Figure 1.

Potential roles of mitochondria in regulating miRNA activities.

The interaction of mitochondria and miRNAs may potentially extend beyond their respective functions. MiRNAs may translocate into mitochondria in order to modulate mitochondrial gene expression either by suppressing (A) or up-regulating (B) genes that are key components of mitochondrial function. In this scenario, miR-181c has been shown to inhibit COX1 expression (A), while miR-1 has been shown to increase (B) COX1 expression (see text for details). Emerging evidence also suggests that mitochondria may participate in regulating miRNA activities by serving as a storage warehouse in which miRNA or miRNA complexes may be recruited and released as needed (C), or as a vehicle to deliver miRNA and its complex to locations throughout cytoplasm (D), or as a network for distributing and exchanging miRNA and their components with other organelles and cytoplasmic foci (E). In this regard, mitochondria-associated miRNAs can utilize the existing network of mitochondrial interaction with other organelles and cellular components, as well as the sensitivity of mitochondria to make appropriate responses in gene expression based on signaling events occurring within the cellular environment. COX1: Cytochrome c oxidase subunit 1; ER: endoplasmic reticulum; ND1: NADH-ubiquinone oxidoreductase chain 1.