RESUMO
Precise polyamine metabolism regulation is vital for cells and organisms. Mutations in spermine synthase (SMS) cause Snyder-Robinson intellectual disability syndrome (SRS), characterized by significant spermidine accumulation and autophagy blockage in the nervous system. Emerging evidence connects polyamine metabolism with other autophagy-related diseases, such as Tauopathy, however, the functional intersection between polyamine metabolism and autophagy in the context of these diseases remains unclear. Here, we altered SMS expression level to investigate the regulation of autophagy by modulated polyamine metabolism in Tauopathy in Drosophila and human cellular models. Interestingly, while complete loss of Drosophila spermine synthase (dSms) impairs lysosomal function and blocks autophagic flux recapitulating SRS disease phenotype, partial loss of dSms enhanced autophagic flux, reduced Tau protein accumulation, and led to extended lifespan and improved climbing performance in Tauopathy flies. Measurement of polyamine levels detected a mild elevation of spermidine in flies with partial loss of dSms. Similarly, in human neuronal or glial cells, partial loss of SMS by siRNA-mediated knockdown upregulated autophagic flux and reduced Tau protein accumulation. Importantly, proteomics analysis of postmortem brain tissue from Alzheimer's disease (AD) patients showed a significant albeit modest elevation of SMS level. Taken together, our study uncovers a functional correlation between polyamine metabolism and autophagy in AD: SMS reduction upregulates autophagy, suppresses Tau accumulation, and ameliorates neurodegeneration and cell death. These findings provide a new potential therapeutic target for AD.
Assuntos
Autofagia , Espermina Sintase , Proteínas tau , Animais , Proteínas tau/metabolismo , Humanos , Espermina Sintase/metabolismo , Espermina Sintase/genética , Drosophila melanogaster/metabolismo , Proteínas de Drosophila/metabolismo , Proteínas de Drosophila/genética , Tauopatias/metabolismo , Tauopatias/patologia , Neurônios/metabolismo , Neurônios/patologia , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Doença de Alzheimer/genética , Espermidina/metabolismo , Modelos Animais de Doenças , Lisossomos/metabolismo , Drosophila/metabolismo , Deficiência Intelectual Ligada ao Cromossomo XRESUMO
Spermine synthase is an aminopropyltransferase that adds an aminopropyl group to the essential polyamine spermidine to form tetraamine spermine, needed for normal human neural development, plant salt and drought resistance, and yeast CoA biosynthesis. We functionally identify for the first time bacterial spermine synthases, derived from phyla Bacillota, Rhodothermota, Thermodesulfobacteriota, Nitrospirota, Deinococcota, and Pseudomonadota. We also identify bacterial aminopropyltransferases that synthesize the spermine same mass isomer thermospermine, from phyla Cyanobacteriota, Thermodesulfobacteriota, Nitrospirota, Dictyoglomota, Armatimonadota, and Pseudomonadota, including the human opportunistic pathogen Pseudomonas aeruginosa. Most of these bacterial synthases were capable of synthesizing spermine or thermospermine from the diamine putrescine and so possess also spermidine synthase activity. We found that most thermospermine synthases could synthesize tetraamine norspermine from triamine norspermidine, that is, they are potential norspermine synthases. This finding could explain the enigmatic source of norspermine in bacteria. Some of the thermospermine synthases could synthesize norspermidine from diamine 1,3-diaminopropane, demonstrating that they are potential norspermidine synthases. Of 18 bacterial spermidine synthases identified, 17 were able to aminopropylate agmatine to form N1-aminopropylagmatine, including the spermidine synthase of Bacillus subtilis, a species known to be devoid of putrescine. This suggests that the N1-aminopropylagmatine pathway for spermidine biosynthesis, which bypasses putrescine, may be far more widespread than realized and may be the default pathway for spermidine biosynthesis in species encoding L-arginine decarboxylase for agmatine production. Some thermospermine synthases were able to aminopropylate N1-aminopropylagmatine to form N12-guanidinothermospermine. Our study reveals an unsuspected diversification of bacterial polyamine biosynthesis and suggests a more prominent role for agmatine.
