The old and new biochemistry of polyamines

Synthesis and evaluation of a 68Ga-labeled spermine derivative for tumor PET imaging

BACKGROUND

The polyamine transporter system (PTS), which renders it a promising target for tumor therapy and imaging applications, facilitates the transmembrane transport of polyamines. We reported a novel derivative of spermine labeled with gallium-68 ([68Ga]Ga-NOTA-Spermine) for the imaging of the PTS in mouse models of tumor.

RESULTS

The radiochemical yield of [68Ga]Ga-NOTA-Spermine was determined to be 64-69 %, demonstrating exceptional stability and radiochemical purity (>98 %). Cellular uptake experiments revealed that A549 cells exhibited peak uptake of [68Ga]Ga-NOTA-Spermine at 90 min (15.4 % ± 0.68 %). Biodistribution analysis demonstrated significant accumulation of [68Ga]Ga-NOTA-Spermine in kidneys and liver, while exhibiting low uptake levels in muscle, brain, and bones. Furthermore, Micro-PET/CT scans conducted on A549 tumor-bearing mouse models indicated substantial uptake of [68Ga]Ga-NOTA-Spermine, with maximum tumor/muscle (T/M) ratios reaching 3.71.

CONCLUSION

These results suggest that [68Ga]Ga-NOTA-Spermine holds potential as a PET imaging agent for tumors with high levels of PTS.

A review on polyamines as promising next-generation neuroprotective and anti-aging therapy

Neurodegenerative disorders are diseases characterized by progressive degeneration of neurons and associated structures and are a major global issue growing more widespread as the global population's average age increases. Despite several investigations on their etiology, the specific cause of these disorders remains unknown. However, there are few symptomatic therapies to treat these disorders. Polyamines (PAs) (putrescine, spermidine, and spermine) are being studied for their role in neuroprotection, aging and cognitive impairment. They are ubiquitous polycations which have relatively higher concentrations in the brain and possess pleiotropic biochemical activities, including regulation of gene expression, ion channels, mitochondria Ca2+ transport, autophagy induction, programmed cell death, and many more. Their cellular content is tightly regulated, and substantial evidence indicates that their altered levels and metabolism are strongly implicated in aging, stress, cognitive dysfunction, and neurodegenerative disorders. In addition, dietary polyamine supplementation has been reported to induce anti-aging effects, anti-oxidant effects, and improve locomotor abnormalities, and cognitive dysfunction. Thus, restoring the polyamine level is considered a promising pharmacological strategy to counteract neurodegeneration. This review highlights PAs' physiological role and the molecular mechanism underpinning their proposed neuroprotective effect in aging and neurodegenerative disorders.

Evolution of polyamine resistance in Staphylococcus aureus through modulation of potassium transport

Microbes must adapt to diverse biotic and abiotic factors encountered in host environments. Polyamines are an abundant class of aliphatic molecules that play essential roles in fundamental cellular processes across the tree of life. Surprisingly, the bacterial pathogen Staphylococcus aureus is highly sensitive to polyamines encountered during infection, and acquisition of a polyamine resistance locus has been implicated in spread of the prominent USA300 methicillin-resistant S. aureus lineage. At present, alternative pathways of polyamine resistance in staphylococci are largely unknown. Here we applied experimental evolution to identify novel mechanisms and consequences of S. aureus adaption when exposed to increasing concentrations of the polyamine spermine. Evolved populations of S. aureus exhibited striking evidence of parallel adaptation, accumulating independent mutations in the potassium transporter genes ktrA and ktrD. Mutations in either ktrA or ktrD are sufficient to confer polyamine resistance and function in an additive manner. Moreover, we find that ktr mutations provide increased resistance to multiple classes of unrelated cationic antibiotics, suggesting a common mechanism of resistance. Consistent with this hypothesis, ktr mutants exhibit alterations in cell surface charge indicative of reduced affinity and uptake of cationic molecules. Finally, we observe that laboratory-evolved ktr mutations are also present in diverse natural S. aureus isolates, suggesting these mutations may contribute to antimicrobial resistance during human infections. Collectively this study identifies a new role for potassium transport in S. aureus polyamine resistance with consequences for susceptibility to both host-derived and clinically-used antimicrobials.

The Many Roads from Alternative Splicing to Cancer: Molecular Mechanisms Involving Driver Genes

Cancer driver genes are either oncogenes or tumour suppressor genes that are classically activated or inactivated, respectively, by driver mutations. Alternative splicing-which produces various mature mRNAs and, eventually, protein variants from a single gene-may also result in driving neoplastic transformation because of the different and often opposed functions of the variants of driver genes. The present review analyses the different alternative splicing events that result in driving neoplastic transformation, with an emphasis on their molecular mechanisms. To do this, we collected a list of 568 gene drivers of cancer and revised the literature to select those involved in the alternative splicing of other genes as well as those in which its pre-mRNA is subject to alternative splicing, with the result, in both cases, of producing an oncogenic isoform. Thirty-one genes fall into the first category, which includes splicing factors and components of the spliceosome and splicing regulators. In the second category, namely that comprising driver genes in which alternative splicing produces the oncogenic isoform, 168 genes were found. Then, we grouped them according to the molecular mechanisms responsible for alternative splicing yielding oncogenic isoforms, namely, mutations in cis splicing-determining elements, other causes involving non-mutated cis elements, changes in splicing factors, and epigenetic and chromatin-related changes. The data given in the present review substantiate the idea that aberrant splicing may regulate the activation of proto-oncogenes or inactivation of tumour suppressor genes and details on the mechanisms involved are given for more than 40 driver genes.

Characterization of polyamine metabolism predicts prognosis, immune profile, and therapeutic efficacy in lung adenocarcinoma patients

Background

Polyamine modification patterns in lung adenocarcinoma (LUAD) and their impact on prognosis, immune infiltration, and anti-tumor efficacy have not been systematically explored.

Methods

Patients from The Cancer Genome Atlas (TCGA) were classified into subtypes according to polyamine metabolism-related genes using the consensus clustering method, and the survival outcomes and immune profile were compared. Meanwhile, the geneCluster was constructed according to the differentially expressed genes (DEGs) of the subtypes. Subsequently, the polyamine metabolism-related score (PMRS) system was established using the least absolute shrinkage and selection operator (LASSO) multivariate regression analysis in the TCGA training cohort (n = 245), which can be applied to characterize the prognosis. To verify the predictive performance of the PMRS, the internal cohort (n = 245) and the external cohort (n = 244) were recruited. The relationship between the PMRS and immune infiltration and antitumor responses was investigated.

Results

Two distinct patterns (C1 and C2) were identified, in which the C1 subtype presented an adverse prognosis, high CD8+ T cell infiltration, tumor mutational burden (TMB), immune checkpoint, and low tumor immune dysfunction and exclusion (TIDE). Furthermore, two geneClusters were established, and similar findings were observed. The PMRS, including three genes (SMS, SMOX, and PSMC6), was then constructed to characterize the polyamine metabolic patterns, and the patients were divided into high- and low-PMRS groups. As confirmed by the validation cohort, the high-PMRS group possessed a poor prognosis. Moreover, external samples and immunohistochemistry confirmed that the three genes were highly expressed in tumor samples. Finally, immunotherapy and chemotherapy may be beneficial to the high-PMRS group based on the immunotherapy cohorts and low half-maximal inhibitory concentration (IC50) values.

Conclusion

We identified distinct polyamine modification patterns and established a PMRS to provide new insights into the mechanism of polyamine action and improve the current anti-tumor strategy of LUAD.

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.

Enhanced mucosal mitochondrial function corrects dysbiosis and OXPHOS metabolism in IBD

Background

Mitochondrial (Mito) dysfunction in IBD reduces mucosal O2 consumption and increases O2 delivery to the microbiome. Increased enteric O2 promotes blooms of facultative anaerobes (eg. Proteobacteria ) and restricts obligate anaerobes (eg. Firmicutes ). Dysbiotic metabolites negatively affect host metabolism and immunity. Our novel compound (AuPhos) upregulates intestinal epithelial cell (IEC) mito function, attenuates colitis and corrects dysbiosis in humanized Il10-/- mice. We posit that AuPhos corrects IBD-associated dysbiotic metabolism.

Methods

Primary effect of AuPhos on mucosal Mito respiration and healing process was studied in ex vivo treated human colonic biopsies and piroxicam-accelerated (Px) Il10-/- mice. Secondary effect on microbiome was tested in DSS-colitis WT B6 and germ-free 129.SvEv WT or Il10-/- mice reconstituted with human IBD stool (Hu- Il10-/- ). Mice were treated orally with AuPhos (10- or 25- mg/kg; q3d) or vehicle, stool samples collected for fecal lipocalin-2 (f-LCN2) assay and microbiome analyses using 16S rRNA sequencing. AuPhos effect on microbial metabolites was determined using untargeted global metabolomics. AuPhos-induced hypoxia in IECs was assessed by Hypoxyprobe-1 staining in sections from pimonidazole HCl-infused DSS-mice. Effect of AuPhos on enteric oxygenation was assessed by E. coli Nissle 1917 WT (aerobic respiration-proficient) and cytochrome oxidase (cydA) mutant (aerobic respiration-deficient).

