title: Regulation of stathmin phosphorylation in mouse liver progenitor-29 cells during proteasome inhibition.
abstract: Proteasome inhibitors are potential therapeutic agents in the treatment of hepatocarcinoma and other liver diseases. The analysis of alternative protein phosphorylation states might contribute to elucidate the underlying mechanisms of proteasome inhibitor-induced apoptosis. We have investigated the response of mouse liver progenitor-29 (MLP-29) cells to MG132 using a combination of phosphoprotein affinity chromatography, DIGE, and nano LC-MS/MS. Thirteen unique deregulated phosphoproteins involved in chaperone activity, stress response, mRNA processing and cell cycle control were unambiguously identified. Alterations in NDRG1 and stathmin suggest new mechanisms associated to proteasome inhibitor-induced apoptosis in MLP-29 cells. Particularly, a transient modification of the phosphorylation state of Ser(16), Ser(25) and Ser(38), which are involved in the regulation of stathmin activity, was detected in three distinct isoforms upon proteasome inhibition. The parallel deregulation of calcium/calmodulin-activated protein kinase II, extracellular regulated kinase-1/2 and cyclin-dependent kinase-2, might explain the modified phosphorylation pattern of stathmin. Interestingly, stathmin phosphorylation profile was also modified in response to epoxomicin treatment, a more specific proteasome inhibitor. In summary, we report here data supporting that regulation of NDRG1 and stathmin by phosphorylation at specific Ser/Thr residues may participate in the cellular response induced by proteasome inhibitors.
authors.affiliation: Center for Applied Medical Research, University of Navarra, Proteomics Laboratory, 31008 Pamplona, Spain.
authors.forename: Enrique
authors.initials: E
authors.lastname: Santamaría
authors.forename: Maria I
authors.initials: MI
authors.lastname: Mora
authors.forename: Javier
authors.initials: J
authors.lastname: Muñoz
authors.forename: Virginia
authors.initials: V
authors.lastname: Sánchez-Quiles
authors.forename: Joaquín
authors.initials: J
authors.lastname: Fernández-Irigoyen
authors.forename: Jesús
authors.initials: J
authors.lastname: Prieto
authors.forename: Fernando J
authors.initials: FJ
authors.lastname: Corrales
mesh_terms: D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism; D002460:Cell Line; D015853:Cysteine Proteinase Inhibitors / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D007976:Leupeptins / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000378:metabolism; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors; D050777:Stathmin / Q000378:metabolism*; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D000099259:N-myc Downstream-Regulated Gene 1 Protein
chemical_list: D018797:Cell Cycle Proteins; D015853:Cysteine Proteinase Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D007976:Leupeptins; D009842:Oligopeptides; D046988:Proteasome Endopeptidase Complex; D061988:Proteasome Inhibitors; D050777:Stathmin; D000099259:N-myc Downstream-Regulated Gene 1 Protein; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde; C078846:epoxomicin