RESUMEN

Low fluorescence under visible light excitation and catalytic activity limit many applications of graphene quantum dots in optical detection, biosensing, catalysis and biomedical. The paper reports design and synthesis of histidine, serine and folic acid-functionalized and boron and iron-doped graphene quantum dot (Fe/B-GQD-HSF). The Fe/B-GQD-HSF shows excellent fluorescence behavior and peroxidase-like activity. Excitation of 330 nm ultraviolet light produces the strongest blue fluorescence and excitation of 480 nm visible light produces the strongest yellow fluorescence. The specific activity reaches 92.67 U g-1, which is higher than that of other graphene quantum dots. The Fe/B-GQD-HSF can catalyze oxidation of 3,3',5,5'-tetramethylbenzidine with H2O2 to form blue compound. Based on this, it was used for colorimetric and fluorescence detection of H2O2. The absorbance at 652 nm linearly increases with the increase of H2O2 concentration between 0.5 and 100 µM with detection limit of 0.43 µM. The fluorescence signal linearly decreases with the increase of H2O2 concentration between 0.05 and 100 µM with detection limit of 0.035 µM. The analytical method has been satisfactorily applied in detection of H2O2 in food. The study also paves one way for design and synthesis of functional graphene quantum dots with ideal fluorescence behavior and catalytic activity.

Asunto(s)

Boro , Colorimetría , Ácido Fólico , Grafito , Histidina , Peróxido de Hidrógeno , Hierro , Puntos Cuánticos , Serina , Puntos Cuánticos/química , Grafito/química , Peróxido de Hidrógeno/análisis , Peróxido de Hidrógeno/química , Colorimetría/métodos , Ácido Fólico/análisis , Ácido Fólico/química , Hierro/análisis , Hierro/química , Boro/química , Histidina/análisis , Histidina/química , Serina/análisis , Serina/química , Espectrometría de Fluorescencia/métodos , Límite de Detección , Análisis de los Alimentos/métodos , Peroxidasa/química , Peroxidasa/metabolismo , Catálisis

RESUMEN

Essential amino acid, tryptophan which intake from food plays a critical role in numerous metabolic functions, exhibiting extensive biological functions and applications. Tryptophan is beneficial for the food sector by enhancing nutritional content and promoting the development of functional foods. A putative gene encoding tryptophan synthase was the first identified in Sphingobacterium soilsilvae Em02, a cellulosic bacterium making it inherently more environmentally friendly. The gene was cloned and expressed in exogenous host Escherichia coli, to elucidate its function. The recombinant tryptophan synthase with a molecular weight 42 KDa was expressed in soluble component. The enzymatic activity to tryptophan synthase in vivo was assessed using indole and L-serine and purified tryptophan synthase. The optimum enzymatic activity for tryptophan synthase was recorded at 50 ºC and pH 7.0, which was improved in the presence of metal ions Mg2+, Sr2+ and Mn2+, whereas Cu2+, Zn2+ and Co2+ proved to be inhibitory. Using site-directed mutagenesis, the consensus pattern HK-S-[GGGSN]-E-S in the tryptophan synthase was demonstrated with K100Q, S202A, G246A, E361A and S385A as the active sites. Tryptophan synthase has been demonstrated to possess the defining characteristics of the ß-subunits. The tryptophan synthase may eventually be useful for tryptophan production on a larger scale. Its diverse applications highlight the potential for improving both the quality and health benefits of food products, making it an essential component in advancing food science and technology.

Asunto(s)

Escherichia coli , Mutagénesis Sitio-Dirigida , Triptófano Sintasa , Triptófano , Triptófano Sintasa/metabolismo , Triptófano Sintasa/genética , Triptófano Sintasa/química , Triptófano/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/química , Sphingomonadaceae/enzimología , Sphingomonadaceae/genética , Sphingomonadaceae/metabolismo , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/química , Dominio Catalítico , Clonación Molecular , Concentración de Iones de Hidrógeno , Indoles/metabolismo , Catálisis , Serina/metabolismo

RESUMEN

RNA polymerase II relies on a repetitive sequence domain (YSPTSPS) within its largest subunit to orchestrate transcription. While phosphorylation on serine-2/serine-5 of the carboxyl-terminal heptad repeats is well established, threonine-4's role remains enigmatic. Paradoxically, threonine-4 phosphorylation was only detected after transcription end sites despite functionally implicated in pausing, elongation, termination, and messenger RNA processing. Our investigation revealed that threonine-4 phosphorylation detection was obstructed by flanking serine-5 phosphorylation at the onset of transcription, which can be removed selectively. Subsequent proteomic analyses identified many proteins recruited to transcription via threonine-4 phosphorylation, which previously were attributed to serine-2. Loss of threonine-4 phosphorylation greatly reduces serine-2 phosphorylation, revealing a cross-talk between the two marks. Last, the function analysis of the threonine-4 phosphorylation highlighted its role in alternative 3'-end processing within pro-proliferative genes. Our findings unveil the true genomic location of this evolutionarily conserved phosphorylation mark and prompt a reassessment of functional assignments of the carboxyl-terminal domain.