Results

Metagenomic (16S) analysis revealed AuPhos reduced relative abundances of Proteobacteria and increased blooms of Firmicutes in uninflamed B6 WT, DSS-colitis, Hu-WT and Hu- Il10-/- mice. AuPhos also increased hypoxyprobe-1 staining in surface IECs suggesting enhanced O2 utilization. AuPhos-induced anaerobiosis was confirmed by a significant increase in cydA mutant compared to WT (O2-utlizing) E.coli . Ex vivo treatment of human biopsies with AuPhos showed significant increase in Mito mass, and complexes I and IV. Further, gene expression analysis of AuPhos-treated biopsies showed increase in stem cell markers (Lgr4, Lgr5, Lrig1), with concomitant decreases in pro-inflammatory markers (IL1β,MCP1, RankL). Histological investigation of AuPhos-fed Px- Il10-/- mice showed significantly decreased colitis score in AuPhos-treated Px- Il10-/- mice, with decrease in mRNA of pro-inflammatory cytokines and increase in Mito complexes ( ND5 , ATP6 ). AuPhos significantly altered microbial metabolites associated with SCFA synthesis, FAO, TCA cycle, tryptophan and polyamine biosynthesis pathways. AuPhos increased pyruvate, 4-hydroxybutyrate, 2-hydroxyglutarate and succinate, suggesting an upregulation of pyruvate and glutarate pathways of butyrate production. AuPhos reduced IBD-associated primary bile acids (BA) with concomitant increase in secondary BA (SBA). AuPhos treatment significantly decreased acylcarnitines and increased L-carnitine reflective of enhanced FAO. AuPhos increases TCA cycle intermediates and creatine, energy reservoir substrates indicating enhanced OxPHOS. Besides, AuPhos also upregulates tryptophan metabolism, decreases Kynurenine and its derivatives, and increases polyamine biosynthesis pathway (Putresceine and Spermine).

Conclusion

These findings indicate that AuPhos-enhanced IEC mitochondrial function reduces enteric O2 delivery, which corrects disease-associated metabolomics by restoring short-chain fatty acids, SBA, AA and IEC energy metabolism.

Graphical abstract

Achieving healthy aging through gut microbiota-directed dietary intervention: Focusing on microbial biomarkers and host mechanisms

BACKGROUND

Population aging has become a primary global public health issue, and the prevention of age-associated diseases and prolonging healthy life expectancies are of particular importance. Gut microbiota has emerged as a novel target in various host physiological disorders including aging. Comprehensive understanding on changes of gut microbiota during aging, in particular gut microbiota characteristics of centenarians, can provide us possibility to achieving healthy aging or intervene pathological aging through gut microbiota-directed strategies.

AIM OF REVIEW

This review aims to summarize the characteristics of the gut microbiota associated with aging, explore potential biomarkers of aging and address microbiota-associated mechanisms of host aging focusing on intestinal barrier and immune status. By summarizing the existing effective dietary strategies in aging interventions, the probability of developing a diet targeting the gut microbiota in future is provided.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review is focused on three key notions: Firstly, gut microbiota has become a new target for regulating health status and lifespan, and its changes are closely related to age. Thus, we summarized aging-associated gut microbiota features at the levels of key genus/species and important metabolites through comparing the microbiota differences among centenarians, elderly people and younger people. Secondly, exploring microbiota biomarkers related to aging and discussing future possibility using dietary regime/components targeted to aging-related microbiota biomarkers promote human healthy lifespan. Thirdly, dietary intervention can effectively improve the imbalance of gut microbiota related to aging, such as probiotics, prebiotics, and postbiotics, but their effects vary among.

Synergistic antitumor efficacy of gemcitabine and cisplatin to induce ferroptosis in pancreatic ductal adenocarcinoma via Sp1-SAT1-polyamine metabolism pathway

PURPOSE

The combination of cisplatin and gemcitabine-based chemotherapy has been recommended as a preferred regimen for pancreatic ductal adenocarcinoma (PDAC) patients with germline-based mutations. However, the underlying mechanism remains poorly elucidated. Therefore, our study aimed to explore the mechanistic basis of the cell-killing activity of gemcitabine plus cisplatin and identify potential therapeutic targets.

METHODS

First, we explored the synergistic cytotoxic effects of gemcitabine and cisplatin on PDAC through in vitro and in vivo experiments. Then, we investigated ferroptosis-related biomarkers, to assess the impact of the combination therapy on ferroptosis. Using bioinformatics methods, we identified SAT1 as a potential key mediator of ferroptosis induced by gemcitabine and cisplatin. We tested the polyamine levels in PDAC cells by LC-MS after overexpressed or knocked down SAT1, and explored the role of polyamines in ferroptosis using exogenous supplementation. Finally, we explored the regulatory effect of Sp1 on SAT1 through ChIP-qPCR and dual-luciferase reporter assay.

RESULTS

Gemcitabine plus cisplatin enhanced cell death and induced ferroptosis in PDAC. This combination upregulated SAT1 transcription by inhibiting Sp1. SAT1 activation promoted the catabolism of spermine and spermidine, leading to iron accumulation and lipid peroxide generation, ultimately resulting in ferroptosis.

CONCLUSIONS

In summary, our findings suggested the gemcitabine and cisplatin combination therapy induced ferroptosis in a GSH-independent manner in PDAC. The combined treatment inhibited Sp1 and upregulated SAT1 transcription, leading to the breakdown of spermine and spermidine. Therefore, targeting SAT1-induced polyamine metabolism may represent a promising therapeutic strategy for PDAC.

Deciphering survival strategies: Oxidative stress and microbial interplay in Eisenia fetida under tetracycline contamination

Soil contamination resulting from residual antibiotics presents a pressing need to understand the survival mechanisms of soil organisms in polluted environments. This study focused on Eisenia fetida, and tetracycline stress experiments were conducted in a controlled environment using sterile artificial soil. The stress concentration ranged from 0 to 600 mg/kg, and stress cycles lasted either 10 or 30 days. The objective of this study was to assess the effects of oxidative stress and the changes in microbial communities both within and outside the earthworms. A comprehensive mathematical model was developed to elucidate the responses of organisms following exposure to stress utilizing factor analysis, grey relational analysis, and hierarchical entropy weight analysis. Under tetracycline stress, the initial stage (1-3 days) exhibited a coordinated regulation of oxidative stress and microbial communities in the soil with the assistance of CAT and GPX enzymes. The subsequent stage (4-5 days) further emphasized the influence of soil microbial communities. A notable "feedback regulation" of soil microbial communities on oxidative stress was observed during the third stage (6-8 days). Earthworms maintained a metabolic balance in the fourth stage (9-10 days). In the long term, the stress-induced a self-detoxification mechanism within soil microbial communities, which collaborated with GPX to respond to oxidative stress.

Analysis of cerebrospinal fluid metabolites affected by WenDanTang based on ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry

WenDanTang (WDT) is a Chinese herbal formula used to treat various diseases, including neurodegenerative diseases. However, the neuroprotective metabolic pathways and the components involved in this process are not fully understood. In this study, we examined the neuroprotective metabolic pathways of WDT in rat brains using cerebrospinal fluid metabolomics and ultra-high-performance liquid chromatography-high-resolution mass spectrometry. Twelve rats were randomly divided into a WDT (administrated with WDT solution) and a control group. The ultra-high-performance liquid chromatography technique was used to explore the components of the WDT solution and cerebrospinal fluid, and secondary mass spectra of cerebrospinal fluid were used to identify possible brain-incorporating components after WDT. The results of the differential metabolism analysis showed that eight metabolites were typically altered (all p < 0.05). By comparing the secondary mass spectra of the cerebrospinal fluid of rats and WDT solution, two possible brain-incorporating components of WDT, stachydrine and α-methoxyphenylacetic acid, were identified. The data also suggested that WDT affects nucleotide metabolism, glutathione metabolism, and B-vitamin metabolic pathways, the central differential metabolic pathways. These data suggest that WDT protects neurons through its active components, such as stachydrine, and regulates biochemical metabolism to affect the brain's energy metabolism and antioxidant capacity.

Polyamines in Edible and Medicinal Fungi from Serbia: A Novel Perspective on Neuroprotective Properties

The therapeutic effectiveness of current neurodegenerative disease treatments is still under debate because of problems with bioavailability and a range of side effects. Fungi, which are increasingly recognized as sources of natural antioxidants and acetylcholinesterase (AChE) enzyme inhibitors, may thus serve as potent neuroprotective agents. Previous studies have associated the anti-AChE and antioxidant activities of fungi mostly with polysaccharides and phenolic compounds, while other secondary metabolites such as polyamines (PAs) have been neglected. This study aimed to investigate eight edible and medicinal fungi from Serbia, marking the initial investigation into the neuroprotective capabilities of Postia caesia, Clitocybe odora, Clitopilus prunulus, and Morchella elata. Neuroprotective activity was examined using the Ellman assay, while the antioxidant capacity was tested by conducting DPPH, NO, ABTS, and FRAP tests. PA levels were determined by high-performance liquid chromatography (HPLC) coupled with fluorescent detection. Ganoderma applanatum and Lepista nuda exhibited the most robust anti-AChE (98.05 ± 0.83% and 99.94 ± 3.10%, respectively) and antioxidant activities, attributed to the synergistic effects of the total protein, total phenolic, and PA levels. Furthermore, P. caesia displayed significant AChE inhibition (88.21 ± 4.76%), primarily linked to the elevated spermidine (SPD) (62.98 ± 3.19 mg/kg d.w.) and putrescine (PUT) levels (55.87 ± 3.16 mg/kg d.w.). Our results highlight the need for thorough research to comprehend the intricate relationships between distinct fungus species and AChE inhibition. However, it is important to recognize that more research is required to identify the precise substances causing the reported inhibitory effects.

