Genetic approaches to the cellular functions of polyamines in mammals

Metabolomic profiling of upper GI malignancies in blood and tissue: a systematic review and meta-analysis

OBJECTIVE

To conduct a systematic review and meta-analysis of case-control and cohort human studies evaluating metabolite markers identified using high-throughput metabolomics techniques on esophageal cancer (EC), cancer of the gastroesophageal junction (GEJ), and gastric cancer (GC) in blood and tissue.

BACKGROUND

Upper gastrointestinal cancers (UGC), predominantly EC, GEJ, and GC, are malignant tumour types with high morbidity and mortality rates. Numerous studies have focused on metabolomic profiling of UGC in recent years. In this systematic review and meta-analysis, we have provided a collective summary of previous findings on metabolites and metabolomic profiling associated with EC, GEJ and GC.

METHODS

Following the PRISMA procedure, a systematic search of four databases (Embase, PubMed, MEDLINE, and Web of Science) for molecular epidemiologic studies on the metabolomic profiles of EC, GEJ and GC was conducted and registered at PROSPERO (CRD42023486631). The Newcastle-Ottawa Scale (NOS) was used to benchmark the risk of bias for case-controlled and cohort studies. QUADOMICS, an adaptation of the QUADAS-2 (Quality Assessment of Diagnostic Accuracy) tool, was used to rate diagnostic accuracy studies. Original articles comparing metabolite patterns between patients with and without UGC were included. Two investigators independently completed title and abstract screening, data extraction, and quality evaluation. Meta-analysis was conducted whenever possible. We used a random effects model to investigate the association between metabolite levels and UGC.

RESULTS

A total of 66 original studies involving 7267 patients that met the required criteria were included for review. 169 metabolites were differentially distributed in patients with UGC compared to healthy patients among 44 GC, 9 GEJ, and 25 EC studies including metabolites involved in glycolysis, anaerobic respiration, tricarboxylic acid cycle, and lipid metabolism. Phosphatidylcholines, eicosanoids, and adenosine triphosphate were among the most frequently reported lipids and metabolites of cellular respiration, while BCAA, lysine, and asparagine were among the most commonly reported amino acids. Previously identified lipid metabolites included saturated and unsaturated free fatty acids and ketones. However, the key findings across studies have been inconsistent, possibly due to limited sample sizes and the majority being hospital-based case-control analyses lacking an independent replication group.

CONCLUSION

Thus far, metabolomic studies have provided new opportunities for screening, etiological factors, and biomarkers for UGC, supporting the potential of applying metabolomic profiling in early cancer diagnosis. According to the results of our meta-analysis especially BCAA and TMAO as well as certain phosphatidylcholines should be implicated into the diagnostic procedure of patients with UGC. We envision that metabolomics will significantly enhance our understanding of the carcinogenesis and progression process of UGC and may eventually facilitate precise oncological and patient-tailored management of UGC.

Unveiling the hidden players: noncoding RNAs orchestrating polyamine metabolism in disease

Polyamines (PA) are polycations with pleiotropic functions in cellular physiology and pathology. In particular, PA have been involved in the regulation of cell homeostasis and proliferation participating in the control of fundamental processes like DNA transcription, RNA translation, protein hypusination, autophagy and modulation of ion channels. Indeed, their dysregulation has been associated to inflammation, oxidative stress, neurodegeneration and cancer progression. Accordingly, PA intracellular levels, derived from the balance between uptake, biosynthesis, and catabolism, need to be tightly regulated. Among the mechanisms that fine-tune PA metabolic enzymes, emerging findings highlight the importance of noncoding RNAs (ncRNAs). Among the ncRNAs, microRNA, long noncoding RNA and circRNA are the most studied as regulators of gene expression and mRNA metabolism and their alteration have been frequently reported in pathological conditions, such as cancer progression and brain diseases. In this review, we will discuss the role of ncRNAs in the regulation of PA genes, with a particular emphasis on the changes of this modulation observed in health disorders.

Effect of S-adenosyl-methionine accumulation on hineka odor in sake brewed with a non-Kyokai yeast

Hineka is a type of off-flavor of sake and is attributed to the presence of several compounds, including a major one called dimethyl trisulfide (DMTS). The production of the main precursor of DMTS involves yeast methionine salvage pathway. The DMTS-producing potential (DMTS-pp) of sake brewed using the Km67 strain, a non-Kyokai sake yeast, is lower than that of sake brewed using Kyokai yeast; however, the detailed mechanism is unclear. We focused on S-adenosyl-methionine (SAM) and aimed to elucidate the mechanism that prevents DMTS production in sake brewed using the Km67 strain. We revealed that SAM is involved in DMTS production in sake, and that the conversion of SAM to the DMTS precursor occurs through an enzymatic reaction rather than a chemical reaction. Based on previous reports on ADO1 and MDE1 genes, sake brewing tests were performed using the Km67 Δmde1, Δado1, and Δmde1Δado1 strains. A comparison of the SAM content of pressed sake cakes and DMTS-pp of sake produced using the Km67 Δado1 strain showed an increase in both SAM content and DMTS-pp compared to those produced using the parent strain. However, the Km67 Δmde1Δado1 strain showed little increase in DMTS-pp compared to the Km67 Δmde1 strain, despite an increase in SAM content. These results suggest that SAM accumulation in yeast plays a role in the production of DMTS in sake through the methionine salvage pathway. Moreover, the low SAM-accumulation characteristic of the Km67 strain contributes to low DMTS production in sake.

Possible Role of Cellular Polyamine Metabolism in Neuronal Apoptosis

Recent studies have shown that cellular levels of polyamines (PAs) are significantly altered in neurodegenerative diseases. Evidence from in vivo animal and in vitro cell experiments suggests that the cellular levels of various PAs may play important roles in the central nervous system through the regulation of oxidative stress, mitochondrial metabolism, cellular immunity, and ion channel functions. Dysfunction of PA metabolism related enzymes also contributes to neuronal injury and cognitive impairment in many neurodegenerative diseases. Therefore, in the current work, evidence was collected to determine the possible associations between cellular levels of PAs, and related enzymes and the development of several neurodegenerative diseases, which could provide a new idea for the treatment of neurodegenerative diseases in the future.

Bachmann-Bupp syndrome and treatment

Bachmann-Bupp syndrome (BABS) is a neurodevelopmental disorder characterized by developmental delay, hypotonia, and varying forms of non-congenital alopecia. The condition is caused by 3'-end mutations of the ornithine decarboxylase 1 (ODC1) gene, which produce carboxy (C)-terminally truncated variants of ODC, a pyridoxal 5'-phosphate-dependent enzyme. C-terminal truncation of ODC prevents its ubiquitin-independent proteasomal degradation and leads to cellular accumulation of ODC enzyme that remains catalytically active. ODC is the first rate-limiting enzyme that converts ornithine to putrescine in the polyamine pathway. Polyamines (putrescine, spermidine, spermine) are aliphatic molecules found in all forms of life and are important during embryogenesis, organogenesis, and tumorigenesis. BABS is an ultra-rare condition with few reported cases, but it serves as a convincing example for drug repurposing therapy. α-Difluoromethylornithine (DFMO, also known as eflornithine) is an ODC inhibitor with a strong safety profile in pediatric use for neuroblastoma and other cancers as well as West African sleeping sickness (trypanosomiasis). Patients with BABS have been treated with DFMO and have shown improvement in hair growth, muscle tone, and development.

