title: Apoptosis induced by the fungal pathogen gliotoxin requires a triple phosphorylation of Bim by JNK.
abstract: We previously reported that gliotoxin (GT), the major virulence factor of the mold Aspergillus fumigatus causing invasive aspergillosis (IA) in immunocompromised patients, induces apoptosis in a Bak-dependent manner. The signaling pathway leading to Bak activation and subsequent mitochondrial outer membrane permeabilization (MOMP) is elusive. Here, we show that GT and the supernatant of A. fumigatus (but not its GT-defective mutant) activate the JNK pathway and require a co-operative JNK-mediated BimEL phosphorylation at three sites (S100, T112 and S114) to induce apoptosis in mouse fibroblasts, human bronchial and mouse alveolar epithelial cells. Cells (i) treated with the JNK inhibitor SP600125, (ii) deleted or knocked down for JNK1/2 or Bim or (iii) carrying the BimEL triple phosphomutant S100A/T112A/S114A instead of wild-type BimEL are similarly resistant to GT-induced apoptosis. Triple-phosphorylated BimEL is more stable, redistributes from a cytoskeletal to a membrane fraction, better interacts with Bcl-2 and Bcl-xL and more effectively activates Bak than the unphosphorylated mutant. These data indicate that JNK-mediated BimEL phosphorylation at S100, T112 and S114 constitutes a novel regulatory mechanism to activate Bim in response to apoptotic stimuli.
authors.affiliation: Institute of Molecular Medicine and Cell Research, Albert Ludwigs University Freiburg, Stefan Meier Strasse 17, D-79104 Freiburg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Geissler
authors.forename: F
authors.initials: F
authors.lastname: Haun
authors.forename: D O
authors.initials: DO
authors.lastname: Frank
authors.forename: K
authors.initials: K
authors.lastname: Wieland
authors.forename: M M
authors.initials: MM
authors.lastname: Simon
authors.forename: M
authors.initials: M
authors.lastname: Idzko
authors.forename: R J
authors.initials: RJ
authors.lastname: Davis
authors.forename: U
authors.initials: U
authors.lastname: Maurer
authors.forename: C
authors.initials: C
authors.lastname: Borner
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D001232:Aspergillus fumigatus / Q000737:chemistry; D000072224:Bcl-2-Like Protein 11; D005912:Gliotoxin / Q000494:pharmacology*; D057809:HEK293 Cells; D006801:Humans; D048670:MAP Kinase Kinase 4 / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D010766:Phosphorylation; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D051017:Apoptosis Regulatory Proteins; C000606775:BCL2L11 protein, human; D000072224:Bcl-2-Like Protein 11; C000606776:Bcl2l11 protein, mouse; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D005912:Gliotoxin; D048670:MAP Kinase Kinase 4