Co-administration of curcumin and polyamines in high-fat diet induced obese rats: Assessment of changes in serum polyamine levels and some tissue parameters

Obesity is a non-communicable chronic disease that continues to increase around the world. Recently, it has been shown that curcumin positively affects lipid, energy metabolism, and body weight change. Moreover, polyamines are aliphatic polycations, which can be found in all mammalian cells and foods and have been shown to prevent obesity through many different mechanisms. However, whether the co-administration of curcumin and polyamines has synergistic effects has yet to be clarified. Our study aimed to examine the effects of curcumin and polyamines on obesity and to assess the changes in serum polyamine levels and tissue parameters. 28 Sprague-Dawley male rats were fed a high-fat diet for 10 weeks to develop obesity, and then they were randomly divided into 4 groups as the control group (CONT), curcumin group (CUR), polyamine group (POL), curcumin and polyamine group (CUR+POL) and supplements were administered for 6 weeks. As a result, the lowest feed consumption in rats was recorded in the CUR+POL group, and the group with the lowest weight after supplements was the POL group, then the CUR+POL, CONT, and CUR groups, respectively. N-acetyl putrescine and GABA levels increased significantly after obesity development. The total histopathological score in fat, liver, and kidney tissues increased significantly in the CONT group. In the CUR+POL group, damage to the tissues was in the direction of recovery compared to the other groups, and the expression of NF-κB was significantly low. These results suggest that combined curcumin and polyamines may have protective effects.

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.

Polyamine metabolite spermidine rejuvenates oocyte quality by enhancing mitophagy during female reproductive aging

Advanced age is a primary risk factor for female infertility due to reduced ovarian reserve and declining oocyte quality. However, as an important contributing factor, the role of metabolic regulation during reproductive aging is poorly understood. Here, we applied untargeted metabolomics to identify spermidine as a critical metabolite in ovaries to protect oocytes against aging. In particular, we found that the spermidine level was reduced in ovaries of aged mice and that supplementation with spermidine promoted follicle development, oocyte maturation, early embryonic development and female fertility of aged mice. By microtranscriptomic analysis, we further discovered that spermidine-induced recovery of oocyte quality was mediated by enhancement of mitophagy activity and mitochondrial function in aged mice, and this mechanism of action was conserved in porcine oocytes under oxidative stress. Altogether, our findings suggest that spermidine supplementation could represent a therapeutic strategy to ameliorate oocyte quality and reproductive outcome in cis-gender women and other persons trying to conceive at an advanced age. Future work is needed to test whether this approach can be safely and effectively translated to humans.

Spermidine suppresses oxidative stress and ferroptosis by Nrf2/HO-1/GPX4 and Akt/FHC/ACSL4 pathway to alleviate ovarian damage

AIMS

Oxidative stress is considered to be one of the culprits of ovarian dysfunction. Spermidine (SPD) is a natural aliphatic polyamine that is widely present in living organisms and has been shown to exert preventive effects on various ageing-related diseases. This study seeks to investigate the potential preventive and protective effects of SPD on ovarian oxidative damage.

MAIN METHODS

Ovarian oxidative stress model in C57BL/6 mice was established by 3-nitropropionic acid. Female mice were administrated 10 mg/kg or 15 mg/kg SPD. The estrous cycle, serum hormone levels and mating test were measured to evaluate ovarian function. Follicle counts and AMH levels to assess ovarian reserve. Masson's trichrome to assess ovarian fibrosis. TUNEL analysis to evaluate follicular granulosa cells (GCs) apoptosis. Oxidative stress and autophagy indicators (Nrf2, HO-1, GPX4, LC3B, P62) were measured in vivo and in vitro. RNA-sequencing was performed on SPD-treated GC to study the effects of SPD on Akt and FHC/ACSL4 signaling.

KEY FINDINGS

SPD supplementation improved ovarian endocrine function and reproductive capacity in oxidative stress mice. SPD regularized the estrous cycle and alleviated oxidative stress. Furthermore, SPD increased the ovarian reserve, reducing GC apoptosis by activating the Nrf2/HO-1/GPX4 pathway. RNA-sequencing showed that SPD induced 230 genes changes in porcine GC, which were mainly involved in oocyte meiosis, arginine biosynthesis and glutathione metabolism pathways. SPD attenuated H2O2-induced ferroptosis by regulating Akt/FHC/ACSL4 signaling.

SIGNIFICANCE

SPD alleviates oxidative stress and ferroptosis by regulating the Nrf2/HO-1/GPX4 and Akt/FHC/ACSL4 pathway, which may be a novel potential strategy to protect ovarian oxidative damage.

Correlation analysis of polyamine metabolism and reproductive hormone levels in goose ovarian follicles

To investigate the relationship between polyamine metabolism and reproductive hormones in ovarian follicles of Sichuan white geese, follicle polyamine content and reproductive hormone levels and gene expressions related to polyamine metabolism, steroidogenesis and steroid hormone receptors were detected by HPLC, ELISA and RT-qPCR. The results showed that the overall trend of spermidine and spermine levels increased first and then decreased as increasing follicle size, with the highest level in F3 and F5 follicles (P < 0.05). Putrescine and 17β-estradiol (E2) levels in hierarchical follicles were significantly lower than those in prehierarchical follicles (P < 0.05). Progesterone (P4) first increased and then decreased, with the highest level in the F5 follicle (P < 0.05). The expression levels of estrogen receptor 1 (ER1) showed an overall increase as increasing follicle size (except in F3 follicles), while estrogen receptor 2 (ER2) in hierarchical follicles was significantly lower than that in the prehierarchical follicles (P < 0.05). In addition, the overall expression level of progesterone receptor (PR) decreased, with no significant differences among F1, F2 and F3 follicles (P > 0.05). Yolk putrescine contents were positively correlated with yolk E2 concentrations and PR expression levels (P < 0.05), A significant positive correlation of spermidine levels with yolk P4 concentrations and PR expressions was also observed, as well as the spermine levels with yolk P4 concentrations (P < 0.05). In summary, polyamines were involved in the regulation of follicular development in geese, and this regulation played a role in affecting steroidogenesis and the expression of genes related to hormone receptors.

Electroacupuncture Alleviates Neuropathic Pain by Suppressing Ferroptosis in Dorsal Root Ganglion via SAT1/ALOX15 Signaling

Neuropathic pain affects globally about 7-10% of the general population. Electroacupuncture (EA) effectively relieves neuropathic pain symptoms without causing any side effects; however, the underlying molecular mechanisms remain unclear. We established a chronic constriction injury (CCI)-induced rat model of neuropathic pain. RNA sequencing was used to screen for differentially expressed genes in the dorsal root ganglion after CCI and EA treatment. We identified gene markers of ferroptosis spermidine/spermine N1-acetyltransferase 1 (Sat1) and arachidonate 15-lipoxygenase (Alox15) to be dysregulated in the CCI-induced neuropathic pain model. Furthermore, EA relieved CCI-induced pain as well as ferroptosis-related symptoms in the dorsal root ganglion, including lipid peroxidation and iron overload. Finally, SAT1 knockdown also alleviated mechanical and thermal pain hypersensitivity and reversed ferroptosis damage. In conclusion, we showed that EA inhibited ferroptosis by regulating the SAT1/ALOX15 pathway to treat neuropathic pain. Our findings provide insight into the mechanisms of EA and suggest a novel therapeutic target for neuropathic pain.

Molecular docking and biological activities of Ni(II), Cu(II) and Co(II) complexes with a new potentially hexadentate polyamine ligand; X-ray crystal structure of the Cu(II) complex

Three new metal complexes have been obtained from the reaction of a new polyamine (L) with Ni(II), Cu(II), and Co(II) ions. The X-ray structural analysis of the Cu(II) complex shows that the copper atom is in a very distorted square pyramidal environment, coordinated by five of the six nitrogen donor atoms of the potentially hexadentate ligand. To evaluate the biological potential of the ligand and the synthesized metal complexes, their binding behavior with DNA was studied by molecular modeling methods. The Molecular docking studies showed that the free ligand and its complexes were bound to the major groove of DNA. The antioxidant activities of the ligand and its metal complexes were also assessed, in vitro, using 2,2-diphenyl-1-picrylhydrazyl. The synthesized compounds were tested for activity against lung carcinoma epithelial cells (A549) using the MTT cell viability assay. A comparative study of the IC50 values indicated that the Cu(II) complex exhibited the highest activity, while the Co(II) and Ni(II) complexes showed more potent antiproliferative activity than the ligand. The antibacterial activities of the synthesized complexes were evaluated using micro-broth dilution and disk diffusion methods. The complexes showed greater antibacterial activity than the free ligand.Communicated by Ramaswamy H. Sarma.

