Sodium-coupled vitamin C transporter (SVCT2): expression, function, and regulation in intervertebral disc cells

A genome-wide association study on growth traits of Korean commercial pig breeds using Bayesian methods

OBJECTIVE

This study aims to identify the significant regions and candidate genes of growth-related traits (adjusted backfat thickness [ABF], average daily gain [ADG], and days to 90 kg [DAYS90]) in Korean commercial GGP pig (Duroc, Landrace, and Yorkshire) populations.

METHODS

A genome-wide association study (GWAS) was performed using single-nucleotide polymorphism (SNP) markers for imputation to Illumina PorcineSNP60. The BayesB method was applied to calculate thresholds for the significance of SNP markers. The identified windows were considered significant if they explained ≥1% genetic variance.

RESULTS

A total of 28 window regions were related to genetic growth effects. Bayesian GWAS revealed 28 significant genetic regions including 52 informative SNPs associated with growth traits (ABF, ADG, DAYS90) in Duroc, Landrace, and Yorkshire pigs, with genetic variance ranging from 1.00% to 5.46%. Additionally, 14 candidate genes with previous functional validation were identified for these traits.

CONCLUSION

The identified SNPs within these regions hold potential value for future markerassisted or genomic selection in pig breeding programs. Consequently, they contribute to an improved understanding of genetic architecture and our ability to genetically enhance pigs. SNPs within the identified regions could prove valuable for future marker-assisted or genomic selection in pig breeding programs.

Ascorbic acid promotes nucleus pulposus cell regeneration by regulating proliferation during intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) affects human health. Ascorbic acid (AA) deficiency is a major factor that contributes to the development of degenerative disc disease in the elderly. Here, as a novel treatment with promising applications, we demonstrate that AA treatment inhibited senescence and maintained the proliferation of nucleus pulposus (NP) cells during long-term culture. AA-treated NP cells and acupuncture-treated rat models exhibited degenerative resistance during cell passaging and AA increased cell proliferation and decreased time-related senescence. Interestingly, Kyoto Encyclopedia of Genes and Genomes pathway mapping revealed five top enriched pathways and four pathways were associated with the aldehyde dehydrogenase (ALDH) enzyme family, especially proliferation-related ALDH1A3. Collectively, our findings demonstrate that ALDH1A3 expression was increased by AA treatment, which counteracted degeneration in NP cells over time and rejuvenated maintenance of proliferation in NP cells, which has a promising therapeutic implications in IVDD.

IGF Signaling in Intervertebral Disc Health and Disease

Low back pain (LBP) is a common musculoskeletal symptom, which brings a lot of pain and economic loss to patients. One of the most common causes of LBP is intervertebral disc degeneration (IVDD). However, pathogenesis is still debated, and therapeutic options are limited. Insulin-like growth factor (IGF) signaling pathways play an important role in regulating different cell processes, including proliferation, differentiation, migration, or cell death, which are critical to the homeostasis of tissues and organs. The IGF signaling is crucial in the occurrence and progression of IVDD. The activation of IGF signaling retards IVDD by increasing cell proliferation, promoting extracellular matrix (ECM) synthesis, inhibiting ECM decomposition, and preventing apoptosis and senescence of disc cells. However, abnormal activation of IGF signaling may promote the process of IVDD. IGF signaling is currently considered to have a promising treatment prospect for IVDD. An in-depth understanding of the role of IGF signaling in IVDD may help find a novel approach for IVDD treatment.

Antioxidant Effects of Resveratrol in Intervertebral Disk

Intervertebral disk (IVD) degeneration (IVDD) can cause various spinal degenerative diseases. Cumulative evidence has indicated that IVDD can result from inflammation, apoptosis, autophagy, biomechanical changes and other factors. Currently, lack of conservative treatment for degenerative spinal diseases leads to an urgent demand for clinically applicable medication to ameliorate the progression of IVDD. Resveratrol (3,5,4'-trihydroxy-trans-stilbene), a polyphenol compound extracted from red wine or grapes, has shown protective effects on IVD, alleviating the progression of IVDD. Resveratrol has been demonstrated as a scavenger of free radicals both in vivo and in vitro. The antioxidant effects of resveratrol are likely attributed to its regulation on mitochondrial dysfunction or the elimination of reactive oxygen species. This review will summarize the mechanisms of the reactive oxygen species production and elaborate the mechanisms of resveratrol in retarding IVDD progression, providing a comprehensive understanding of the antioxidant effects of resveratrol in IVD.

