RESUMO
Colon cancer cells rely on mitochondrial respiration as major source of energy for supporting their proliferation and invasion, thus promoting colon cancer malignancy and progression. In this study, we comprehensively investigated the prognostic significance of mitochondria-related genes in colon cancer and identified the hub genes that control colon cancer cell mitochondrial respiration and proliferation. We first systematically evaluated the prognostic significance of differentially expressed mitochondria-related genes in colon cancer specimens. Furthermore, a protein-protein interaction network was constructed to explore the hub genes. Eventually, five hub genes were identified, namely, POLG, FASTK, MRPS5, AARS2, and VARS2. Functional analyses showed that all these five hub genes are essential for maintaining mitochondrial respiration and proliferation of colon cancer cells. Mechanistic studies revealed the roles of these five hub genes in modulating mitochondrial DNA expression, that in turn influence mitochondrial respiration. In summary, our study demonstrated that POLG, FASTK, MRPS5, AARS2, and VARS2 may potentially serve as prognostic biomarkers and therapeutic targets for colon cancer.
Assuntos
Neoplasias do Colo , Proliferação de Células/genética , Neoplasias do Colo/genética , Neoplasias do Colo/patologia , Antígenos HLA , Humanos , Mitocôndrias/metabolismo , Proteínas Serina-Treonina Quinases , Respiração , Valina-tRNA Ligase/metabolismoRESUMO
Mitochondrial transcription termination factor 4, MTERF4, a member of the MTERF family, has been implicated in the regulation of mitochondrial translation by targeting NSUN4 to the large mitochondrial ribosome. Here, we found a novel role for MTERF4 in regulating mitochondrial dysfunction induced by MPP(+). We observed that knockdown of MTERF4 in SH-SY5Y cells resulted in increased mitochondrial DNA transcription levels and decreased mitochondrial DNA translation levels. In addition, after treatment with 2 mM MPP(+) for 24 h, the expression levels of MTERF4 were decreased compared to wide-type SH-SY5Y cells. Moreover, after exposure to 2 mM MPP(+) for 24 h, knockdown of MTERF4 in SH-SY5Y cells worsened the mitochondrial dysfunction induced by MPP(+), including increased reactive oxygen species, accumulated cleaved PARP-1, decreased mitochondrial membrane potential and depressed mitochondrial complexes. Furthermore, overexpression of MTERF4 in SH-SY5Y cells partially alleviated the mitochondrial dysfunction induced by MPP(+). Based on these findings, we suggest that the main function of MTERF4 is regulating mtDNA expression, and it is the crucial factor in the mechanism of mitochondrial dysfunction in SH-SY5Y cells induced by MPP(+). MTERF4 probably is the triggering of the pathogenesis of Parkinson's disease induced by environmental toxin.
Assuntos
1-Metil-4-fenilpiridínio/toxicidade , DNA Mitocondrial/antagonistas & inibidores , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Fatores de Transcrição/metabolismo , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Sobrevivência Celular , DNA Mitocondrial/biossíntese , Regulação da Expressão Gênica , Células HEK293 , Humanos , Metiltransferases/genética , Metiltransferases/metabolismo , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Neurônios/metabolismo , Neurônios/patologia , Poli(ADP-Ribose) Polimerase-1 , Poli(ADP-Ribose) Polimerases/genética , Poli(ADP-Ribose) Polimerases/metabolismo , Biossíntese de Proteínas , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Transdução de Sinais , Fatores de Transcrição/antagonistas & inibidores , Fatores de Transcrição/genética , Transcrição GênicaRESUMO
Objective To explore the changes of expression levels of 12S rRNA and cytochrome oxidase subunit Ⅰ (COXⅠ) mRNA encoded by mtDNA in rat cerebral cortex after rat exposure to hypobaric hypoxia for different days. Methods Healthy male Wistar rats were exposed to hypobaric chamber simulating 5 000 m above sea level (23 5 h/day) for 2, 5, 15 and 30 d. Rats in the control group were not exposed to hypoxia. Rats were sacrificed by decapitation. Total RNA in cerebral cortex was extracted using a standard program. Transcriptional levels of 12S rRNA and COXⅠ mRNA were determined by reverse transcription polymerase chain reaction (RT PCR). Results Compared with that in the control, the expression of 12S rRNA increased by 57% after hypoxic exposure for 2 d ( P 0 05). Compared with that in the control group, the expression of COXⅠ mRNA increased significantly by 55% and 106% after hypoxic exposure for 2 and 5 d ( P 0 05). Conclusion Hypoxic exposure may have effect on both protein gene and ribosome gene expression encoded by mtDNA, and the expression changes in a hypoxic exposure time dependent manner. This suggests that hypoxia can have effect on mitochondrial oxidative phosphorylation gene expression at both mitochondrial transcriptional and translational levels.
