RESUMEN
Neuroinflammation is a major characteristic of pathology in several neurodegenerative diseases. Microglia, the brain's resident myeloid cells, shift between activation states under neuroinflammatory conditions, both responding to, but also driving damage in the brain. Vitamin C (ascorbate) is an essential antioxidant for central nervous system function that may have a specific role in the neuroinflammatory response. Uptake of ascorbate throughout the central nervous system is facilitated by the sodium-dependent vitamin C transporter 2 (SVCT2). SVCT2 transports the reduced form of ascorbate into neurons and microglia, however the contribution of altered SVCT2 expression to the neuroinflammatory response in microglia is not well understood. In this study we demonstrate that SVCT2 expression modifies microglial response, as shown through changes in cell morphology and mRNA expression, following a mild traumatic brain injury (mTBI) in mice with decreased or increased expression of SVCT2. Results were supported by in vitro studies in an immortalized microglial cell line and in primary microglial cultures derived from SVCT2-heterozygous and transgenic animals. Overall, this work demonstrates the importance of SVCT2 and ascorbate in modulating the microglial response to mTBI and suggests a potential role for both in response to neuroinflammatory challenges.
Asunto(s)
Ácido Ascórbico , Microglía , Transportadores de Sodio Acoplados a la Vitamina C , Animales , Transportadores de Sodio Acoplados a la Vitamina C/metabolismo , Transportadores de Sodio Acoplados a la Vitamina C/genética , Microglía/metabolismo , Ratones , Ácido Ascórbico/metabolismo , Ácido Ascórbico/farmacología , Ratones Transgénicos , Ratones Endogámicos C57BL , Enfermedades Neuroinflamatorias/metabolismo , Masculino , Encéfalo/metabolismo , Neuronas/metabolismo , Conmoción Encefálica/metabolismo , Línea CelularRESUMEN
Vitamin C plays important roles as a cofactor in many enzymatic reactions and as an antioxidant against oxidative stress. As some mammals including humans cannot synthesize vitamin C de novo from glucose, its uptake from dietary sources is essential, and is mediated by the sodium-dependent vitamin C transporter 1 (SVCT1). Despite its physiological significance in maintaining vitamin C homeostasis, the structural basis of the substrate transport mechanism remained unclear. Here, we report the cryo-EM structures of human SVCT1 in different states at 2.5-3.5 Å resolutions. The binding manner of vitamin C together with two sodium ions reveals the counter ion-dependent substrate recognition mechanism. Furthermore, comparisons of the inward-open and occluded structures support a transport mechanism combining elevator and distinct rotational motions. Our results demonstrate the molecular mechanism of vitamin C transport with its underlying conformational cycle, potentially leading to future industrial and medical applications.
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Ácido Ascórbico , Microscopía por Crioelectrón , Transportadores de Sodio Acoplados a la Vitamina C , Humanos , Transportadores de Sodio Acoplados a la Vitamina C/metabolismo , Transportadores de Sodio Acoplados a la Vitamina C/química , Transportadores de Sodio Acoplados a la Vitamina C/genética , Ácido Ascórbico/metabolismo , Ácido Ascórbico/química , Transporte Biológico , Sodio/metabolismo , Modelos Moleculares , Multimerización de Proteína , Unión Proteica , Células HEK293 , Conformación ProteicaRESUMEN
Ascorbate is a small antioxidant molecule essential for the proper development and function of the brain. Ascorbate is transported into the brain and between brain cells via the Sodium vitamin C co-transporter 2 (SVCT2). This review provides an in-depth analysis of ascorbate's physiology, including how ascorbate is absorbed from food into the CNS, emphasizing cellular mechanisms of ascorbate recycling and release in different CNS compartments. Additionally, the review delves into the various functions of ascorbate in the CNS, including its impact on epigenetic modulation, synaptic plasticity, and neurotransmission. It also emphasizes ascorbate's role on neuromodulation and its involvement in neurodevelopmental processes and disorders. Furthermore, it analyzes the relationship between the duo ascorbate/SVCT2 in neuroinflammation, particularly its effects on microglial activation, cytokine release, and oxidative stress responses, highlighting its association with neurodegenerative diseases, such as Alzheimer's disease (AD). Overall, this review emphasizes the crucial role of the dynamic duo ascorbate/SVCT2 in CNS physiology and pathology and the need for further research to fully comprehend its significance in a neurobiological context and its potential therapeutic applications.
