Editing Cell nucleus (section)

====Clastosomes====

Clastosomes are small nuclear bodies (0.2–0.5&nbsp;μm) described as having a thick ring-shape due to the peripheral capsule around these bodies.<ref name="Lafarga-2002">{{cite journal | vauthors = Lafarga M, Berciano MT, Pena E, Mayo I, Castaño JG, Bohmann D, Rodrigues JP, Tavanez JP, Carmo-Fonseca M | display-authors = 6 | title = Clastosome: a subtype of nuclear body enriched in 19S and 20S proteasomes, ubiquitin, and protein substrates of proteasome | journal = Molecular Biology of the Cell | volume = 13 | issue = 8 | pages = 2771–82 | date = August 2002 | pmid = 12181345 | pmc = 117941 | doi = 10.1091/mbc.e02-03-0122 | citeseerx = 10.1.1.321.6138 | department = Primary }}</ref> This name is derived from the Greek ''klastos'' ([[wikt:κλαστός|κλαστός]]), broken and ''soma'' ([[wikt:σῶμα|σῶμα]]), body.<ref name="Lafarga-2002" /> Clastosomes are not typically present in normal cells, making them hard to detect. They form under high [[Proteolysis|proteolytic]] conditions within the nucleus and degrade once there is a decrease in activity or if cells are treated with [[proteasome inhibitor]]s.<ref name="Lafarga-2002" /><ref>{{cite journal | vauthors = Kong XN, Yan HX, Chen L, Dong LW, Yang W, Liu Q, Yu LX, Huang DD, Liu SQ, Liu H, Wu MC, Wang HY | display-authors = 6 | title = LPS-induced down-regulation of signal regulatory protein {alpha} contributes to innate immune activation in macrophages | journal = The Journal of Experimental Medicine | volume = 204 | issue = 11 | pages = 2719–31 | date = October 2007 | pmid = 17954568 | pmc = 2118489 | doi = 10.1084/jem.20062611 | department = Primary }}</ref> The scarcity of clastosomes in cells indicates that they are not required for [[proteasome]] function.<ref name="Carmo-Fonseca-2010">{{cite journal | vauthors = Carmo-Fonseca M, Berciano MT, Lafarga M | title = Orphan nuclear bodies | journal = Cold Spring Harbor Perspectives in Biology | volume = 2 | issue = 9 | pages = a000703 | date = September 2010 | pmid = 20610547 | pmc = 2926751 | doi = 10.1101/cshperspect.a000703 | department = Review }}</ref> [[Osmotic shock|Osmotic stress]] has also been shown to cause the formation of clastosomes.<ref>{{cite journal | vauthors = Sampuda KM, Riley M, Boyd L | title = Stress induced nuclear granules form in response to accumulation of misfolded proteins in Caenorhabditis elegans | journal = BMC Cell Biology | volume = 18 | issue = 1 | pages = 18 | date = April 2017 | pmid = 28424053 | pmc = 5395811 | doi = 10.1186/s12860-017-0136-x | department = Primary | doi-access = free }}</ref> These nuclear bodies contain catalytic and regulatory subunits of the proteasome and its substrates, indicating that clastosomes are sites for degrading proteins.<ref name="Carmo-Fonseca-2010" />