Assuntos
Bactérias , Proteínas de Bactérias , Espermidina Sintase , Espermina Sintase , Bactérias/enzimologia , Bactérias/genética , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Espermidina/metabolismo , Espermidina/análogos & derivados , Espermidina/biossíntese , Espermidina Sintase/metabolismo , Espermidina Sintase/genética , Espermina/metabolismo , Espermina/análogos & derivados , Espermina/biossíntese , Espermina Sintase/metabolismo , Espermina Sintase/genética , Poliaminas/metabolismo , Alquil e Aril Transferases/biossíntese , Alquil e Aril Transferases/genética , Agmatina/química , Agmatina/metabolismoRESUMO
Snyder-Robinson syndrome (SRS) is a rare X-linked recessive disorder caused by a mutation in the SMS gene, which encodes spermine synthase, and aberrant polyamine metabolism. SRS is characterized by intellectual disability, thin habitus, seizure, low muscle tone/hypotonia and osteoporosis. Progress towards understanding and treating SRS requires a model that recapitulates human gene variants and disease presentations. Here, we evaluated molecular and neurological presentations in the G56S mouse model, which carries a missense mutation in the Sms gene. The lack of SMS protein in the G56S mice resulted in increased spermidine/spermine ratio, failure to thrive, short stature and reduced bone density. They showed impaired learning capacity, increased anxiety, reduced mobility and heightened fear responses, accompanied by reduced total and regional brain volumes. Furthermore, impaired mitochondrial oxidative phosphorylation was evident in G56S cerebral cortex, G56S fibroblasts and Sms-null hippocampal cells, indicating that SMS may serve as a future therapeutic target. Collectively, our study establishes the suitability of the G56S mice as a preclinical model for SRS and provides a set of molecular and functional outcome measures that can be used to evaluate therapeutic interventions for SRS.
Assuntos
Comportamento Animal , Modelos Animais de Doenças , Deficiência Intelectual Ligada ao Cromossomo X , Poliaminas , Espermina Sintase , Animais , Deficiência Intelectual Ligada ao Cromossomo X/patologia , Deficiência Intelectual Ligada ao Cromossomo X/genética , Espermina Sintase/metabolismo , Espermina Sintase/genética , Poliaminas/metabolismo , Mitocôndrias/metabolismo , Masculino , Camundongos , Fibroblastos/metabolismo , Fibroblastos/patologia , Fosforilação Oxidativa , Hipocampo/patologia , Hipocampo/metabolismo , Ansiedade/patologia , Densidade Óssea , Encéfalo/patologia , Encéfalo/metabolismo , Medo , Humanos , Tamanho do ÓrgãoRESUMO
Despite the well-known relevance of polyamines to many forms of life, little is known about how polyamines regulate osteogenesis and skeletal homeostasis. Here, we report a series of in vitro studies conducted with human-bone-marrow-derived pluripotent stromal cells (MSCs). First, we show that during osteogenic differentiation, mRNA levels of most polyamine-associated enzymes are relatively constant, except for the catabolic enzyme spermidine/spermine N1-acetyltransferase 1 (SAT1), which is strongly increased at both mRNA and protein levels. As a result, the intracellular spermidine to spermine ratio is significantly reduced during the early stages of osteoblastogenesis. Supplementation of cells with exogenous spermidine or spermine decreases matrix mineralization in a dose-dependent manner. Employing N-cyclohexyl-1,3-propanediamine (CDAP) to chemically inhibit spermine synthase (SMS), the enzyme catalyzing conversion of spermidine into spermine, also suppresses mineralization. Intriguingly, this reduced mineralization is rescued with DFMO, an inhibitor of the upstream polyamine enzyme ornithine decarboxylase (ODC1). Similarly, high concentrations of CDAP cause cytoplasmic vacuolization and alter mitochondrial function, which are also reversible with the addition of DFMO. Altogether, these studies suggest that excess polyamines, especially spermidine, negatively affect hydroxyapatite synthesis of primary MSCs, whereas inhibition of polyamine synthesis with DFMO rescues most, but not all of these defects. These findings are relevant for patients with Snyder-Robinson syndrome (SRS), as the presenting skeletal defects-associated with SMS deficiency-could potentially be ameliorated by treatment with DFMO.