Asunto(s)
Ácido Ascórbico , Simportadores , Transportadores de Sodio Acoplados a la Vitamina C/genética , Neurobiología , Antioxidantes , VitaminasRESUMEN
Radial glia (RG) cells generate neurons and glial cells that make up the cerebral cortex. Both in rodents and humans, these stem cells remain for a specific time after birth, named late radial glia (lRG). The knowledge of lRG and molecules that may be involved in their differentiation is based on very limited data. We analyzed whether ascorbic acid (AA) and its transporter SVCT2, are involved in lRG cells differentiation. We demonstrated that lRG cells are highly present between the first and fourth postnatal days. Anatomical characterization of lRG cells, revealed that lRG cells maintained their bipolar morphology and stem-like character. When lRG cells were labeled with adenovirus-eGFP at 1 postnatal day, we detected that some cells display an obvious migratory neuronal phenotype, suggesting that lRG cells continue generating neurons postnatally. Moreover, we demonstrated that SVCT2 was apically polarized in lRG cells. In vitro studies using the transgenic mice SVCT2+/- and SVCT2tg (SVCT2-overexpressing mouse), showed that decreased SVCT2 levels led to accelerated differentiation into astrocytes, whereas both AA treatment and elevated SVCT2 expression maintain the lRG cells in an undifferentiated state. In vivo overexpression of SVCT2 in lRG cells generated cells with a rounded morphology that were migratory and positive for proliferation and neuronal markers. We also examined mediators that can be involved in AA/SVCT2-modulated signaling pathways, determining that GSK3-ß through AKT, mTORC2, and PDK1 is active in brains with high levels of SVCT2/AA. Our data provide new insights into the role of AA and SVCT2 in late RG cells.
Asunto(s)
Ácido Ascórbico , Transportadores de Sodio Acoplados a la Vitamina C , Animales , Humanos , Ratones , Ácido Ascórbico/farmacología , Células Ependimogliales/metabolismo , Glucógeno Sintasa Quinasa 3/metabolismo , Proteínas de Transporte de Membrana/metabolismo , Ratones Transgénicos , Neuronas/metabolismo , Transportadores de Sodio Acoplados a la Vitamina C/genéticaRESUMEN
The ubiquitin-proteasomal pathway regulates the functional expression of many membrane transporters in a variety of cellular systems. Nothing is currently known about the role of ubiquitin E3 ligase, neural precursor cell-expressed developmentally down-regulated gene 4 (Nedd4-1) and the proteasomal degradation pathway in regulating human vitamin C transporter-2 (hSVCT2) in neuronal cells. hSVCT2 mediates the uptake of ascorbic acid (AA) and is the predominantly expressed vitamin C transporter isoform in neuronal systems. Therefore, we addressed this knowledge gap in our study. Analysis of mRNA revealed markedly higher expression of Nedd4-1 in neuronal samples than that of Nedd4-2. Interestingly, Nedd4-1 expression in the hippocampus was higher in patients with Alzheimer's disease (AD) and age-dependently increased in the J20 mouse model of AD. The interaction of Nedd4-1 and hSVCT2 was confirmed by coimmunoprecipitation and colocalization. While the coexpression of Nedd4-1 with hSVCT2 displayed a significant decrease in AA uptake, siRNA-mediated knockdown of Nedd4-1 expression up-regulated the AA uptake. Further, we mutated a classical Nedd4 protein interacting motif ("PPXY") within the hSVCT2 polypeptide and observed markedly decreased AA uptake due to the intracellular localization of the mutated hSVCT2. Also, we determined the role of the proteasomal degradation pathway in hSVCT2 functional expression in SH-SY5Y cells and the results indicated that the proteasomal inhibitor (MG132) significantly up-regulated the AA uptake and hSVCT2 protein expression level. Taken together, our findings show that the regulation of hSVCT2 functional expression is at least partly mediated by the Nedd4-1 dependent ubiquitination and proteasomal pathways.