Polyamines and hormesis: Making sense of a dose response dichotomy

The diverse biological effects of polyamines (putrescine, spermidine and spermine) were reviewed in the context of hormesis in an integrative manner for the first time. The findings illustrate that each of these polyamines commonly induces hormetic dose responses in a wide range of biological models and types of cells for multiple endpoints in numerous plant species and animal models. Plant research emphasized preconditioning experimental studies in which the respective polyamines conferred some protection against the damaging effects of a broad range of environmental stressors such as drought, salinity, cold/heat, heavy metals and UV-damage in an hormetic manner. Polyamine-based animal hormesis studies emphasized biomedical endpoints such as longevity and neuroprotection. These findings have important biological and biomedical implications and should guide experimental designs of low dose investigations.

Comparison of the signaling pathways of wing dimorphism regulated by biotic and abiotic stress in the brown planthopper

Wing polymorphism is an evolutionary trait that is widely present in various insects and provides a model system for studying the evolutionary significance of insect dispersal. The brown planthopper (BPH, Nilaparvata lugens) can alter its wing morphs under biotic and abiotic stress. However, whether differential signaling pathways are induced by the 2 types of stress remain largely unknown. Here, we screened a number of candidate genes through weighted gene co-expression network analysis (WGCNA) and found that ornithine decarboxylase (NlODC), a key enzyme in the synthesis of polyamines, was associated with wing differentiation in BPH and mainly responded to abiotic stress stimuli. We analyzed the Kyoto Encyclopedia of Genes and Genomes enrichment pathways of differentially expressed genes under the 2 stresses by transcriptomic comparison, and found that biotic stress mainly influenced insulin-related signaling pathways while abiotic stress mainly influenced hormone-related pathways. Moreover, we found that insulin receptor 1 (NlInR1) may regulate wing differentiation of BPH by responding to both biotic and abiotic stress, but NlInR2 only responded to biotic stress. Similarly, the juvenile hormone epoxide hydrolase associated with juvenile hormone degradation and NlODC may regulate wing differentiation mainly through abiotic stress. A model based on the genes and stresses to modulate the wing dimorphism of BPH was proposed. These findings present a comprehensive molecular mechanism for wing polymorphism in BPH induced by biotic and abiotic stress.

Structural change study of pepsin in the presence of spermidine trihydrochloride: Insights from spectroscopic to molecular dynamics methods

Spermidine is an aliphatic polyamine that directs a set of biological processes. This work aimed to use UV-Vis spectroscopy, fluorescence spectroscopy, thermal stability, kinetic methods, docking, and molecular dynamic simulations to examine the influence of spermidine trihydrochloride (SP) on the structure and function of pepsin. The results of the fluorescence emission spectra indicated that spermidine could quench pepsin's intrinsic emission in a static quenching process, resulting in the formation of the pepsin-spermidine complex. The results discovered that spermidine had a strong affinity to the pepsin structure because of its high binding constant. The obtained results from spectroscopy and molecular dynamic approaches showed the binding interaction between spermidine and pepsin, induced micro-environmental modifications around tryptophan residues that caused a change in the tertiary and secondary structure of the enzyme. FTIR analysis showed hypochromic effects in the spectra of amide I and II and redistribution of the helical structure. Moreover, the molecular dynamic (MD) and docking studies confirmed the experimental data. Both experimental and molecular dynamics simulation results clarified that electrostatic bond interactions were dominant forces.

Changes in the Localization of Polyamine Spermidine in the Rat Retina with Age

Polyamines (PAs) in the nervous system has a key role in regeneration and aging. Therefore, we investigated age-related changes in the expression of PA spermidine (SPD) in the rat retina. Fluorescent immunocytochemistry was used to evaluate the accumulation of SPD in retinae from rats of postnatal days 3, 21, and 120. Glial cells were identified using glutamine synthetase (GS), whereas DAPI, a marker of cell nuclei, was used to differentiate between retinal layers. SPD localization in the retina was strikingly different between neonates and adults. In the neonatal retina (postnatal day 3-P3), SPD is strongly expressed in practically all cell types, including radial glia and neurons. SPD staining showed strong co-localization with the glial marker GS in Müller Cells (MCs) in the outer neuroblast layer. In the weaning period (postnatal day 21-P21), the SPD label was strongly expressed in all MCs, but not in neurons. In early adulthood (postnatal day 120-P120), SPD was localized in MCs only and was co-localized with the glial marker GS. A decline in the expression of PAs in neurons was observed with age while glial cells accumulated SPD after the differentiation stage (P21) and during aging in MC cellular endfoot compartments.

Impact of Postharvest Putrescine Treatments on Phenolic Compounds, Antioxidant Capacity, Organic Acid Contents and Some Quality Characteristics of Fresh Fig Fruits during Cold Storage

The storage and shelf life of the fig, which has a sensitive fruit structure, is short, and this results in excessive economic losses. In a study carried out to contribute to the solution of this problem, the effect of postharvest putrescine application at different doses (0, 0.5, 1.0, 2.0, and 4.0 mM) on fruit quality characteristics and biochemical content during cold storage in figs was determined. At the end of the cold storage, the decay rate and weight loss in the fruit were in the ranges of 1.0-1.6% and 1.0-5.0 %, respectively. The decay rate and weight loss were lower in putrescine-applied fruit during cold storage. Putrescine application had a positive effect on the changes in fruit flesh firmness values. The SSC rate of fruit varied between 14 and 20%, while significant differences in the SSC rate occurred depending on storage time and putrescine application dose. With putrescine application, the decrease in the acidity rate of the fig fruit during cold storage was smaller. At the end of the cold storage, the acidity rate was between 1.5-2.5% and 1.0-5.0. Putrescine treatments affected total antioxidant activity values and changes occurred in total antioxidant activity depending on the application dose. In the study, it was observed that the amount of phenolic acid in fig fruit decreased during storage and putrescine doses prevented this decrease. Putrescine treatment affected the changes in the quantity of organic acids during cold storage, and this effect varied depending on the type of organic acid and the length of the cold storage period. As a result, it was revealed that putrescine treatments can be used as an effective method to maintain postharvest fruit quality in figs.

Progress in fed-batch culture for recombinant protein production in CHO cells

Nearly 80% of the approved human therapeutic antibodies are produced by Chinese Hamster Ovary (CHO) cells. To achieve better cell growth and high-yield recombinant protein, fed-batch culture is typically used for recombinant protein production in CHO cells. According to the demand of nutrients consumption, feed medium containing multiple components in cell culture can affect the characteristics of cell growth and improve the yield and quality of recombinant protein. Fed-batch optimization should have a connection with comprehensive factors such as culture environmental parameters, feed composition, and feeding strategy. At present, process intensification (PI) is explored to maintain production flexible and meet forthcoming demands of biotherapeutics process. Here, CHO cell culture, feed composition in fed-batch culture, fed-batch culture environmental parameters, feeding strategies, metabolic byproducts in fed-batch culture, chemostat cultivation, and the intensified fed-batch are reviewed. KEY POINTS: • Fed-batch culture in CHO cells is reviewed. • Fed-batch has become a common technology for recombinant protein production. • Fed batch culture promotes recombinant protein production in CHO cells.