Assuntos
Células-Tronco Mesenquimais , Espermidina , Humanos , Espermidina/metabolismo , Espermina/metabolismo , Espermina Sintase/genética , Ornitina Descarboxilase/metabolismo , Osteogênese , Poliaminas/metabolismo , Células-Tronco Mesenquimais/metabolismo , RNA MensageiroRESUMO
Potentilla sericea is resistant and tolerates rough management. It is an excellent garden groundcover for ecological restoration and soil consolidation for slope protection. Polyamines have functions such as promoting tissue growth and physiological resistance, while spermine synthase catalyzes the production of spermine. The PsSPMS gene from Potentilla sericea was cloned and transformed into Arabidopsis thaliana to study the response of transgenic Arabidopsis thaliana to cadmium stress. The results showed that the contents of spermidine, spermine as well as glutathione were higher in PsSPMS overexpressing Arabidopsis thaliana than the control, while the contents of putrescine were less than the control. Net photosynthetic rate, stomatal conductance, chlorophyll content, water use efficiency, electron transfer rate, PSII-related parameters, proline content, superoxide dismutase, and glutathione reductase activities were higher in PsSPMS overexpressing Arabidopsis thaliana than the control, while malondialdehyde, superoxide anion, and hydrogen peroxide contents were lower than the control. Correlation analysis showed significant differences between the indicators (P < 0.05 and P < 0.01). Expression of AtSPMS, AtSPD3, AtGSH2 and AtGR in transgenic Arabidopsis thaliana was higher than that of the control. Therefore, this study provides a genetic reference for the cultivation of cadmium-tolerant plants through genetic engineering and lays the foundation for further research on cadmium-tolerant Potentilla sericea.
Assuntos
Arabidopsis , Potentilla , Espermina/metabolismo , Cádmio/toxicidade , Cádmio/metabolismo , Arabidopsis/metabolismo , Potentilla/genética , Potentilla/metabolismo , Espermina Sintase/genética , Espermina Sintase/metabolismo , Plantas Geneticamente Modificadas/genética , Regulação da Expressão Gênica de PlantasRESUMO
Snyder-Robinson syndrome (SRS) results from mutations in spermine synthase (SMS), which converts the polyamine spermidine into spermine. Affecting primarily males, common manifestations of SRS include intellectual disability, osteoporosis, hypotonia, and seizures. Symptom management is the only treatment. Reduced SMS activity causes spermidine accumulation while spermine levels are reduced. The resulting exaggerated spermidine:spermine ratio is a biochemical hallmark of SRS that tends to correlate with symptom severity. Our studies aim to pharmacologically manipulate polyamine metabolism to correct this imbalance as a therapeutic strategy for SRS. Here we report the repurposing of 2-difluoromethylornithine (DFMO), an FDA-approved inhibitor of polyamine biosynthesis, in rebalancing spermidine:spermine ratios in SRS patient cells. Mechanistic in vitro studies demonstrate that, while reducing spermidine biosynthesis, DFMO also stimulates the conversion of spermidine into spermine in hypomorphic SMS cells and induces uptake of exogenous spermine, altogether reducing the aberrant ratios. In a Drosophila SRS model characterized by reduced lifespan, DFMO improves longevity. As nearly all SRS patient mutations are hypomorphic, these studies form a strong foundation for translational studies with significant therapeutic potential.
Assuntos
Poliaminas , Espermidina , Masculino , Humanos , Poliaminas/metabolismo , Espermidina/metabolismo , Espermidina/farmacologia , Espermina/metabolismo , Eflornitina/farmacologia , Eflornitina/uso terapêutico , Espermina Sintase/genética , Espermina Sintase/metabolismoRESUMO
Snyder-Robinson syndrome is an extremely rare genetic disorder, caused by mutations of the spermine synthase gene. We report a novel case of Snyder-Robinson syndrome, caused by a de novo mutation and first misdiagnosed with osteogenesis imperfecta. Clinical features, course, and genetic analysis are presented. The patient was treated with bisphosphonates for a decade, until developing an atypical femoral fracture. Teriparatide was then administered for 2 years and then changed to denosumab every 6 months, improving his bone density mass and preventing further fractures.
Assuntos
Deficiência Intelectual Ligada ao Cromossomo X , Osteogênese Imperfeita , Espermina Sintase , Diagnóstico Diferencial , Humanos , Deficiência Intelectual Ligada ao Cromossomo X/diagnóstico , Deficiência Intelectual Ligada ao Cromossomo X/genética , Osteogênese Imperfeita/diagnóstico , Osteogênese Imperfeita/tratamento farmacológico , Osteogênese Imperfeita/genética , Espermina Sintase/genéticaRESUMO
There is increasing recognition for the contribution of genetic mosaicism to human disease, particularly as high-throughput sequencing has enabled detection of sequence variants at very low allele frequencies. Here, we describe an infant male who presented at 9 mo of age with hypotonia, dysmorphic features, congenital heart disease, hyperinsulinemic hypoglycemia, hypothyroidism, and bilateral sensorineural hearing loss. Whole-genome sequencing of the proband and the parents uncovered an apparent de novo mutation in the X-linked SMS gene. SMS encodes spermine synthase, which catalyzes the production of spermine from spermidine. Inactivation of the SMS gene disrupts the spermidine/spermine ratio, resulting in Snyder-Robinson syndrome. The variant in our patient is absent from the gnomAD and ExAC databases and causes a missense change (p.Arg130Cys) predicted to be damaging by most in silico tools. Although Sanger sequencing confirmed the de novo status in our proband, polymerase chain reaction (PCR) and deep targeted resequencing to â¼84,000×-175,000× depth revealed that the variant is present in blood from the unaffected mother at â¼3% variant allele frequency. Our findings thus provided a long-sought diagnosis for the family while highlighting the role of parental mosaicism in severe genetic disorders.