Metabolomics in aging research: aging markers from organs

Metabolism plays an important role in regulating aging at several levels, and metabolic reprogramming is the main driving force of aging. Due to the different metabolic needs of different tissues, the change trend of metabolites during aging in different organs and the influence of different levels of metabolites on organ function are also different, which makes the relationship between the change of metabolite level and aging more complex. However, not all of these changes lead to aging. The development of metabonomics research has opened a door for people to understand the overall changes in the metabolic level in the aging process of organisms. The omics-based "aging clock" of organisms has been established at the level of gene, protein and epigenetic modifications, but there is still no systematic summary at the level of metabolism. Here, we reviewed the relevant research published in the last decade on aging and organ metabolomic changes, discussed several metabolites with high repetition rate, and explained their role in vivo, hoping to find a group of metabolites that can be used as metabolic markers of aging. This information should provide valuable information for future diagnosis or clinical intervention of aging and age-related diseases.

Targeted metabolomics characterizes metabolite occurrence and variability in stable freshwater mussel populations

Freshwater mussels (order Unionida) play a key role in freshwater systems as ecosystem engineers and indicators of aquatic ecosystem health. The fauna is globally imperilled due to a diversity of suspected factors; however, causes for many population declines and mortality events remain unconfirmed due partly to limited health assessment tools. Mussel-monitoring activities often rely on population-level measurements, such as abundance and age structure, which reflect delayed responses to environmental conditions. Measures of organismal health would enable preemptive detection of declining condition before population-level effects manifest. Metabolomic analysis can identify shifts in biochemical pathways in response to stressors and changing environmental conditions; however, interpretation of the results requires information on inherent variability of metabolite concentrations in mussel populations. We targeted metabolites in the haemolymph of two common mussels, Lampsilis cardium and Lampsilis siliquoidea, from three Indiana streams (USA) using ultra-high-performance liquid chromatography combined with quadrupole time-of-flight mass spectroscopy. The influence of species, stream and sex on metabolite variability was examined with distance-based redundancy analysis. Metabolite variability was most influenced by species, followed by site and sex. Inter- and intraspecies metabolite variability among sexes was less distinct than differences among locations. We further categorized metabolites by occurrence and variability in mussel populations. Metabolites with high occurrence (Categories 1 and 2) included those indicative of energy status (catabolism versus anabolism; arginine, proline, carnitine, nicotinic acid, pantothenic acid), oxidative stress (proline, glutamine, glutamate) and protein metabolism (thymidine, cytidine, inosine). Metabolites with lower occurrence (Category 3) are constituents of assorted metabolic pathways and can be important biomarkers with additional temporal sampling to characterize their variability. These data provide a reference for future temporal (before/after) monitoring and for studies of stressor-metabolite linkages in freshwater mussels.

Polyamines and Physical Activity in Musculoskeletal Diseases: A Potential Therapeutic Challenge

Autophagy dysregulation is commonplace in the pathogenesis of several invalidating diseases, such as musculoskeletal diseases. Polyamines, as spermidine and spermine, are small aliphatic cations essential for cell growth and differentiation, with multiple antioxidant, anti-inflammatory, and anti-apoptotic effects. Remarkably, they are emerging as natural autophagy regulators with strong anti-aging effects. Polyamine levels were significantly altered in the skeletal muscles of aged animals. Therefore, supplementation of spermine and spermidine may be important to prevent or treat muscle atrophy. Recent in vitro and in vivo experimental studies indicate that spermidine reverses dysfunctional autophagy and stimulates mitophagy in muscles and heart, preventing senescence. Physical exercise, as polyamines, regulates skeletal muscle mass inducing proper autophagy and mitophagy. This narrative review focuses on the latest evidence regarding the efficacy of polyamines and exercise as autophagy inducers, alone or coupled, in alleviating sarcopenia and aging-dependent musculoskeletal diseases. A comprehensive description of overall autophagic steps in muscle, polyamine metabolic pathways, and effects of the role of autophagy inducers played by both polyamines and exercise has been presented. Although literature shows few data in regard to this controversial topic, interesting effects on muscle atrophy in murine models have emerged when the two "autophagy-inducers" were combined. We hope these findings, with caution, can encourage researchers to continue investigating in this direction. In particular, if these novel insights could be confirmed in further in vivo and clinical studies, and the two synergic treatments could be optimized in terms of dose and duration, then polyamine supplementation and physical exercise might have a clinical potential in sarcopenia, and more importantly, implications for a healthy lifestyle in the elderly population.

Comparative Study of Adenosine Analogs as Inhibitors of Protein Arginine Methyltransferases and a Clostridioides difficile-Specific DNA Adenine Methyltransferase

S-Adenosyl-l-methionine (SAM) analogs are adaptable tools for studying and therapeutically inhibiting SAM-dependent methyltransferases (MTases). Some MTases play significant roles in host-pathogen interactions, one of which is Clostridioides difficile-specific DNA adenine MTase (CamA). CamA is needed for efficient sporulation and alters persistence in the colon. To discover potent and selective CamA inhibitors, we explored modifications of the solvent-exposed edge of the SAM adenosine moiety. Starting from the two parental compounds (6e and 7), we designed an adenosine analog (11a) carrying a 3-phenylpropyl moiety at the adenine N6-amino group, and a 3-(cyclohexylmethyl guanidine)-ethyl moiety at the sulfur atom off the ribose ring. Compound 11a (IC50 = 0.15 μM) is 10× and 5× more potent against CamA than 6e and 7, respectively. The structure of the CamA-DNA-inhibitor complex revealed that 11a adopts a U-shaped conformation, with the two branches folded toward each other, and the aliphatic and aromatic rings at the two ends interacting with one another. 11a occupies the entire hydrophobic surface (apparently unique to CamA) next to the adenosine binding site. Our work presents a hybrid knowledge-based and fragment-based approach to generating CamA inhibitors that would be chemical agents to examine the mechanism(s) of action and therapeutic potentials of CamA in C. difficile infection.

The oncogenic properties of the EWSR1::CREM fusion gene are associated with polyamine metabolism

The EWSR1::CREM fusion gene, caused by a chromosomal translocation t(10;22)(p11;q12), has been discovered in divergent malignancies, ranging from low-grade to highly malignant cancers. The translocation gives rise to a chimeric protein, EWSR1::CREM. The molecular mechanisms behind the oncogenic properties of the EWSR1::CREM protein have not previously been systematically characterized. In this study, we performed transcriptional profiling of the melanoma cell line CHL-1, with depletion of endogenous EWSR1::CREM protein using siRNA mediated knockdown. We found that the expression of 712 genes was altered (Log2 fold-change ≥ 2). We performed pathway analysis to identify EWSR1::CREM mediated pathways and cell studies to examine functional differences brought upon by the knockdown. Altered pathways involved cell cycle and proliferation, this was further validated by the cell studies where cell migration was affected as well. Among the target genes with the greatest downregulation, we discovered ODC1-a well-established oncogenic enzyme that can be pharmacologically inhibited and is essential for polyamine synthesis. We found that the main effects seen upon EWSR1::CREM knockdown can be reproduced by directly silencing ODC1 expression. These findings provide novel insights into pathogenesis of tumors harboring a EWSR1::CREM fusion gene, hopefully facilitating the development of novel therapeutic strategies.

Spermidine dietary supplementation and polyamines level in reference to survival and lifespan of honey bees

Honey bee health has been an important and ongoing topic in recent years. Honey bee is also an important model organism for aging studies. Polyamines, putrescine, spermidine and spermine, are ubiquitous polycations, involved in a wide range of cellular processes such as cell growth, gene regulation, immunity, and regulation of lifespan. Spermidine, named longevity elixir, has been most analysed in the context of aging. One of the several proposed mechanisms behind spermidine actions is antioxidative activity. In present study we showed that dietary spermidine supplementation: (a) improved survival, (b) increased the average lifespan, (c) influenced the content of endogenous polyamines by increasing the level of putrescine and spermidine and decreasing the level of spermine, (d) reduced oxidative stress (MDA level), (e) increased the antioxidant capacity of the organism (FRAP), (f) increased relative gene expression of five genes involved in polyamine metabolism, and (g) upregulated vitellogenin gene in honey bees. To our knowledge, this is the first study on honey bee polyamine levels in reference to their longevity. These results provide important information on possible strategies for improving honey bee health by introducing spermidine into their diet. Here, we offer spermidine concentrations that could be considered for that purpose.

T cell-mediated targeted delivery of tadalafil regulates immunosuppression and polyamine metabolism to overcome immune checkpoint blockade resistance in hepatocellular carcinoma

BACKGROUND

Immune checkpoint blockade (ICB) monotherapy provides poor survival benefit in hepatocellular carcinoma (HCC) due to ICB resistance caused by immunosuppressive tumor microenvironment (TME) and drug discontinuation resulting from immune-related side effects. Thus, novel strategies that can simultaneously reshape immunosuppressive TME and ameliorate side effects are urgently needed.

