NAD+ affects differentially expressed genes-MBOAT2-SLC25A21-SOX6 in experimental autoimmune encephalomyelitis model.

BACKGROUND: Nicotinamide adenine dinucleotide (NAD+) plays a key role in neuroinflammation and neurodegeneration and provides anti-inflammatory and neuroprotective effects in multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE). AIM: In this study, we aimed to investigate whether NAD+ affects differentially expressed genes (DEGs) in splenocytes of EAE mice to reveal candidate genes for the pathogenesis of MS. METHODS: The EAE model was used to perform an intervention on NAD+ to investigate its potential as a protective agent in inflammation and demyelination. Transcriptome analysis of nerve tissue was carried out to gain better insights into NAD+ function. Effects of NAD+ on DEGs in the splenocytes of EAE mice were investigated to determine its anti-inflammatory effect. RESULTS: NAD+ in EAE mice showed the clinical score was significantly improved (EAE 3.190 ± 0.473 vs. NAD+ 2.049 ± 0.715). DEGs (MBOAT2, SLC25A21, and SOX6) between the EAE and the EAE + NAD+ groups showed that SOX6 was significantly improved after NAD+ treatment compared with the EAE group, and other indicators were improved but did not reach statistical significance. NAD+ exhibited clinical scores in EAE mice, and key inflammation was ameliorated in EAE mice spleen after NAD+ intervention, while transcriptome analysis between EAE and EAE + NAD+ groups showed several DEGs in the underlying mechanism. CONCLUSION: NAD+ on DEGs attenuates disease severity in EAE. Transcriptome analysis on nerve tissue reveals several protein targets in the underlying mechanisms. However, NAD+ does not significantly improve DEGs in the splenocytes of the EAE model.

MBOAT2, SLC25A21, and SOX6 show significant fold change in EAE mice, while SOX6 shows significantly lower expression in the EAE group and the EAE + NAD⁺ group compared with the Ctrl.NAD⁺ in the EAE model provides its protective role in inflammation and demyelination.NAD⁺ exhibits clinical scores in EAE mice.NAD⁺ does not significantly improve DEGs in splenocytes of the EAE.

LncRNA SLC25A21-AS1 increases the chemosensitivity and inhibits the progression of ovarian cancer by upregulating the expression of KCNK4.

Owing to high mortality rate, ovarian cancer seriously threatens women's health. Extensive abdominal metastasis and chemoresistance are the leading causes of ovarian cancer deaths. Through lncRNA sequencing, our previous study identified lncRNA SLC25A21-AS1, which was significantly downregulated in chemoresistant ovarian cancer cells. In this study, we aimed to evaluate the role and mechanism of SLC25A21-AS1 in ovarian cancer. The expression of SLC25A21-AS1 was analyzed by qRT-PCR and online database GEPIA. The biological functions of SLC25A21-AS1 and KCNK4 were analyzed by CCK-8, transwell, and flow cytometry. The specific mechanism was analyzed by RNA-sequencing, RNA binding protein immunoprecipitation, rescue experiments, and bioinformatic analysis. SLC25A21-AS1 was decreased in ovarian cancer tissues and cell lines. Overexpression of SLC25A21-AS1 enhanced the sensitivity of ovarian cancer cells to paclitaxel and cisplatin, and inhibited cell proliferation, invasion, and migration, while SLC25A21-AS1-silencing showed the opposite effect. Potassium channel subfamily K member 4 (KCNK4) was significantly up-regulated upon enforced expression of SLC25A21-AS1. Overexpression of KCNK4 inhibited cell proliferation, invasion, migration ability, and enhanced the sensitivity of ovarian cancer cells to paclitaxel and cisplatin. Meanwhile, KNCK4-overexpression rescued the promotive effect of SLC25A21-AS1-silencing on cell proliferation, invasion and migration. In addition, SLC25A21-AS1 could interact with the transcription factor Enhancer of Zeste Homolog 2 (EZH2), while EZH2 knockdown increased the expression of KCNK4 in some of the ovarian cancer cell lines. SLC25A21-AS1 enhanced the chemosensitivity and inhibited the proliferation, migration, and invasion ability of ovarian cancer cells at least partially by blocking EZH2-mediated silencing of KCNK4.

