title: Down-regulation of proteolytic complexes following EBV activation in BL cells.
abstract: In Burkitt's lymphoma cells, Epstein Barr virus (EBV) latency products interact with the ubiquitin-proteasome system to promote episomal maintenance and immunological evasion while the tripeptidylpeptidase II (TPPII) functions as an alternative protease. In the present study, we have examined the activities and levels of the proteasome and TPPII complex in Raji and in Akata cells after induction of EBV lytic cycle. The results show that the chymotrypsin-like and caspase-like activities of the proteasome were substantially reduced in Raji and Akata cells. Similarly, TPPII activity was diminished in both cell lines but was recovered in Akata cells at longer time after induction. Protein levels of the alpha/beta subunits of the 20S proteasome and TPPII concentration decreased to different extents after EBV activation, whereas the ubiquitin binding S6' subunit of the 19S regulatory complex increased three to fourfold along with the levels of ubiquitin-conjugates. Collectively, these observations demonstrate impairment of two major cellular proteolytic systems at the onset of EBV lytic infection.
authors.affiliation: Department of Public Health Sciences, University "La Sapienza", P. le A. Moro 5, 00185 Rome, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Matusali
authors.forename: Alessandra
authors.initials: A
authors.lastname: De Leo
authors.forename: Riccardo
authors.initials: R
authors.lastname: Gavioli
authors.forename: Laura
authors.initials: L
authors.lastname: Bertelli
authors.forename: Livia
authors.initials: L
authors.lastname: Di Renzo
authors.forename: Elena
authors.initials: E
authors.lastname: Mattia
mesh_terms: D002051:Burkitt Lymphoma / Q000201:enzymology*; D002460:Cell Line; D015536:Down-Regulation; D004854:Herpesvirus 4, Human / Q000502:physiology*; D010447:Peptide Hydrolases / Q000378:metabolism*; D014775:Virus Activation
chemical_list: D010447:Peptide Hydrolases