Asunto(s)

ARN Polimerasa II , Treonina , Transcripción Genética , Fosforilación , ARN Polimerasa II/metabolismo , ARN Polimerasa II/genética , Treonina/metabolismo , Humanos , Procesamiento de Término de ARN 3' , Serina/metabolismo , Proteómica/métodos

RESUMEN

Rationale: Tumor cells remodel transcriptome to construct an ecosystem with stemness features, which maintains tumor growth and highly malignant characteristics. However, the core regulatory factors involved in this process still need to be further discovered. Methods: Single cell RNA-sequncing (scRNA-seq) and bulk RNA-sequencing profiles derived from fetal liver, normal liver, liver tumors, and their adjacent samples were collected to analyze the ecosystem of liver cancer. Mouse models were established to identify molecular functions of oncofetal-related oncogenes using hydrodynamic tail vein injection. Results: We found that liver cancer rebuilt oncofetal ecosystem to maintain malignant features. Interestingly, we identified a group of RNA-binding proteins (RBPs) that were highly overexpressed with oncofetal features. Among them, TRIM71 was specifically expressed in liver cancers and was associated with poor outcomes. TRIM71 drove the carcinogenesis of hepatocellular carcinoma (HCC), and knockdown of TRIM71 significantly abolished liver cancer cell proliferation. Mechanistically, TRIM71 formed a protein complex with IGF2BP1, bound to and stabilized the mRNA of CEBPA in an m6A-dependent manner, enhance the serine/glycine metabolic pathway, and ultimately promoted liver cancer progression. Furthermore, we identified that all-trans-retinoic acid (ATRA) combined with e1A binding protein p300 (EP300) inhibitor A-485 repressed TRIM71, attenuated glycine/serine metabolism, and inhibited liver cancer cell proliferation with high TRIM71 levels. Conclusions: We demonstrated the oncofetal status in liver cancer and highlighted the crucial role of TRIM71 and provided potential therapeutic strategies and liver cancer-specific biomarker for liver cancer patients.

Asunto(s)

Carcinogénesis , Carcinoma Hepatocelular , Glicina , Neoplasias Hepáticas , Serina , Animales , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patología , Neoplasias Hepáticas/genética , Ratones , Humanos , Serina/metabolismo , Carcinogénesis/genética , Carcinogénesis/metabolismo , Glicina/metabolismo , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/patología , Carcinoma Hepatocelular/genética , Línea Celular Tumoral , Proliferación Celular , Regulación Neoplásica de la Expresión Génica , Proteínas de Motivos Tripartitos/metabolismo , Proteínas de Motivos Tripartitos/genética , Proteínas de Unión al ARN/metabolismo , Proteínas de Unión al ARN/genética , Ratones Desnudos

RESUMEN

Meningiomas are associated with inactivation of NF2/Merlin, but approximately one-third of meningiomas with favorable clinical outcomes retain Merlin expression. Biochemical mechanisms underlying Merlin-intact meningioma growth are incompletely understood, and non-invasive biomarkers that may be used to guide treatment de-escalation or imaging surveillance are lacking. Here, we use single-cell RNA sequencing, proximity-labeling proteomic mass spectrometry, mechanistic and functional approaches, and magnetic resonance imaging (MRI) across meningioma xenografts and patients to define biochemical mechanisms and an imaging biomarker that underlie Merlin-intact meningiomas. We find Merlin serine 13 (S13) dephosphorylation drives meningioma Wnt signaling and tumor growth by attenuating inhibitory interactions with ß-catenin and activating the Wnt pathway. MRI analyses show Merlin-intact meningiomas with S13 phosphorylation and favorable clinical outcomes are associated with high apparent diffusion coefficient (ADC). These results define mechanisms underlying a potential imaging biomarker that could be used to guide treatment de-escalation or imaging surveillance for patients with Merlin-intact meningiomas.

