RESUMO
A study is presented on the regulation of alternative splicing (AS) of the Ndufb11 gene of complex I of the mitochondrial respiratory chain and the impact on this process of rotenone treatment in neuroblastoma cells. In physiological conditions the Ndufb11 gene produces at high level a short transcript isoform encoding for a 153 aa protein. This subunit is essential for the assembly of a functional and stable mammalian complex I. The gene produces also, at low level, a longer transcript isoform encoding for a 163 aa protein whose role is unknown. Evidence is presented here showing that the level of the two isoforms is regulated by three DGGGD ESS elements located in exon 2 which can bind the hnRNPH1 protein. In neuronal cells rotenone treatment affects the Ndufb11 alternative splicing pathway, with the increase of the 163/153 mRNAs ratio. This effect appears to be due to the down-regulation of the hnRNPH1 protein. Since rotenone induces apoptosis in neuronal cells, the post-transcriptional regulation of the Ndufb11 gene can be involved in the programmed cell death process.
Assuntos
Processamento Alternativo/genética , Complexo I de Transporte de Elétrons , Neuroblastoma , Apoptose/efeitos dos fármacos , Apoptose/genética , Linhagem Celular Tumoral , Complexo I de Transporte de Elétrons/genética , Complexo I de Transporte de Elétrons/metabolismo , Éxons , Regulação da Expressão Gênica , Genes Ligados ao Cromossomo X , Células HEK293 , Células HeLa , Humanos , Neuroblastoma/genética , Neuroblastoma/metabolismo , Isoformas de Proteínas/genética , Rotenona/farmacologiaRESUMO
In this study the impact of hUPF1 and hUPF2 knockdown on alternative splicing (AS) isoforms of different genes encoding subunits of respiratory chain complex I and complex IV is described. As expected, loss of both hUPF1 and hUPF2 led to impairment of nonsense-mediated mRNA decay (NMD) and accumulation of PTC-containing NMD substrates generated by both complex I and complex IV genes. The levels of some complex I splice variants, which did not contain PTC as well as the level of some complex I canonical transcripts were, however, affected only by hUPF1 knockdown. This finding confirms that NMD plays a role in the maintenance of the transcriptome integrity and reveals a specific impact of hUPF1 on the regulation of complex I genes.