SLC3A2 and SLC7A2 Mediate the Exogenous Putrescine-Induced Adipocyte Differentiation

Exogenous polyamines are able to induce life span and improve glucose homeostasis and insulin sensitivity. However, the effects of exogenous polyamines on adipocyte differentiation and which polyamine transporters mediate them have not been elucidated yet. Here, we identified for the first time that exogenous polyamines can clearly stimulate adipocyte differentiation through polyamine transporters, solute carrier family 3 member A2 (SLC3A2) and SLC7A1. Exogenous polyamines markedly promote 3T3-L1 adipocyte differentiation by increasing the intracellular lipid accumulation and the expression of both adipogenic and lipogenic genes in a concentration-dependent manner. In particular, exogenous putrescine mainly regulates adipocyte differentiation in the early and intermediate stages. Moreover, we have assessed the expression of polyamine transporter genes in 3T3-L1 preadipocytes and adipocytes. Interestingly, the putrescine-induced adipocyte differentiation was found to be significantly suppressed in response to a treatment with a polyamine transporter inhibitor (AMXT-1501). Furthermore, knockdown experiments using siRNA that specifically targeted SLC3A2 or SLC7A2, revealed that both SLC3A2 and SLC7A2 act as important transporters in the cellular importing of exogenous putrescine. Thus, the exogenous putrescine entering the adipocytes via cellular transporters is involved in adipogenesis through a modulation of both the mitotic clonal expansion and the expression of master transcription factors. Taken together, these results suggest that exogenous polyamines (such as putrescine) entering the adipocytes through polyamine transporters, can stimulate adipogenesis.

The role of polyamine metabolism in remodeling immune responses and blocking therapy within the tumor immune microenvironment

The study of metabolism provides important information for understanding the biological basis of cancer cells and the defects of cancer treatment. Disorders of polyamine metabolism is a common metabolic change in cancer. With the deepening of understanding of polyamine metabolism, including molecular functions and changes in cancer, polyamine metabolism as a new anti-cancer strategy has become the focus of attention. There are many kinds of polyamine biosynthesis inhibitors and transport inhibitors, but not many drugs have been put into clinical application. Recent evidence shows that polyamine metabolism plays essential roles in remodeling the tumor immune microenvironment (TIME), particularly treatment of DFMO, an inhibitor of ODC, alters the immune cell population in the tumor microenvironment. Tumor immunosuppression is a major problem in cancer treatment. More and more studies have shown that the immunosuppressive effect of polyamines can help cancer cells to evade immune surveillance and promote tumor development and progression. Therefore, targeting polyamine metabolic pathways is expected to become a new avenue for immunotherapy for cancer.

Dietary Polyamines Intake and Risk of Colorectal Cancer: A Case-Control Study

Polyamines (including putrescine, spermidine, and spermine) are small, cationic molecules that are necessary for cell proliferation and differentiation. Few studies have examined the association of dietary polyamines intake with colorectal cancer risk. The aim of this study was to evaluate total polyamines, putrescine, spermidine, and spermine intake in relation to colorectal cancer risk in China. In total, 2502 colorectal cancer cases and 2538 age-(5-year interval) and sex-matched controls were recruited from July 2010 to April 2019. Odds ratios (ORs) and 95% confidence intervals (CI) were calculated by multivariable unconditional logistic regression after adjustment for various potential confounding factors. Higher intake of total polyamine, putrescine and spermidine was significantly associated with reduced risk of colorectal cancer. The adjusted ORs for the highest compared with the lowest quartile of intake were 0.60 (95% CI 0.50, 0.72; P_trend < 0.001) for total polyamines, 0.35 (95% CI 0.29, 0.43; P_trend < 0.001) for putrescine and 0.79 (95% CI 0.66, 0.95; P_trend = 0.001) for spermidine, respectively. However, higher intake of spermine was associated with increased risk of colorectal cancer, with an adjusted OR of 1.58 (95% CI 1.29, 1.93; P_trend < 0.001). This data indicate that higher intake of total polyamines, putrescine and spermidine, as well as lower intake of spermine, is associated with a decreased risk of colorectal cancer.

S-adenosyl methionine synthetase SAMS-5 mediates dietary restriction-induced longevity in Caenorhabditis elegans

S-adenosyl methionine synthetase (SAMS) catalyzes the biosynthesis of S-adenosyl methionine (SAM), which serves as a universal methyl group donor for numerous biochemical reactions. Previous studies have clearly demonstrated that SAMS-1, a C. elegans homolog of mammalian SAMS, is critical for dietary restriction (DR)-induced longevity in Caenorhabditis elegans. In addition to SAMS-1, three other SAMS paralogs have been identified in C. elegans. However, their roles in longevity regulation have never been explored. Here, we show that depletion of sams-5, but not sams-3 or sams-4, can extend lifespan in worms. However, the phenotypes and expression pattern of sams-5 are distinct from sams-1, suggesting that these two SAMSs might regulate DR-induced longevity via different mechanisms. Through the genetic epistasis analysis, we have identified that sams-5 is required for DR-induced longevity in a pha-4/FOXA dependent manner.

Spermidine alleviates cardiac aging by improving mitochondrial biogenesis and function

Polyamines have been shown to delay cellular and organismal aging and to provide cardiovascular protection in humans. Because age-related cardiovascular dysfunction is often accompanied by impaired mitochondrial biogenesis and function, we explored the ability of spermidine (SPD), a major mammalian polyamine, to attenuate cardiac aging through activation of mitochondrial biogenesis. Cardiac polyamine levels were reduced in aged (24-month-old) rats. Six-week SPD supplementation restored cardiac polyamine content, preserved myocardial ultrastructure, and inhibited mitochondrial dysfunction. Immunoblotting showed that ornithine decarboxylase (ODC) and SPD/spermine N1-acetyltransferase (SSAT) were downregulated and upregulated, respectively, in the myocardium of older rats. These changes were paralleled by age-dependent downregulation of components of the sirtuin-1/peroxisome proliferator-activated receptor gamma coactivator alpha (SIRT1/PGC-1α) signaling pathway, an important regulator of mitochondrial biogenesis. SPD administration increased SIRT1, PGC-1α, nuclear respiratory factors 1 and 2 (NRF1, NRF2), and mitochondrial transcription factor A (TFAM) expression; decreased ROS production; and improved OXPHOS performance in senescent (H₂O₂-treated) cardiomyocytes. Inhibition of polyamine biosynthesis or SIRT1 activity abolished these effects. PGC-1α knockdown experiments confirmed that SPD activated mitochondrial biogenesis through SIRT1-mediated deacetylation of PGC-1α. These data provide new insight into the antiaging effects of SPD, and suggest potential applicability to protect against deterioration of cardiac function with aging.