Asunto(s)

Imagen por Resonancia Magnética , Neoplasias Meníngeas , Meningioma , Neurofibromina 2 , Vía de Señalización Wnt , Meningioma/diagnóstico por imagen , Meningioma/metabolismo , Meningioma/patología , Meningioma/genética , Humanos , Fosforilación , Neurofibromina 2/metabolismo , Neurofibromina 2/genética , Animales , Imagen por Resonancia Magnética/métodos , Neoplasias Meníngeas/diagnóstico por imagen , Neoplasias Meníngeas/metabolismo , Neoplasias Meníngeas/patología , Neoplasias Meníngeas/genética , Ratones , Línea Celular Tumoral , beta Catenina/metabolismo , beta Catenina/genética , Femenino , Serina/metabolismo , Masculino , Proteómica/métodos , Biomarcadores de Tumor/metabolismo , Biomarcadores de Tumor/genética

RESUMEN

Dedifferentiated and Well-differentiated liposarcoma are characterized by a systematic amplification of the Murine Double Minute 2 (MDM2) oncogene. We demonstrate that p53-independent metabolic functions of chromatin-bound MDM2 are exacerbated in liposarcoma and mediate an addiction to serine metabolism to sustain tumor growth. However, the origin of exogenous serine remains unclear. Here, we show that elevated serine levels in mice harboring liposarcoma-patient derived xenograft, released by distant muscle is essential for liposarcoma cell survival. Repressing interleukine-6 expression, or treating liposarcoma cells with Food and Drugs Administration (FDA) approved anti-interleukine-6 monoclonal antibody, decreases de novo serine synthesis in muscle, impairs proliferation, and increases cell death in vitro and in vivo. This work reveals a metabolic crosstalk between muscle and liposarcoma tumor and identifies anti-interleukine-6 as a plausible treatment for liposarcoma patients.

Asunto(s)

Proliferación Celular , Liposarcoma , Proteínas Proto-Oncogénicas c-mdm2 , Serina , Liposarcoma/metabolismo , Liposarcoma/patología , Liposarcoma/genética , Animales , Humanos , Proteínas Proto-Oncogénicas c-mdm2/metabolismo , Proteínas Proto-Oncogénicas c-mdm2/genética , Ratones , Línea Celular Tumoral , Serina/metabolismo , Proteína p53 Supresora de Tumor/metabolismo , Músculo Esquelético/metabolismo , Músculo Esquelético/patología , Femenino , Masculino

RESUMEN

Peptides are receiving significant attention in pharmaceutical sciences due to their applications as anti-inflammatory drugs; however, many aspects of their interactions and mechanisms at the molecular level are not well-known. This work explores the molecular structure of two peptides-(i) cysteine (Cys)-asparagine (Asn)-serine (Ser) (CNS) as a molecule in the gas phase and solvated in water in zwitterion form, and (ii) the crystal structure of the dipeptide serine-asparagine (SN), a reliable peptide indication whose experimental cell parameters are well known. A search was performed by means of atomistic calculations based on density functional theory (DFT). These calculations matched the experimental crystal structure of SN, validating the CNS results and useful for assignments of our experimental spectroscopic IR bands. Our calculations also explore the intercalation of CNS into the interlayer space of montmorillonite (MNT). Our quantum mechanical calculations show that the conformations of these peptides change significantly during intercalation into the confined interlayer space of MNT. This intercalation is energetically favorable, indicating that this process can be a useful preparation for therapeutic anti-inflammatory applications and showing high stability and controlled release processes.

Asunto(s)

Antiinflamatorios , Bentonita , Cisteína , Teoría Funcional de la Densidad , Serina , Bentonita/química , Antiinflamatorios/química , Antiinflamatorios/farmacología , Cisteína/química , Serina/química , Asparagina/química , Modelos Moleculares , Péptidos/química , Sustancias Intercalantes/química

RESUMEN

N-doped TiO2/carbon composites (N-TiPC) have shown excellent photodegradation performances to the organic contaminants but are limited by the multistage preparation (i.e., preparation of porous carbon, preparation of N-doped TiO2, and loading of N-doped TiO2 on porous carbon). Here, we develop a handy way by combining the Pickering emulsion-gel template route and chelation reaction of polysaccharides. The N-TiPC is obtained by calcinating pectin/Dl-serine hydrazide hydrochloride (SHH)-Ti4+ chelate and is further described by modern characterization techniques. The results show that the N atom is successfully doped into the TiO2 lattice, and the bandgap value of N-TiPC is reduced to 2.3 eV. Moreover, the particle size of N-TiPC remains about 10 nm. The configurations of the composites are simulated using DFT calculation. The photocatalytic experiments show that N-TiPC has a high removal efficiency for methylene blue (MB) and oxytetracycline hydrochloride (OTC-HCL). The removal ratios of MB (20 mg/L, 50 mL) and OTC-HCL (30 mg/L, 50 mL) are 99.41 % and 78.29 %, respectively. The cyclic experiments show that the photocatalyst has good stability. Overall, this study provides a handy way to form N-TiPC with enhanced photodegradation performances. It can also be promoted to other macromolecules such as cellulose and its derivatives, sodium alginate, chitosan, lignin, etc.