Vitamin C supplementation for the treatment of osteoarthritis: perspectives on the past, present, and future

According to the US Centers for Disease Control and Prevention (CDC), an estimated 14% of adults in the United States have either been diagnosed with osteoarthritis (OA) or have symptoms suggestive of the disease. The CDC also points out that the incidence of OA has been gradually increasing over the past 30 years. What is more worrisome is that this trend is going to accelerate due to the aging demographics of the United States and the increasing prevalence of obesity seen in the country. The need for better preventive treatments and efficacious therapeutics are direly needed to combat this public health crisis. Among the possible treatments being hypothesized, antioxidant supplementation has become one of the most widely studied over the past decade due to its ability to attenuate reactive oxygen species (ROS) formation within chondrocytes, a critical step in the pathogenesis of this disease. Vitamin C has emerged as among the most promising of the antioxidant group, with many animal and human studies having been conducted in recent years. Although many of the studies have shown encouraging results in terms of preventing OA, others have reached opposite conclusions, thus making the data controversial. However, after reviewing several of these studies, we hypothesize that certain parameters may not have been properly considered during data collection. In the end, more randomized placebo-controlled trials in humans are desperately needed in order to fully understand whether vitamin C therapy is efficacious in treating and/or preventing OA.

Mutation SVCT2 promotes cell proliferation, invasion and migration in colorectal cancer

The sodium-dependent vitamin C transporter 2 (SVCT2) surface glycoprotein regulates ascorbate accumulation in the plasma, often resulting in the induction of cancer cell death. Therefore, high expression of this gene associates with increased overall survival in several cancers. However, in colorectal cancer (CRC), high (likely mutated) SVCT2 expression relates to poor overall survival, and its functional significance has not been studied. Thus, we hypothesize that mutant SVCT2 expression could affect CRC patient survival. According to biological databases, SVCT2 has been found to be mutated frequently, and SVCT2 E264K has a particularly high pathogenic score (0.98), compared to other SVCT2 mutant sites, in CRC patients. Interestingly, our results reveal expression of SVCT2 E264K in many CRC tissues and cells. Also, we found wild-type SVCT2 expression to be largely localized to the cytoplasm and membrane, while SVCT2 E264K was restricted to the cytoplasm. We further found that SVCT2 E264K overexpression increases cell growth. By contrast, SVCT2 E264K knockdown significantly reduced cell proliferation and promoted cell apoptosis, resulting in inhibition of cell invasion and migration. Taken together, SVCT2 E264K plays a critical role in proliferation in CRC. Our results suggest that SVCT2 E264K could be a promising novel therapeutic target in CRC.

Upregulation of glycosaminoglycan synthesis by Neurotropin in nucleus pulposus cells via stimulation of chondroitin sulfate N-acetylgalactosaminyltransferase 1: A new approach to attenuation of intervertebral disc degeneration

It is suggested that most cases of low back pain are related to degeneration of intervertebral discs. Disc degeneration is a chronic and progressive disease and the search for effective medical treatments continues. Neurotropin is widely used in Japan and China to treat low back pain and neck–shoulder–arm syndrome. The present study aimed to investigate the effect of Neurotropin on glycosaminoglycan synthesis in nucleus pulposus cells. Cultured human nucleus pulposus cells were treated with Neurotropin every second day for two weeks. Production of glycosaminoglycan was assessed using a dimethyl-methylene blue assay and PicoGreen was used to measure DNA content. Microarray analysis, real-time PCR, and western blotting were performed to assess the biological processes related to Neurotropin-stimulated glycosaminoglycan synthesis. The results showed that the level of glycosaminoglycan normalized to DNA content was significantly upregulated by the addition of Neurotropin. Gene expression profiling showed over two-fold upregulation of 697 genes in response to Neurotropin treatment. Among these genes, ontological analysis suggested significant implication of phosphatidylinositol 3-kinase signaling, and analysis focused on this pathway demonstrated marked upregulation of angiopoietin 1 and insulin-like growth factor 1. Activation of phosphorylation of the signal transducer protein AKT was detected by western blotting. Of the genes related to sulfated glycosaminoglycan synthesis, the greatest increase in mRNA levels was observed for chondroitin sulfate N-acetylgalactosaminyltransferase 1, an enzyme initiating synthesis of chondroitin sulfate side chains attached to a core protein of aggrecan, which is a predominant disc matrix component. These findings suggest that Neurotropin may activate the phosphatidylinositol 3-kinase–AKT pathway and stimulate glycosaminoglycan synthesis through upregulation of expression of mRNA for chondroitin sulfate N-acetylgalactosaminyltransferase 1. Because there was no cytotoxic cellular growth inhibition, Neurotropin treatment might offer an accessible therapeutic strategy for intervertebral disc degeneration.

