Transglutaminase 2 and phospholipase A2 interactions in the inflammatory response in human Thp-1 monocytes

Monica Currò, Nadia Ferlazzo, Roberto Risitano, Salvatore Condello, Mercurio Vecchio, Daniela Caccamo, Riccardo Ientile*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Several experimental approaches have demonstrated that transglutaminase 2 (TG2) increased activity is involved in monocyte activation and inflammatory response. Preliminary results also demonstrate a TG-mediated post-translational modification of phospholipase A2 (PLA2), which catalyzes the release of arachidonic acid from its lipid storage sites. The control of PLA2-mediated production of eicosanoids has been found to be of great benefit for inflammatory disease treatment. However, the identification of the mechanisms of PLA2 activation is a very complex issue, because of the presence of multiple PLA2 forms. The aim of this study was to characterize the interactions between TG2 and sPLA2 in LPS-stimulated THP-1 cells, which were treated with TPA to induce early differentiated macrophage-type model. We demonstrated that increases in TG2 enzyme activity and protein expression may be considered an early event in monocyte/macrophage activation by LPS. Under these conditions, TG2 protein was co-immunoprecipitated with PLA2 by monoclonal antibody directed against the secretory form of the enzyme (sPLA2-V). Concomitantly, the PLA2 enzyme activity increased in TPA-treated cells exposed to LPS; these high levels of enzyme activity were significant reduced by R283, a site-specific inhibitor of TG2. Moreover, confocal laser scanning microscopy analysis of double-immunostained cytochemical specimens confirmed a co-localization of BAPA-labeled proteins and sPLA2-V in LPS-treated cells. These findings give evidence of a complex TG2/sPLA2-V, suggesting the possibility that sPLA2-V is a substrate for TG2. These results demonstrated that TG2 increases produced a sustained activation of PLA2 activity, suggesting a functional interaction between these enzymes in the regulation of inflammatory response.

Original languageEnglish (US)
Pages (from-to)759-766
Number of pages8
JournalAmino Acids
Volume46
Issue number3
DOIs
StatePublished - Jan 1 2014

Keywords

  • Inflammation
  • Macrophages
  • Polyamination
  • Transglutaminase 2

ASJC Scopus subject areas

  • Biochemistry
  • Clinical Biochemistry
  • Organic Chemistry

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