Unforeseen Possibilities To Investigate the Regulation of Polyamine Metabolism Revealed by Novel C-Methylated Spermine Derivatives

The biogenic polyamines, spermine (Spm) and spermidine, are organic polycations present in millimolar concentrations in all eukaryotic cells participating in the regulation of vital cellular functions including proliferation and differentiation. The design and biochemical evaluation of polyamine analogues are cornerstones of polyamine research. Here we synthesized and studied novel C-methylated Spm analogues: 2,11-dimethylspermine (2,11-Me2Spm), 3,10-dimethylspermine (3,10-Me2Spm), 2-methylspermine, and 2,2-dimethylspermine. The tested analogues overcame growth arrest induced by a 72 h treatment with α-difluoromethylornithine, an ornithine decarboxylase (ODC) inhibitor, and entered into DU145 cells via the polyamine transporter. 3,10-Me2Spm was a poor substrate of spermine oxidase and spermidine/spermine-N1-acetyltransferase (SSAT) when compared with 2,11-Me2Spm, thus resembling 1,12-dimethylspermine, which lacks the substrate properties required for the SSAT reaction. The antizyme (OAZ1)-mediated downregulation of ODC and inhibition of polyamine transport are crucial in the maintenance of polyamine homeostasis. Interestingly, 3,10-Me2Spm was found to be the first Spm analogue that did not induce OAZ1 and, consequently, was a weak downregulator of ODC activity in DU145 cells.

Polyamines: The possible missing link between mental disorders and epilepsy (Review)

Polyamines are small positively charged alkylamines that are essential in a number of crucial eukaryotic processes, like normal cell growth and development. In normal physiological conditions, intracellular polyamine content is tightly regulated through a fine regulated network of biosynthetic and catabolic enzymes and a transport system. The dysregulation of this network is frequently associated to different tumors, where high levels of polyamines has been detected. Polyamines also modulate ion channels and ionotropic glutamate receptors and altered levels of polyamines have been observed in different brain diseases, including mental disorders and epilepsy. The goal of this article is to review the role of polyamines in mental disorders and epilepsy within a frame of the possible link between these two brain pathologies. The high comorbidity between these two neurological illnesses is strongly suggestive that they share a common background in the central nervous system. This review proposes an additional association between the noradrenalin/serotonin and glutamatergic neuronal circuits with polyamines. Polyamines can be considered supplementary defensive shielding molecules, important to protect the brain from the development of epilepsy and mental illnesses that are caused by different types of neurons. In this contest, the modulation of polyamine metabolism may be a novel important target for the prevention and therapeutic treatment of these diseases that have a high impact on the costs of public health and considerably affect quality of life.

Dietary and Gut Microbiota Polyamines in Obesity- and Age-Related Diseases

The polyamines putrescine, spermidine, and spermine are widely distributed polycationic compounds essential for cellular functions. Intracellular polyamine pools are tightly regulated by a complex regulatory mechanism involving de novo biosynthesis, catabolism, and transport across the plasma membrane. In mammals, both the production of polyamines and their uptake from the extracellular space are controlled by a set of proteins named antizymes and antizyme inhibitors. Dysregulation of polyamine levels has been implicated in a variety of human pathologies, especially cancer. Additionally, decreases in the intracellular and circulating polyamine levels during aging have been reported. The differences in the polyamine content existing among tissues are mainly due to the endogenous polyamine metabolism. In addition, a part of the tissue polyamines has its origin in the diet or their production by the intestinal microbiome. Emerging evidence has suggested that exogenous polyamines (either orally administrated or synthetized by the gut microbiota) are able to induce longevity in mice, and that spermidine supplementation exerts cardioprotective effects in animal models. Furthermore, the administration of either spermidine or spermine has been shown to be effective for improving glucose homeostasis and insulin sensitivity and reducing adiposity and hepatic fat accumulation in diet-induced obesity mouse models. The exogenous addition of agmatine, a cationic molecule produced through arginine decarboxylation by bacteria and plants, also exerts significant effects on glucose metabolism in obese models, as well as cardioprotective effects. In this review, we will discuss some aspects of polyamine metabolism and transport, how diet can affect circulating and local polyamine levels, and how the modulation of either polyamine intake or polyamine production by gut microbiota can be used for potential therapeutic purposes.

Novel de novo pathogenic variant in the ODC1 gene in a girl with developmental delay, alopecia, and dysmorphic features

The ornithine decarboxylase 1 (ODC1) gene plays an important role in physiological and cell developmental processes including embryogenesis, organogenesis, and neoplastic cell growth. Here, we report an 32-month-old Caucasian female with a heterozygous de novo nonsense mutation in the ODC1 gene that leads to a premature abrogation of 14-aa residues at the ODC protein c-terminus. This is the first human case confirming similar symptoms observed in a transgenic ODC1 mouse model first described over 20 years ago. Phenotypic manifestations include macrosomia, macrocephaly, developmental delay, alopecia, spasticity, hypotonia, cutaneous vascular malformation, delayed visual maturation, and sensorineural hearing loss. We here describe for the first time a new pediatric disorder that is directly linked to a de novo pathogenic variant in the ODC1 gene. The ODC1 gene mutation (c.1342 A>T) was identified by whole-exome sequencing and confirmed by Sanger sequencing. Red blood cells obtained from our patient showed elevated ODC protein and polyamine levels compared to healthy controls. Our autosomal dominant patient who carries this gain-of-function ODC1 mutation may benefit from treatment with α-difluoromethylornithine, a well-tolerated, U.S. Food and Drug Administration (FDA). FDA-approved drug.

Proteomic profile approach of effect of putrescine depletion over Trichomonas vaginalis

Infection with Trichomonas vaginalis produces a malodorous seropurulent vaginal discharge due to several chemicals, including polyamines. The presence of 1,4-diamino-2-butanone (DAB) reduces the amount of intracellular putrescine by 90%, preventing the cotransport of exogenous spermine. DAB-treated parasites present morphological changes, which are restored by adding exogenous putrescine into the culture medium. However, the effect of polyamines over the trichomonad proteomic profile is unknown. In this study, we used a proteomic approach to analyze the polyamine-depletion and restoration effect by exogenous putrescine on T. vaginalis proteome. In the presence of inhibitor DAB, we obtained 369 spots in polyamine-depleted condition and observed 499 spots in the normal culture media. With DAB treatment, the intensity of 43 spots was increased but was found to be reduced in 39 spots, as compared to normal conditions. Interestingly, in DAB-treated parasites restored with a medium with added exogenous putrescine, 472 spots were found, of which 33 were upregulated and 63 were downregulated in protein intensity. Some of these downregulated proteins in DAB-treated parasites are involved in several cellular pathways such as glycolysis, glycolytic fermentation, arginine dihydrolase pathway, redox homeostasis, host cell binding mediated by carbohydrate, chaperone function, and cytoskeletal remodeling. Interestingly, the intensity of some of the proteins was restored by adding exogenous putrescine. In conclusion, the presence of DAB altered the proteomic profile of T. vaginalis, resulting in a decrease in the intensity of 130 proteins and an increase in the intensity of 43 proteins that was restored by the addition of putrescine.

