCT116 cells decreased after metformin treatment. These results demonstrate that metformin inhibited CRC cell proliferation via activating AMPK/p53 and that there was an association between metformin, urea cycle inhibition and a reduction in putrescine generation.

Keywords:  ARG1; CPS1; ODC; OTC; colorectal cancer (CRC); human colorectal cancer HCT116 cell line; metformin; p53; proliferation; putrescine; urea cycle

DOI:  https://doi.org/10.3390/molecules26071990
Biomolecules. 2021 Apr 19. pii: 604. [Epub ahead of print]11(4):

Dual Role for Astroglial Copper-Assisted Polyamine Metabolism during Intense Network Activity.

Zsolt Szabó, Márton Péter, László Héja, Julianna Kardos.

  Astrocytes serve essential roles in human brain function and diseases. Growing evidence indicates that astrocytes are central players of the feedback modulation of excitatory Glu signalling during epileptiform activity via Glu-GABA exchange. The underlying mechanism results in the increase of tonic inhibition by reverse operation of the astroglial GABA transporter, induced by Glu-Na+ symport. GABA, released from astrocytes, is synthesized from the polyamine (PA) putrescine and this process involves copper amino oxidase. Through this pathway, putrescine can be considered as an important source of inhibitory signaling that counterbalances epileptic discharges. Putrescine, however, is also a precursor for spermine that is known to enhance gap junction channel communication and, consequently, supports long-range Ca2+ signaling and contributes to spreading of excitatory activity through the astrocytic syncytium. Recently, we presented the possibility of neuron-glia redox coupling through copper (Cu+/Cu2+) signaling and oxidative putrescine catabolism. In the current work, we explore whether the Cu+/Cu2+ homeostasis is involved in astrocytic control on neuronal excitability by regulating PA catabolism. We provide supporting experimental data underlying this hypothesis. We show that the blockade of copper transporter (CTR1) by AgNO3 (3.6 µM) prevents GABA transporter-mediated tonic inhibitory currents, indicating causal relationship between copper (Cu+/Cu2+) uptake and the catabolism of putrescine to GABA in astrocytes. In addition, we show that MnCl2 (20 μM), an inhibitor of the divalent metal transporter DMT1, also prevents the astrocytic Glu-GABA exchange. Furthermore, we observed that facilitation of copper uptake by added CuCl2 (2 µM) boosts tonic inhibitory currents. These findings corroborate the hypothesis that modulation of neuron-glia coupling by copper uptake drives putrescine → GABA transformation, which leads to subsequent Glu-GABA exchange and tonic inhibition. Findings may in turn highlight the potential role of copper signaling in fine-tuning the activity of the tripartite synapse.

Keywords:  Cx43 gap junction channel; astroglial GABA transporter; astroglial tonic inhibitory feedback; copper amino oxidase; copper transporter CTR1; putrescine catabolism

DOI:  https://doi.org/10.3390/biom11040604
Int J Mol Sci. 2021 Apr 15. pii: 4094. [Epub ahead of print]22(8):

Putrescine Depletion Affects Arabidopsis Root Meristem Size by Modulating Auxin and Cytokinin Signaling and ROS Accumulation.

Ahmed M Hashem, Simon Moore, Shangjian Chen, Chenchen Hu, Qing Zhao, Ibrahim Eid Elesawi, Yanni Feng, Jennifer F Topping, Junli Liu, Keith Lindsey, Chunli Chen.

  Polyamines (PAs) dramatically affect root architecture and development, mainly by unknown mechanisms; however, accumulating evidence points to hormone signaling and reactive oxygen species (ROS) as candidate mechanisms. To test this hypothesis, PA levels were modified by progressively reducing ADC1/2 activity and Put levels, and then changes in root meristematic zone (MZ) size, ROS, and auxin and cytokinin (CK) signaling were investigated. Decreasing putrescine resulted in an interesting inverted-U-trend in primary root growth and a similar trend in MZ size, and differential changes in putrescine (Put), spermidine (Spd), and combined spermine (Spm) plus thermospermine (Tspm) levels. At low Put concentrations, ROS accumulation increased coincidently with decreasing MZ size, and treatment with ROS scavenger KI partially rescued this phenotype. Analysis of double AtrbohD/F loss-of-function mutants indicated that NADPH oxidases were not involved in H2O2 accumulation and that elevated ROS levels were due to changes in PA back-conversion, terminal catabolism, PA ROS scavenging, or another pathway. Decreasing Put resulted in a non-linear trend in auxin signaling, whereas CK signaling decreased, re-balancing auxin and CK signaling. Different levels of Put modulated the expression of PIN1 and PIN2 auxin transporters, indicating changes to auxin distribution. These data strongly suggest that PAs modulate MZ size through both hormone signaling and ROS accumulation in Arabidopsis.

Keywords:  PIN transporter; ROS; auxin response; cytokinin response; hormone signaling; polyamine; root meristem

DOI:  https://doi.org/10.3390/ijms22084094
Cancers (Basel). 2021 Apr 09. pii: 1807. [Epub ahead of print]13(8):

A G316A Polymorphism in the Ornithine Decarboxylase Gene Promoter Modulates MYCN-Driven Childhood Neuroblastoma.

Laura D Gamble, Stefania Purgato, Michelle J Henderson, Simone Di Giacomo, Amanda J Russell, Paolo Pigini, Jayne Murray, Emanuele Valli, Giorgio Milazzo, Federico M Giorgi, Mark Cowley, Lesley J Ashton, Jaydutt Bhalshankar, Gudrun Schleiermacher, Ali Rihani, Tom Van Maerken, Jo Vandesompele, Frank Speleman, Rogier Versteeg, Jan Koster, Angelika Eggert, Rosa Noguera, Raymond L Stallings, Gian Paolo Tonini, Kwun Fong, Zalman Vaksman, Sharon J Diskin, John M Maris, Wendy B London, Glenn M Marshall, David S Ziegler, Michael D Hogarty, Giovanni Perini, Murray D Norris, Michelle Haber.

  Ornithine decarboxylase (ODC1), a critical regulatory enzyme in polyamine biosynthesis, is a direct transcriptional target of MYCN, amplification of which is a powerful marker of aggressive neuroblastoma. A single nucleotide polymorphism (SNP), G316A, within the first intron of ODC1, results in genotypes wildtype GG, and variants AG/AA. CRISPR-cas9 technology was used to investigate the effects of AG clones from wildtype MYCN-amplified SK-N-BE(2)-C cells and the effect of the SNP on MYCN binding, and promoter activity was investigated using EMSA and luciferase assays. AG clones exhibited decreased ODC1 expression, growth rates, and histone acetylation and increased sensitivity to ODC1 inhibition. MYCN was a stronger transcriptional regulator of the ODC1 promoter containing the G allele, and preferentially bound the G allele over the A. Two neuroblastoma cohorts were used to investigate the clinical impact of the SNP. In the study cohort, the minor AA genotype was associated with improved survival, while poor prognosis was associated with the GG genotype and AG/GG genotypes in MYCN-amplified and non-amplified patients, respectively. These effects were lost in the GWAS cohort. We have demonstrated that the ODC1 G316A polymorphism has functional significance in neuroblastoma and is subject to allele-specific regulation by the MYCN oncoprotein.

Keywords:  MYCN; ODC1; SNP; neuroblastoma

DOI:  https://doi.org/10.3390/cancers13081807