Nuclear dots: actors on many stages.

Nuclear dots (NDs), alternatively designated nuclear bodies (NBs), PML oncogenic domains (PODs), nuclear domain 10 (ND10) or Kr-bodies, became a major topic for researchers in many fields only recently. Originally described as an autoantigenic target in patients with primary biliary cirrhosis, they are now also known to play a role in development of acute promyelocytic leukemia (APL) and possibly other forms of neoplasia. Size, number and composition of NDs are regulated throughout the cell cycle. Infection with herpes simplex virus, adenovirus, cytomegalovirus, Epstein-Barr-virus, influenza virus and human T cell lymphotropic virus type I (HTLV I) strongly modifies ND structure through viral regulatory proteins. Due to this finding and because at least three of the cellular ND proteins are highly interferon-inducible, a function of NDs in early viral infection or in antiviral response has been postulated. Functional data are currently available only for two of the ND-associated proteins. The Sp100 protein seems to have transcriptional transactivating property, whereas the promyelocytic leukemia protein (PML) was reported to suppress growth and transformation. Here, we give a brief overview of the data currently available on NDs. Thus, we hope to link seemingly unrelated findings in the literature on oncology, virology, cell biology and immunology.