Asunto(s)
Neuroblastoma , Transportadores de Sodio Acoplados a la Vitamina C , Animales , Humanos , Ratones , Ácido Ascórbico/farmacología , Ácido Ascórbico/metabolismo , Complejos de Clasificación Endosomal Requeridos para el Transporte/genética , Complejos de Clasificación Endosomal Requeridos para el Transporte/metabolismo , Células Epiteliales/metabolismo , Ubiquitina-Proteína Ligasas Nedd4/genética , Ubiquitina-Proteína Ligasas Nedd4/metabolismo , Transportadores de Sodio Acoplados a la Vitamina C/genética , Transportadores de Sodio Acoplados a la Vitamina C/metabolismo , Ubiquitina/metabolismo , Ubiquitina-Proteína Ligasas/genética , Ubiquitina-Proteína Ligasas/metabolismo , UbiquitinaciónRESUMEN
Urate transporters play a pivotal role in urate handling in the human body, but the urate transporters identified to date do not account for all known molecular processes of urate handling, suggesting the presence of latent machineries. We recently showed that a urate transporter SLC2A12 is also a physiologically important exporter of ascorbate (the main form of vitamin C in the body) that would cooperate with an ascorbate importer, sodium-dependent vitamin C transporter 2 (SVCT2). Based on the dual functions of SLC2A12 and cooperativity between SLC2A12 and SVCT2, we hypothesized that SVCT2 might be able to transport urate. To test this proposal, we conducted cell-based analyses using SVCT2-expressing mammalian cells. The results demonstrated that SVCT2 is a novel urate transporter. Vitamin C inhibited SVCT2-mediated urate transport with a half-maximal inhibitory concentration of 36.59 µM, suggesting that the urate transport activity may be sensitive to physiological ascorbate levels in blood. Similar results were obtained for mouse Svct2. Further, using SVCT2 as a sodium-dependent urate importer, we established a cell-based urate efflux assay that will be useful for identification of other novel urate exporters as well as functional characterization of nonsynonymous variants of already-identified urate exporters including ATP-binding cassette transporter G2. While more studies will be needed to elucidate the physiological impact of SVCT2-mediated urate transport, our findings deepen understanding of urate transport machineries.
Asunto(s)
Transportadores de Anión Orgánico Sodio-Dependiente , Transportadores de Sodio Acoplados a la Vitamina C , Ácido Úrico , Animales , Humanos , Ratones , Ácido Ascórbico/metabolismo , Transportadores de Anión Orgánico Sodio-Dependiente/genética , Transportadores de Anión Orgánico Sodio-Dependiente/metabolismo , Transportadores de Sodio Acoplados a la Vitamina C/genética , Ácido Úrico/metabolismoRESUMEN
This study aimed to determine the mechanisms of heat-induced oxidative stress in the thymus and spleen of broilers. After 28 d, 30 broilers were randomly divided into the control (25°C ± 2°C; 24 h/d) and heat-stressed (36°C ± 2°C; 8 h/d) groups; the experiment lasted for 1 wk. The broilers in each group were euthanized, and some samples were collected and analyzed at 35 d. The results showed that the birds subjected to heat stress reduced the weight (P < 0.01) and the indices of thymus (P < 0.01), the activities of T-AOC (P < 0.01) and SOD (P < 0.05) of spleen, and levels of IL-10 (P < 0.05) and the GSH-PX (P < 0.05) in thymus and spleen, and increased the IL-6 content of thymus (P < 0.05), the MDA content (P < 0.01), and the reactive oxygen species (ROS) levels (P < 0.01) in thymus and spleen. Moreover, the expression of the IgG gene in the thymus and spleen of heat-stressed broilers was increased (P < 0.05); however, the expression of the IgM gene in the spleen was increased (P < 0.05), with no difference (P > 0.05) in the thymus of heat-stressed broilers compared with the control. Furthermore, the relative expression of adenosine triphosphate-binding cassette subfamily G member 2 (ABCG2) in the thymus and spleen both increased (P < 0.05). The sodium-dependent vitamin C transporter-2 (SVCT-2) (P < 0.01) and mitochondrial calcium uniporter (MCU) (P < 0.01) mRNA levels in the thymus of heat-stressed broilers increased, and the expression of ABCG2 (P < 0.05), SVCT-2 (P < 0.01), and MCU (P < 0.01) proteins in the thymus and spleen of heat-stressed broilers increased compared with the control group. This study confirmed that heat stress-induced oxidative stress in the immune organs of broilers, further reducing immune function.
Asunto(s)
Pollos , Suplementos Dietéticos , Animales , Pollos/metabolismo , Transportadores de Sodio Acoplados a la Vitamina C/metabolismo , Estrés Oxidativo , Respuesta al Choque Térmico , Alimentación Animal/análisis , Dieta/veterinariaRESUMEN
Vitamin C (VC) is a key antioxidant of the Central Nervous System (CNS) and SLC23A2 (SVCT2) is the only transporter that actively transports VC into the brain. While the existing animal models of VC deficiency are in the whole body, the essential role of VC in brain development remains elusive. In our study presented here, the CRISPR/Cas9 technology was applied for the construction of a C57BL/6J-SLC23A2 em1(flox)Smoc mouse model, which was crossed with the Glial fibrillary acidic protein-driven Cre Recombinase (GFAP-Cre) genotype mice to generate a conditional knockout model of SLC23A2(SVCT2) gene in mice brain (GFAP-Cre;SLC23A2 flox/flox) after generations of crossbreeding. Our results showed that the expression of SVCT2 in GFAP-Cre;SLC23A2 flox/flox (Cre;svct2 f/f) mice brain was significantly decreased, and consistently, the expression of Neuronal nuclei antigen (NeuN), Glial fibrillary acidic protein (GFAP), calbindin-28k, brain-derived neurotrophic factor (BDNF) was down-regulated but Ionized calcium binding adapter molecule 1 (Iba-1) was up-regulated in Cre;svct2 f/f mice brain tissues. On the other hand, the levels of Glutathione, Reduced (GSH), myeloperoxidase (MDA), 8-isoprostane, tumor necrosis factor-α (TNF-α) and interleukin-6(IL-6) were significantly increased, but the levels of VC in brain tissue of the model group were decreased in Cre;svct2 f/f mice brain tissues, indicating the protective effect of VC against oxidative stress and inflammation during pregnancy. Thus, the conditional knockout of the SLC23A2 gene in the brain of mouse was successfully established by the CRISPR/Cas9 technology in our study, providing an effective animal model for studying the role of VC in fetal brain development.