Assuntos
Deficiência Intelectual Ligada ao Cromossomo X , Mosaicismo , Humanos , Lactente , Masculino , Mutação de Sentido Incorreto , Espermina Sintase/genéticaRESUMO
Polyamines are small organic cations that are important for several biological processes such as cell proliferation, cell cycle progression, and apoptosis. The dysregulation of intracellular polyamines is often associated with diseases such as cancer, diabetes, and developmental disorders. Although polyamine metabolism has been well studied, the effects of key enzymes in the polyamine pathway on lipid metabolism are not well understood. Here, we determined metabolic effects resulting from the absence of spermidine synthase (SpdS) and spermine synthase (Sms) in Drosophila. While SpdS mutants developed normally and accumulated triglycerides, Sms mutants had reduced viability and stored less triglyceride than the controls. Interestingly, when decreasing SpdS and Sms, specifically in the fat body, triglyceride storage increased. While there was no difference in triglycerides stored in heads, thoraxes and abdomen fat bodies, abdomen fat body DNA content increased, and protein/DNA decreased in both SpdS- and Sms-RNAi flies, suggesting that fat body-specific knockdown of SpdS and Sms causes the production of smaller fat body cells and triglycerides to accumulate in non-fat body tissues of the abdomen. Together, these data provide support for the role that polyamines play in the regulation of metabolism and can help enhance our understanding of polyamine function in metabolic diseases.
Assuntos
Fenômenos Biológicos , Proteínas de Drosophila/genética , Drosophila/fisiologia , Espermidina Sintase , Espermina Sintase/metabolismo , Triglicerídeos/metabolismo , Animais , DNA , Drosophila/genética , Poliaminas , Espermidina Sintase/genética , Espermidina Sintase/metabolismo , Espermina Sintase/genéticaRESUMO
Snyder-Robinson syndrome (OMIM #309583) is a rare X-linked condition, caused by mutation in the SMS gene (MIM *300105), characterized by a wide spectrum of clinical signs including developmental delay, epilepsy, asthenic habitus, dysmorphism, osteopenia, and renal or genital anomalies. Here we describe two maternal half-brothers who both presented with severe neurodevelopmental delay, seizures, hearing loss, facial dysmorphism, renal and ophthalmologic anomalies, failure to thrive and premature death. A novel p.(Gly203Asp) variant was found at the hemizygous state in the two boys, and an elevated Spermidine/Spermine ratio confirmed the diagnosis of Snyder-Robinson syndrome. One of the brothers presented with gastrointestinal symptoms, with jejunal stenosis, enteral feeding intolerance, failure to thrive due to a dysfunctional gastrointestinal system, cholestasis and exocrine pancreatic insufficiency. Although more studies will be needed to understand its mechanisms, this observation lends further support to the possibility of severe digestive involvement in Snyder Robinson syndrome.
