bims-polyam 2020-11-15 papers

Acta Naturae. 2020 Jul-Sep;12(3):12(3): 140-144

Identification of a Novel Substrate-Derived Spermine Oxidase Inhibitor.

T T Dunston, M A Khomutov, S B Gabelli, T M Stewart, J R Foley, S N Kochetkov, A R Khomutov, R A Casero.

Homeostasis of the biogenic polyamines spermine (Spm) and spermidine (Spd), present in μM-mM concentrations in all eukaryotic cells, is precisely regulated by coordinated activities of the enzymes of polyamine synthesis, degradation, and transport, in order to sustain normal cell growth and viability. Spermine oxidase (SMOX) is the key and most recently discovered enzyme of polyamine metabolism that plays an essential role in regulating polyamine homeostasis by catalyzing the back-conversion of Spm to Spd. The development of many types of epithelial cancer is associated with inflammation, and disease-related inflammatory stimuli induce SMOX. MDL72527 is widely used in vitro and in vivo as an irreversible inhibitor of SMOX, but it is also potent towards N1-acetylpolyamine oxidase. Although SMOX has high substrate specificity, Spm analogues have not been systematically studied as enzyme inhibitors. Here we demonstrate that 1,12-diamino-2,11-bis(methylidene)-4,9-diazadodecane (2,11-Met2-Spm) has, under standard assay conditions, an IC50 value of 169 μM towards SMOX and is an interesting instrument and lead compound for studying polyamine catabolism.

Keywords: 2,11-Met2-Spm; MDL72527; inhibitors; spermine analogues; spermine oxidase

DOI: https://doi.org/10.32607/actanaturae.10992

Autophagy. 2020 Nov 10.

Hydrogen peroxide mediates spermidine-induced autophagy to alleviate salt stress in cucumber.

Yuemei Zhang, Yu Wang, Wenxu Wen, Zhengrong Shi, Qinsheng Gu, Golam Jalal Ahammed, Kai Cao, Mohammad Shah Jahan, Sheng Shu, Jian Wang, Jin Sun, Shirong Guo.

Autophagy, an evolutionally conserved cellular degradation process, plays critical roles in plant development and stress response. Despite the wealth of information on the vital role of autophagy in responses to environmental stresses, little is known about the regulation of autophagy. In this study, we demonstrated that spermidine (Spd), a kind of polyamine, was involved in the regulation of salt tolerance through activating the expression of ATG (autophagy-related) genes and the formation of autophagosomes in cucumber under salt stress. Furthermore, NADPH oxidase-derived apoplastic H2O2-mediated Spd-induced salt tolerance and autophagy. Exogenous Spd significantly increased the tolerance to salt stress and inhibited the accumulation and ubiquitination of insoluble proteins. Foliar application of Spd promoted the transcript levels of ATG genes and autophagosomes formation. Besides, Spd induced the expression of RBOH (respiratory burst oxidase homolog), and the accumulation of H2O2 both in leaves and roots. However, either pretreatment with dimethylthiourea (DMTU, an H2O2 scavenger) or diphenyleneiodonium chloride (DPI, an inhibitor of NADPH oxidase) reduced Spd-induced accumulation of apoplastic H2O2. Importantly, Spd-induced salt tolerance and autophagy were compromised when plants were pretreated with DMTU or DPI. Furthermore, the silencing of ATG4 and ATG7 reduced Spd-induced salt tolerance and autophagosomes formation. Taken together, these results revealed that RBOH-dependent H2O2 mediated the Spd-induced autophagy and salt tolerance in cucumber.

Keywords: autophagy; cucumber; hydrogen peroxide; salt stress; spermidine

DOI: https://doi.org/10.1080/15548627.2020.1847797

Biochemistry. 2020 Nov 11.

Polyamines Mediate Folding of Primordial Hyperacidic Helical Proteins.

Dragana Despotović, Liam M Longo, Einav Aharon, Amit Kahana, Tali Scherf, Ita Gruic-Sovulj, Dan S Tawfik.

Polyamines are known to mediate diverse biological processes, and specifically to bind and stabilize compact conformations of nucleic acids, acting as chemical chaperones that promote folding by offsetting the repulsive negative charges of the phosphodiester backbone. However, whether and how polyamines modulate the structure and function of proteins remain unclear. In particular, early proteins are thought to have been highly acidic, like nucleic acids, due to a scarcity of basic amino acids in the prebiotic context. Perhaps polyamines, the abiotic synthesis of which is simple, could have served as chemical chaperones for such primordial proteins? We replaced all lysines of an ancestral 60-residue helix-bundle protein with glutamate, resulting in a disordered protein with 21 glutamates in total. Polyamines efficiently induce folding of this hyperacidic protein at submillimolar concentrations, and their potency scaled with the number of amine groups. Compared to cations, polyamines were several orders of magnitude more potent than Na+, while Mg2+ and Ca2+ had an effect similar to that of a diamine, inducing folding at approximately seawater concentrations. We propose that (i) polyamines and dications may have had a role in promoting folding of early proteins devoid of basic residues and (ii) coil-helix transitions could be the basis of polyamine regulation in contemporary proteins.

