PaCS is a novel cytoplasmic structure containing functional proteasome and inducible by cytokines/trophic factors

Patrizia Sommi, Vittorio Necchi, Agostina Vitali, Daniela Montagna, Ada De Luigi, Mario Salmona, Vittorio Ricci, Enrico Solcia

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

A variety of ubiquitinated protein-containing cytoplasmic structures has been reported, from aggresomes to aggresome-like induced structures/ sequestosomes or particle-rich cytoplasmic structures (PaCSs) that we recently observed in some human diseases. Nevertheless, the morphological and cytochemical patterns of the different structures remain largely unknown thus jeopardizing their univocal identification. Here, we show that PaCSs resulted from proteasome and polyubiquitinated protein accumulation into well-demarcated, membrane-free, cytoskeleton-poor areas enriched in glycogen and glycosaminoglycans. A major requirement for PaCS detection by either electron or confocal microscopy was the addition of osmium to aldehyde fixatives. However, by analyzing living cells, we found that proteasome chymotrypsin-like activity concentrated in well-defined cytoplasmic structures identified as PaCSs by ultrastructural morphology and immunocytochemistry of the same cells. PaCSs differed ultrastructurally and cytochemically from sequestosomes which may coexist with PaCSs. In human dendritic or natural killer cells, PaCSs were induced in vitro by cytokines/trophic factors during differentiation/activation from blood progenitors. Our results provide evidence that PaCS is indeed a novel distinctive cytoplasmic structure which may play a critical role in the ubiquitin-proteasome system response to immune, infectious or proneoplastic stimuli.

Original languageEnglish
Article numbere82560
JournalPLoS One
Volume8
Issue number12
DOIs
Publication statusPublished - Dec 17 2013

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Cytoplasmic Structures
proteasome endopeptidase complex
Proteasome Endopeptidase Complex
cytokines
Cytokines
Ubiquitinated Proteins
Osmium
Fixatives
Confocal microscopy
Chymotrypsin
Ubiquitin
Glycosaminoglycans
Glycogen
Aldehydes
Electron microscopy
Blood
Chemical activation
Cells
Membranes
osmium

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

PaCS is a novel cytoplasmic structure containing functional proteasome and inducible by cytokines/trophic factors. / Sommi, Patrizia; Necchi, Vittorio; Vitali, Agostina; Montagna, Daniela; De Luigi, Ada; Salmona, Mario; Ricci, Vittorio; Solcia, Enrico.

In: PLoS One, Vol. 8, No. 12, e82560, 17.12.2013.

Research output: Contribution to journalArticle

Sommi, Patrizia ; Necchi, Vittorio ; Vitali, Agostina ; Montagna, Daniela ; De Luigi, Ada ; Salmona, Mario ; Ricci, Vittorio ; Solcia, Enrico. / PaCS is a novel cytoplasmic structure containing functional proteasome and inducible by cytokines/trophic factors. In: PLoS One. 2013 ; Vol. 8, No. 12.
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