2002/08/01 by Miguel Lafarga, Marı́a T. Berciano, Emma Pena +6 · 3 citations
Biochemistry, Genetics and Molecular Biology · #Ubiquitin and proteasome pathways #Genetics and Neurodevelopmental Disorders #RNA modifications and cancer
paper · doi:10.1091/mbc.e02-03-0122
openalex publication_date 2002/08/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/22
Nuclear bodies represent a heterogeneous class of nuclear structures. Herein, we describe that a subset of nuclear bodies is highly enriched in components of the ubiquitin-proteasome pathway of proteolysis. We coined the term clastosome (from the Greek klastos, broken and soma, body) to refer to this type of nuclear body. Clastosomes contain a high concentration of 1) ubiquitin conjugates, 2) the proteolytically active 20S core and the 19S regulatory complexes of the 26S proteasome, and 3) protein substrates of the proteasome. Although detected in a variety of cell types, clastosomes are scarce under normal conditions; however, they become more abundant when proteasomal activity is stimulated. In contrast, clastosomes disappear when cells are treated with proteasome inhibitors. Protein substrates of the proteasome that are found concentrated in clastosomes include the short-lived transcription factors c-Fos and c-Jun, adenovirus E1A proteins, and the PML protein. We propose that clastosomes are sites where proteolysis of a variety of protein substrates is taking place.