METHODS

Both in vitro and orthotopic HCC models were used to explore and demonstrate the new role of a conventional, clinically used drug, tadalafil (TA), in conquering immunosuppressive TME. In detail, the effect of TA on M2 polarization and polyamine metabolism in tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs) was identified. After making clear the aforementioned immune regulatory effect of TA, we introduced a nanomedicine-based strategy of tumor-targeted drug delivery to make better use of TA to reverse immunosuppressive TME and overcome ICB resistance for HCC immunotherapy. A dual pH-sensitive nanodrug simultaneously carrying both TA and programmed cell death receptor 1 antibody (aPD-1) was developed, and its ability for tumor-targeted drug delivery and TME-responsive drug release was evaluated in an orthotopic HCC model. Finally, the immune regulatory effect, antitumor therapeutic effect, as well as side effects of our nanodrug combining both TA and aPD-1 were analyzed.

RESULTS

TA exerted a new role in conquering immunosuppressive TME by inhibiting M2 polarization and polyamine metabolism in TAMs and MDSCs. A dual pH-sensitive nanodrug was successfully synthesized to simultaneously carry both TA and aPD-1. On one hand, the nanodrug realized tumor-targeted drug delivery by binding to circulating programmed cell death receptor 1-positive T cells and following their infiltration into tumor. On the other hand, the nanodrug facilitated efficient intratumoral drug release in acidic TME, releasing aPD-1 for ICB and leaving TA-encapsulated nanodrug to dually regulate TAMs and MDSCs. By virtue of the combined application of TA and aPD-1, as well as the efficient tumor-targeted drug delivery, our nanodrug effectively inhibited M2 polarization and polyamine metabolism in TAMs and MDSCs to conquer immunosuppressive TME, which contributed to remarkable ICB therapeutic efficacy with minimal side effects in HCC.

CONCLUSIONS

Our novel tumor-targeted nanodrug expands the application of TA in tumor therapy and holds great potential to break the logjam of ICB-based HCC immunotherapy.

Blue light stimulates light stress and phototactic behavior when received in the brain of Diaphorina citri

Blue light with a wavelength of 400-470 nm is the composition of the visible light. However, in recent years, blue light contributed the most significance to light pollution due to the artificial light at night. Previously, we have demonstrated that the Asian citrus psyllid (ACP), Diaphorina citri, an important pest in citrus production, has significant positive phototaxis with a light-emitting diode light of 400 nm. In this study, ACP with positive phototactic behavior to 400 nm light (PH) and non-phototactic behavior to 400 nm light (NP) were collected, individually. Transcriptome dynamics of head tissues of PH and NP groups were captured by using RNA-sequencing technology, respectively. Forty-three to 46 million clean reads with high-quality values were obtained, and 1773 differential expressed genes (DEGs) were detected. Compared with the NP group, there were 841 up-regulated DEGs and 932 down-regulated DEGs in the PH group. Eight pathways were significantly enriched in the PH group in the KEGG database, while 43 up-regulated pathways and 25 down-regulated pathways were significantly enriched in the PH group in the GO database. The DGE approach was reliable validated by real time quantitative PCR. Results indicated that the blue light acted as an abiotic stress causing physiological and biochemical responses such as oxidative stress, protein denaturation, inflammation and tumor development in ACPs. Additionally, the light was absorbed by photoreceptors of ACPs, and converted into electrical signal to regulate neuromodulation. This study provides basic information for understanding the molecular mechanisms of ACP in response to blue light and provides a reference for further studies to elucidate phototactic behavior.

Pentafluoropropionic Anhydride Derivatization and GC-MS Analysis of Histamine, Agmatine, Putrescine, and Spermidine: Effects of Solvents and Starting Column Temperature

Gas chromatography-mass spectrometry (GC-MS) is useful for the quantitative determination of the polyamines spermidine (SPD) and putrescine (PUT) and of the biogenic amine agmatine (AGM) in biological samples after derivatization. This GC-MS method involves a two-step extraction with n-butanol and hydrochloric acid, derivatization with pentafluoropropionic anhydride (PFPA) in ethyl acetate, and extraction of the pentafluoropropionic (PFP) derivatives by toluene of SPD, PUT, and AGM. We wanted to extend this GC-MS method for the biogenic amine histamine (HA), but we faced serious problems that did not allow reliable quantitative analysis of HA. In the present work, we addressed this issue and investigated the derivatization of HA and the effects of toluene and ethyl acetate, two commonly used water-insoluble organic solvents in GC-MS, and oven temperature program. Derivatization of unlabelled HA (d₀-HA) and deuterium-labelled HA (d₄-HA) with PFPA in ethyl acetate (PFPA-EA, 1:4, v/v; 30 min, 65 °C) resulted in the formation of d₀-HA-(PFP)₂ and d₄-HA-(PFP)₂ derivatives. d₄-HA and ¹³C₄-SPD were used as internal standards for the amines after standardization. Considerable quantitative effects of toluene and ethyl acetate were observed. The starting GC column temperature was also found to influence considerably the GC-MS analysis of HA. Our study shows the simultaneous quantitative analysis of HA as HA-(PFP)₂, AGM as AGM-(PFP)₃, PUT as PUT-(PFP)₂, and SPD as SPD-(PFP)₃ derivatives requires the use of ethyl acetate for their extraction and injection into the GC-MS apparatus and a starting GC column temperature of 40 °C instead of 70 °C. The PFP derivatives of HA, AGM, PUT, and SPD were found to be stable in ethyl acetate for several hours at room temperature. Analytically satisfactory linearity, precision, and accuracy were observed for HA, AGM, PUT, and SPD in biologically relevant ranges (0 to 700 pmol). The limits of detection of AGM, PUT, and SPD were about two times lower in ethyl acetate compared to toluene (range, 1-22 fmol). The limits of detection were 1670 fmol for d₀-HA and 557 fmol for d₄-HA. Despite the improvements achieved in the study for HA, its analysis by GC-MS as a PFP derivative is challenging and less efficient than that of PUT, AGM, and SPD.

Quantitative Metabolomics to Explore the Role of Plasma Polyamines in Colorectal Cancer

Colorectal cancer (CRC) is one of the major public health and socio-economic problems, which management demands the development of non-invasive screening tests. Assessment of circulating polyamines could be a valuable tool, although analytical problems still preclude its clinical practice. We exploited ultra-high-resolution liquid chromatography and mass spectrometry, as a highly sensitive and innovative method, to profile eleven polyamines, including spermine and spermidine with their acetylated forms. These data together with an evaluation of the inflammatory indexes might represent suitable biomarkers for the identification of CRC patients. The statistical models revealed good discrimination in distinguishing CRC patients from healthy subjects. The plasma assessment of ornithine and acetylspermine, as well as lymphocyte/platelet ratio, revealed helpful information on the progression of CRC. The combined profiles of circulating polyamines and inflammatory indexes, together with the application of an innovative technology, could represent a valuable tool for discriminating patients from different clinical groups.

P5B-ATPases in the mammalian polyamine transport system and their role in disease

Polyamines (PAs) are physiologically relevant molecules that are ubiquitous in all organisms. The vitality of PAs to the healthy functioning of a cell is due to their polycationic nature causing them to interact with a vast plethora of cellular players and partake in numerous cellular pathways. Naturally, the homeostasis of such essential molecules is tightly regulated in a strictly controlled interplay between intracellular synthesis and degradation, uptake from and secretion to the extracellular compartment, as well as intracellular trafficking. Not surprisingly, dysregulated PA homeostasis and signaling are implicated in multiple disorders, ranging from cancer to neurodegeneration; leading many to propose rectifying the PA balance as a potential therapeutic strategy. Despite being well characterized in bacteria, fungi and plants, the molecular identity and properties of the PA transporters in animals are poorly understood. This review brings together the current knowledge of the cellular function of the mammalian PA transport system (PTS). We will focus on the role of P5B-ATPases ATP13A2-5 which are PA transporters in the endosomal system that have emerged as key players in cellular PA uptake and organelle homeostasis. We will discuss recent breakthroughs on their biochemical and structural properties as well as their implications for disease and therapy.

Spermidine/Spermine N1-Acetyltransferase 1 (SAT1)-A Potential Gene Target for Selective Sensitization of Glioblastoma Cells Using an Ionizable Lipid Nanoparticle to Deliver siRNA

Spermidine/spermine N1-acetyltransferase 1 (SAT1) responsible for cell polyamine catabolism is overexpressed in glioblastoma multiforme (GB). Its role in tumor survival and promoting resistance towards radiation therapy has made it an interesting target for therapy. In this study, we prepared a lipid nanoparticle-based siRNA delivery system (LNP-siSAT1) to selectively knockdown (KD) SAT1 enzyme in a human glioblastoma cell line. The LNP-siSAT1 containing ionizable DODAP lipid was prepared following a microfluidics mixing method and the resulting nanoparticles had a hydrodynamic size of around 80 nm and a neutral surface charge. The LNP-siSAT1 effectively knocked down the SAT1 expression in U251, LN229, and 42MGBA GB cells, and other brain-relevant endothelial (hCMEC/D3), astrocyte (HA) and macrophage (ANA-1) cells at the mRNA and protein levels. SAT1 KD in U251 cells resulted in a 40% loss in cell viability. Furthermore, SAT1 KD in U251, LN229 and 42MGBA cells sensitized them towards radiation and chemotherapy treatments. In contrast, despite similar SAT1 KD in other brain-relevant cells no significant effect on cytotoxic response, either alone or in combination, was observed. A major roadblock for brain therapeutics is their ability to cross the highly restrictive blood-brain barrier (BBB) presented by the brain microcapillary endothelial cells. Here, we used the BBB circumventing approach to enhance the delivery of LNP-siSAT1 across a BBB cell culture model. A cadherin binding peptide (ADTC5) was used to transiently open the BBB tight junctions to promote paracellular diffusion of LNP-siSAT1. These results suggest LNP-siSAT1 may provide a safe and effective method for reducing SAT1 and sensitizing GB cells to radiation and chemotherapeutic agents.