Assuntos
Deficiência Intelectual Ligada ao Cromossomo X/genética , Fenótipo , Pré-Escolar , Insuficiência de Crescimento , Humanos , Lactente , Jejuno/patologia , Masculino , Deficiência Intelectual Ligada ao Cromossomo X/patologia , Mutação de Sentido Incorreto , Espermidina/sangue , Espermina/sangue , Espermina Sintase/genéticaRESUMO
The study tested the function of exogenous spermine (Spm) in resisting salinity-alkalinity stress in tomato seedlings and found that tomato Spm synthase gene (SlSPMS) was involved in this regulation. The tomato seedlings cultivated in normal conditions or salinity-alkalinity conditions were irrigated with 100 ml one strength Hoagland nutrient solution 100 ml mixed solution (5 ml 300 mmol/L NaCl, 45 ml 300 mmol/L Na2SO4, 45 ml 300 mmol/L NaHCO3, and 5 ml 300 mmol/L Na2CO3 (pH = 8.90)) every 2 days, respectively. The 0.5 mM Spm pretreatment improved superoxide dismutase (SOD; EC 1.15.1.1) activity, catalase (CAT; EC 1.11.1.6) activity, ascorbate peroxidase (APX; EC 1.11.1.11) activity, and glutathione reductase (GR; EC 1.6.4.2) activity and decreased endogenous hydrogen peroxide (H2O2) content, malondialdehyde (MDA) content, and relative electrical conductivity (REC) in tomato leaves. Na+ content declined and K+ concentration rose in tomato seedlings when pre-treated with Spm. However the results showed that under salinity-alkalinity stress, silencing of SlSPMS with virus-induced gene silencing had lower antioxidant enzyme activities and higher Na+ content and lower K+ content than normal tomato seedlings, meaning that they had low salinity-alkalinity tolerance. Exogenous Spm could not reconstruct the tolerance to salinity-alkalinity stress in SlSPMS gene-silencing tomato seedlings. Taken together, exogenous Spm could induce the expression level of SlSPMS, which regulated the antioxidant enzyme system and ion homeostasis in tomato seedlings living in salinity-alkalinity environment, thereby improving the ability of tomato seedlings to resist salinity-alkalinity stress.
Assuntos
Antioxidantes/fisiologia , Salinidade , Solanum lycopersicum/fisiologia , Espermina Sintase/genética , Espermina/farmacologia , Estresse Fisiológico , Regulação da Expressão Gênica de Plantas , Homeostase , Concentração de Íons de Hidrogênio , Solanum lycopersicum/efeitos dos fármacos , Plântula/fisiologiaRESUMO
Cellular adhesion mediates many important plant-microbe interactions. In the devastating blast fungus Magnaporthe oryzae1, powerful glycoprotein-rich mucilage adhesives2 cement melanized and pressurized dome-shaped infection cells-appressoria-to host rice leaf surfaces. Enormous internal turgor pressure is directed onto a penetration peg emerging from the unmelanized, thin-walled pore at the appressorial base1-4, forcing it through the leaf cuticle where it elongates invasive hyphae in underlying epidermal cells5. Mucilage sealing around the appressorial pore facilitates turgor build-up2, but the molecular underpinnings of mucilage secretion and appressorial adhesion are unknown. Here, we discovered an unanticipated and sole role for spermine in facilitating mucilage production by mitigating endoplasmic reticulum (ER) stress in the developing appressorium. Mutant strains lacking the spermine synthase-encoding gene SPS1 progressed through all stages of appressorial development, including penetration peg formation, but cuticle penetration was unsuccessful due to reduced appressorial adhesion, which led to solute leakage. Mechanistically, spermine neutralized off-target oxygen free radicals produced by NADPH oxidase-1 (Nox1)3,6 that otherwise elicited ER stress and the unfolded protein response, thereby critically reducing mucilage secretion. Our study reveals that spermine metabolism via redox buffering of the ER underpins appressorial adhesion and rice cell invasion and provides insights into a process that is fundamental to host plant infection.
Assuntos
Ascomicetos/metabolismo , Oryza/microbiologia , Doenças das Plantas/virologia , Espermina/metabolismo , Ascomicetos/genética , Ascomicetos/crescimento & desenvolvimento , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Hifas/genética , Hifas/crescimento & desenvolvimento , Hifas/metabolismo , Espermina Sintase/genética , Espermina Sintase/metabolismoRESUMO
BACKGROUND: Loss of function mutations in the spermine synthase gene (SMS) have been reported to cause a rare X-linked intellectual disability known as Snyder-Robinson Syndrome (SRS). Besides intellectual disability, SRS is also characterized by reduced bone density, osteoporosis and facial dysmorphism. SRS phenotypes evolve with age from childhood to adulthood. METHODS: Whole exome sequencing was performed to know the causative gene/pathogenic variant. Later we confirmed the pathogenic variant through Sanger sequencing. Furthermore, we also performed the mutational analysis through HOPE SERVER and SWISS-MODEL. Also, radiographs were also obtained for affected individual to confirm the disease features. RESULTS: In this article, we report the first Pakistani family consisting of three patients with SRS and a novel missense pathogenic variant in the SMS gene (c.905 C > T p.(Ser302Leu)). In addition to the typical phenotypes, one patient presented with early-onset seizures. Clinical features, genetic and in-silico analysis linked the affected patients of the family with Snyder-Robinson and suggest that this novel mutation affects the spermine synthase activity. CONCLUSION: A novel missense variant in the SMS, c.905C > T p. (Ser302Leu), causing Snyder- Robinson Syndrome (SRS) is reported in three members of Pakistani Family.
