Inositol pyrophosphates: metabolism and signaling

Inositol pyrophosphates belong to the diverse family of inositol polyphosphate species that have a range of signaling functions. Since the discovery of inositol pyrophosphates in the early 1990s, enormous progress has been achieved in characterising this class of molecules, linking their biological presence to a wide range of cellular functions, including vesicular trafficking, apoptosis, telomere maintenance and protein phosphorylation. The activity of inositol pyrophosphates appears to be related to their rapid turnover in cells and also to their pyrophosphate groups, which are considered to contain high-energy bonds. Together, these observations suggest that inositol pyrophosphates may represent a class of cellular messengers with basic and not yet fully characterised functions. This review aims at summarising the recent progress of our knowledge of this exciting class of molecules, from inositol pyrophosphate discovery to the description of their physiological functions.