Asunto(s)
Ácido Ascórbico , Encéfalo , Transportadores de Sodio Acoplados a la Vitamina C , Animales , Femenino , Ratones , Embarazo , Ácido Ascórbico/metabolismo , Encéfalo/metabolismo , Técnicas de Inactivación de Genes , Proteína Ácida Fibrilar de la Glía/metabolismo , Ratones Endogámicos C57BL , Ratones Noqueados , Transportadores de Sodio Acoplados a la Vitamina C/genéticaRESUMEN
Curcumin is a natural polyphenol that is extracted from the rhizomes of the turmeric plant (Curcuma longa), a member of the ginger family. It has been used for centuries in traditional Indian and Chinese medicine for its medicinal properties, including anti-inflammatory, antioxidant and antitumor effects. SVCT2 (Solute Carrier Family 23 Member 2, also known as SLC23A2) is a protein that plays a role in the transport of Vitamin C (Ascorbic Acid) into cells. SVCT2 plays an important role in tumor progression and metastasis, however, the molecular mechanisms of curcumin on SVCT2 have not been studied to date. Curcumin treatment inhibited proliferation and migration of cancer cells in a dose dependent manner. We found that curcumin reduced the expression of SVCT2 in cancer cells with a wild type p53, but not in those with a mutant type of p53. SVCT2 downregulation also reduced the MMP2 activity. Taken together, our results indicate that curcumin inhibited human cancer cell growth and migration by regulating SVCT2 through a downregulating p53. These findings provide new insights into the molecular mechanisms of curcumin's anticancer effects and potential therapeutic strategies for the treatment of metastatic migration.
Asunto(s)
Curcumina , Neoplasias , Transportadores de Sodio Acoplados a la Vitamina C , Humanos , Antiinflamatorios/farmacología , Antioxidantes/farmacología , Curcumina/farmacología , Regulación hacia Abajo , Neoplasias/tratamiento farmacológico , Proteína p53 Supresora de Tumor , Transportadores de Sodio Acoplados a la Vitamina C/efectos de los fármacosRESUMEN
Vitamin C (VC)-based cancer therapy is a promising therapeutic approach for a variety of cancers due to its profound effects on redox reactions and metabolic pathways. However, high administration dosage of VC for necessary therapeutic efficacy for cancers increases the risk of overt side effects and limits its clinical use. Here, we show cutaneous blue light irradiation can specifically upregulate the sodium-dependent vitamin C transporter 2 (SVCT2) of the tumor and increase effectively the VC concentration at the tumor sites by an overall low dosage administration. In the mouse melanoma model, blue light stimulates the SVCT2 expression through the nuclear factor-kappa B (NF-κB) signaling pathway both in vitro and in vivo. The increased cellular VC together with Fe2+ generated by blue light simultaneously elevate cellular oxidative stress and trigger the ferroptosis of melanoma. With this revealed mechanism, the synergistic actions of blue light on the VC transporter and Fe2+ generation lead to a ca. 20-fold reduction in the administration dosage of VC with an effective melanoma elimination and prolonged survival. The work defines the killing mechanism of blue light on VC-based cancer therapy and provides a practical approach for promoting VC uptake. This light-assisted VC therapy is not only highly efficient for melanoma but also considerable for a broad clinical utility.