Assuntos
Sequenciamento do Exoma/métodos , Deficiência Intelectual Ligada ao Cromossomo X/genética , Mutação de Sentido Incorreto/genética , Espermina Sintase/genética , Adolescente , Criança , Face/anormalidades , Saúde da Família , Feminino , Humanos , Masculino , Deficiência Intelectual Ligada ao Cromossomo X/complicações , Osteoporose/complicações , Osteoporose/diagnóstico , Paquistão , LinhagemRESUMO
Snyder-Robinson syndrome (SRS) is an X-linked intellectual disability syndrome caused by a loss-of-function mutation in the spermine synthase (SMS) gene. Primarily affecting males, the main manifestations of SRS include osteoporosis, hypotonic stature, seizures, cognitive impairment, and developmental delay. Because there is no cure for SRS, treatment plans focus on alleviating symptoms rather than targeting the underlying causes. Biochemically, the cells of individuals with SRS accumulate excess spermidine, whereas spermine levels are reduced. We recently demonstrated that SRS patient-derived lymphoblastoid cells are capable of transporting exogenous spermine and its analogs into the cell and, in response, decreasing excess spermidine pools to normal levels. However, dietary supplementation of spermine does not appear to benefit SRS patients or mouse models. Here, we investigated the potential use of a metabolically stable spermine mimetic, (R,R)-1,12-dimethylspermine (Me2SPM), to reduce the intracellular spermidine pools of SRS patient-derived cells. Me2SPM can functionally substitute for the native polyamines in supporting cell growth while stimulating polyamine homeostatic control mechanisms. We found that both lymphoblasts and fibroblasts from SRS patients can accumulate Me2SPM, resulting in significantly decreased spermidine levels with no adverse effects on growth. Me2SPM administration to mice revealed that Me2SPM significantly decreases spermidine levels in multiple tissues. Importantly, Me2SPM was detectable in brain tissue, the organ most affected in SRS, and was associated with changes in polyamine metabolic enzymes. These findings indicate that the (R,R)-diastereomer of 1,12-Me2SPM represents a promising lead compound in developing a treatment aimed at targeting the molecular mechanisms underlying SRS pathology.
Assuntos
Deficiência Intelectual Ligada ao Cromossomo X/patologia , Espermidina/metabolismo , Espermina/análogos & derivados , Acetiltransferases/genética , Acetiltransferases/metabolismo , Animais , Encéfalo/metabolismo , Cromatografia Líquida de Alta Pressão , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Humanos , Masculino , Deficiência Intelectual Ligada ao Cromossomo X/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Poliaminas/análise , Poliaminas/metabolismo , Espermina/administração & dosagem , Espermina/metabolismo , Espermina/farmacologia , Espermina Sintase/genética , Células Tumorais CultivadasRESUMO
BACKGROUND: MYC is an oncogenic driver of development and progression in triple-negative breast cancer (TNBC). Ornithine decarboxylase, the rate-limiting enzyme in polyamine metabolism, is a transcriptional target of MYC. We therefore hypothesized that a plasma polyamine signature may be predictive of TNBC development and progression. METHODS: Using liquid chromatography mass spectrometry, polyamine levels were determined in plasma samples from newly diagnosed patients with TNBC (n = 87) and cancer-free controls (n = 115). Findings were validated in plasma samples from an independent prospective cohort of 54 TNBC, 55 estrogen receptor negative (ER-) and progesterone receptor negative (PR-) and HER2 positive (HER2+), and 73 ER+ case patients, and 30 cancer-free control subjects. Gene expression data and clinical data for 921 and 2359 breast cancer tumors were obtained from The Cancer Genome Atlas repository and the Oncomine database, respectively. Relationships between plasma diacetylspermine (DAS) and tumor spermine synthase (SMS) mRNA expression with metastasis-free survival and overall survival were determined using Cox proportional hazard models; Fisher exact tests were used to assess risk of distant metastasis in relation to tumor SMS mRNA expression. RESULTS: An increase in plasma DAS, a catabolic product of spermine mediated through SMS, was observed in the TNBC subtype of breast cancer. Plasma levels of DAS in TNBC associated with increased risk of metastasis (plasma DAS value ≥ 1.16, hazard ratio = 3.06, 95% confidence interval [CI] = 1.15 to 8.13, two-sided P = .03). SMS mRNA expression in TNBC tumor tissue was also found to be predictive of poor overall survival (top 25th percentile hazard ratio = 2.06, 95% CI = 1.04 to 4.08, one-sided P = .04) and increased risk of distant metastasis in TNBC (comparison of lowest SMS quartile [reference] to highest SMS quartile relative risk = 1.90, 95% CI = 0.97 to 4.06, one-sided Fisher exact test P=.03). CONCLUSIONS: Metabolomic profiling identified plasma DAS as a predictive marker for TNBC progression and metastasis.