Asunto(s)

Carbono , Pectinas , Serina , Titanio , Pectinas/química , Titanio/química , Carbono/química , Serina/química , Nitrógeno/química , Catálisis , Fotólisis , Porosidad , Azul de Metileno/química

RESUMEN

Parasitic weeds, such as Orobanche and Striga, threaten crops globally. Contiguous efforts on the discovery and development of structurally novel seed germination stimulants targeting HYPOSENSITIVE TO LIGHT/KARRIKIN INSENSITIVE 2 (HTL/KAI2) have been made with the goal of weed control. Here, we demonstrate that a natural compound dehydrocostus lactone (DCL) exhibits effective "suicide germination" activity against Orobanche cumana and covalently binds to OcKAI2d2 on two catalytic serine sites with the second modification dependent on the first one. The same interactions and covalent modifications of DCL are also confirmed in AtKAI2. Further in-depth evolution analysis indicates that the proposed two catalytic sites are present throughout the streptophyte algae, hornworts, lycophytes, and seed plants. This discovery is particularly noteworthy as it signifies the first confirmation of a plant endogenous molecule directly binding to KAI2, which is valuable for unraveling the elusive identity of the KAI2 ligand and for targeting KAI2 paralogues for the development of novel germination stimulants.

Asunto(s)

Proteínas de Arabidopsis , Arabidopsis , Germinación , Lactonas , Orobanche , Serina , Orobanche/química , Orobanche/metabolismo , Orobanche/crecimiento & desarrollo , Arabidopsis/metabolismo , Arabidopsis/química , Arabidopsis/crecimiento & desarrollo , Germinación/efectos de los fármacos , Serina/metabolismo , Serina/química , Lactonas/metabolismo , Lactonas/química , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/química , Semillas/química , Semillas/metabolismo , Semillas/crecimiento & desarrollo , Malezas/metabolismo , Malezas/efectos de los fármacos , Malezas/crecimiento & desarrollo , Malezas/química , Unión Proteica , Hidrolasas

RESUMEN

Cultured cancer cells frequently rely on the consumption of glutamine and its subsequent hydrolysis by glutaminase (GLS). However, this metabolic addiction can be lost in the tumour microenvironment, rendering GLS inhibitors ineffective in the clinic. Here we show that glutamine-addicted breast cancer cells adapt to chronic glutamine starvation, or GLS inhibition, via AMPK-mediated upregulation of the serine synthesis pathway (SSP). In this context, the key product of the SSP is not serine, but α-ketoglutarate (α-KG). Mechanistically, we find that phosphoserine aminotransferase 1 (PSAT1) has a unique capacity for sustained α-KG production when glutamate is depleted. Breast cancer cells with resistance to glutamine starvation or GLS inhibition are highly dependent on SSP-supplied α-KG. Accordingly, inhibition of the SSP prevents adaptation to glutamine blockade, resulting in a potent drug synergism that suppresses breast tumour growth. These findings highlight how metabolic redundancy can be context dependent, with the catalytic properties of different metabolic enzymes that act on the same substrate determining which pathways can support tumour growth in a particular nutrient environment. This, in turn, has practical consequences for therapies targeting cancer metabolism.

Asunto(s)

Neoplasias de la Mama , Glutamina , Transaminasas , Glutamina/metabolismo , Humanos , Transaminasas/metabolismo , Transaminasas/antagonistas & inhibidores , Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/tratamiento farmacológico , Línea Celular Tumoral , Femenino , Glutaminasa/antagonistas & inhibidores , Glutaminasa/metabolismo , Animales , Ácidos Cetoglutáricos/metabolismo , Adaptación Fisiológica , Ratones , Serina/metabolismo , Microambiente Tumoral

RESUMEN

The cGAS/STING pathway is a crucial immune activator in cancer biology, triggering innate immunosurveillance against tumors by sensing and reacting to endogenous mitochondrial DNA (mtDNA). In this issue of Cancer Research, research by Saha and colleagues highlights the significant impact of serine deprivation on this pathway, thereby unveiling its potential for anticancer therapy. Serine is essential for cellular metabolism and influences tumor growth and immune responses. Depriving cells of serine caused mitochondrial dysfunction and the release of mtDNA into the cytosol, activating the cGAS/STING pathway and inducing type I IFN responses. In mouse models, serine deprivation enhanced antitumor immunity, with increased tumoral immune infiltration, including CD4+/CD8+ T cells and type I IFN responses. Clinically, a genetic signature indicative of lower serine enrichment in colorectal cancer patients correlated with immune activation and improved survival. Furthermore, combining serine deprivation with PD1 blockade significantly reduced tumor volume and led to long-term immunity in mice, suggesting that serine depletion enhances the efficacy of immune checkpoint blockade. These findings propose serine deprivation as a promising strategy to boost antitumor immunity and improve cancer patient outcomes. See related article by Saha et al., p. 2645.