Mercury Induced Tissue Damage, Redox Metabolism, Ion Transport, Apoptosis, and Intestinal Microbiota Change in Red Swamp Crayfish (Procambarus clarkii): Application of Multi-Omics Analysis in Risk Assessment of Hg

As one of the most toxic elements, mercury (Hg) is a widespread toxicant in aquatic environments. Crayfish are considered suitable for indicating the impact of heavy metals on aquatic crustaceans. Nevertheless, Hg toxicity on Procambarus clarkii is largely unknown. In this research, the acute Hg-induced alterations of biochemical responses, histopathology, hepatopancreatic transcriptome, and intestinal microbiome of Procambarus clarkii were studied. Firstly, Hg induced significant changes in reactive oxygen species (ROS) and malonaldehyde (MDA) content as well as antioxidant enzyme activity. Secondly, Hg exposure caused structural damage to the hepatopancreas (e.g., vacuolization of the epithelium and dilatation of the lumen) as well as to the intestines (e.g., dysregulation of lamina epithelialises and extension of lamina proprias). Thirdly, after treatment with three different concentrations of Hg, RNA-seq assays of the hepatopancreas revealed a large number of differentially expressed genes (DEGs) linked to a specific function. Among the DEGs, a lot of redox metabolism- (e.g., ACOX3, SMOX, GPX3, GLO1, and P4HA1), ion transport- (e.g., MICU3, MCTP, PYX, STEAP3, and SLC30A2), drug metabolism- (e.g., HSP70, HSP90A, CYP2L1, and CYP9E2), immune response- (e.g., SMAD4, HDAC1, and DUOX), and apoptosis-related genes (e.g., CTSL, CASP7, and BIRC2) were identified, which suggests that Hg exposure may perturb the redox equilibrium, disrupt the ion homeostasis, weaken immune response and ability, and cause apoptosis. Fourthly, bacterial 16S rRNA gene sequencing showed that Hg exposure decreased bacterial diversity and dysregulated intestinal microbiome composition. At the phylum level, there was a marked decrease in Proteobacteria and an increase in Firmicutes after exposure to high levels of Hg. With regards to genus, abundances of Bacteroides, Dysgonomonas, and Arcobacter were markedly dysregulated after Hg exposures. Our findings elucidate the mechanisms involved in Hg-mediated toxicity in aquatic crustaceans at the tissue, cellular, molecular as well as microbial levels.

A systematic exploration reveals the potential of spermidine for hypopigmentation treatment through the stabilization of melanogenesis-associated proteins

Spermidine (SPD), a polyamine naturally present in living organisms, is known to prolong the lifespan of animals. In this study, the role of SPD in melanogenesis was investigated, showing potential as a pigmenting agent. SPD treatment increased melanin production in melanocytes in a dose dependent manner. Computational analysis with RNA-sequencing data revealed the alteration of protein degradation by SPD treatment without changes in the expressions of melanogenesis-related genes. Indeed, SPD treatment significantly increased the stabilities of tyrosinase-related protein (TRP)-1 and -2 while inhibiting ubiquitination, which was confirmed by treatment of proteasome inhibitor MG132. Inhibition of protein synthesis by cycloheximide (CHX) showed that SPD treatment increased the resistance of TRP-1 and TRP-2 to protein degradation. To identify the proteins involved in SPD transportation in melanocytes, the expression of several solute carrier (SLC) membrane transporters was assessed and, among 27 transporter genes, SLC3A2, SLC7A1, SLC18B1, and SLC22A18 were highly expressed, implying they are putative SPD transporters in melanocytes. Furthermore, SLC7A1 and SLC22A18 were downregulated by SPD treatment, indicating their active involvement in polyamine homeostasis. Finally, we applied SPD to a human skin equivalent and observed elevated melanin production. Our results identify SPD as a potential natural product to alleviate hypopigmentation.

Effects of glycolysis and polyamine predation on intestinal epithelial barrier in colorectal cancer

Colorectal cancer (CRC) is the second most lethal cancer and the third most common cancer in the world, and its prognosis is severely affected by high intestinal mucosal permeability and increasing tumor burden. Studies have shown that the expression of hypoxia induce factor 1α (HIF1α) is up-regulated in a variety of tumor tissues, which is related to multiple metabolic reprogramming of tumor cells. However, the role of HIF1α in CRC tumor growth, tumor polyamine metabolism and intestinal mucosal barrier damage has not been studied. Here, we constructed different types of CRC tumor-bearing mice models by inoculating HCT116 cells with different levels of HIF1α expression (knockdown, wild type, overexpression) in the armpits of mice to explore the upstream and downstream regulators of HIF1α, the effects of HIF1α on the growth of CRC, and the CRC polyamine metabolism and its effect on the intestinal mucosal barrier. We found that with the increase of HIF1 gene expression, tumor growth was promoted and intestinal mucosal permeability was increased. The expression of glycolysis-related proteins was up-regulated, the rate-limiting enzyme ODC of polyamine synthesis was decreased, and the transfer protein of polyamine was increased. HPLC showed that the polyamine content in the tumor tissue of the overexpression group HIF1α OE was higher than that of the wild group HIF1α (+/+), and higher than that of the knockdown group HIF1α (-/-), but the content of polyamines in intestinal mucosa was the opposite. After supplementation of exogenous polyamines, the content of polyamines in intestinal mucosa and tumor tissue increased, and the damage of intestinal mucosa was alleviated. In conclusion, upon activation of the MYC/HIF1 pathway, tumor glycolysis is enhanced, tumors require more energy and endogenous polyamine synthesis is reduced. Therefore, in order to meet its growth needs, tumor will rob polyamines in the intestinal mucosa, resulting in intestinal mucosal epithelial barrier dysfunction.

Application of gold nanoparticles to determine spermine in the presence of other polyamines

The development of methods for the detection of polyamines in biological fluids is essential to improve early diagnosis and treatment of patients with prostate cancer. One of the promising areas is the use of noble metal nanoparticles. According to the literature data, there is no methodological approach have been developed to reliably distinguish spermine from other polyamines, in particular, from their acetylated forms and related compounds present in biological fluids. The paper presents the results of spectrophotometric determination of spermine both alone and in the presence of putrescine, spermidine or urea in the urine using gold nanoparticles. The results of the experiments proved that the developed method is suitable for the selective determination of spermine. It was shown that the presence of spermidine, putrescine, acetylated forms of polyamines or carbamide does not affect the results of the analysis.

Polyamine Oxidase Expression Is Downregulated by 17β-Estradiol via Estrogen Receptor 2 in Human MCF-7 Breast Cancer Cells

Polyamine levels decrease with menopause; however, little is known about the mechanisms regulated by menopause. In this study, we found that among the genes involved in the polyamine pathway, polyamine oxidase (PAOX) mRNA levels were the most significantly reduced by treatment with 17β-estradiol in estrogen receptor (ESR)-positive MCF-7 breast cancer cells. Treatment with 17β-estradiol also reduced the PAOX protein levels. Treatment with selective ESR antagonists and knockdown of ESR members revealed that estrogen receptor 2 (ESR2; also known as ERβ) was responsible for the repression of PAOX by 17β-estradiol. A luciferase reporter assay showed that 17β-estradiol downregulates PAOX promoter activity and that 17β-estradiol-dependent PAOX repression disappeared after deletions (−3126/−2730 and −1271/−1099 regions) or mutations of activator protein 1 (AP-1) binding sites in the PAOX promoter. Chromatin immunoprecipitation analysis showed that ESR2 interacts with AP-1 bound to each of the two AP-1 binding sites. These results demonstrate that 17β-estradiol represses PAOX transcription by the interaction of ESR2 with AP-1 bound to the PAOX promoter. This suggests that estrogen deficiency may upregulate PAOX expression and decrease polyamine levels.

