Translational regulation of mitochondrial biogenesis.

Mitochondria are generated by the expression of genes on both nuclear and mitochondrial genome. Mitochondrial biogenesis is highly plastic in response to cellular energy demand, developmental signals and environmental stimuli. Mechanistic target of rapamycin (mTOR) pathway regulates mitochondrial biogenesis to co-ordinate energy homeostasis with cell growth. The local translation of mitochondrial proteins on the outer membrane facilitates their efficient import and thereby allows prodigious mitochondrial biogenesis during rapid cell growth and proliferation. We postulate that the local translation may also allow cells to promote mitochondrial biogenesis selectively based on the fitness of individual organelle. MDI-Larp complex promotes the biogenesis of healthy mitochondria and thereby is essential for the selective transmission of healthy mitochondria. On the other hand, PTEN-induced putative kinase 1 (PINK1)-Pakin activates protein synthesis on damaged mitochondria to maintain the organelle homeostasis and activity. We also summarize some recent progress on miRNAs' regulation on mitochondrial biogenesis.