title: Particle-rich cytoplasmic structure (PaCS): identification, natural history, role in cell biology and pathology.
abstract: Cytoplasmic structures showing a selective concentration of both polyubiquitinated proteins and proteasome have been described in various epithelial, hematopoietic, mesenchymal and neural cells in vitro or in fetal tissues, as well as in chronically-infected, mutated preneoplastic and neoplastic tissues. These cytoplasmic structures differ from other ubiquitin-reactive cytoplasmic bodies, like sequestosomes, aggresome-like-induced structures in dendritic cells (DALIS)/non-dendritic cells (ALIS) and aggresomes in showing distinctive ultrastructural organization (particle-rich cytoplasmic structure or PaCS), a cytochemical pattern and a functional profile. Their formation can be induced in vitro in dendritic or natural killer cells by trophic factors and interleukin treatment. They originate in close connection with ribosomes, while, as a result of their growth, the cytoskeleton and other surrounding organelles are usually dislocated outside their core. Interestingly, these particulate cytoplasmic structures are often found to fill cytoplasmic blebs forming proteasome- and polyubiquitinated protein-discharging vesicles, called ectosomes, which are found to detach from the cell and freely float in the extracellular space. To clearly point out the importance of the polyubiquitinated proteins and proteasome containing cytoplasmic structures, their role in cell biology and pathology has been carefully analyzed.
authors.affiliation: Department of Molecular Medicine, University of Pavia, Pavia 27100, Italy. solciae@smatteo.pv.it.
authors.forename: Enrico
authors.initials: E
authors.lastname: Solcia
authors.affiliation: Department of Molecular Medicine, University of Pavia, Pavia 27100, Italy. patrizia.sommi@unipv.it.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Sommi
authors.affiliation: Department of Molecular Medicine, University of Pavia, Pavia 27100, Italy. vittorio.necchi@unipv.it.
authors.forename: Vittorio
authors.initials: V
authors.lastname: Necchi
authors.affiliation: Department of Molecular Medicine, University of Pavia, Pavia 27100, Italy. agostina.vitali@unipv.it.
authors.forename: Agostina
authors.initials: A
authors.lastname: Vitali
authors.affiliation: Pathologic Anatomy Unit, IRCCS Policlinico San Matteo, Pavia 27100, Italy. rachelemanca@libero.it.
authors.forename: Rachele
authors.initials: R
authors.lastname: Manca
authors.affiliation: Department of Molecular Medicine, University of Pavia, Pavia 27100, Italy. vricci@unipv.it.
authors.forename: Vittorio
authors.initials: V
authors.lastname: Ricci
mesh_terms: D000818:Animals; D003585:Cell Biology; D022083:Cytoplasmic Structures / Q000473:pathology* / Q000648:ultrastructure; D004194:Disease; D005110:Extracellular Space / Q000378:metabolism; D006801:Humans; D025801:Ubiquitin / Q000378:metabolism
chemical_list: D025801:Ubiquitin