Beyond ATP, new roles of mitochondria

Mitochondria, special double-membraned intracellular compartments or 'organelles', are popularly known as the 'powerhouses of the cell', as they generate the bulk of ATP used to fuel cellular biochemical reactions. Mitochondria are also well known for generating metabolites for the synthesis of macromolecules (e.g., carbohydrates, proteins, lipids and nucleic acids). In the mid-1990s, new evidence suggesting that mitochondria, beyond their canonical roles in bioenergetics and biosynthesis, can act as signalling organelles began to emerge, bringing a dramatic shift in our view of mitochondria's roles in controlling cell function. Over the next two and half decades, works from multiple groups have demonstrated how mitochondrial signalling can dictate diverse physiological and pathophysiological outcomes. In this article, we will briefly discuss different mechanisms by which mitochondria can communicate with cytosol and other organelles to regulate cell fate and function and exert paracrine effects. Our molecular understanding of mitochondrial communication with the rest of the cell, i.e. mitochondrial signalling, could reveal new therapeutic strategies to improve health and ameliorate diseases.