Mitochondrial poly(ADP-ribosylation): from old data to new perspectives.

Poly(ADP-ribosylation) is involved in DNA repair and replication, transcription, and cell death. For a long time, only one poly(ADP-ribosylating) enzyme was known, named ADPRT/PARP (EC 2.4.2.30). The recent discovery of a family of PARPs has provided a high degree of complexity in the field. Moreover, the finding that poly(ADP-ribosylation) is not confined to the nucleus but is also carried out by cytoplasmic enzymes supports the idea that it could regulate proteins localized in different cellular compartments. In this respect, a reappraisal of the literature on mitochondrial poly(ADP-ribosylation) could be useful, as well as a discussion of its relevance regarding the current "hot" view of poly(ADP-ribosylation) as a mediator of cell death.