Asunto(s)

Proteínas de la Membrana , Neoplasias , Nucleotidiltransferasas , Nucleotidiltransferasas/metabolismo , Nucleotidiltransferasas/genética , Humanos , Animales , Proteínas de la Membrana/metabolismo , Proteínas de la Membrana/genética , Ratones , Neoplasias/inmunología , Neoplasias/patología , Neoplasias/metabolismo , Neoplasias/genética , ADN Mitocondrial/genética , ADN Mitocondrial/inmunología , Transducción de Señal/inmunología , Serina/metabolismo

RESUMEN

Astrocytes control brain activity via both metabolic processes and gliotransmission, but the physiological links between these functions are scantly known. Here we show that endogenous activation of astrocyte type-1 cannabinoid (CB1) receptors determines a shift of glycolysis towards the lactate-dependent production of D-serine, thereby gating synaptic and cognitive functions in male mice. Mutant mice lacking the CB1 receptor gene in astrocytes (GFAP-CB1-KO) are impaired in novel object recognition (NOR) memory. This phenotype is rescued by the gliotransmitter D-serine, by its precursor L-serine, and also by lactate and 3,5-DHBA, an agonist of the lactate receptor HCAR1. Such lactate-dependent effect is abolished when the astrocyte-specific phosphorylated-pathway (PP), which diverts glycolysis towards L-serine synthesis, is blocked. Consistently, lactate and 3,5-DHBA promoted the co-agonist binding site occupancy of CA1 post-synaptic NMDA receptors in hippocampal slices in a PP-dependent manner. Thus, a tight cross-talk between astrocytic energy metabolism and gliotransmission determines synaptic and cognitive processes.

Asunto(s)

Astrocitos , Cognición , Glucólisis , Ácido Láctico , Ratones Noqueados , Serina , Animales , Masculino , Astrocitos/metabolismo , Cognición/fisiología , Ratones , Ácido Láctico/metabolismo , Serina/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Receptores de N-Metil-D-Aspartato/genética , Hipocampo/metabolismo , Sinapsis/metabolismo , Ratones Endogámicos C57BL , Receptores Acoplados a Proteínas G/metabolismo , Receptores Acoplados a Proteínas G/genética

RESUMEN

BACKGROUND: The plasma metabolome reflects the physiological state of various biological processes and can serve as a proxy for disease risk. Plasma metabolite variation, influenced by genetic and epigenetic mechanisms, can also affect the cellular microenvironment and blood cell epigenetics. The interplay between the plasma metabolome and the blood cell epigenome remains elusive. In this study, we performed an epigenome-wide association study (EWAS) of 1183 plasma metabolites in 693 participants from the LifeLines-DEEP cohort and investigated the causal relationships in DNA methylation-metabolite associations using bidirectional Mendelian randomization and mediation analysis. RESULTS: After rigorously adjusting for potential confounders, including genetics, we identified five robust associations between two plasma metabolites (L-serine and glycine) and three CpG sites located in two independent genomic regions (cg14476101 and cg16246545 in PHGDH and cg02711608 in SLC1A5) at a false discovery rate of less than 0.05. Further analysis revealed a complex bidirectional relationship between plasma glycine/serine levels and DNA methylation. Moreover, we observed a strong mediating role of DNA methylation in the effect of glycine/serine on the expression of their metabolism/transport genes, with the proportion of the mediated effect ranging from 11.8 to 54.3%. This result was also replicated in an independent population-based cohort, the Rotterdam Study. To validate our findings, we conducted in vitro cell studies which confirmed the mediating role of DNA methylation in the regulation of PHGDH gene expression. CONCLUSIONS: Our findings reveal a potential feedback mechanism in which glycine and serine regulate gene expression through DNA methylation.