Asunto(s)
Ferroptosis , Melanoma , Ratones , Animales , Ácido Ascórbico/farmacología , Transportadores de Sodio Acoplados a la Vitamina C/metabolismo , Melanoma/terapia , Estrés Oxidativo/fisiología , Modelos Animales de EnfermedadRESUMEN
Vitamin C (L-ascorbic acid) is an essential nutrient for human health, and its deficiency has long been known to cause scurvy. Sodium-dependent vitamin C transporters (SVCTs) are responsible for vitamin C uptake and tissue distribution in mammals. Here, we present cryogenic electron microscopy structures of mouse SVCT1 in both the apo and substrate-bound states. Mouse SVCT1 forms a homodimer with each protomer containing a core domain and a gate domain. The tightly packed extracellular interfaces between the core domain and gate domain stabilize the protein in an inward-open conformation for both the apo and substrate-bound structures. Vitamin C binds at the core domain of each subunit, and two potential sodium ions are identified near the binding site. The coordination of sodium ions by vitamin C explains their coupling transport. SVCTs probably deliver substrate through an elevator mechanism in combination with local structural arrangements. Altogether, our results reveal the molecular mechanism by which SVCTs recognize vitamin C and lay a foundation for further mechanistic studies on SVCT substrate transport.
Asunto(s)
Ácido Ascórbico , Transportadores de Sodio Acoplados a la Vitamina C , Simportadores , Animales , Humanos , Ratones , Ácido Ascórbico/metabolismo , Transportadores de Anión Orgánico Sodio-Dependiente/metabolismo , Sodio/metabolismo , Transportadores de Sodio Acoplados a la Vitamina C/metabolismo , Simportadores/metabolismo , VitaminasRESUMEN
Uric acid, the end product of purine metabolism in humans, is crucial because of its anti-oxidant activity and a causal relationship with hyperuricemia and gout. Several physiologically important urate transporters regulate this water-soluble metabolite in the human body; however, the existence of latent transporters has been suggested in the literature. We focused on the Escherichia coli urate transporter YgfU, a nucleobase-ascorbate transporter (NAT) family member, to address this issue. Only SLC23A proteins are members of the NAT family in humans. Based on the amino acid sequence similarity to YgfU, we hypothesized that SLC23A1, also known as sodium-dependent vitamin C transporter 1 (SVCT1), might be a urate transporter. First, we identified human SVCT1 and mouse Svct1 as sodium-dependent low-affinity/high-capacity urate transporters using mammalian cell-based transport assays. Next, using the CRISPR-Cas9 system followed by the crossing of mice, we generated Svct1 knockout mice lacking both urate transporter 1 and uricase. In the hyperuricemic mice model, serum urate levels were lower than controls, suggesting that Svct1 disruption could reduce serum urate. Given that Svct1 physiologically functions as a renal vitamin C re-absorber, it could also be involved in urate re-uptake from urine, though additional studies are required to obtain deeper insights into the underlying mechanisms. Our findings regarding the dual-substrate specificity of SVCT1 expand the understanding of urate handling systems and functional evolutionary changes in NAT family proteins.
Asunto(s)
Transportadores de Anión Orgánico , Ácido Úrico , Animales , Humanos , Ratones , Secuencia de Aminoácidos , Ácido Ascórbico/metabolismo , Transporte Biológico , Mamíferos/metabolismo , Transportadores de Anión Orgánico/metabolismo , Transportadores de Sodio Acoplados a la Vitamina C/genética , Transportadores de Sodio Acoplados a la Vitamina C/metabolismo , Ácido Úrico/metabolismoRESUMEN
Ascorbic acid (AA; vitamin C) plays a crucial role in the biosynthesis and secretion of collagen to produce the organic matrix of hard tissues. Nevertheless, the detailed mechanism by which AA induces reparative dentinogenesis is still unknown. This study aimed to investigate the pathway and function of AA during wound healing in a rat pulpotomy model. Sodium-dependent vitamin C transporter (SVCT) 2 and glucose transporter (GLUT) 1 were detected in odontoblasts, endothelial cells, and nerve fibers in normal pulp tissues. SVCT2 and GLUT1 were also expressed in odontoblast-like cells in pulpotomized tissues of Wistar rats, and immunopositive cells of SVCT2 were significantly increased at 5 days after pulpotomy (p < 0.05). By contrast, osteogenic disorder Shionogi (ODS) rats, which cannot generate AA, also expressed SVCT2 and GLUT1 in normal and wound healing conditions. However, in ODS rats, when compared with the AA-addition group, the formation of dentin bridges in the AA-loss group was not evident, a layer of osteopontin was significantly increased beneath the wound surface (p < 0.05), and alpha smooth muscle actin at the odontoblast-like cells observed along this layer was significantly increased (p < 0.05), but not Nestin. Moreover, the amounts of type 1 collagen generated in the reparative dentin and beneath the wound healing site were significantly diminished (p < 0.05). Macrophages expressing CD68 and CD206 increased beneath the wound site. Hence, AA may be involved in odontoblast-like cell differentiation and anti-inflammatory response during dental pulp wound healing. Our results provide new insights into the function of AA through SVCT2 and GLUT1 in reparative dentinogenesis and may help in developing new therapeutic targets for dental pulpal disease.