DOI: https://doi.org/10.1021/acs.biochem.0c00800

Zhongguo Ying Yong Sheng Li Xue Za Zhi. 2020 Jul;36(4): 330-335

[Effects of a novel polyamine metabolic enzyme inhibitor SI-4650 on proliferation of colon cancer CT-26 cells and its mechanism].

Jiao-Jiao Huang, Yan-Lin Wang, Li-Dan Sun, Chun-Yu Cao, Ye Qin, Jian-Lin Yang.

OBJECTIVE: To investigate the effects of a novel polyamine metabolism enzyme inhibitor SI-4650 on autophagy and apoptosis of colon cancer CT-26 cells as well as their correlation.
METHODS: CT-26 cells treated with 40, 80 μmol·L-1 SI-4650 alone or in combination with 3-MA were used as experimental group. CT-26 cells treated with 0 μmol·L-1 SI-4650 alone or in combination with 3-MA were used as control group. Chemiluminescence was used to analyze the effect of SI-4650 on spermine oxidase (SMO) and acetylpolyamine oxidase(APAO) activity. High performance liquid chromatography (HPLC) was performed to detect cellular polyamine content.The CCK8 method was used to detect the inhibitory effect of SI-4650 on proliferation of CT-26 cells. PI single-staining/flow cytometry (FCM) were used to analyze cell cycle. Western blot were used to analyze autophagy. Apoptosis was analyzed by PI/FITC-Annexin V double staining, JC-1 fluorescent probe and Fluo-3 AM calcium ion fluorescent probe combined with flow cytometry and Western blot.
RESULTS: CCK8 assay showed that 24-,48-,72-hours treated with SI-4650 all could inhibit the proliferative activity of CT-26 cells in a dose- and time-dependent manner (P＜0.01) . The inhibition rate was 36.98% and 46.91% in 40 μmol·L-1 SI-4650 group and 80 μmol·L-1 SI-4650 group respectively. SI-4650 could significantly inhibit the activities of SMO and APAO interfere with polyamine metabolism and reduce the content of total polyamine in CT-26 cells (P＜0.01). SI-4650 could block CT-26 cells in G0/G1 phase, significantly reduce the number of cells in S phase(P＜0.01), and lead to a significant increase in the contents of autophagy-related Beclin-1, LC3-II in CT-26 cells(P＜0.01); At the same time, the concentration of calcium in CT-26 cells was increased, the mitochondrial membrane potential was decreased, the expressions of c-PARP and Bax were increased, the content of Bcl-2 was decreased, and the number of apoptotic cells was increased. After SI-4650 combined with autophagy inhibitor 3-MA treatment of CT-26 cells, the level of autophagy, the apoptosis-related protein, mitochondrial membrane potential and calcium ion concentration were decreased, and the number of apoptotic cells was decreased.
CONCLUSION: SI-4650 has the pharmacological activity of killing colon cancer CT-26 cells, and its mechanism may be related to the interference of polyamine metabolism and induction of cell apoptosis and autophagy. In this process, autophagy is inhibited to block apoptosis, autophagy and apoptosis combined to kill tumor cells.

Keywords: CT26; apoptosis; autophagy; polyamine metabolic enzyme inhibitor

DOI: https://doi.org/10.12047/j.cjap.5968.2020.071

Plants (Basel). 2020 Nov 09. pii: E1519. [Epub ahead of print]9(11):

The Arabidopsis L-Type Amino Acid Transporter 5 (LAT5/PUT5) Is Expressed in the Phloem and Alters Seed Nitrogen Content When Knocked Out.

Rowshon A Begam, Jayne D'Entremont, Allen Good.

