Nuclear respiratory factor 1 overexpression attenuates anti-benzopyrene-7,8-diol-9,10-epoxide-induced S-phase arrest of bronchial epithelial cells

MED28 Over-Expression Shortens the Cell Cycle and Induces Genomic Instability

The mammalian mediator complex subunit 28 (MED28) is overexpressed in a variety of cancers and it regulates cell migration/invasion and epithelial-mesenchymal transition. However, transcription factors that increase MED28 expression have not yet been identified. In this study, we performed a luciferase reporter assay to identify and characterize the prospective transcription factors, namely E2F transcription factor 1, nuclear respiratory factor 1, E-26 transforming sequence 1, and CCAAT/enhancer-binding protein β, which increased MED28 expression. In addition, the release from the arrest at the G1−S or G2−M phase transition after cell cycle synchronization using thymidine or nocodazole, respectively, showed enhanced MED28 expression at the G1−S transition and mitosis. Furthermore, the overexpression of MED28 significantly decreased the duration of interphase and mitosis. Conversely, a knockdown of MED28 using si-RNA increased the duration of interphase and mitosis. Of note, the overexpression of MED28 significantly increased micronucleus and nuclear budding in HeLa cells. In addition, flow cytometry and fluorescence microscopy analyses showed that the overexpression of MED28 significantly increased aneuploid cells. Taken together, these results suggest that MED28 expression is increased by oncogenic transcription factors and its overexpression disturbs the cell cycle, which results in genomic instability and aneuploidy.

Genome-wide identification and functional analysis of long non-coding RNAs in human endothelial cell line after incubation with PM2.5

Epidemiological studies and experimental research have illustrated that PM2.5 has an association with cardiovascular adverse events. However, the underlying mechanisms are still unknown. Long non-coding RNAs (lncRNAs) have been proposed to take part in diverse diseases. To comprehensively gain insight into the molecular toxicity of PM2.5, expression patterns are analyzed in EA.hy926 cell line through RNAs microarray. A total of 356 lncRNA transcripts are dysregulated in 2.5 μg/cm² group, and there are 1283 lncRNAs differentially expressed in 10 μg/cm² group. From functional analysis, several lncRNAs may be implicated in the bio-pathways of phagosome, TNF signaling pathway, chemokine signaling pathway and gap junction. Moreover, certain lncRNAs participate in the toxicity of PM2.5 through cis- and/or trans-regulation of their co-expressed genes. Therefore, lncRNAs may be used as new candidate biomarkers and potentially preventive targets in cardiotoxicity of PM2.5. Our study indicates that not limited to transcriptional regulation, post-transcriptional regulation plays a pivotal role in PM2.5-caused toxicity.