Assuntos
Espermina Sintase/sangue , Espermina/análogos & derivados , Neoplasias de Mama Triplo Negativas/sangue , Animais , Cromatografia Líquida , Feminino , Expressão Gênica , Humanos , Camundongos , Camundongos Transgênicos , Metástase Neoplásica , Estadiamento de Neoplasias , Prognóstico , Espermina/biossíntese , Espermina/sangue , Espermina Sintase/biossíntese , Espermina Sintase/genética , Espermina Sintase/imunologia , Espectrometria de Massas em Tandem , Neoplasias de Mama Triplo Negativas/genética , Neoplasias de Mama Triplo Negativas/imunologia , Neoplasias de Mama Triplo Negativas/patologiaRESUMO
Snyder-Robinson syndrome (SRS) is an X-linked syndromic intellectual disability condition caused by variants in the spermine synthase gene (SMS). The syndrome is characterized by facial dysmorphism, thin body build, kyphoscoliosis, osteoporosis, hypotonia, developmental delay and associated neurological features (seizures, unsteady gait, abnormal speech). Until now, only missense variants with a functionally characterized partial loss of function (LoF) have been described. Here we describe the first complete LoF variant, Met303Lysfs*, in a male patient with a severe form of Snyder-Robinson syndrome. He presented with multiple malformations and severly delayed development, and died at 4 months of age. Functional in vitro assays showed a complete absence of functional SMS protein. Taken together, our findings and those of previously reported patients confirm that pathogenic variants of SMS are indeed LoF and that there might exist a genotype-phenotype correlation between the type of variant and the severity of the syndrome.
Assuntos
Mutação com Perda de Função , Deficiência Intelectual Ligada ao Cromossomo X/etiologia , Espermina Sintase/genética , Humanos , Lactente , Masculino , Deficiência Intelectual Ligada ao Cromossomo X/patologia , PrognósticoRESUMO
Patients with Snyder-Robinson Syndrome (SRS) exhibit deficient Spermidine Synthase (SMS) gene expression, which causes neurodevelopmental defects and osteoporosis, often leading to extremely fragile bones. To determine the underlying mechanism for impaired bone formation, we modelled the disease by silencing SMS in human bone marrow - derived multipotent stromal cells (MSCs) derived from healthy donors. We found that silencing SMS in MSCs led to reduced cell proliferation and deficient bone formation in vitro, as evidenced by reduced mineralization and decreased bone sialoprotein expression. Furthermore, transplantation of MSCs in osteoconductive scaffolds into immune deficient mice shows that silencing SMS also reduces ectopic bone formation in vivo. Tag-Seq Gene Expression Profiling shows that deficient SMS expression causes strong transcriptome changes, especially in genes related to cell proliferation and metabolic functions. Similarly, metabolome analysis by mass spectrometry, shows that silencing SMS strongly impacts glucose metabolism. This was consistent with observations using electron microscopy, where SMS deficient MSCs show high levels of mitochondrial fusion. In line with these findings, SMS deficiency causes a reduction in glucose consumption and increase in lactate secretion. Our data also suggests that SMS deficiency affects iron metabolism in the cells, which we hypothesize is linked to deficient mitochondrial function. Altogether, our studies suggest that SMS deficiency causes strong transcriptomic and metabolic changes in MSCs, which are likely associated with the observed impaired osteogenesis both in vitro and in vivo.
