title: Caspases are not involved in the cleavage of translation initiation factor eIF4GI during picornavirus infection.
abstract: Infection of cells by many picornaviruses results in the rapid inhibition of cellular protein synthesis due to cleavage of the translation initiation factor eIF4G. The poliovirus (PV) 2A and foot-and-mouth disease virus (FMDV) L proteases are each sufficient to mediate this cleavage, but the cleavage mechanism may be indirect, involving an unidentified cellular protease(s). eIF4G is also targetted for cleavage by caspase-3 during apoptosis. Here, it is shown that caspase inhibitors do not inhibit the cleavage of eIF4GI during PV or FMDV infection. Similarly, in transient-expression studies, the cleavage of eIF4GI induced by PV 2A or FMDV L was unaffected by these inhibitors. Furthermore, the cleavage of eIF4GI was observed in PV-infected MCF-7 cells lacking caspase-3. These data, and the fact that induction of apoptosis yields different eIF4GI cleavage fragments, indicate that caspases do not have a major role in the cleavage of eIF4GI during PV or FMDV infection.
authors.affiliation: School of Biological Sciences, University of Surrey, Guildford, Surrey GU2 5XH, UK. l.roberts@surrey.ac.uk
authors.forename: L O
authors.initials: LO
authors.lastname: Roberts
authors.forename: A J
authors.initials: AJ
authors.lastname: Boxall
authors.forename: L J
authors.initials: LJ
authors.lastname: Lewis
authors.forename: G J
authors.initials: GJ
authors.lastname: Belsham
authors.forename: G E
authors.initials: GE
authors.lastname: Kass
mesh_terms: D000818:Animals; D005537:Aphthovirus / Q000502:physiology*; D017209:Apoptosis; D020169:Caspases / Q000502:physiology*; D006224:Cricetinae; D039603:Eukaryotic Initiation Factor-4G; D006367:HeLa Cells; D006801:Humans; D010448:Peptide Initiation Factors / Q000378:metabolism*; D017955:Poliovirus / Q000502:physiology*
chemical_list: D039603:Eukaryotic Initiation Factor-4G; D010448:Peptide Initiation Factors; D020169:Caspases