Glucocorticoids, genes and brain function

The identification of key genes in transcriptomic data constitutes a huge challenge. Our review of microarray reports revealed 88 genes whose transcription is consistently regulated by glucocorticoids (GCs), such as cortisol, corticosterone and dexamethasone, in the brain. Replicable transcriptomic data were combined with biochemical and physiological data to create an integrated view of the effects induced by GCs. The most frequently reported genes were Errfi1 and Ddit4. Their up-regulation was associated with the altered transcription of genes regulating growth factor and mTORC1 signaling (Gab1, Tsc22d3, Dusp1, Ndrg2, Ppp5c and Sesn1) and progression of the cell cycle (Ccnd1, Cdkn1a and Cables1). The GC-induced reprogramming of cell function involves changes in the mRNA level of genes responsible for the regulation of transcription (Klf9, Bcl6, Klf15, Tle3, Cxxc5, Litaf, Tle4, Jun, Sox4, Sox2, Sox9, Irf1, Sall2, Nfkbia and Id1) and the selective degradation of mRNA (Tob2). Other genes are involved in the regulation of metabolism (Gpd1, Aldoc and Pdk4), actin cytoskeleton (Myh2, Nedd9, Mical2, Rhou, Arl4d, Osbpl3, Arhgef3, Sdc4, Rdx, Wipf3, Chst1 and Hepacam), autophagy (Eva1a and Plekhf1), vesicular transport (Rhob, Ehd3, Vps37b and Scamp2), gap junctions (Gjb6), immune response (Tiparp, Mertk, Lyve1 and Il6r), signaling mediated by thyroid hormones (Thra and Sult1a1), calcium (Calm2), adrenaline/noradrenaline (Adcy9 and Adra1d), neuropeptide Y (Npy1r) and histamine (Hdc). GCs also affected genes involved in the synthesis of polyamines (Azin1) and taurine (Cdo1). The actions of GCs are restrained by feedback mechanisms depending on the transcription of Sgk1, Fkbp5 and Nr3c1. A side effect induced by GCs is increased production of reactive oxygen species. Available data show that the brain's response to GCs is part of an emergency mode characterized by inactivation of non-core activities, restrained inflammation, restriction of investments (growth), improved efficiency of energy production and the removal of unnecessary or malfunctioning cellular components to conserve energy and maintain nutrient supply during the stress response.

Alpha-Difluoromethylornithine, an Irreversible Inhibitor of Polyamine Biosynthesis, as a Therapeutic Strategy against Hyperproliferative and Infectious Diseases

The fluorinated ornithine analog α-difluoromethylornithine (DFMO, eflornithine, ornidyl) is an irreversible suicide inhibitor of ornithine decarboxylase (ODC), the first and rate-limiting enzyme of polyamine biosynthesis. The ubiquitous and essential polyamines have many functions, but are primarily important for rapidly proliferating cells. Thus, ODC is potentially a drug target for any disease state where rapid growth is a key process leading to pathology. The compound was originally discovered as an anticancer drug, but its effectiveness was disappointing. However, DFMO was successfully developed to treat African sleeping sickness and is currently one of few clinically used drugs to combat this neglected tropical disease. The other Food and Drug Administration (FDA) approved application for DFMO is as an active ingredient in the hair removal cream Vaniqa. In recent years, renewed interest in DFMO for hyperproliferative diseases has led to increased research and promising preclinical and clinical trials. This review explores the use of DFMO for the treatment of African sleeping sickness and hirsutism, as well as its potential as a chemopreventive and chemotherapeutic agent against colorectal cancer and neuroblastoma.

Polyamines: Bio-Molecules with Diverse Functions in Plant and Human Health and Disease

Biogenic amines-polyamines (PAs), particularly putrescine, spermidine and spermine are ubiquitous in all living cells. Their indispensable roles in many biochemical and physiological processes are becoming commonly known, including promoters of plant life and differential roles in human health and disease. PAs positively impact cellular functions in plants-exemplified by increasing longevity, reviving physiological memory, enhancing carbon and nitrogen resource allocation/signaling, as well as in plant development and responses to extreme environments. Thus, one or more PAs are commonly found in genomic and metabolomics studies using plants, particulary during different abiotic stresses. In humans, a general decline in PA levels with aging occurs parallel with some human health disorders. Also, high PA dose is detrimental to patients suffering from cancer, aging, innate immunity and cognitive impairment during Alzheimer and Parkinson diseases. A dichotomy exists in that while PAs may increase longevity and reduce some age-associated cardiovascular diseases, in disease conditions involving higher cellular proliferation, their intake has negative consequences. Thus, it is essential that PA levels be rigorously quantified in edible plant sources as well as in dietary meats. Such a database can be a guide for medical experts in order to recommend which foods/meats a patient may consume and which ones to avoid. Accordingly, designing both high and low polyamine diets for human consumption are in vogue, particularly in medical conditions where PA intake may be detrimental, for instance, cancer patients. In this review, literature data has been collated for the levels of the three main PAs, putrescine, spermidine and spermine, in different edible sources-vegetables, fruits, cereals, nuts, meat, sea food, cheese, milk, and eggs. Based on our analysis of vast literature, the effects of PAs in human/animal health fall into two broad, Yang and Yin, categories: beneficial for the physiological processes in healthy cells and detrimental under pathological conditions.

Advances in Degradable Embolic Microspheres: A State of the Art Review

Considerable efforts have been placed on the development of degradable microspheres for use in transarterial embolization indications. Using the guidance of the U.S. Food and Drug Administration (FDA) special controls document for the preclinical evaluation of vascular embolization devices, this review consolidates all relevant data pertaining to novel degradable microsphere technologies for bland embolization into a single reference. This review emphasizes intended use, chemical composition, degradative mechanisms, and pre-clinical safety, efficacy, and performance, while summarizing the key advantages and disadvantages for each degradable technology that is currently under development for transarterial embolization. This review is intended to provide an inclusive reference for clinicians that may facilitate an understanding of clinical and technical concepts related to this field of interventional radiology. For materials scientists, this review highlights innovative devices and current evaluation methodologies (i.e., preclinical models), and is designed to be instructive in the development of innovative/new technologies and evaluation methodologies.

Polyamines, folic acid supplementation and cancerogenesis

Clinical practice and experimental studies have shown the necessity of sufficient quantities of folic acid intake for normal embryogenesis and fetal development in the prevention of neural tube defects (NTDs) and neurological malformations. So, women of childbearing age must be sure to have an adequate folate intake periconceptionally, prior to and during pregnancy. Folic acid fortification of all enriched cereal grain product flour has been implemented in many countries. Thus, hundreds of thousands of people have been exposed to an increased intake of folic acid. Folate plays an essential role in the biosynthesis of methionine. Methionine is the principal aminopropyl donor required for polyamine biosynthesis, which is up-regulated in actively growing cells, including cancer cells. Folates are important in RNA and DNA synthesis, DNA stability and integrity. Clinical and epidemiological evidence links folate deficiency to DNA damage and cancer. On the other hand, long-term folate oversupplementation leads to adverse toxic effects, resulting in the appearance of malignancy. Considering the relationship of polyamines and rapidly proliferating tissues (especially cancers), there is a need for better investigation of the relationship between the ingestion of high amounts of folic acid in food supplementation and polyamine metabolism, related to malignant processes in the human body.

