Novel participation of transglutaminase-2 through c-Jun N-terminal kinase activation in sphingosylphosphorylcholine-induced keratin reorganization of PANC-1 cells

Biochim Biophys Acta. 2011 Dec;1811(12):1021-9. doi: 10.1016/j.bbalip.2011.07.007. Epub 2011 Jul 26.


Sphingosylphosphorylcholine (SPC) is found at increased levels in the malignant ascites of tumor patients and induces perinuclear reorganization of keratin 8 (K8) filaments that contribute to the viscoelasticity of metastatic cancer cells. In this study, we investigated the role and molecular mechanisms of Tgase-2 in SPC-induced K8 phosphorylation and perinuclear reorganization in PANC-1 cells (PAN(WT)), and in PANC-1 cells that stably expressed shTgase-2 or Tgase-2 (PAN(shTg2) and PAN(Tg2)). SPC induces the expression of Tgase-2 in a time- and dose-dependent manner. Gene silencing of Tgase-2 or cystamine suppressed the SPC-induced phosphorylation and perinuclear reorganization of K8 and suppressed the SPC-induced migration of PANC-1 cells. An inhibitor of c-Jun N-terminal kinase (JNK), SP600125, suppressed the SPC-induced phosphorylation of serine 431 in K8 and keratin reorganization. Next, we examined the effect of Tgase-2 on JNK activation of serine 431 phosphorylation in K8. Tgase-2 gene silencing suppressed the expression of active form JNK (pJNK). Constitutive or tetracyclin-induced conditional expression of Tgase-2 increased the levels of pJNK. Tgase-2 was coimmunoprecipitated with K8 and JNK. In addition, K8 was coimmunoprecipitated with Tgase-2 and JNK. JNK was also coimmunoprecipitated with K8 and Tgase-2. Overall, these results suggest that Tgase-2 is involved in SPC-induced phosphorylation and perinuclear reorganization of K8 by activating JNK and forming a triple complex with K8 and JNK. Therefore, SPC-induced Tgase-2 might be a new target for modulating keratin reorganization, metastasis of cancer cells and JNK activation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anthracenes / pharmacology
  • Cell Line, Tumor
  • Cell Movement / drug effects
  • Cystamine / pharmacology
  • Cytoskeleton / genetics
  • Cytoskeleton / metabolism
  • GTP-Binding Proteins* / deficiency
  • GTP-Binding Proteins* / genetics
  • Gene Expression Regulation, Neoplastic* / drug effects
  • Gene Silencing
  • Humans
  • Immunoprecipitation
  • JNK Mitogen-Activated Protein Kinases / antagonists & inhibitors
  • JNK Mitogen-Activated Protein Kinases / metabolism*
  • Keratin-8 / antagonists & inhibitors
  • Keratin-8 / metabolism*
  • MAP Kinase Signaling System / drug effects
  • MAP Kinase Signaling System / genetics*
  • Pancreatic Neoplasms / genetics
  • Pancreatic Neoplasms / metabolism*
  • Phosphorylation
  • Phosphorylcholine / adverse effects
  • Phosphorylcholine / analogs & derivatives*
  • Phosphorylcholine / metabolism
  • Protein Kinase Inhibitors / pharmacology
  • RNA, Small Interfering / genetics
  • RNA, Small Interfering / metabolism
  • Serine / genetics
  • Serine / metabolism
  • Sphingosine / adverse effects
  • Sphingosine / analogs & derivatives*
  • Sphingosine / metabolism
  • Transglutaminases* / deficiency
  • Transglutaminases* / genetics


  • Anthracenes
  • Keratin-8
  • Protein Kinase Inhibitors
  • RNA, Small Interfering
  • sphingosine phosphorylcholine
  • Phosphorylcholine
  • pyrazolanthrone
  • Serine
  • transglutaminase 2
  • Transglutaminases
  • JNK Mitogen-Activated Protein Kinases
  • GTP-Binding Proteins
  • Sphingosine
  • Cystamine