Analysis of disulfidptosis- and cuproptosis-related LncRNAs in modulating the immune microenvironment and chemosensitivity in colon adenocarcinoma.

The main objective was to establish a prognostic model utilising long non-coding RNAs associated with disulfidptosis and cuproptosis. The data for RNA-Sequence and clinicopathological information of Colon adenocarcinoma (COAD) were acquired from The Cancer Genome Atlas. A prognostic model was constructed using Cox regression and the Least Absolute Shrinkage and Selection Operator method. The model's predictive ability was assessed through principal component analysis, Kaplan-Meier analysis, nomogram etc. The ability of identifying the rates of overall survival, infiltration of immune cells, and chemosensitivity was also explored. In vitro experiments were conducted for the validation of differential expression and function of lncRNAs. A disulfidptosis and cuproptosis-related lncRNA prognostic model was constructed. The prognostic model exhibits excellent independent predictive capability for patient outcomes. Based on the authors' model, the high-risk group exhibited higher tumour mutation burdened worse survival. Besides, differences in immune cell infiltration and responsiveness to chemotherapeutic medications exist among patients with different risk scores. Furthermore, aberrant expressions in certain lncRNAs have been validated in HCT116 cells. In particular, FENDRR and SNHG7 could affect the proliferation and migration of colorectal cancer cells. Our study developed a novel prognostic signature, providing valuable insights into prognosis, immune infiltration, and chemosensitivity in COAD patients.

High glucose and palmitic acid induces neuronal senescence by NRSF/REST elevation and the subsequent mTOR-related autophagy suppression.

Cell senescence is a basic aging mechanism. Previous studies have found that the cellular senescence in adipose tissue and other tissues, such as the pancreas, muscle and liver, is associated with the pathogenesis and progression of type 2 diabetes; however, strong evidence of whether diabetes directly causes neuronal senescence in the brain is still lacking. In this study, we constructed a high glucose and palmitic acid (HGP) environment on PC12 neuronal cells and primary mouse cortical neurons to simulate diabetes. Our results showed that after HGP exposure, neurons exhibited obvious senescence-like phenotypes, including increased NRSF/REST level, mTOR activation and cell autophagy suppression. Downregulation of NRSF/REST could remarkably alleviate p16, p21 and γH2A.X upregulations induced by HGP treatment, and enhance mTOR-autophagy of neurons. Our results suggested that the diabetic condition could directly induce neuronal senescence, which is mediated by the upregulation of NRSF/REST and subsequent reduction of mTOR-autophagy.

Transcription-replication collision increases recombination efficiency between plasmids.

It has been proposed that the stalling of the replication forks can induce homologous recombination in several organisms, and that arrested replication forks may offer nuclease targets, thereby providing a substrate for proteins involved in double-strand repair. In this article, we constructed a plasmid with the potential for transcription-replication collision (TRC), in which DNA replication and RNA transcription occur on the same DNA template simultaneously. Theoretically, transcription will impede DNA replication and increase homologous recombination. To validate this hypothesis, another plasmid was constructed that contained a homologous sequence with the exception of some mutated sites. Co-transfection of these two plasmids into 293T cells resulted in increased recombination frequency. The ratio of these two plasmids also affected the recombination frequency. Moreover, we found high expression levels of RAD51, which indicated that the increase in the recombination rate was probably via the homologous recombination pathway. These results indicate that mutant genes in plasmids can be repaired by TRC-induced recombination.

NF-E2: a novel regulator of alpha-hemoglobin stabilizing protein gene expression.

OBJECTIVE: To investigate whether α-hemoglobin stabilizing protein (AHSP), the α-globin-specific molecular chaperone, is regulated by erythroid transcription factor NF-E2. METHODS: We established the stable cell line with NF-E2p45 (the larger subunit of NF-E2) short hairpin RNA to silence its expression. Western blot, real-time polymerase chain reaction, and chromatin immunoprecipitation (ChIP) analysis were performed to detect the expression of AHSP, the histone modifications at AHSP gene locus, and the binding of GATA-1 at the AHSP promoter with NF-E2p45 deficiency. ChIP was also carried out in dimethyl sulfoxide (DMSO)-induced DS19 cells and estrogen-induced G1E-ER4 cells to examine NF-E2 binding to the AHSP gene locus and its changes during cell erythroid differentiation. Finally, luciferase assay was applied in HeLa cells transfected with AHSP promoter fragments to examine AHSP promoter activity in the presence of exogenous NF-E2p45. RESULTS: We found that AHSP expression was highly dependent on NF-E2p45. NF-E2 bound to the regions across AHSP gene locus in vivo, and the transcription of AHSP was transactivated by exogenous NF-E2p45. In addition, we observed the decrease of H3K4 trimethylation and GATA-1 occupancy at the AHSP gene locus in NF-E2p45-deficient cells. Restoration of GATA-1 in G1E-ER4 cells in turn led to increased DNA binding of NF-E2p45. CONCLUSION: NF-E2 may play an important role in AHSP gene regulation, providing new insights into the molecular mechanisms underlying the erythroid-specific expression of AHSP as well as new possibilities for ß-thalassemia treatment.

Epigenetic repression of SATB1 by polycomb group protein EZH2 in epithelial cells.

OBJECTIVE: To study the regulatory mechanism of SATB1 repression in cells other than T cells or erythroid cells, which have high expression level of SATB1. METHODS: HeLa epithelial cells were treated with either histone deacetylase inhibitor (HDACi) trichostatin A (TSA) or DNA methylation inhibitor 5-Aza-C before detecting SATB1 expression. Luciferase reporter system was applied to measure effects of EZH2 on SATB1 promoter activity. Over-expression or knockdown of EZH2 and subsequent quantitative reverse transcription-polymerase chain reaction were performed to determine the effect of this Polycomb group protein on SATB1 transcription. Chromatin immunoprecipitation (ChIP) assay was applied to measure enrichment of EZH2 and trimethylated H3K27 (H3K27me3) at SATB1 promoter in HeLa cells. K562 cells and Jurkat cells, both having high-level expression of SATB1, were used in the ChIP experiment as controls. RESULTS: Both TSA and 5-Aza-C increased SATB1 expression in HeLa cells. Over-expression of EZH2 reduced promoter activity as well as the mRNA level of SATB1, while knockdown of EZH2 apparently enhanced SATB1 expression in HeLa cells but not in K562 cells and Jurkat cells. ChIP assay Results suggested that epigenetic silencing of SATB1 by EZH2 in HeLa cells was mediated by trimethylation modification of H3K27. In contrast, enrichment of EZH2 and H3K27me3 was not detected within proximal promoter region of SATB1 in either K562 or Jurkat cells. CONCLUSION: SATB1 is a bona fide EZH2 target gene in HeLa cells and the repression of SATB1 by EZH2 may be mediated by trimethylation modification on H3K27.