In silico, in vitro, X-ray crystallography, and integrated strategies for discovering spermidine synthase inhibitors for Chagas disease

Chagas disease results from infection by Trypanosoma cruzi and is a neglected tropical disease (NTD). Although some treatment drugs are available, their use is associated with severe problems, including adverse effects and limited effectiveness during the chronic disease phase. To develop a novel anti-Chagas drug, we virtually screened 4.8 million small molecules against spermidine synthase (SpdSyn) as the target protein using our super computer “TSUBAME2.5” and conducted in vitro enzyme assays to determine the half-maximal inhibitory concentration values. We identified four hit compounds that inhibit T. cruzi SpdSyn (TcSpdSyn) by in silico and in vitro screening. We also determined the TcSpdSyn–hit compound complex structure using X-ray crystallography, which shows that the hit compound binds to the putrescine-binding site and interacts with Asp171 through a salt bridge.

Arginase Is Essential for Survival of Leishmania donovani Promastigotes but Not Intracellular Amastigotes

Studies of Leishmania donovani have shown that both ornithine decarboxylase and spermidine synthase, two enzymes of the polyamine biosynthetic pathway, are critical for promastigote proliferation and required for maximum infection in mice. However, the importance of arginase (ARG), the first enzyme of the polyamine pathway in Leishmania, has not been analyzed in L. donovani. To test ARG function in intact parasites, we generated Δarg null mutants in L. donovani and evaluated their ability to proliferate in vitro and trigger infections in mice. The Δarg knockout was incapable of growth in the absence of polyamine supplementation, but the auxotrophic phenotype could be bypassed by addition of either millimolar concentrations of ornithine or micromolar concentrations of putrescine or by complementation with either glycosomal or cytosolic versions of ARG. Spermidine supplementation of the medium did not circumvent the polyamine auxotrophy of the Δarg line. Although ARG was found to be essential for ornithine and polyamine synthesis, ornithine decarboxylase appeared to be the rate-limiting enzyme for polyamine production. Mouse infectivity studies revealed that the Δarg lesion reduced parasite burdens in livers by an order of magnitude but had little impact on the numbers of parasites recovered from spleens. Thus, ARG is essential for proliferation of promastigotes but not intracellular amastigotes. Coupled with previous studies, these data support a model in which L. donovani amastigotes readily salvage ornithine and have some access to host spermidine pools, while host putrescine appears to be unavailable for salvage by the parasite.

[Enantioselective Synthesis of (R)- and (S)-3-Methylspermidines]

Earlier unknown enantiomerically pure (R)- and (S)-1,8-diamino-3-methyl-4-azaoctane's (3-MeSpd's) were synthesized with high overall yields and optical purity starting from commercially available R- and S-isomers of N-Boc-2-aminopropanol-1. Application of R- and S-isomers of 3-MeSpd for the investigation of the stereospecificity of spermidine transporter and peculiarities of deoxyhypusine synthase reaction are discussed.

Key metabolites in tissue extracts of Elliptio complanata identified using (1)H nuclear magnetic resonance spectroscopy

We used (1)H nuclear magnetic resonance spectroscopy to describe key metabolites of the polar metabolome of the freshwater mussel, Elliptio complanata. Principal components analysis documented variability across tissue types and river of origin in mussels collected from two rivers in North Carolina (USA). Muscle, digestive gland, mantle and gill tissues yielded identifiable but overlapping metabolic profiles. Variation in digestive gland metabolic profiles between the two mussel collection sites was characterized by differences in mono- and disaccharides. Variation in mantle tissue metabolomes appeared to be associated with sex. Nuclear magnetic resonance spectroscopy is a sensitive means to detect metabolites in the tissues of E. complanata and holds promise as a tool for the investigation of freshwater mussel health and physiology.

α-Hemolysin nanopore studies reveal strong interactions between biogenic polyamines and DNA hairpins

The α-hemolysin (α-HL) nanopore analyzes DNA as it is electrophoretically driven through the pore. The respective current vs. time (i-t) traces depends on the DNA sequence, its secondary structures, or on the physical conditions of the analysis. The current study describes analysis of a DNA hairpin with a 5'-extension with the α-HL nanopore in the presence of the polyamines spermine (Spm), spermidine (Spd), and putrescine (Put). These studies identified a new i-t trace characteristic of the DNA-polyamine complex. Voltage-dependent studies determined that the hairpin-Spm complex formed with excess Spm was not unzipped and translocated through the pore even when the voltage was increased to 180 mV. The DNA hairpin sample was titrated with Spm, Spd, or Put that showed a dose-dependent response in the characteristic event patterns for hairpins bound to Spm or Spd, but not for Put. Plots of the event types vs. count were used to calculate binding constants for the Spm or Spd hairpin interactions under these conditions. The titration also demonstrated that the event rate decreased ~10-fold when the Spm or Spd concentration was increased from 0 to 4 mM. These observations impose practical limitations on the ability to use Spm or Spd for DNA studies with the α-HL nanopore.

Isoform-level brain expression profiling of the spermidine/spermine N1-Acetyltransferase1 (SAT1) gene in major depression and suicide

Low brain expression of the spermidine/spermine N-1 acetyltransferase (SAT1) gene, the rate-limiting enzyme involved in catabolism of polyamines that mediate the polyamine stress response (PSR), has been reported in depressed suicides. However, it is unknown whether this effect is associated with depression or with suicide and whether all or only specific isoforms expressed by SAT1, such as the primary 171 amino acid protein-encoding transcript (SSAT), or an alternative splice variant (SSATX) that is involved in SAT1 regulated unproductive splicing and transcription (RUST), are involved. We applied next generation sequencing (RNA-seq) to assess gene-level, isoform-level, and exon-level SAT1 expression differences between healthy controls (HC, N = 29), DSM-IV major depressive disorder suicides (MDD-S, N = 21) and MDD non-suicides (MDD, N = 9) in the dorsal lateral prefrontal cortex (Brodmann Area 9, BA9) of medication-free individuals postmortem. Using small RNA-seq, we also examined miRNA species putatively involved in SAT1 post-transcriptional regulation. A DSM-IV diagnosis was made by structured interview. Toxicology and history ruled out recent psychotropic medication. At the gene-level, we found low SAT1 expression in both MDD-S (vs. HC, p = 0.002) and MDD (vs. HC, p = 0.002). At the isoform-level, reductions in MDD-S (vs. HC) were most pronounced in four transcripts including SSAT and SSATX, while reductions in MDD (vs. HC) were pronounced in three transcripts, one of which was reduced in MDD relative to MDD-S (all p < 0.1 FDR corrected). We did not observe evidence for differential exon-usage (i.e. splicing) nor differences in miRNA expression. Results replicate the finding of low SAT1 brain expression in depressed suicides in an independent sample and implicate low SAT1 brain expression in MDD independent of suicide. Low expressions of both SSAT and SATX isoforms suggest that shared transcriptional mechanisms involved in RUST may account for low SAT1 brain expression in depressed suicides. Future studies are required to understand the functions and regulation of SAT1 isoforms, and how they relate to the pathogenesis of MDD and suicide.

