Matrin 3 co-immunoprecipitates with the heat shock proteins glucose-regulated protein 78 (GRP78), GRP75 and glutathione S-transferase pi isoform 2 (GST pi 2) in thymoma cells

Ahmed M. Osman*, Henk van Loveren

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

5 Citations (Web of Science)

Abstract

Here, we report evidence that matrin 3 (MATR3), a highly conserved inner nuclear matrix phosphoprotein, whose function is largely unknown, interacts specifically with the heat shock proteins glucose-regulated protein 78 (GR278), GRP75 and glutathione S-transferase pi isoform 2 (GST pi 2). Using immunoprecipitation experiments of lysates obtained from control and tributyltin oxide (TBTO)-treated thymoma cell line (EL4), we identified MATR3 and its partners by MS/MS analysis and confirmed by immunoblot. We also show that MATR3 undergoes degradation as reported before and that this cleavage process, which is inhibited by the broad-spectrum caspase inhibitor, z-VAD-FMK, is more marked in TBTO-treated cells. Further, we found that the heat shock protein glucose-regulated protein 78 was downregulated in the TBTO-treated cells. The GRP78 protein is known to protect cells from apoptosis by complexing with procaspase 7 thereby preventing caspase activation cascade. By immunoblot analysis, we found that the levels of procaspases-3 and -7 were lower in TBTO-treated cells; in contrast, the level of p20, the active form of caspase 3, was relatively higher in the treated cells compared to that of control cells. We propose that the TBTO-mediated downregulation of GRP78 triggers the caspase cascade pathway leading to MATR3 degradation.
Original languageEnglish
Pages (from-to)208-214
JournalBiochimie
Volume101
DOIs
Publication statusPublished - Jun 2014

Keywords

  • Matrin 3
  • Immunoprecipitation
  • Proteomics
  • TBTO
  • Protein-interactions
  • Proteolysis

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