Asunto(s)
Dentina Secundaria , Células Endoteliales , Ratas , Animales , Ratas Wistar , Células Endoteliales/metabolismo , Pulpa Dental/metabolismo , Transportador de Glucosa de Tipo 1 , Cicatrización de Heridas , Odontoblastos/metabolismo , Transportadores de Sodio Acoplados a la Vitamina C , Ácido Ascórbico/metabolismoRESUMEN
The human sodium-dependent vitamin C transporter-1 (hSVCT1) is localized at the apical membrane domain of polarized intestinal and renal epithelial cells to mediate ascorbic acid (AA) uptake. Currently, little is known about the array of interacting proteins that aid hSVCT1 trafficking and functional expression at the cell surface. Here we used an affinity tagging ('One-STrEP') and proteomic approach to identify hSVCT1 interacting proteins, which resolved secretory carrier-associated membrane protein-2 (SCAMP2) as a novel accessary protein partner. SCAMP2 was validated as an accessory protein by co-immunoprecipitation with hSVCT1. Co-expression of hSVCT1 and SCAMP2 in HEK-293 cells revealed both proteins co-localized in intracellular structures and at the plasma membrane. Functionally, over-expression of SCAMP2 potentiated 14C-AA uptake, and reciprocally silencing endogenous SCAMP2 decreased 14C-AA uptake. Finally, knockdown of endogenous hSVCT1 or SCAMP2 impaired differentiation of human-induced pluripotent stem cells (hiPSCs) toward a neuronal fate. These results establish SCAMP2 as a novel hSVCT1 accessary protein partner that regulates AA uptake in absorptive epithelia and during neurogenesis.
Asunto(s)
Proteómica , Transportadores de Sodio Acoplados a la Vitamina C , Humanos , Células HEK293 , Membrana Celular/metabolismo , Transportadores de Sodio Acoplados a la Vitamina C/genética , Transportadores de Sodio Acoplados a la Vitamina C/metabolismo , Ácido Ascórbico/farmacología , Ácido Ascórbico/metabolismo , Neuronas/metabolismo , Transporte de Proteínas , Proteínas Portadoras/metabolismo , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismoRESUMEN
Vitamin C, a key antioxidant in the central nervous system, cycles between ascorbic acid and dehydroascorbic acid under pathophysiological conditions. Clinical evidence supports that the absence of vitamin C may be linked to depressive symptoms, but much less is known about the mechanism. Herein, we show that chronic stress disrupts the expression of ascorbic acid transporter, sodium-dependent vitamin C transport 2, and induces a deficiency in endogenous ascorbic acid in the medial prefrontal cortex, leading to depressive-like behaviors by disturbing redox-dependent DNA methylation reprogramming. Attractively, ascorbic acid (100 mg/kg-1000 mg/kg, intraperitoneal injection, as bioequivalent of an intravenous drip dose of 0.48 g-4.8 g ascorbic acid per day in humans) produces rapid-acting antidepressant effects via triggering DNA demethylation catalyzed by ten-eleven translocation dioxygenases. In particular, the mechanistic studies by both transcriptome sequencing and methylation sequencing have shown that S100 calcium binding protein A4, a potentially protective factor against oxidative stress and brain injury, mediates the antidepressant activity of ascorbic acid via activating erb-b2 receptor tyrosine kinase 4 (ErbB4)-brain derived neurotrophic factor (BDNF) signaling pathway. Overall, our findings reveal a novel nutritional mechanism that couples stress to aberrant DNA methylation underlying depressive-like behaviors. Therefore, application of vitamin C may be a potential strategy for the treatment of depression.