Asunto(s)

Metilación de ADN , Epigénesis Genética , Estudio de Asociación del Genoma Completo , Glicina , Metaboloma , Serina , Humanos , Glicina/sangre , Serina/sangre , Serina/genética , Metilación de ADN/genética , Masculino , Femenino , Estudio de Asociación del Genoma Completo/métodos , Metaboloma/genética , Epigénesis Genética/genética , Persona de Mediana Edad , Islas de CpG/genética , Epigenoma/genética , Adulto , Anciano , Análisis de la Aleatorización Mendeliana

RESUMEN

Cancer cells secrete extracellular vesicles (EVs) to regulate cells in the tumor microenvironment to benefit their own growth and survive in the patient's body. Although emerging evidence has demonstrated the molecular mechanisms of EV release, regulating cancer-specific EV secretion remains challenging. In this study, we applied a microRNA library to reveal the universal mechanisms of EV secretion from cancer cells. Here, we identified miR-891b and its direct target gene, phosphoserine aminotransferase 1 (PSAT1), which promotes EV secretion through the serine-ceramide synthesis pathway. Inhibition of PSAT1 affected EV secretion in multiple types of cancer, suggesting that the miR-891b/PSAT1 axis shares a common mechanism of EV secretion from cancer cells. Interestingly, aberrant PSAT1 expression also regulated cancer metastasis via EV secretion. Our data link the PSAT1-controlled EV secretion mechanism and cancer metastasis and show the potential of this mechanism as a therapeutic target in multiple types of cancer.

Asunto(s)

Vesículas Extracelulares , MicroARNs , Neoplasias , Serina , Transaminasas , Humanos , Vesículas Extracelulares/metabolismo , MicroARNs/metabolismo , MicroARNs/genética , Serina/metabolismo , Animales , Neoplasias/metabolismo , Neoplasias/patología , Neoplasias/genética , Línea Celular Tumoral , Transaminasas/metabolismo , Transaminasas/genética , Progresión de la Enfermedad , Regulación Neoplásica de la Expresión Génica , Ratones , Ceramidas/metabolismo , Microambiente Tumoral , Metástasis de la Neoplasia , Ratones Desnudos

RESUMEN

The non-essential amino acid serine is a critical nutrient for cancer cells due to its diverse biosynthetic functions. While some tumors can synthesize serine de novo, others are auxotrophic and therefore reliant on serine uptake. Importantly, despite several transporters being known to be capable of transporting serine, the transporters that mediate serine uptake in cancer cells are not known. Here, we characterize the amino acid transporter ASCT2 (SLC1A5) as a major contributor to serine uptake in cancer cells. ASCT2 is well known as a glutamine transporter in cancer, and our work demonstrates that serine and glutamine compete for uptake through ASCT2. We further show that ASCT2-mediated serine uptake is essential for purine nucleotide biosynthesis and that estrogen receptor α (ERα) promotes serine uptake by directly activating SLC1A5 transcription. Collectively, our work defines an additional important role for ASCT2 as a serine transporter in cancer and evaluates ASCT2 as a potential therapeutic target.

Asunto(s)

Sistema de Transporte de Aminoácidos ASC , Antígenos de Histocompatibilidad Menor , Serina , Sistema de Transporte de Aminoácidos ASC/metabolismo , Sistema de Transporte de Aminoácidos ASC/genética , Humanos , Serina/metabolismo , Antígenos de Histocompatibilidad Menor/metabolismo , Antígenos de Histocompatibilidad Menor/genética , Glutamina/metabolismo , Línea Celular Tumoral , Receptor alfa de Estrógeno/metabolismo , Neoplasias/metabolismo , Neoplasias/patología , Neoplasias/genética , Animales , Transporte Biológico , Femenino , Células MCF-7

RESUMEN

BACKGROUND: ß-adrenergic receptor (ß-AR) overactivation is a major pathological cue associated with cardiac injury and diseases. AMPK (AMP-activated protein kinase), a conserved energy sensor, regulates energy metabolism and is cardioprotective. However, whether AMPK exerts cardioprotective effects via regulating the signaling pathway downstream of ß-AR remains unclear. METHODS: Using immunoprecipitation, mass spectrometry, site-specific mutation, in vitro kinase assay, and in vivo animal studies, we determined whether AMPK phosphorylates ß-arrestin-1 at serine (Ser) 330. Wild-type mice and mice with site-specific mutagenesis (S330A knock-in [KI]/S330D KI) were subcutaneously injected with the ß-AR agonist isoproterenol (5 mg/kg) to evaluate the causality between ß-adrenergic insult and ß-arrestin-1 Ser330 phosphorylation. Cardiac transcriptomics was used to identify changes in gene expression from ß-arrestin-1-S330A/S330D mutation and ß-adrenergic insult. RESULTS: Metformin could decrease cAMP/PKA (protein kinase A) signaling induced by isoproterenol. AMPK bound to ß-arrestin-1 and phosphorylated Ser330 with the highest phosphorylated mass spectrometry score. AMPK activation promoted ß-arrestin-1 Ser330 phosphorylation in vitro and in vivo. Neonatal mouse cardiomyocytes overexpressing ß-arrestin-1-S330D (active form) inhibited the ß-AR/cAMP/PKA axis by increasing PDE (phosphodiesterase) 4 expression and activity. Cardiac transcriptomics revealed that the differentially expressed genes between isoproterenol-treated S330A KI and S330D KI mice were mainly involved in immune processes and inflammatory response. ß-arrestin-1 Ser330 phosphorylation inhibited isoproterenol-induced reactive oxygen species production and NLRP3 (NOD-like receptor protein 3) inflammasome activation in neonatal mouse cardiomyocytes. In S330D KI mice, the ß-AR-activated cAMP/PKA pathways were attenuated, leading to repressed inflammasome activation, reduced expression of proinflammatory cytokines, and mitigated macrophage infiltration. Compared with S330A KI mice, S330D KI mice showed diminished cardiac fibrosis and improved cardiac function upon isoproterenol exposure. However, the cardiac protection exerted by AMPK was abolished in S330A KI mice. CONCLUSIONS: AMPK phosphorylation of ß-arrestin-1 Ser330 potentiated PDE4 expression and activity, thereby inhibiting ß-AR/cAMP/PKA activation. Subsequently, ß-arrestin-1 Ser330 phosphorylation blocks ß-AR-induced cardiac inflammasome activation and remodeling.

