title: Multiple host kinases contribute to Akt activation during Salmonella infection.
abstract: SopB is a type 3 secreted effector with phosphatase activity that Salmonella employs to manipulate host cellular processes, allowing the bacteria to establish their intracellular niche. One important function of SopB is activation of the pro-survival kinase Akt/protein kinase B in the infected host cell. Here, we examine the mechanism of Akt activation by SopB during Salmonella infection. We show that SopB-mediated Akt activation is only partially sensitive to PI3-kinase inhibitors LY294002 and wortmannin in HeLa cells, suggesting that Class I PI3-kinases play only a minor role in this process. However, depletion of PI(3,4) P2/PI(3-5) P3 by expression of the phosphoinositide 3-phosphatase PTEN inhibits Akt activation during Salmonella invasion. Therefore, production of PI(3,4) P2/PI(3-5) P3 appears to be a necessary event for Akt activation by SopB and suggests that non-canonical kinases mediate production of these phosphoinositides during Salmonella infection. We report that Class II PI3-kinase beta isoform, IPMK and other kinases identified from a kinase screen all contribute to Akt activation during Salmonella infection. In addition, the kinases required for SopB-mediated activation of Akt vary depending on the type of infected host cell. Together, our data suggest that Salmonella has evolved to use a single effector, SopB, to manipulate a remarkably large repertoire of host kinases to activate Akt for the purpose of optimizing bacterial replication in its host.
authors.affiliation: Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Roppenser
authors.forename: Hyunwoo
authors.initials: H
authors.lastname: Kwon
authors.forename: Veronica
authors.initials: V
authors.lastname: Canadien
authors.forename: Risheng
authors.initials: R
authors.lastname: Xu
authors.forename: Peter N
authors.initials: PN
authors.lastname: Devreotes
authors.forename: Sergio
authors.initials: S
authors.lastname: Grinstein
authors.forename: John H
authors.initials: JH
authors.lastname: Brumell
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism; D002867:Chromones / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D006367:HeLa Cells; D054884:Host-Pathogen Interactions; D006801:Humans; D051379:Mice; D009025:Morpholines / Q000494:pharmacology; D009841:Oligonucleotides / Q000737:chemistry; D010766:Phosphorylation; D010770:Phosphotransferases / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D012480:Salmonella Infections / Q000201:enzymology* / Q000382:microbiology*; D012486:Salmonella typhimurium / Q000378:metabolism*; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D001426:Bacterial Proteins; D002867:Chromones; D009025:Morpholines; D009841:Oligonucleotides; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D010770:Phosphotransferases; C494918:AKT1 protein, human; D051057:Proto-Oncogene Proteins c-akt; C489224:SopB protein, Salmonella; D000077191:Wortmannin