Asunto(s)
Ácido Ascórbico , Transportadores de Sodio Acoplados a la Vitamina C , Humanos , Ácido Ascórbico/farmacología , Ácido Ascórbico/metabolismo , Transporte Biológico , ADN/metabolismo , Proteína de Unión al Calcio S100A4/metabolismo , Transportadores de Sodio Acoplados a la Vitamina C/genética , Transportadores de Sodio Acoplados a la Vitamina C/metabolismoRESUMEN
Solute carrier family 23 member 1 (SVCT1) and solute carrier family 23 member 2 (SVCT2), encoded by SLC23A1 and SLC23A2, may be associated with preeclampsia (PE). The purpose of this study was to investigate the association between polymorphisms of SLC23A1 and SLC23A2 and PE in Chinese Han population. The primers and double-labeled probes were designed according to the SNPs of rs10063949 in SLC23A1, rs6133175 and rs1279683 in SLC23A2. Genomic DNA was extracted from peripheral blood of 2,066 subjects (1,029 with PE and 1,037 without PE), and Taqman real-time PCR was used to detect the three SNPs. We observed a significant difference in genotypic frequency of the SLC23A2 rs6133175 polymorphism (χ2=8.08, p=0.02) between PE patients and controls, while no significant differences were found in the allelic frequencies (χ2=1.45, p=0.23). Then we fractionized these samples into the dominant model of the allele G (GG/AG+AA group) or the recessive model of the A allele (AA/AG+GG group), and observed a significant difference under the recessive model of the A allele (p=0.01, OR=0.71, 95% CI 0.55-0.92). Furthermore, there were no significant differences in the genotypic and allelic frequencies of rs10063949 and rs1279683 between PE patients and controls (for rs10063949, χ2=2.96, p=0.23 by genotype, χ2=2.11, p=0.15 by allele; for rs1279683, χ2=1.52, p=0.47 by genotype, χ2=0.64, p=0.44 by allele). We first found that SLC23A2 rs6133175 may be the certain genetic polymorphisms modulating their effects in the development of PE in a Chinese Han population and the AG or GG genotypes may be a risk factor for PE.
Asunto(s)
Preeclampsia , Transportadores de Sodio Acoplados a la Vitamina C , Femenino , Humanos , Embarazo , Alelos , Pueblo Asiatico/genética , Estudios de Casos y Controles , China , Predisposición Genética a la Enfermedad , Genotipo , Polimorfismo de Nucleótido Simple , Preeclampsia/genética , Transportadores de Sodio Acoplados a la Vitamina C/genéticaRESUMEN
Neuronal uptake of ascorbic acid (AA) in humans occurs via the human sodium-dependent vitamin C transporter-2 (hSVCT2). Recent studies show that a significantly lower level of vitamin C is present in the blood of epileptic patients. Consequently, focused studies investigating the involved molecular mechanisms for hSVCT2 regulation are vital to enhance vitamin C body homeostasis. Currently, little is known about the role of valproic acid (VPA), a drug utilized to treat epilepsy and a class I histone deacetylase inhibitor (HDACi), on AA uptake in neuronal systems. Thus, this study aims to examine the effect of VPA on hSVCT2 functional expression in neuronal cells. VPA treatment upregulated the AA uptake and this increased AA uptake was associated with a significant increase in hSVCT2 expression and SLC23A2 promoter activity in SH-SY5Y cells. Knockdown of HDAC2, a predominant isoform in neuronal systems, significantly increased hSVCT2 functional expression. VPA treatment in mice displayed increased mouse (m)SVCT2 protein, mRNA and heterogenous nuclear RNA (hnRNA) expression in the brain. In addition, Yin Yang-1 (YY1), a transcription factor that drives the SLC23A2 promoter activity, protein and mRNA expression levels were markedly upregulated in VPA-treated SH-SY5Y cells and mice brain. Together, our findings suggest that VPA upregulates the functional expression of SVCT2 via HDAC2 and transcriptional mechanism(s).
Asunto(s)
Neuroblastoma , Transportadores de Sodio Acoplados a la Vitamina C , Animales , Ácido Ascórbico/farmacología , Inhibidores de Histona Desacetilasas/farmacología , Humanos , Ratones , Isoformas de Proteínas/metabolismo , ARN Nuclear Heterogéneo , ARN Mensajero/genética , Transportadores de Sodio Acoplados a la Vitamina C/genética , Transportadores de Sodio Acoplados a la Vitamina C/metabolismo , Factores de Transcripción/metabolismo , Ácido Valproico/farmacología , VitaminasRESUMEN
The α thalassemia/mental retardation syndrome X-linked (ATRX) mutation impairs DNA damage repair in glioblastoma (GBM), making these cells more susceptible to treatment, which may contribute to the survival advantage in patients with GBM containing ATRX mutations. To better understand the role of ATRX in GBM, genes correlated with ATRX expression were screened in the Cancer Genome Atlas (702 cases) and Chinese Glioma Genome Atlas (325 cases) databases. Sodium-vitamin C cotransporter 2 (SVCT2) was the most positively correlated gene with ATRX expression. ATRX (about 1.99-fold) and SVCT2 (about 2.25-fold) were upregulated in GBM tissues from 40 patients compared with normal brain tissues from 23 subjects. ShSVCT2 transfection did not alter the in vitro viability of GL261 cells. At the same time, it could inhibit the proliferation of GL261 cells in the orthotopic transplantation model with diminished infiltrating macrophages (CD45highCD11b+), downregulated chemokine (C-C motif) ligand 2 (Ccl2), Ccl4, C-X-C motif chemokine ligand 1 (Cxcl1), and Cxcl15 expression, and decreased p-IκBα and p-c-Jun expression. Effect of ShSVCT2 transfection could be reversed by overexpression of SVCT2. siRNA interference of ATRX-dependent SVCT2 signal with shSVCT2 could inhibit tumor cell proliferation in Glu261-LuNeo xenograft tumor model with more survival advantage, probably by the inhibited macrophage chemotaxis. These results indicate that ATRX-dependent SVCT2-mediated chemokine-induced macrophage infiltration is regulated by the NF-κB pathway, which could be considered as treatment targets.NEW & NOTEWORTHY This study demonstrates that interference of ATRX-dependent SVCT2-mediated chemokine-induced macrophage infiltration could inhibit tumor cell proliferation in the GBM cell line-derived xenograft model. ATRX and SVCT2 are potential treatment targets identified in this study.