Asunto(s)

Proteínas Quinasas Activadas por AMP , Isoproterenol , Miocitos Cardíacos , beta-Arrestina 1 , Animales , Fosforilación , beta-Arrestina 1/metabolismo , beta-Arrestina 1/genética , Ratones , Proteínas Quinasas Activadas por AMP/metabolismo , Isoproterenol/toxicidad , Isoproterenol/farmacología , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/patología , Ratones Endogámicos C57BL , Masculino , Receptores Adrenérgicos beta/metabolismo , Serina/metabolismo , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Agonistas Adrenérgicos beta/farmacología , Agonistas Adrenérgicos beta/toxicidad , Células Cultivadas , Transducción de Señal , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 4/metabolismo , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 4/genética , Humanos

RESUMEN

RNA can directly control protein activity in a process called riboregulation; only a few mechanisms of riboregulation have been described in detail, none of which have been characterized on structural grounds. Here, we present a comprehensive structural, functional, and phylogenetic analysis of riboregulation of cytosolic serine hydroxymethyltransferase (SHMT1), the enzyme interconverting serine and glycine in one-carbon metabolism. We have determined the cryoelectron microscopy (cryo-EM) structure of human SHMT1 in its free- and RNA-bound states, and we show that the RNA modulator competes with polyglutamylated folates and acts as an allosteric switch, selectively altering the enzyme's reactivity vs. serine. In addition, we identify the tetrameric assembly and a flap structural motif as key structural elements necessary for binding of RNA to eukaryotic SHMT1. The results presented here suggest that riboregulation may have played a role in evolution of eukaryotic SHMT1 and in compartmentalization of one-carbon metabolism. Our findings provide insights for RNA-based therapeutic strategies targeting this cancer-linked metabolic pathway.

Asunto(s)

Microscopía por Crioelectrón , Glicina Hidroximetiltransferasa , Glicina Hidroximetiltransferasa/metabolismo , Glicina Hidroximetiltransferasa/genética , Glicina Hidroximetiltransferasa/química , Humanos , ARN/metabolismo , ARN/genética , Serina/metabolismo , Regulación Alostérica , Unión Proteica , Filogenia , Modelos Moleculares , Conformación Proteica , Relación Estructura-Actividad , Glicina/metabolismo , Glicina/química , Sitios de Unión

RESUMEN

The loss of E-cadherin, an epithelial cell adhesion molecule, has been implicated in metastasis by mediating the epithelial-mesenchymal transition, which promotes invasion and migration of cancer cells. However, recent studies have demonstrated that E-cadherin supports the survival and proliferation of metastatic cancer cells. Here, we identified a metabolic role for E-cadherin in breast cancer by upregulating the de novo serine synthesis pathway (SSP). The upregulated SSP provided metabolic precursors for biosynthesis and resistance to oxidative stress, enabling E-cadherin+ breast cancer cells to achieve faster tumor growth and enhanced metastases. Inhibition of phosphoglycerate dehydrogenase, a rate-limiting enzyme in the SSP, significantly and specifically hampered proliferation of E-cadherin+ breast cancer cells and rendered them vulnerable to oxidative stress, inhibiting their metastatic potential. These findings reveal that E-cadherin reprograms cellular metabolism, promoting tumor growth and metastasis of breast cancers. Significance: E-Cadherin promotes the progression and metastasis of breast cancer by upregulating the de novo serine synthesis pathway, offering promising targets for inhibiting tumor growth and metastasis in E-cadherin-expressing tumors.