The positive effect of chick embryo and nutrient mixture on bone marrow- derived mesenchymal stem cells from aging rats

The aging of many mammalian tissues is associated with loss of functional adult stem cells, especially bone marrow-derived mesenchymal stem cells (BMSCs). This study was aimed to analyze the biological effect of chick embryo (CE) and nutrient mixture (NM) on the BMSCs of aging rats. The aging rat model was established to be induced by D-galactose (500 mg/kg/d) for 90 days. Meanwhile, aging rats were fed with CE and NM in different dose manner by intragastric administration. At the end of the experimental period, serum was collected from rats and used for BMSCs culture. Flow cytometric analysis was used to investigate the BMSCs surface markers. Alizarin Red and oil red O staining were performed to evaluate the multi-lineage differentiation of BMSCs. The results showed that CE plus NM increased the telomere length of BMSCs and promoted BMSCs proliferation. Moreover, CE plus NM administration promoted BMSCs differentiation into osteoblasts and suppressed differentiation into adipocytes. High-throughput sequencing analysis revealed that there were 326 genes were up-regulated and 59 genes were down-regulated in BMSCs of aging rats treated with CE plus NM. In conclusion, CE plus NM supplement had potential to delay aging through the recovery of BMSCs senescence and could be used as a safe effective approach for nutritional therapy of anti-aging.

Possible involvement of the oxLDL/LOX-1 system in the pathogenesis and progression of human intervertebral disc degeneration or herniation

Epidemiological studies have concluded that hyperlipidemia and atherosclerosis were related to intervertebral disc degeneration (IVDD). The presence of oxidized low density lipoprotein (ox-LDL) and the expression of lectin-like oxidized low density lipoprotein receptor 1 (LOX-1) have not been explored in this tissue. In this study, we investigated the presence of ox-LDL and the expression of its receptor LOX-1 in non-degenerated, degenerated or herniated human intervertebral discs (IVDs). The expression of LOX-1 and matrix metalloproteinase 3 (MMP3) were studied after incubating nucleus pulposus cells (NPCs) with ox-LDL. The presence of ox-LDL and LOX-1 was positively related with the extent of IVDD in nucleus pulposus (NP), end-plate cartilage and outer annulus fibrous, but not with the extent of degeneration of inter annulus fibrous. Ox-LDL significantly reduced the viability of human NPCs in a dose and time-dependent manner, and increased the expression of MMP3 induced by LOX-1. Pretreatment with anti-human LOX-1 monoclonal antibody reversed these effects. Ox-LDL, principally mediated by LOX-1, enhanced MMP3 production in NPCs through the NF-κB signaling pathway. In conclusion, increased accumulation of ox-LDL and LOX-1 in IVDs indicates a specific role of the receptor-ligand interaction in degeneration or herniation of IVDs.

The Efficacy of Vitamin C on Postoperative Outcomes after Posterior Lumbar Interbody Fusion: A Randomized, Placebo-Controlled Trial

Background

Vitamin C has critical features relavant to postoperative pain management and functional improvement; however, no study has yet evaluated the effectiveness of vitamin C on improving the surgical outcomes for spine pathologies. Thus, this study aimed to explore the impact of vitamin C on postoperative outcomes after single-level posterior lumbar interbody fusion (PLIF) for lumbar spinal stenosis in prospectively randomized design. We conducted a 1-year prospective, randomized, placebo-controlled, double-blind study to evaluate the impact of vitamin C on the postoperative outcomes after PLIF surgery.

Methods

A total of 123 eligible patients were randomly assigned to either group A (62 patients with vitamin C) or group B (61 patients with placebo). Patient follow-up was continued for at least 1 year after surgery. The primary outcome measure was pain intensity in the lower back using a visual analogue scale. The secondary outcome measures were: (1) the clinical outcome assessed using the Oswestry Disability Index (ODI); (2) the fusion rate assessed using dynamic radiographs and computed tomography scans; and (3) complications.

Results

Pain intensity in the lower back was significantly improved in both groups compared with preoperative pain intensity, but no significant difference was observed between the 2 groups over the follow-up period. The ODI score of group A at the third postoperative month was significantly higher than the score of group B. After the sixth postoperative month, the ODI score of group A was slightly higher than the score of group B; however, this difference was not significant. The fusion rates at 1 year after surgery and the complication rates were not significantly different between the 2 groups.

Conclusions

Postoperative pain intensity, the primary outcome measure, was not significantly different at 1 year after surgery between the 2 groups. However, vitamin C may be associated with improving functional status after PLIF surgery, especially during the first 3 postoperative months.