Assuntos
Deficiência Intelectual Ligada ao Cromossomo X/metabolismo , Células-Tronco Mesenquimais/metabolismo , Mitocôndrias/metabolismo , Osteogênese , Animais , Células Cultivadas , Glucose/metabolismo , Humanos , Ácido Láctico/metabolismo , Masculino , Deficiência Intelectual Ligada ao Cromossomo X/genética , Deficiência Intelectual Ligada ao Cromossomo X/patologia , Células-Tronco Mesenquimais/citologia , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Espermina Sintase/genética , TranscriptomaRESUMO
A recent paper in Bioscience Reports (BSR20182189) describes the discovery of an interaction between the motor protein myosin Va and the metabolic enzyme spermine synthase. Myosin Va is a molecular motor which plays a key role in vesicle transport. Mutations in the gene which encodes this protein are associated with Griscelli syndrome type 1 and the 'dilute' phenotype in animals. Spermine synthase catalyzes the conversion of spermidine to spermine. This largely cytoplasmic enzyme can also be localized to the soluble fraction in exosomes. Mutations in the spermine synthase gene are associated with Snyder Robinson mental retardation syndrome. The interaction between the two proteins was detected using the yeast two hybrid method and verified by microscale thermophoresis of recombinant proteins. Knockdown of the MYO5A gene reduced the expression of mRNA coding for spermine synthase. The amount of this transcript was also reduced in cells derived from a patient with Griscelli syndrome type 1. This suggests that, in addition to a direct physical interaction between the two proteins, myosin Va also modulates the transcription of the spermine synthase gene. The mechanism for this modulation is currently unknown. These findings have implications for Griscelli syndrome type 1 and Snyder Robinson mental retardation syndrome. They also suggest that interactions between myosin Va and soluble exosome proteins such as spermine synthase may be important in the mechanism of exosome transport.
Assuntos
Exossomos , Deficiência Intelectual Ligada ao Cromossomo X/genética , Animais , Humanos , Espermidina , Espermina , Espermina Sintase/genéticaRESUMO
Myosin Va (MyoVa) is an actin-based molecular motor that plays key roles in the final stages of secretory pathways, including neurotransmitter release. Several studies have addressed how MyoVa coordinates the trafficking of secretory vesicles, but why this molecular motor is found in exosomes is still unclear. In this work, using a yeast two-hybrid screening system, we identified the direct interaction between the globular tail domain (GTD) of MyoVa and four protein components of exosomes: the WD repeat-containing protein 48 (WDR48), the cold shock domain-containing protein E1 (CSDE1), the tandem C2 domain-containing protein 1 (TC2N), and the enzyme spermine synthase (SMS). The interaction between the GTD of MyoVa and SMS was further validated in vitro and displayed a Kd in the low micromolar range (3.5 ± 0.5 µM). SMS localized together with MyoVa in cytoplasmic vesicles of breast cancer MCF-7 and neuroblastoma SH-SY5Y cell lines, known to produce exosomes. Moreover, MYO5A knockdown decreased the expression of SMS gene and rendered the distribution of SMS protein diffuse, supporting a role for MyoVa in SMS expression and targeting.
Assuntos
Vesículas Citoplasmáticas/metabolismo , Exossomos/metabolismo , Cadeias Pesadas de Miosina/metabolismo , Miosina Tipo V/metabolismo , Espermina Sintase/metabolismo , Sítios de Ligação , Linhagem Celular Tumoral , Células Cultivadas , Exossomos/genética , Fibroblastos/citologia , Fibroblastos/metabolismo , Regulação da Expressão Gênica , Humanos , Células MCF-7 , Cadeias Pesadas de Miosina/genética , Miosina Tipo V/genética , Ligação Proteica , Transporte Proteico , Interferência de RNA , Espermina Sintase/genética , Técnicas do Sistema de Duplo-HíbridoRESUMO
Polyamines, including putrescine, spermidine, and spermine, play essential roles in a wide variety of prokaryotic and eukaryotic organisms. Rice (Oryza sativa) contains four putative spermidine/spermine synthase (SPMS)-encoding genes (OsSPMS1, OsSPMS2, OsSPMS3, and OsACAULIS5), but none have been functionally characterized. In this study, we used a reverse genetic strategy to investigate the biological function of OsSPMS1 We generated several homozygous RNA interference (RNAi) and overexpression (OE) lines of OsSPMS1 Phenotypic analysis indicated that OsSPMS1 negatively regulates seed germination, grain size, and grain yield per plant. The ratio of spermine to spermidine was significantly lower in the RNAi lines and considerably higher in the OE lines than in the wild type, suggesting that OsSPMS1 may function as a SPMS. S-Adenosyl-l-methionine is a common precursor of polyamines and ethylene biosynthesis. The 1-aminocyclopropane-1-carboxylic acid (ACC) and ethylene contents in seeds increased significantly in RNAi lines and decreased in OE lines, respectively, compared with the wild type. Additionally, the reduced germination rates and growth defects of OE lines could be rescued with ACC treatment. These data suggest that OsSPMS1 affects ethylene synthesis and may regulate seed germination and plant growth by affecting the ACC and ethylene pathways. Most importantly, an OsSPMS1 knockout mutant showed an increase in grain yield per plant in a high-yield variety, Suken118, suggesting that OsSPMS1 is an important target for yield enhancement in rice.