Nuclear bodies (also known as nuclear domains, or nuclear dots) are membraneless structures found in the cell nucleiofeukaryotic cells.[1] Nuclear bodies include Cajal bodies, the nucleolus, and promyelocytic leukemia protein (PML) nuclear bodies (also called PML oncogenic dots).[2] Nuclear bodies also include ND10s. ND stands for nuclear domain, and 10 refers to the number of dots seen.[3]
Nuclear bodies were first seen as prominent interchromatin structures in the nuclei of malignant or hyperstimulated animal cells[4][5] identified using anti-sp100 autoantibodies from primary biliary cirrhosis and subsequently the promyelocytic leukemia (PML) factor, but appear also to be elevated in many autoimmune and cancerous diseases.[6] Nuclear dots are metabolically stable and resistant to nuclease digestion and salt extraction.[7]
A nuclear body subtype is a clastosome suggested to be a site of protein degradation.[8]
Simple nuclear bodies (types I and II) and the shells of complex nuclear bodies (types III, IVa and V) consist of a non-chromatinic fibrillar material which is most likely proteinaceous.[9] 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.[9] The primary components of the nuclear dots are the proteins sp100 nuclear antigen, LYSP100(a homolog of sp100),[10] ISG20,[11] PML antigen, NDP55 and 53kDa protein associated with the nuclear matrix.[12] Other proteins, such as PIC1/SUMO-1, which are associated with nuclear pore complex also associate with nuclear dots.[13] The proteins can reorganize in the nucleus, by increasing number of dispersion in response to different stress (stimulation or heat shock, respectively).[14]
One of the nuclear body proteins appears to be involved in transcriptional active regions.[15] 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,[5] and specifically inhibits the infection of vesicular stomatitis virus (VSV) (a rhabdovirus) and influenza A virus,[16] 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.[17] whereas overexpression of PML results in programmed cell death.[18]
One hypothesized function of the dots is as a 'nuclear dump' or 'storage depot'. [19] The nuclear bodies may not all perform the same function. Sp140 associates with certain bodies and appears to be involved in transcriptional activation.[20]
ND10 nuclear bodies have been shown to play a major role in chromatin regulation.[21]
These, or similar, bodies have been found increased in the presence of lymphoid cancers[22][23] and SLE (lupus).[24] 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.[25]
{{cite book}}
: |journal=
ignored (help)