Application of NMR-based metabolomics for environmental assessment in the Great Lakes using zebra mussel (Dreissena polymorpha)

Zebra mussel, Dreissena polymorpha, in the Great Lakes is being monitored as a bio-indicator organism for environmental health effects by the National Oceanic and Atmospheric Administration's Mussel Watch program. In order to monitor the environmental effects of industrial pollution on the ecosystem, invasive zebra mussels were collected from four stations-three inner harbor sites (LMMB4, LMMB1, and LMMB) in Milwaukee Estuary, and one reference site (LMMB5) in Lake Michigan, Wisconsin. Nuclear magnetic resonance (NMR)-based metabolomics was used to evaluate the metabolic profiles of the mussels from these four sites. The objective was to observe whether there were differences in metabolite profiles between impacted sites and the reference site; and if there were metabolic profile differences among the impacted sites. Principal component analyses indicated there was no significant difference between two impacted sites: north Milwaukee harbor (LMMB and LMMB4) and the LMMB5 reference site. However, significant metabolic differences were observed between the impacted site on the south Milwaukee harbor (LMMB1) and the LMMB5 reference site, a finding that correlates with preliminary sediment toxicity results. A total of 26 altered metabolites (including two unidentified peaks) were successfully identified in a comparison of zebra mussels from the LMMB1 site and LMMB5 reference site. The application of both uni- and multivariate analysis not only confirmed the variability of altered metabolites but also ensured that these metabolites were identified via unbiased analysis. This study has demonstrated the feasibility of the NMR-based metabolomics approach to assess whole-body metabolomics of zebra mussels to study the physiological impact of toxicant exposure at field sites.

Stability and Solution Structure of Binary and Ternary Cu(II) Complexes with l-Glutamic Acid and Diamines as Well as Adducts in Metal-Free Systems in Aqueous Solution

Binary and ternary complexes of copper(II) with l-glutamic acid (Glu) and diamines 1,3-diaminopropane and 1,4-diaminobutane, putrescine (tn, Put), as well as adducts formed in the metal-free systems, have been investigated in aqueous solutions. The types of complexes formed and their overall stability constants were established on the basis of computer analysis of potentiometric results. The reaction centers and the modes of interaction were identified on the basis of spectroscopic studies (NMR, Vis and EPR). In the ligands studied the interaction centers are the oxygen atoms from carboxyl groups, nitrogen atom from the amine group of glutamic acid and the nitrogen atoms from amine groups of the diamines. The centers of noncovalent interaction in the adducts that formed in the metal-free systems are also potential sites of metal ion coordination, which is important in biological systems. In the Glu–diamine systems, molecular complexes of the (Glu)H_x(diamine) type are formed. In the (Glu)H₂(tn) adduct, in contrast to the corresponding complex with Put, an inversion effect was observed in which the first deprotonated amine group of tn became a negative reaction center and interacted with the protonated amine groups from Glu. Depending on the pH, the amine groups from the diamine can be either a positive or a negative center of interaction. In the Cu(Glu)₂ species the first molecule of Glu takes part in metallation through all functional groups, whereas the second molecule makes a “glycine-like” coordination with the Cu(II) ions that is only through two functional groups. According to the results, introduction of Cu(II) ions into metal-free systems (Glu–diamine) changes the character of interactions between the bioligands in the complexes that form in Cu(II)–Glu–diamine systems and no ML…L′ type complexes are formed. However, in the ternary systems only the heteroligand complexes Cu(Glu)(diamine) and Cu(Glu)(diamine)(OH) are observed.

Commentary on: Hairless and the polyamine putrescine form a negative regulatory loop in the epidermis

Polyamines are cationic amines essential for cellular proliferation. Recently, their role in hair follicle (HF) growth has started to be explored, but their exact function is still obscure. In the October issue of Experimental Dermatology, Luke et al. follow the observation that putrescine overproducing mice and hairless (HR) mutant mice show a similar clinical phenotype of hair loss and dermal cyst formation. They show that HR and putrescine form a negative regulatory feedback mechanism, which might regulate hair cycling and therefore control hair growth. This study clearly demonstrates that a strong connection exists between HR and polyamines although there are probably additional molecular pathways involved in the polyamine regulation of hair growth which remain to be discovered.

Endogenous polyamine function--the RNA perspective

Recent progress with techniques for monitoring RNA structure in cells such as ‘DMS-Seq’ and ‘Structure-Seq’ suggests that a new era of RNA structure-function exploration is on the horizon. This will also include systematic investigation of the factors required for the structural integrity of RNA. In this context, much evidence accumulated over 50 years suggests that polyamines play important roles as modulators of RNA structure. Here, we summarize and discuss recent literature relating to the roles of these small endogenous molecules in RNA function. We have included studies directed at understanding the binding interactions of polyamines with polynucleotides, tRNA, rRNA, mRNA and ribozymes using chemical, biochemical and spectroscopic tools. In brief, polyamines bind RNA in a sequence-selective fashion and induce changes in RNA structure in context-dependent manners. In some cases the functional consequences of these interactions have been observed in cells. Most notably, polyamine-mediated effects on RNA are frequently distinct from those of divalent cations (i.e. Mg²⁺) confirming their roles as independent molecular entities which help drive RNA-mediated processes.

Polyamines and their metabolites as diagnostic markers of human diseases

Polyamines, putrescine, spermidine and spermine, are ubiquitous in living cells and are essential for eukaryotic cell growth. These polycations interact with negatively charged molecules such as DNA, RNA, acidic proteins and phospholipids and modulate various cellular functions including macromolecular synthesis. Dysregulation of the polyamine pathway leads to pathological conditions including cancer, inflammation, stroke, renal failure and diabetes. Increase in polyamines and polyamine synthesis enzymes is often associated with tumor growth, and urinary and plasma contents of polyamines and their metabolites have been investigated as diagnostic markers for cancers. Of these, diacetylated derivatives of spermidine and spermine are elevated in the urine of cancer patients and present potential markers for early detection. Enhanced catabolism of cellular polyamines by polyamine oxidases (PAO), spermine oxidase (SMO) or acetylpolyamine oxidase (AcPAO), increases cellular oxidative stress and generates hydrogen peroxide and a reactive toxic metabolite, acrolein, which covalently incorporates into lysine residues of cellular proteins. Levels of protein-conjuagated acrolein (PC-Acro) and polyamine oxidizing enzymes were increased in the locus of brain infarction and in plasma in a mouse model of stroke and also in the plasma of stroke patients. When the combined measurements of PC-Acro, interleukin 6 (IL-6), and C-reactive protein (CRP) were evaluated, even silent brain infarction (SBI) was detected with high sensitivity and specificity. Considering that there are no reliable biochemical markers for early stage of stroke, PC-Acro and PAOs present promising markers. Thus the polyamine metabolites in plasma or urine provide useful tools in early diagnosis of cancer and stroke.