Asunto(s)
Neoplasias Encefálicas , Glioblastoma , Simportadores , Talasemia alfa , Animales , Ácido Ascórbico , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patología , Modelos Animales de Enfermedad , Glioblastoma/genética , Glioblastoma/metabolismo , Glioblastoma/patología , Xenoinjertos , Humanos , Macrófagos/metabolismo , Macrófagos/patología , Discapacidad Intelectual Ligada al Cromosoma X , Sodio/metabolismo , Transportadores de Sodio Acoplados a la Vitamina C , Proteína Nuclear Ligada al Cromosoma X/genética , Proteína Nuclear Ligada al Cromosoma X/metabolismoRESUMEN
Aims: Glioblastoma (GB) is one of the most aggressive brain tumors. These tumors modify their metabolism, increasing the expression of glucose transporters, GLUTs, which incorporate glucose and the oxidized form of vitamin C, dehydroascorbic acid (DHA). We hypothesized that GB cells preferentially take up DHA, which is intracellularly reduced and compartmentalized into the endoplasmic reticulum (ER), promoting collagen biosynthesis and an aggressive phenotype. Results: Our results showed that GB cells take up DHA using GLUT1, while GLUT3 and sodium-dependent vitamin C transporter 2 (SVCT2) are preferably intracellular. Using a baculoviral system and reticulum-enriched extracts, we determined that SVCT2 is mainly located in the ER and corresponds to a short isoform. Ascorbic acid (AA) was compartmentalized, stimulating collagen IV secretion and increasing in vitro and in situ cell migration. Finally, orthotopic xenografts induced in immunocompetent guinea pigs showed that vitamin C deficiency retained collagen, reduced blood vessel invasion, and affected glomeruloid vasculature formation, all pathological conditions associated with malignancy. Innovation and Conclusion: We propose a functional role for vitamin C in GB development and progression. Vitamin C is incorporated into the ER of GB cells, where it favors the synthesis of collagen, thus impacting tumor development. Collagen secreted by tumor cells favors the formation of the glomeruloid vasculature and enhances perivascular invasion. Antioxid. Redox Signal. 37, 538-559.
Asunto(s)
Ácido Ascórbico , Glioblastoma , Animales , Ácido Ascórbico/metabolismo , Ácido Ascórbico/farmacología , Colágeno/metabolismo , Ácido Deshidroascórbico/metabolismo , Ácido Deshidroascórbico/farmacología , Glucosa/metabolismo , Cobayas , Humanos , Transportadores de Sodio Acoplados a la Vitamina C/metabolismo , VitaminasRESUMEN
Ascorbate is an important element of a variety of cellular processes including the control of reactive oxygen species levels. Since reactive oxygen species are implicated as a key factor in tumorigenesis and antitumor therapy, the injection of a large amount of ascorbate is considered beneficial in cancer therapy. Recent studies have shown that ascorbate can cross the plasma membrane through passive diffusion. In contrast to absorption by active transport, which is facilitated by transport proteins (SVCT1 and SVCT2). The passive diffusion of a weak acid across membranes depends on the electrostatic potential and the pH gradients. This has been used to construct a new theoretical model capable of providing steady-state ascorbate concentration in the intracellular space and evaluating the time needed to reach it. The main conclusion of the analysis is that the steady-state intracellular ascorbate concentration weakly depends on its serum concentration but requires days of exposure to saturate. Based on these findings, it can be hypothesized that extended oral ascorbate delivery is possibly more effective than a short intravenous infusion of high ascorbate quantities.