Nuclear bodies


Nuclear bodies nuclear bodies. Nuclear bodies also include ND10s. ND stands for nuclear domain, and 10 refers to the number of dots seen.
Nuclear bodies were first seen as prominent interchromatin structures in the nuclei of malignant or hyperstimulated animal cells identified using anti-sp100 autoantibodies from primary biliary cirrhosis and subsequently the promyelocytic leukemia factor, but appear also to be elevated in many autoimmune and cancerous diseases. Nuclear dots are metabolically stable and resistant to nuclease digestion and salt extraction.
A nuclear body subtype is a clastosome suggested to be a site of protein degradation.

Structure

Simple nuclear bodies and the shells of complex nuclear bodies consist of a non-chromatinic fibrillar material which is most likely proteinaceous. That nuclear bodies co-isolated with the nuclear matrix, and were linked to the fibrogranular nuclear matrix component by projections from the surface of the nuclear bodies. The primary components of the nuclear dots are the proteins sp100 nuclear antigen, LYSP100, ISG20, PML antigen, NDP55 and 53kDa protein associated with the nuclear matrix. Other proteins, such as PIC1/SUMO-1, which are associated with nuclear pore complex also associate with nuclear dots. The proteins can reorganize in the nucleus, by increasing number of dispersion in response to different stress.

Function

One of the nuclear body proteins appears to be involved in transcriptional active regions. Expression of PML antigen and sp100 is responsive to interferons. Sp100 seems to have transcriptional transactivating properties. PML protein was reported to suppress growth and transformation, and specifically inhibits the infection of vesicular stomatitis virus and influenza A virus, but not other types of viruses. The SUMO-1 ubiquitin like protein is responsible for modifying PML protein such that it is targeted to dots. whereas overexpression of PML results in programmed cell death.
One hypothesized function of the dots is as a 'nuclear dump' or 'storage depot'.
The nuclear bodies may not all perform the same function. Sp140 associates with certain bodies and appears to be involved in transcriptional activation.
ND10 nuclear bodies have been shown to play a major role in chromatin regulation.

Pathology

These, or similar, bodies have been found increased in the presence of lymphoid cancers and SLE. They are also observed at higher frequencies in
subacute sclerosing panencephalitis; in this instance, antibodies to measles show expression in and localization to the nuclear bodies.