Long non-coding RNA SLC25A21-AS1 inhibits the development of epithelial ovarian cancer by specifically inducing PTBP3 degradation.

BACKGROUND: Epithelial ovarian cancer (EOC) is a highly prevalent disease that rapidly metastasizes and has poor prognosis. Most women are in the middle or late stages when diagnosed and have low survival rates. Recently, long non-coding RNAs (lncRNAs) were recognized to play pivotal roles in the development of EOC. METHODS: The expression of SLC25A21 antisense RNA 1 (SLC25A21-AS1) and Polypyrimidine Tract Binding Protein 3 (PTBP3) in EOC cells was assessed via qPCR. The proliferation activity of these cells was detected by EdU and Cell counting kit-8 (CCK8) assays, while the death rate of apoptotic cells and the cell cycle were detected by flow cytometry. Detection of cell transfer rate by transwell assay. Protein expression was measured through western blotting. Interactions between SLC25A21-AS1 and PTBP3 were detected through RNA immunoprecipitation (RIP), IF-FISH co-localization experiments and electrophoretic mobility shift assay (EMSA). The in vivo importance of SLC25A21-AS1 as a tumor suppressor modulator was assessed using murine xenograft models. RESULTS: The lncRNA SLC25A21-AS1 has negligible expression in ovarian cancer tissues compared with that in normal ovarian tissues. A series of functional experiments revealed that the upregulation of SLC25A21-AS1 markedly blocked the proliferation and metastasis of EOC cells in vitro, while its downregulation had the opposite effect. Overexpression of SLC25A21-AS1 in a nude mouse model of EOC in vivo resulted in slower tumor growth and weakened metastatic potential. Moreover, SLC25A21-AS1 reduced the protein stability of PTBP3 and promoted its degradation. A series of subsequent experiments found that SLC25A21-AS1 inhibits EOC cell proliferation and metastasis by modulating PTBP3 through the ubiquitin-proteasome pathway and that the combination of SLC25A21-AS1 and PTBP3 provides the necessary conditions for the for the function to be realized. CONCLUSIONS: Our research reveals the effect of SLC25A21-AS1 in EOC development and suggests SLC25A21-AS1 can serve as a prognostic target by promoting the degradation of PTBP3 to improve patient survival.

Low expression of the metabolism-related gene SLC25A21 predicts unfavourable prognosis in patients with acute myeloid leukaemia.

Acute myeloid leukaemia (AML) is a heterogeneous disease associated with poor outcomes. To identify AML-specific genes with prognostic value, we analysed transcriptome and clinical information from The Cancer Genome Atlas (TCGA) database, Gene Expression Omnibus (GEO) datasets, and Genotype-Tissue Expression (GTEx) project. The metabolism-related gene, SLC25A21 was found to be significantly downregulated in AML, and was associated with high white blood cell (WBC) counts, high pretrial blood (PB) and bone marrow (BM) blast abundance, FLT3 mutation, NPM1 mutation, and death events (all p value <0.05). We validated the expression of SLC25A21 in our clinical cohort, and found that SLC25A21 was downregulated in AML. Moreover, we identified low expression of SLC25A21 as an independent prognostic factor by univariate Cox regression (hazard ratio [HR]: 0.550; 95% Confidence interval [CI]: 0.358-0.845; p value = 0.006) and multivariate Cox regression analysis (HR: 0.341; 95% CI: 0.209-0.557; p value <0.05). A survival prediction nomogram was established with a C-index of 0.735, which indicated reliable prognostic prediction. Subsequently, based on the median SLC25A21 expression level, patients in the TCGA-LAML cohort were divided into low- and high-expression groups. Gene ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses of DEGs highlighted growth factor binding, extracellular structure organization, cytokine‒cytokine receptor interaction, etc. The results of gene set enrichment analysis (GSEA) indicated that the epithelial-mesenchymal transition, KRAS signalling, oxidative phosphorylation, and reactive oxygen species pathways were enriched. Through gene coexpression and protein‒protein interaction (PPI) network analysis, we identified two hub genes, EGFR and COL1A2, which were linked to worse clinical outcomes. Furthermore, we found that lower SLC25A21 expression was closely associated with a significant reduction in the levels of infiltrating immune cells, which might be associated with immune escape of AML cells. A similar trend was observed for the expression of checkpoint genes (CTLA4, LAG3, TIGIT, and HAVCR2). Finally, drug sensitivity testing suggested that the low-expression SLC25A21 group is sensitive to doxorubicin, mitomycin C, linifanib but resistant to JQ1, belinostat, and dasatinib. Hence, our study demonstrated that a low expression level of SLC25A21 predicts an unfavourable prognosis in patients with AML.

