title: Phosphorylation of beta-actin by protein kinase C-delta in camptothecin analog-induced leukemic cell apoptosis.
abstract: OBJECTIVE
  This study was conducted to reveal new proteins involved in acute myeloid leukemia (AML) cell apoptosis.
  
  
  METHODS
  Using camptothecin analog NSC606985- induced leukemic U937 cell apoptosis as a model, this study performed a differential proteomic analysis during apoptosis induction. The significantly modulated protein was underwent further investigation in the apoptotic process.
  
  
  RESULTS
  We found that beta-actin protein presented two different spots on the two-dimensional electrophoresis (2-DE) map, which shared similar molecular weight and different pI. Those two spots demonstrated contrary changes (disappeared on the basic-end and increased on the acid-end spot) during apoptosis induction, although the total level of beta-actin kept constant. This observation was further confirmed by immunoblot analysis on 2-DE gel. When NSC606985-treated cell lysate was incubated with alkaline phosphotase, beta-actin on the basic-end spot was restored, indicating increased phosphorylation of beta-actin during NSC606985- induced apoptosis. Moreover, the polymerization of actin also decreased after NSC606985 treatment. The increased beta-actin phosphorylation and decreased actin polymerization was antagonized by pre-treatment of rottlerin, a specific protein kinase C-delta (PKC delta) inhibitor.
  
  
  CONCLUSIONS
  All these results indicate that beta-actin was phosphorylated during apoptosis induction, which was mediated by activated PKC delta.
authors.affiliation: Department of Pathophysiology, Xiangya Medical College, Central South University, Changsha, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Wang
authors.forename: Ying
authors.initials: Y
authors.lastname: Zheng
authors.forename: Yun
authors.initials: Y
authors.lastname: Yu
authors.forename: Li
authors.initials: L
authors.lastname: Xia
authors.forename: Guo-qiang
authors.initials: GQ
authors.lastname: Chen
authors.forename: Yong-zong
authors.initials: YZ
authors.lastname: Yang
authors.forename: Li-shun
authors.initials: LS
authors.lastname: Wang
mesh_terms: D000199:Actins / Q000378:metabolism*; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D006801:Humans; D010766:Phosphorylation; D051745:Protein Kinase C-delta / Q000378:metabolism*; D020298:U937 Cells
chemical_list: D000199:Actins; D000972:Antineoplastic Agents, Phytogenic; D051745:Protein Kinase C-delta; D002166:Camptothecin