The Arabidopsis L-type Amino Acid Transporter-5 (LAT5; At3g19553) was recently studied for its role in developmental responses such as flowering and senescence, under an assumption that it is a polyamine uptake transporter (PUT5). The LATs in Arabidopsis have a wide range of substrates, including amino acids and polyamines. This report extensively studied the organ and tissue-specific expression of the LAT5/PUT5 and investigated its role in mediating amino acid transport. Organ-specific quantitative RT-PCR detected LAT5/PUT5 transcripts in all organs with a relatively higher abundance in the leaves. Tissue-specific expression analysis identified GUS activity in the phloem under the LAT5/PUT5 promoter. In silico analysis identified both amino acid transporter and antiporter domains conserved in the LAT5/PUT5 protein. The physiological role of the LAT5/PUT5 was studied through analyzing a mutant line, lat5-1, under various growth conditions. The mutant lat5-1 seedlings showed increased sensitivity to exogenous leucine in Murashige and Skoog growth medium. In soil, the lat5-1 showed reduced leaf growth and altered nitrogen content in the seeds. In planta radio-labelled leucine uptake studies showed increased accumulation of leucine in the lat5-1 plants compared to the wild type when treated in the dark prior to the isotopic feeding. These studies suggest that LAT5/PUT5 plays a role in mediating amino acid transport.

Keywords: Arabidopsis; L-type amino acid transporter; LAT; LAT5; PUT5; amino acid translocation; amino acids; nitrogen; polyamine uptake transporter; seed nitrogen

DOI: https://doi.org/10.3390/plants9111519

Life Sci. 2020 Nov 10. pii: S0024-3205(20)31492-2. [Epub ahead of print] 118739

Spermidine ameliorates high-fat diet-induced hepatic steatosis and adipose tissue inflammation in preexisting obese mice.

Lingyan Ma, Yinhua Ni, Luting Hu, Yufeng Zhao, Liujie Zheng, Song Yang, Liyang Ni, Zhengwei Fu.

AIMS: The therapeutic effects of spermidine on preexisting obese mice have been not fully elucidated. In this study, we assessed the anti-obesity impact of spermidine on high-fat diet (HFD)-induced obese mice.
MAIN METHODS: C57BL/6J mice were fed a HFD for 16 weeks to induce obesity, and then treated with or without spermidine via drinking water for additional 8 weeks. The contributions of spermidine in regulating obesity phenotypes and metabolic syndrome were further evaluated.
KEY FINDINGS: Spermidine administration lowered fat mass and plasma lipid profile in HFD-induced obese mice without affecting body weight. In addition, spermidine attenuated hepatic steatosis by regulating lipid metabolism and enhancing antioxidant capacity. Moreover, spermidine reduced adipose tissue inflammation by decreasing inflammatory cytokine and chemokines expression, and these results might contributed to the enhanced thermogenic gene expression in brown adipose tissue. Furthermore, spermidine treatment enhanced gut barrier function by up-regulating tight junction- and mucin-related gene expression.
SIGNIFICANCE: Spermidine-mediated protective impacts involve the regulation of lipid metabolism, inflammation response, gut barrier function and thermogenesis. These findings demonstrate that spermidine has potentials in treating obesity.

Keywords: Gut barrier; Hepatic steatosis; Inflammation; Obesity; Spermidine

DOI: https://doi.org/10.1016/j.lfs.2020.118739

Eur J Med Genet. 2020 Nov 10. pii: S1769-7212(20)30807-7. [Epub ahead of print] 104097

Digestive involvement in a severe form of Snyder-Robinson syndrome: possible expansion of the phenotype.

Pauline Dontaine, Elisa Kottos, Martine Dassonville, Ovidiu Balasel, Véronique Catros, Julie Soblet, Pascale Perlot, Catheline Vilain.

Snyder-Robinson syndrome (OMIM #309583) is a rare X-linked condition, caused by mutation in the SMS gene (MIM *300105), characterized by a wide spectrum of clinical signs including developmental delay, epilepsy, asthenic habitus, dysmorphism, osteopenia, and renal or genital anomalies. Here we describe two maternal half-brothers who both presented with severe neurodevelopmental delay, seizures, hearing loss, facial dysmorphism, renal and ophthalmologic anomalies, failure to thrive and premature death. A novel p.(Gly203Asp) variant was found at the hemizygous state in the two boys, and an elevated Spermidine/Spermine ratio confirmed the diagnosis of Snyder-Robinson syndrome. One of the brothers presented with gastrointestinal symptoms, with jejunal stenosis, enteral feeding intolerance, failure to thrive due to a dysfunctional gastrointestinal system, cholestasis and exocrine pancreatic insufficiency. Although more studies will be needed to understand its mechanisms, this observation lends further support to the possibility of severe digestive involvement in Snyder Robinson syndrome.

Keywords: Main text; SMS; Snyder-Robinson; failure to thrive; mendeliome; new variant

DOI: https://doi.org/10.1016/j.ejmg.2020.104097