Adenosine-to-inosine (A-to-I) RNA editing is an important posttranscriptional event in eukaryotes; however, many features remain largely unexplored in prokaryotes. This study focuses on a serine-to-proline recoding event (S128P) that originated in the mRNA of fliC , which encodes a flagellar filament protein; the editing event was observed in RNA-seq samples exposed to oxidative stress. Using Sanger sequencing, we show that the S128P editing event is induced by H 2 O 2 . To investigate the in vivo interaction between RNAs and TadA, which is the principal enzyme for A-to-I editing, genome-wide RNA immunoprecipitation–coupled high-throughput sequencing (iRIP-Seq) analysis was performed using HA-tagged TadA from Xanthomonas oryzae pv. oryzicola . We found that TadA can bind to the mRNA of fliC and the binding motif is identical to that previously reported by Bar-Yaacov and colleagues. This editing event increased motility and enhanced tolerance to oxidative stress due to changes in flagellar filament structure, which was modelled in 3D and measured by TEM. The change in filament structure due to the S128P mutant increased biofilm formation, which was measured by the 3D laser scanning confocal microscopy. RNA-seq revealed that a gene cluster that contributes to siderophore biosynthesis and Fe 3+ uptake was upregulated in S128P compared with WT. Based on intracellular levels of reactive oxygen species and an oxidative stress survival assay, we found that this gene cluster can contribute to the reduction of the Fenton reaction and increases biofilm formation and bacterial virulence. This oxidative stress response was also confirmed in Pseudomonas putida . Overall, our work demonstrates that A-to-I RNA editing plays a role in bacterial pathogenicity and adaptation to oxidative stress.
Colorectal cancer (CRC) is the third most common cancer type and the fourth leading cause of cancer‑associated mortality worldwide. MicroRNA (miR)‑1246 is involved in differentiation, invasion, metastasis and chemoresistance of certain types of tumor cells. CCNG2 encodes an unconventional cyclin homolog, cyclin G2 (CycG2), associated with growth inhibition, which correlated significantly with lymph node metastasis, clinical stage, histological grade and poor overall survival in numerous cancer types. To investigate the regulation of miR‑1246 on CycG2 expression, and their effects on proliferation and metastasis of CRC, HCT‑116 and LOVO cells were transfected with pre‑miR‑1246 anti‑miR‑1246 and their negative controls. It was demonstrated that the expression of miR‑1246 was significantly increased in CRC tissues and cell lines, which was the opposite of CycG2. miR‑1246 negatively regulated the expression of CycG2 in HCT‑116 and LOVO CRC cells. CCNG2 is a direct target of miR‑1246 in CRC cells. Overexpression of miR‑1246 induced cell proliferation, migration and invasion, while knockdown of miR‑1246 inhibited proliferation, migration and invasion in the CRC cells. Upregulation of miR‑1246 mediated the malignant progression of CRC and is partly attributed to the downregulation of the expression of CycG2. Consequently, these findings provided a molecular basis for the role of miR‑1246/CCNG2 in the progression of human CRC and suggested a novel target for the treatment of CRC.
Hepatic annexin A2 (ANXA2) orchestrates multiple biologic processes and clinical symptoms and plays a key role in development, metastasis, and drug resistance of lethal hepatocellular carcinoma (HCC). However, the prognostic significance of ANXA2 for HCC has not been elucidated up to now. In this study, ANXA2 was frequently found to be up-regulated in HCC tissues compared with benign liver disease (BLD) tissues, which was consistent with the results in serum samples and tissue specimens of patients with HCC. Furthermore, ANXA2 expression was significantly correlated with differentiated degree, intrahepatic metastasis, portal vein thrombus, and tumor node metastasis (TNM) staging. More importantly, increased ANXA2 level was first confirmed to be closely associated with shortened overall survival of HCC (χ (2) = 12.872, P = 0.005) and identified as an independent prognostic factor (hazard ratio 1.338, 95 % confidence interval (CI) 1.013 ~ 1.766, P = 0.040), suggesting that ANXA2 up-regulation might represent an acquired metastasis phenotype of HCC, help to screen out high-risk population for HCC, or more effectively treat a subset of postsurgical HCC patients positive for ANXA2.
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