The involvement of Importin-β and peroxiredoxin-6005 in mitochondrial biogenesis.

Importin-β is encoded by the Ketel gene in Drosophila. Upon running out of the maternal Importin-β dowry larvae without the Ketel gene slow down and before dying possess symptoms characteristic for mitochondrial cytopathies. Death of the larvae is almost certainly the consequence of ceasing import of proteins, including some of the transcription factors, into the nuclei. We report here that the ensuing altered gene expression pattern leads to cessation of mitochondrial biogenesis. A transcriptome comparison between larvae with and without Ketel gene revealed altered expression level for 30 genes that are all nuclear. The seven downregulated genes have C/EBP transcription factor binding site in their promoter. RNAi silencing the function of peroxiredoxin-6005, one of the 23 upregulated genes, leads to excessive mitochondrial biogenesis, free radical production and death of the larvae. It appears that peroxiredoxin-6005 is engaged in mitochondrial biogenesis possibly as a component of redox-signaling.