Asunto(s)

Neoplasias de la Mama , Cadherinas , Progresión de la Enfermedad , Serina , Serina/metabolismo , Cadherinas/metabolismo , Femenino , Humanos , Neoplasias de la Mama/patología , Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/genética , Animales , Ratones , Proliferación Celular , Línea Celular Tumoral , Transición Epitelial-Mesenquimal , Fosfoglicerato-Deshidrogenasa/metabolismo , Fosfoglicerato-Deshidrogenasa/genética , Metástasis de la Neoplasia , Antígenos CD/metabolismo , Movimiento Celular , Estrés Oxidativo , Ratones Desnudos

RESUMEN

Mistranslation is the misincorporation of an amino acid into a polypeptide. Mistranslation has diverse effects on multicellular eukaryotes and is implicated in several human diseases. In Drosophila melanogaster, a serine transfer RNA (tRNA) that misincorporates serine at proline codons (P→S) affects male and female flies differently. The mechanisms behind this discrepancy are currently unknown. Here, we compare the transcriptional response of male and female flies to P→S mistranslation to identify genes and cellular processes that underlie sex-specific differences. Both males and females downregulate genes associated with various metabolic processes in response to P→S mistranslation. Males downregulate genes associated with extracellular matrix organization and response to negative stimuli such as wounding, whereas females downregulate aerobic respiration and ATP synthesis genes. Both sexes upregulate genes associated with gametogenesis, but females also upregulate cell cycle and DNA repair genes. These observed differences in the transcriptional response of male and female flies to P→S mistranslation have important implications for the sex-specific impact of mistranslation on disease and tRNA therapeutics.

Asunto(s)

Drosophila melanogaster , Prolina , Biosíntesis de Proteínas , Serina , Transcriptoma , Animales , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Masculino , Femenino , Prolina/metabolismo , Serina/metabolismo , ARN de Transferencia/genética , ARN de Transferencia/metabolismo , ARN de Transferencia de Serina/genética , ARN de Transferencia de Serina/metabolismo , Regulación de la Expresión Génica

RESUMEN

BACKGROUND: Endoplasmic reticulum stress and synthesis of serine are essential for tumor growth, but the mechanism of their interaction is not clarified yet. The overarching goal of this work was to investigate the impact of ERN1 (endoplasmic reticulum to nucleus signaling 1) inhibition on the expression of serine synthesis genes in U87MG glioblastoma cells concerning the suppression of cell proliferation. METHODS: Wild type U87MG glioblastoma cells and their clones with overexpression of transgenes dnERN1 (without cytoplasmic domain of ERN1) and dnrERN1 (with mutation in endoribonuclease of ERN1), and empty vector (as control) were used. The silencing of ERN1 and XBP1 was also used to inhibition of ERN1 and its function. Gene expression was measured by qPCR. RESULTS: We show that the expression of PSAT1 and several other related to serine synthesis genes is suppressed in cells with ERN1 inhibition by dissimilar mechanisms: PHGDH gene through ERN1 protein kinase, because its expression was resistant to inhibition of ERN1 endoribonuclease, but ATF4 gene via endoribonuclease of ERN1. However, in the control of PSAT1 and PSPH genes both enzymatic activities of ERN1 signaling protein are involved. At the same time, ERN1 knockdown strongly increased SHMT1 expression, which controls serine metabolism and enhances the proliferation and invasiveness of glioma cells. The level of microRNAs, which have binding sites in PSAT1, SHMT1, and PSPH mRNAs, was also changed in cells harboring dnERN1 transgene. Inhibition of ERN1 suppressed cell proliferation and enzymatic activity of PHGDH, a rate-limiting enzyme for serine synthesis. CONCLUSION: Changes in the expression of phosphoserine aminotransferase 1 and other genes related to serine synthesis are mediated by diverse ERN1-dependent mechanisms and contributed to suppressed proliferation and enhanced invasiveness of ERN1 knockdown glioblastoma cell.

Asunto(s)

Proliferación Celular , Regulación Neoplásica de la Expresión Génica , Glioblastoma , Proteínas Serina-Treonina Quinasas , Transaminasas , Humanos , Glioblastoma/genética , Glioblastoma/metabolismo , Glioblastoma/patología , Proteínas Serina-Treonina Quinasas/genética , Proteínas Serina-Treonina Quinasas/metabolismo , Línea Celular Tumoral , Transaminasas/genética , Transaminasas/metabolismo , Endorribonucleasas/metabolismo , Endorribonucleasas/genética , Técnicas de Silenciamiento del Gen , Serina/metabolismo , Proteína 1 de Unión a la X-Box/metabolismo , Proteína 1 de Unión a la X-Box/genética