Nanospermidine in Combination with Nanofenretinide Induces Cell Death in Neuroblastoma Cell Lines

A new strategy to cause cell death in tumors might be the increase of intracellular polyamines at concentrations above their physiological values to trigger the production of oxidation metabolites at levels exceeding cell tolerance. To test this hypothesis, we prepared nanospermidine as a carrier for spermidine penetration into the cells, able to escape the polyamine transport system that strictly regulates intracellular polyamine levels. Nanospermidine was prepared by spermidine encapsulation in nanomicelles and was characterized by size, zeta potential, loading, dimensional stability to dilution, and stability to spermidine leakage. Antitumor activity, ROS production, and cell penetration ability were evaluated in vitro in two neuroblastoma cell lines (NLF and BR6). Nanospermidine was tested as a single agent and in combination with nanofenretinide. Free spermidine was also tested as a comparison. The results indicated that the nanomicelles successfully transported spermidine into the cells inducing cell death in a concentration range (150–200 μM) tenfold lower than that required to provide similar cytotoxicity with free spermidine (1500–2000 μM). Nanofenretinide provided a cytostatic effect in combination with the lowest nanospermidine concentrations evaluated and slightly improved nanospermidine cytotoxicity at the highest concentrations. These data suggest that nanospermidine has the potential to become a new approach in cancer treatment. At the cellular level, in fact, it exploits polyamine catabolism by means of biocompatible doses of spermidine and, in vivo settings, it can exploit the selective accumulation of nanomedicines at the tumor site. Nanofenretinide combination further improves its efficacy. Furthermore, the proven ability of spermidine to activate macrophages and lymphocytes suggests that nanospermidine could inhibit immunosuppression in the tumor environment.

Elevated spermidine serum levels in mild cognitive impairment, a potential biomarker of progression to Alzheimer dementia, a pilot study

BACKGROUND/AIMS

There is a close link between iron and polyamine biosynthesis and metabolism. In a recent study, we reported alterations in the serum levels of hepcidin and other iron-related proteins in Alzheimer's disease (AD) patients (Sternberg et al., 2017). Based on these findings, this pilot study compared serum levels of one of the polyamines, Spermidine, between AD, mild cognitive impairment (MCI), and control subjects, correlating the levels with the existing clinical and neuroimaging data.

METHODS

This cross-sectional study measured Spermidine levels in frozen serum samples of 43 AD patients, 12 MCI patients, and 21 age-matched controls, provided by the Oregon Alzheimer's Disease Center Bio-repository, using enzyme-linked immunosorbent assay.

RESULTS

MCI patients showed significantly higher mean Spermidine serum levels compared to controls (P = 0.01), with a non-significant trend for higher Spermidine serum levels in pure AD (P = 0.08) participants compared to controls. Spermidine serum levels correlated with the values of cognitive assessment tests including MMSE (r = -0.705, P = 0.003), CDR (r = 0.751, P = 0.002), and CDR-SOB (r = 0.704, P = 0.007), in "pure" AD subgroup, suggesting that higher Spermidine serum levels in MCI can be a potential biomarker of conversion to dementia in subjects with AD underlying pathology. Furthermore, Spermidine serum levels correlated with serum levels of the chief iron regulatory protein, hepcidin in AD participants with a more advanced disease stage, indicated by MMSE (strata of 8-19, P = 0.02), and CDR-SOB (strata of 6-12, P = 0.03).

CONCLUSION

Studies with larger cohort are warranted for defining the role of Spermidine in AD pathophysiology, and the utility of polyamines as biomarkers of progression of MCI to AD.

Polyamine-metabolizing enzymes are activated to promote the proper assembly of rice stripe mosaic virus in insect vectors

Both viruses and host cells compete for intracellular polyamines for efficient propagation. Currently, how the key polyamine-metabolizing enzymes, including ornithine decarboxylase 1 (ODC1) and its antizyme 1 (OAZ1), are activated to co-ordinate viral propagation and polyamine biosynthesis remains unknown. Here, we report that the matrix protein of rice stripe mosaic virus (RSMV), a cytorhabdovirus, directly hijacks OAZ1 to ensure the proper assembly of rigid bacilliform non-enveloped virions in leafhopper vector. Viral matrix protein effectively competes with ODC1 to bind to OAZ1, and thus, the ability of OAZ1 to target and mediate the degradation of ODC1 is significantly inhibited during viral propagation, which finally promotes polyamines production. Thus, OAZ1 and ODC1 are activated to synergistically promote viral persistent propagation and polyamine biosynthesis in viruliferous vectors. Our data suggest that it is a novel mechanism for rhabdovirus to exploit OAZ1 for facilitating viral assembly.

Involvement of Polyamines From Cardiac Mast Cells in Myocardial Remodeling Induced by Pressure Overload Through Mitochondrial Permeability Transition Pore Opening

Objective

Polyamines mainly contain spermine (SPM), spermidine (SPD), and putrescine (PUT). Many research results suggest that polyamines participate in cell proliferation, differentiation, and the regulation of gene expression, and have a close relationship with the occurrence and development of many diseases. However, the role and possible mechanisms of action of polyamines from cardiac mast cells in myocardial remodeling induced by pressure overload remain to be elucidated.

Methods

Pressure overload was induced by abdominal aortic constriction (AAC). Toluidine blue staining was used to visualize mast cells in cardiac tissue. The polyamine content of cardiac tissue was analyzed using high-performance liquid chromatography. Opening of the mitochondrial permeability transition pore (MPTP) was determined by the Ca²⁺-induced swelling of isolated cardiac mitochondria, measured as a reduction in A₅₂₀.

Results

Compared with sham rats, the cardiac mast cell density, the polyamine content (PUT, SPB, and SPM), and myocardial MPTP opening in rats with AAC were significantly increased (P < 0.05), and were accompanied by increased myocardial fibrosis and heart weight/body weight ratio. Intraperitoneal injection of polyamines mimicked these results, and these effects were reversed by cromolyn sodium, a mast cell stabilizer (P < 0.05). Myocardial MPTP opening increased in rats with AAC (P < 0.05), and the three polyamines also increased myocardial MPTP opening (P < 0.05).

Conclusion

Mast cell-derived polyamines are involved in pressure overload-induced myocardial remodeling by increasing opening of the MPTP.

Ornithine decarboxylase deficiency critically impairs nitrogen metabolism and survival in Aedes aegypti mosquitoes

Ornithine decarboxylase (ODC; EC 4.1.1.17) catalyzes the conversion of ornithine to putrescine, the rate-limiting first step for de novo polyamine biosynthesis. Previously, we reported that genetic knockdown of xanthine dehydrogenase 1 (XDH1)-a gene encoding the enzyme involved in the last two steps of uric acid synthesis-causes an increase in ODC transcript levels in fat body of blood-fed Aedes aegypti mosquitoes, suggesting a crosstalk at molecular level between XDH1 and ODC during nitrogen disposal. To further investigate the role of ODC in nitrogen metabolism, we conducted several biochemical and genetic analyses in sugar- and blood-fed A. aegypti females. Distinct ODC gene and protein expression patterns were observed in mosquito tissues dissected during the first gonotrophic cycle. Both pharmacological and RNA interference-mediated knockdown of ODC negatively impacted mosquito survival, disrupted nitrogen waste disposal, delayed oviposition onset, and decreased fecundity in vitellogenic blood-fed females. A lag in the expression of two major digestive serine proteases, a reduction of blood meal digestion in the midgut, and a decrease in vitellogenin yolk protein uptake in ovarian follicles were observed by western blots in ODC-deficient females. Moreover, genetic silencing of ODC showed a broad transcriptional modulation of genes encoding proteins involved in multiple metabolic pathways in mosquito fat body, midgut, and Malpighian tubules prior to and after blood feeding. All together, these data demonstrate that ODC plays an essential role in mosquito metabolism, and that ODC crosstalks with multiple genes and proteins to prevent deadly nitrogen perturbations in A. aegypti females.

Biogenic Amines in Meat and Meat Products: A Review of the Science and Future Perspectives

Biogenic amines (BAs) can be found in a wide range of meat and meat products, where they are important as an index for product stability and quality, but also for their impact on public health. This review analyzes the scientific evidence gathered so far on the presence and role of biogenic amines in meat and meat products, also considering the effect of technological conditions on BAs accumulation or decrease. The data provided can be useful for developing solutions to control BAs formation during the shelf-life, for example by novel starters for dry cured products, as well as by packaging technologies and materials for fresh meats. Further research, whose trends are reviewed in this paper, will fill the knowledge gaps, and allow us to protect such perishable products along the distribution chain and in the home environment.

Assessing the biological effects of microwave irradiation on human semen in vitro and determining the role of seminal plasma polyamines in this process

The aim of the present study was to investigate the influence of millimeter-wave electromagnetic (MW) irradiation on normal and pathological human sperm in vitro, and to evaluate a possible role of polyamines (PA) in this process. The stability of sperm membranes, the number of apoptotic gametes, and the content of seminal plasma PA in the ejaculates of fertile and subfertile men were compared before and after short-term MW electromagnetic exposure in vitro. The ejaculate samples were collected from healthy donors [n=25, age 22-38 years old (y.o.), average age 30.6±1.1 y.o. (mean ± SEM)] and from subfertile men (n=78, age 25-48 y.o., average age 34.1±0.8 y.o.) and exposed to MW radiation. The electromagnetic field had a wavelength of 7.1 mm, a frequency of 42.194 GHz and an exposure time of 20 min. The fragility of sperm membranes was evaluated by their resistance to sodium chloride solution (Milovanov test) and to acetic acid (Joel test). Acrosin activity was assayed spectrophotometrically. Apoptosis was determined by the externalization of phosphatidylserine on the outer side of the sperm membrane and propidium iodide staining. The PA levels were determined by agar gel electrophoretic fractionation. An increase in the resistance of sperm membranes, a decrease in acrosin activity, a decrease in the number of apoptotic gametes and a decrease in the seminal plasma PA concentrations were found after exposure of the native human sperm to low-intensity MW irradiation. Two types of reactions were revealed for the subfertile samples. The results revealed positive bio-effects of specific microwaves on the human semen and the participation of PA in the realization of these effects.