Toxicity of polyamines and their metabolic products

Polyamines are ubiquitous and essential components of mammalian cells. They have multiple functions including critical roles in nucleic acid and protein synthesis, gene expression, protein function, protection from oxidative damage, the regulation of ion channels, and maintenance of the structure of cellular macromolecules. It is essential to maintain a correct level of polyamines, and this amount is tightly regulated at the levels of transport, synthesis, and degradation. Catabolic pathways generate reactive aldehydes including acrolein and hydrogen peroxide via a number of oxidases. These metabolites, particularly those from spermine, can cause significant toxicity with damage to proteins, DNA, and other cellular components. Their production can be increased as a result of infection or cell damage that releases free polyamines and activates the oxidative catabolic pathways. Since polyamines also have an important physiological role in protection from oxidative damage, the reduction in polyamine content may exacerbate the toxic potential of these agents. Increases in polyamine catabolism have been implicated in the development of diseases including stroke, other neurological diseases, renal failure, liver disease, and cancer. These results provide new opportunities for the early diagnosis, prevention, and treatment of disease.

Polyamine delivery as a tool to modulate stem cell differentiation in skeletal tissue engineering

The first step in skeleton development is the condensation of mesenchymal precursors followed by any of two different types of ossification, depending on the type of bone segment: in intramembranous ossification, the bone is deposed directly in the mesenchymal anlagen, whereas in endochondral ossification, the bone is deposed onto a template of cartilage that is subsequently substituted by bone. Polyamines and polyamine-related enzymes have been implicated in bone development as global regulators of the transcriptional and translational activity of stem cells and pivotal transcription factors. Therefore, it is tempting to investigate their use as a tool to improve regenerative medicine strategies in orthopedics. Growing evidence in vitro suggests a role for polyamines in enhancing differentiation in both adult stem cells and differentiated chondrocytes. Adipose-derived stem cells have recently proved to be a convenient alternative to bone marrow stromal cells, due to their easy accessibility and the high frequency of stem cell precursors per volume unit. State-of-the-art "prolotherapy" approaches for skeleton regeneration include the use of adipose-derived stem cells and platelet concentrates, such as platelet-rich plasma (PRP). Besides several growth factors, PRP also contains polyamines in the micromolar range, which may also exert an anti-apoptotic effect, thus helping to explain the efficacy of PRP in enhancing osteogenesis in vitro and in vivo. On the other hand, spermidine and spermine are both able to enhance hypertrophy and terminal differentiation of chondrocytes and therefore appear to be inducers of endochondral ossification. Finally, the peculiar activity of spermidine as an inducer of autophagy suggests the possibility of exploiting its use to enhance this cytoprotective mechanism to counteract the degenerative changes underlying either the aging or degenerative diseases that affect bone or cartilage.

Downregulation of the polyamine regulator spermidine/spermine N(1)-acetyltransferase by Epstein-Barr virus in a Burkitt's lymphoma cell line

Transition of Akata Burkitt's lymphoma (BL) from a malignant to nonmalignant phenotype upon loss of Epstein-Barr virus (EBV) is evidence for a viral contribution to tumorigenesis despite the tight restriction of EBV gene expression in BL. Examination of global cellular gene expression in Akata subclones that retained or lost EBV identified spermidine/spermine N(1)-acetyltransferase (SAT1), an inducible enzyme whose catabolism of polyamines affects both apoptosis and cell growth, as one of a limited number of cellular genes downregulated by EBV. Re-infection of the EBV-negative Akata clone reduced SAT1 mRNA to a level comparable with the parental EBV-positive Akata. EBV-positive Akata cells demonstrated decreased SAT1 enzyme activity concomitant with altered intracellular polyamine constituents. Reduction of SAT1 in EBV-positive BL was a transcriptional effect. Forced expression of the viral BCL2 homologue, BHRF1, in an EBV-negative Akata clone reduced SAT1 mRNA. Thus, EBV repression of polyamine catabolism becomes a complementary alteration to dysregulated c-myc enhancement of polyamine synthesis in BL and favorable to BL lymphomagenesis.

A New Transgenic Mouse Model for Studying the Neurotoxicity of Spermine Oxidase Dosage in the Response to Excitotoxic Injury

Spermine oxidase is a FAD-containing enzyme involved in polyamines catabolism, selectively oxidizing spermine to produce H2O2, spermidine, and 3-aminopropanal. Spermine oxidase is highly expressed in the mouse brain and plays a key role in regulating the levels of spermine, which is involved in protein synthesis, cell division and cell growth. Spermine is normally released by neurons at synaptic sites where it exerts a neuromodulatory function, by specifically interacting with different types of ion channels, and with ionotropic glutamate receptors. In order to get an insight into the neurobiological roles of spermine oxidase and spermine, we have deregulated spermine oxidase gene expression producing and characterizing the transgenic mouse model JoSMOrec, conditionally overexpressing the enzyme in the neocortex. We have investigated the effects of spermine oxidase overexpression in the mouse neocortex by transcript accumulation, immunohistochemical analysis, enzymatic assays and polyamine content in young and aged animals. Transgenic JoSMOrec mice showed in the neocortex a higher H2O2 production in respect to Wild-Type controls, indicating an increase of oxidative stress due to SMO overexpression. Moreover, the response of transgenic mice to excitotoxic brain injury, induced by kainic acid injection, was evaluated by analysing the behavioural phenotype, the immunodistribution of neural cell populations, and the ultrastructural features of neocortical neurons. Spermine oxidase overexpression and the consequently altered polyamine levels in the neocortex affects the cytoarchitecture in the adult and aging brain, as well as after neurotoxic insult. It resulted that the transgenic JoSMOrec mouse line is more sensitive to KA than Wild-Type mice, indicating an important role of spermine oxidase during excitotoxicity. These results provide novel evidences of the complex and critical functions carried out by spermine oxidase and spermine in the mammalian brain.

Rational development of a serum-free medium and fed-batch process for a GS-CHO cell line expressing recombinant antibody

A serum-free medium (CHO-SFM) together with a fed-batch process was developed for the cultivation of a recombinant GS-CHO cell line producing TNFR-Fc. According to the metabolic characteristics of GS-CHO cell, a basal medium was prepared by supplementing DMEM:F12:RPMI1640 (2:1:1) with amino acids, insulin, transferrin, Pluronic F68 and some other ingredients. Statistical optimization approaches based on Plackett-Burman and central composite designs were then adopted to identify additional positive determinants and determine their optimal concentrations, which resulted in the final CHO-SFM medium formulations. The maximum antibody titer reached was 90.95 mg/l in the developed CHO-SFM, which was a 18 % and 10 fold higher than that observed in the commercial EX-CELL™ 302 medium (76.95 mg/l) and basal medium (8.28 mg/l), respectively. Subsequently, a reliable, reproducible and robust fed-batch strategy was designed according to the offline measurement of glucose, giving a final antibody yield of 378 mg/l, which was a threefold improvement over that in conventional batch culture (122 mg/l) using CHO-SFM. In conclusion, the use of design of experiment (DoE) method facilitated the development of CHO-SFM medium and fed-batch process for the production of recombinant antibody using GS-CHO cells.