Gender-specific differential expression of exosomal miRNA in synovial fluid of patients with osteoarthritis

The pathogenesis of osteoarthritis (OA) is poorly understood, and therapeutic approaches are limited to preventing progression of the disease. Recent studies have shown that exosomes play a vital role in cell-to-cell communication, and pathogenesis of many age-related diseases. Molecular profiling of synovial fluid derived exosomal miRNAs may increase our understanding of OA progression and may lead to the discovery of novel biomarkers and therapeutic targets. In this article we report the first characterization of exosomes miRNAs from human synovial fluid. The synovial fluid exosomes share similar characteristics (size, surface marker, miRNA content) with previously described exosomes in other body fluids. MiRNA microarray analysis showed OA specific exosomal miRNA of male and female OA. Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis identified gender-specific target genes/signaling pathways. These pathway analyses showed that female OA specific miRNAs are estrogen responsive and target TLR (toll-like receptor) signaling pathways. Furthermore, articular chondrocytes treated with OA derived extracellular vesicles had decreased expression of anabolic genes and elevated expression of catabolic and inflammatory genes. In conclusion, synovial fluid exosomal miRNA content is altered in patients with OA and these changes are gender specific.

Surgical anatomy, radiological features, and molecular biology of the lumbar intervertebral discs

The intervertebral disc (IVD) is a joint unique in structure and functions. Lying between adjacent vertebrae, it provides both the primary support and the elasticity required for the spine to move stably. Various aspects of the IVD have long been studied by researchers seeking a better understanding of its dynamics, aging, and subsequent disorders. In this article, we review the surgical anatomy, imaging modalities, and molecular biology of the lumbar IVD. Clin. Anat. 30:251-266, 2017. © 2017 Wiley Periodicals, Inc.

MicroRNAs-141 and 200a regulate the SVCT2 transporter in bone marrow stromal cells

Vitamin C is a micro-nutrient which plays an important role in bone marrow stromal cell (BMSCs) differentiation to osteogenesis. This vitamin is transported into the BMSCs through the sodium dependent vitamin C transporter 2 (SVCT2). We previously reported that knockdown of the SVCT2 transporter decreases osteogenic differentiation. However, our understanding of the post-transcriptional regulatory mechanism of the SVCT2 transporter remains poor. MicroRNAs (miRNAs) are small non-coding RNAs that post-transcriptionally regulate the messenger RNAs of protein-coding genes. In this study, we aimed to investigate the impact of miR-141 and miR-200a on SVCT2 expression. We found that mouse BMSCs expressed miR-141 and miR-200a and repressed SVCT2 expression at the functional level by targeting the 3'-untranslated region of mRNA. We also found that miR-141 and miR-200a decreased osteogenic differentiation. Furthermore, miRNA inhibitors increased SVCT2 and osteogenic gene expression in BMSCs. Taken together, these results indicate that both miRNAs are novel regulators of the SVCT2 transporter and play an important role in the osteogenic differentiation of BMSCs.

The crucial role of vitamin C and its transporter (SVCT2) in bone marrow stromal cell autophagy and apoptosis

Vitamin C is an antioxidant that plays a vital role in various biological processes including bone formation. Previously, we reported that vitamin C is transported into bone marrow stromal cells (BMSCs) through the sodium dependent Vitamin C Transporter 2 (SVCT2) and this transporter plays an important role in osteogenic differentiation. Furthermore, this transporter is regulated by oxidative stress. To date, however, the exact role of vitamin C and its transporter (SVCT2) in ROS regulated autophagy and apoptosis in BMSCs is poorly understood. In the present study, we observed that oxidative stress decreased survival of BMSCs in a dose-dependent manner and induced growth arrest in the G1 phase of the cell cycle. These effects were accompanied by the induction of autophagy, confirmed by P62 and LC3B protein level and punctate GFP-LC3B distribution. The supplementation of vitamin C significantly rescued the BMSCs from oxidative stress by regulating autophagy. Knockdown of the SVCT2 transporter in BMSCs synergistically decreased cell survival even under low oxidative stress conditions. Also, supplementing vitamin C failed to rescue cells from stress. Our results reveal that the SVCT2 transporter plays a vital role in the mechanism of BMSC survival under stress conditions. Altogether, this study has given new insight into the role of the SVCT2 transporter in oxidative stress related autophagy and apoptosis in BMSCs.

Ascorbic acid and the brain: rationale for the use against cognitive decline

This review is focused upon the role of ascorbic acid (AA, vitamin C) in the promotion of healthy brain aging. Particular attention is attributed to the biochemistry and neuronal metabolism interface, transport across tissues, animal models that are useful for this area of research, and the human studies that implicate AA in the continuum between normal cognitive aging and age-related cognitive decline up to Alzheimer’s disease. Vascular risk factors and comorbidity relationships with cognitive decline and AA are discussed to facilitate strategies for advancing AA research in the area of brain health and neurodegeneration.