Imaging Intron Evolution.

Intron evolution may be readily imaged through the combined use of the "dot plot" function of the NCBI BLAST, aligning two sequences at a time, and the Vertebrate "Multiz" alignment and conservation tool of the UCSC Genome Browser. With the NCBI BLAST, an ideal alignment of two highly conserved sequences generates a diagonal straight line in the plot from the lower left corner to the upper right corner. Gaps in this line correspond to non-conserved sections. In addition, the dot plot of the alignment of a sequence with the same sequence after the removal of the Transposable Elements (TEs) can be observed along the diagonal gaps that correspond to the sites of TE insertion. The UCSC Genome Browser can graph, along the entire sequence of a single gene, the level of overall conservation in vertebrates. This level can be compared with the conservation level of the gene in one or more selected vertebrate species. As an example, we show the graphic analysis of the intron conservation in two genes: the mitochondrial solute carrier 21 (SLC25A21) and the growth hormone receptor (GHR), whose coding sequences are conserved through vertebrates, while their introns show dramatic changes in nucleotide composition and even length. In the SLC25A21, a few short but significant nucleotide sequences are conserved in zebrafish, Xenopus and humans, and the rate of conservation steadily increases from chicken/human to mouse/human alignments. In the GHR, a less conserved gene, the earlier indication of intron conservation is a small signal in chicken/human alignment. The UCSC tool may simultaneously display the conservation level of a gene in different vertebrates, with reference to the level of overall conservation in Vertebrates. It is shown that, at least in SLC25A21, the sites of higher conservation are not always coincident in chicken and zebrafish nor are the sites of higher vertebrate conservation.

Gliomas with Downregulation of lncRNA SLC25A21-AS1 Carry a Dismal Prognosis and an Accelerated Progression in Cell Proliferation, Migration and Invasion.

Glioma is one type of primary intracranial carcinoma with a relatively poor prognosis. We investigated the level of SLC25A21-AS1 in gliomas and the association with survival and progression in patients with glioma. Specimens of gliomas from patients were assessed by quantitative real-time polymerase chain reaction analysis of the SLC25A21-AS1 level (117 specimens). For prognostic value assessment, χ2 test, Kaplan-Meier method with the log-rank test, and Multivariate survival analysis were performed. The direct targets for SLC25A21-AS1 were explored. The biological roles of SLC25A21-AS1 were investigated by manipulating the expression level of SLC25A21-AS1 in glioma cells. SLC25A21-AS1 was significantly downregulated in glioma specimens and cell lines compared to non-cancerous ones. Significant associations were found between SLC25A21-AS1 downregulation and WHO stage, IDH status, poor disease-free survival/overall survival. miR-221-3p/miR-222-3p were the target miRNAs for SLC25A21-AS1. Overexpression of SLC25A21-AS1 inhibited glioma cell growth, invasion, and migration while miR-221-3p/miR-222-3p-overexpressed groups could offset this effect. Downregulation of SLC25A21-AS1 in gliomas carries a universally poor prognosis. Overexpression of SLC25A21-AS1 inhibited glioma progression via miR-221-3p/miR-222-3p.