A new signal that shrinks fat

Healthy white adipose tissue is dependent on proliferation of endothelial cells to maintain homeostasis or undergo expansion. A new study shows that endothelial cells communicate with adipocytes via polyamines to promote vascularization of adipose tissue, thereby reversing the metabolic effects of obesity.

Abundant expression of ferroptosis-related SAT1 is related to unfavorable outcome and immune cell infiltration in low-grade glioma

Background

Low-grade glioma (LGG) is susceptible to ferroptosis, which is involved in TMZ resistance. Ferroptosis induction can enhance the sensitivity to TMZ and synergistically kill glioma cells. T cell-promoted tumor ferroptosis is a vital anti-tumor mechanism of immune checkpoint inhibitors. The SAT1 activation is closely related to ferroptosis upon ROS induction due to the upregulation of arachidonate 15-lipoxygenase (ALOX15) expression.

Methods

The expression of SAT1 in pan-cancer and corresponding normal tissue from the TCGA data portal was primarily explored. The landscape of SAT1 and immune cell infiltration and their corresponding gene marker sets in different tissues were further explored. Additionally, we evaluated the relationships between SAT1 and the clinicopathologic parameters of LGG, and the disease-specific survival (DSS), progression-free interval (PFI), and overall survival (OS) were also assessed using KM survival curves and multivariate analysis in LGG. Meanwhile, the Gene Set Enrichment Analysis (GSEA) was also implemented to determine the potential effect of the SAT1 gene in LGG. Furthermore, the predictive power of SAT1 was validated using an independent LGG cohort from the Chinese Glioma Genome Atlas (CGGA) data.

Results

In general, the expression of SAT1 is different between most tumors and their adjacent normal tissues. The results demonstrated that SAT1 expression is positively associated with TMB in LGG, BRCA, and THYM. The results displayed that the expression level of SAT1 is obviously correlated with the level of infiltrating macrophages and CD8 + T cells, and the levels of most immune gene sets were associated with the SAT1 expression in LGG. Interestingly, univariate and multivariate models significantly indicated that the OS and PFI of patients with LGG with high SAT1 levels were poorer than those with low SAT1 expression in the TCGA LGG cohort. GSEA showed that SAT1 was involved in immune regulation and multiple signaling pathways. Finally, our analysis demonstrated that SAT1 was closely associated with IDH mutation, 1p19q codeletion, chemoradiotherapy resistance and disease recurrence.

Conclusions

Abundant expression of SAT1 was related to poor disease prognosis and abundant immune cell infiltration in LGG.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09313-w.

Inhibitory Effect of Ursolic Acid on the Migration and Invasion of Doxorubicin-Resistant Breast Cancer

The cause of death in most breast cancer patients is disease metastasis and the occurrence of multidrug resistance (MDR). Ornithine decarboxylase (ODC), which is involved into multiple pathways, is closely related to carcinogenesis and development. Ursolic acid (UA), a natural triterpenoid compound, has been shown to reverse the MDR characteristics of tumor cells. However, the effect of UA on the invasion and metastasis of tumor cells with MDR is not known. Therefore, we investigated the effects of UA on invasion and metastasis, ODC-related polyamine metabolism, and MAPK-Erk-VEGF/MMP-9 signaling pathways in a doxorubicin-resistant breast cancer cell (MCF-7/ADR) model. The obtained results showed that UA significantly inhibited the adhesion and migration of MCF-7/ADR cells, and had higher affinities with key active cavity residues of ODC compared to the known inhibitor di-fluoro-methyl-ornithine (DFMO). UA could downregulate ODC, phosphorylated Erk (P-Erk), VEGF, and matrix metalloproteinase-9 (MMP-9) activity. Meanwhile, UA significantly reduced the content of metabolites of the polyamine metabolism. Furthermore, UA increased the intracellular accumulation of Dox in MCF-7/ADR cells. Taken together, UA can inhibit against tumor progression during the treatment of breast cancer with Dox, and possibly modulate the Erk-VEGF/MMP-9 signaling pathways and polyamine metabolism by targeting ODC to exert these effects.

Genome-wide RNAi screen identifies novel players in human 60S subunit biogenesis including key enzymes of polyamine metabolism

Ribosome assembly is an essential process that is linked to human congenital diseases and tumorigenesis. While great progress has been made in deciphering mechanisms governing ribosome biogenesis in eukaryotes, an inventory of factors that support ribosome synthesis in human cells is still missing, in particular regarding the maturation of the large 60S subunit. Here, we performed a genome-wide RNAi screen using an imaging-based, single cell assay to unravel the cellular machinery promoting 60S subunit assembly in human cells. Our screen identified a group of 310 high confidence factors. These highlight the conservation of the process across eukaryotes and reveal the intricate connectivity of 60S subunit maturation with other key cellular processes, including splicing, translation, protein degradation, chromatin organization and transcription. Intriguingly, we also identified a cluster of hits comprising metabolic enzymes of the polyamine synthesis pathway. We demonstrate that polyamines, which have long been used as buffer additives to support ribosome assembly in vitro, are required for 60S maturation in living cells. Perturbation of polyamine metabolism results in early defects in 60S but not 40S subunit maturation. Collectively, our data reveal a novel function for polyamines in living cells and provide a rich source for future studies on ribosome synthesis.

Functional characterization of arginine metabolic pathway enzymes in the antibacterial immune response of penaeid shrimp

Arginine metabolism pathway enzymes and products are important modulators of several physiological processes in animals, including immune response. Although some components of the arginine metabolic pathway have been reported in penaeid shrimps, no systematic study has explored all the key pathway enzymes involved in shrimp antimicrobial response. Here, we explored the role of the three key arginine metabolism enzymes (nitric-oxide synthase (NOS), arginase (ARG), agmatinase (AGM)) in Penaeus vannamei antimicrobial immunity. First, P. vannamei homologs of ARG and AGM (PvARG and PvAGM) were cloned and found to be evolutionally conserved with invertebrate counterparts. Transcript levels of PvARG, PvAGM, and PvNOS were ubiquitously expressed in healthy shrimp tissues and induced in hemocytes and hepatopancreas upon challenge with Gram-negative (Vibrio parahaemolyticus) and Gram-positive (Streptoccocus iniae) bacteria, suggesting their involvement in shrimp antimicrobial immune response. Besides, RNA interference knockdown and enzyme activity assay revealed an antagonistic relationship between PvARG/PvAGM and PvNOS, while this relationship was broken upon pathogen stimulation. Interestingly, knockdown of PvNOS increased Vibrio abundance in shrimp hemolymph, whereas knockdown of PvAGR reduced Vibrio abundance. Taken together, our present data shows that homologs of the key arginine metabolism pathway enzymes in penaeid shrimp (PvARG, PvAGM, and PvNOS) work synergistically and/or antagonistically to modulate antibacterial immune response.

Influence of the Type of Breastfeeding and Human Milk Polyamines on Infant Anthropometric Parameters

Feeding choices in the early months of life are key determinants of growth during infancy. Polyamines participate in cell proliferation and differentiation, and it has also been suggested that polyamine metabolism plays a role in adipogenesis. As the main exogenous source of polyamines in the infant is human milk, the aim of this work was to study if the type of breastfeeding received and the polyamine intake from human milk has an influence on infant anthropometric parameters. A cohort of 78 full-term healthy newborns was followed up until 4 months of age; 55 were fully and 23 partially breastfed. Anthropometric measurements were taken at 2 and 4 months, when human milk samples were also collected for analysis of polyamine content by UHPLC-FL. Fully breastfed infants had a better anthropometric profile than those partially breastfed (p < 0.05). Furthermore, polyamine intake in partially breastfed infants was significantly lower compared to those fully breastfed. However, only two of the 15 anthropometric indicators evaluated (triceps skinfold and mean upper arm circumference) showed a significant inverse association with polyamine content in human milk and intake (p < 0.05). Infant growth and body composition differ according to the type of breastfeeding received. Based on the weak associations between polyamines and anthropometric indicators, it is not possible to conclude the influence of polyamines in infant growth and body composition.

The Potential Role of Spermine and Its Acetylated Derivative in Human Malignancies

Polyamines are essential biomolecules for normal cellular metabolism in humans. The roles of polyamines in cancer development have been widely discussed in recent years. Among all, spermine alongside with its acetylated derivative, N¹, N¹²-Diacetylspermine, demonstrate a relationship with the diagnosis and staging of various cancers, including lung, breast, liver, colorectal and urogenital. Numerous studies have reported the level of spermine in different body fluids and organ tissues in patients with different types of cancers. Currently, the role and the underlying mechanisms of spermine in cancer development and progression are still under investigation. This review summarized the roles of spermine in cancer development and as a diagnostic, prognostic and therapeutic tool in various cancers.