SLC25A21 Suppresses Cell Growth in Bladder Cancer via an Oxidative Stress-Mediated Mechanism.

BACKGROUND: Bladder cancer (BCa) is a commonly diagnosed malignancy worldwide that has poor survival depending on its intrinsic biologic aggressiveness and a peculiar radio- and chemoresistance features. Gaining a better understanding of tumorigenesis and developing new diagnosis and treatment strategies for BCa is important for improving BCa clinical outcome. SLC25 family member 21 (SLC25A21), a carrier transporting C5-C7 oxodicarboxylates, has been reported to contribute to oxoadipate acidemia. However, the potential role of SLC25A21 in cancer remains absolutely unknown. METHODS: The expression levels of SLC25A21 in BCa and normal tissues were examined by real-time PCR and immunohistochemistry. Gain-of- and loss-of-function experiments were performed to detect the biological functions of SLC25A21 in vitro and in vivo by CCK-8 assay, plate colony formation assay, cell migration, invasion assay and experimental animal models. The subcellular distribution of substrate mediated by SLC25A21, mitochondrial membrane potential and ROS production were assessed to explore the potential mechanism of SLC25A21 in BCa. RESULTS: We found that the expression of SLC25A21 was downregulated in BCa tissues compared to normal tissues. A significant positive correlation between decreased SLC25A21 expression and poor prognosis was observed in BCa patients. Overexpression of SLC25A21 significantly inhibited cell proliferation, migration and invasion and induced apoptosis in vitro. Moreover, the enhanced SLC25A21 expression significantly suppressed tumor growth in a xenograft mouse model. Furthermore, we revealed that SLC25A21 suppressed BCa growth by inducing the efflux of mitochondrial α-KG to the cytosol, decreasing to against oxidative stress, and activating the ROS-mediated mitochondrion-dependent apoptosis pathway. CONCLUSIONS: Our findings provide the first link between SLC25A21 expression and BCa and demonstrate that SLC25A21 acts as a crucial suppressor in BCa progression, which may help to provide new targets for BCa intervention.

Long Non-Coding RNA SLC25A21-AS1 Promotes Multidrug Resistance in Nasopharyngeal Carcinoma by Regulating miR-324-3p/IL-6 Axis.

BACKGROUND: Nasopharyngeal carcinoma (NPC), one of the most common types of head and neck tumor, occurred in the epithelial lining of the nasopharynx and is mainly prevalent in Southeast Asia and Southern China. However, the molecular mechanisms of NPC multidrug resistance still remained largely unclear. METHODS: The qRT-PCR assay was performed to examine SLC25A21-AS1, miR-324-3p and IL-6 expression in NPC tissues and cell. The CCK8 assay and colony formation assay were used to detect cell growth. In addition, CCK8 assay was performed to detect IC50 values of different drugs in NPC cell. RESULTS: In this study, we found that SLC25A21-AS1 expression was increased in NPC tissues and cell line, and knockdown of SLC25A21-AS1 inhibited cell growth and MDR in NPC cell. Moreover, SLC25A21-AS1 acted as a ceRNA for miR-324-3p and facilitates NPC cell growth and MDR by regulating the miR-324-3p/IL-6 axis. CONCLUSION: Our findings demonstrated the role of SLC25A21-AS1/miR-324-3p/IL-6 axis in cell growth and MDR in NPC, which might be a potential prognostic and diagnostic marker in NPC patients and provide new insight into the molecular mechanism of MDR in NPC chemotherapy.

Identification of a Novel 14q13.3 Deletion Involving the SLC25A21 Gene Associated with Familial Synpolydactyly.

Synpolydactyly is a relatively rare malformation. Recently, we came across a male infant with a familial synpolydactyly of the hands and feet. As most familial synpolydactyly syndromes have not been linked to any specific mutations, we felt further investigation was warranted. Using microarray and fluorescent in situ hybridization analysis, we identified a novel mutation of the SLC25A21 gene on chromosome 14.