Pdcd4 Is Involved in the Formation of Stress Granule in Response to Oxidized Low-Density Lipoprotein or High-Fat Diet

PLoS One. 2016 Jul 25;11(7):e0159568. doi: 10.1371/journal.pone.0159568. eCollection 2016.

Abstract

Stress granules (SGs) in response to various stresses have been reported in many diseases. We previously reported the implication of programmed cell death 4 (Pdcd4) in obesity-induced stress responses, but the possible link between Pdcd4 and SGs remains lacking. In this study we showed that oxidized low-density lipoprotein (ox-LDL) or high-fat diet (HFD) induced SG formation in mouse macrophages and liver tissues, and Pdcd4 deficiency in mice remarkably reduced its formation. In response to ox-LDL, either endogenous or ectopic Pdcd4 displayed granule-like expression and co-localized with SG markers including T-cell-restricted intracellular antigen-1, fragile X mental retardation-related protein 1, and eukaryotic initiation factor 4A. Ectopic expression of truncated Pdcd4 that depleted specific RNA-binding motif significantly disrupted the SG formation, suggesting the direct involvement of Pdcd4 in ox-LDL-induced SGs through its RNA-binding activity. Additionally, Pdcd4 deficiency drove AKT activation and suppression of eIF2α phosphorylation, thereby contributing to the resistance to ox-LDL or HFD-induced SG formation. Collectively, our data suggest that Pdcd4 as a crucial regulator in SGs induced by ox-LDL or HFD maybe a potential target for mitigating SG-associated stress responses in obesity and related diseases.

MeSH terms

  • Animals
  • Apoptosis Regulatory Proteins / deficiency
  • Apoptosis Regulatory Proteins / genetics*
  • Apoptosis Regulatory Proteins / metabolism
  • Cell Line
  • Cells, Cultured
  • Cytoplasmic Granules / metabolism*
  • Diet, High-Fat*
  • Eukaryotic Initiation Factor-2 / metabolism
  • Humans
  • Lipoproteins, LDL / metabolism*
  • Lipoproteins, LDL / pharmacology
  • Liver / metabolism
  • Liver / pathology
  • Macrophages / drug effects
  • Macrophages / metabolism
  • Macrophages / pathology
  • Male
  • Mice
  • Mice, Knockout
  • Obesity / genetics
  • Obesity / metabolism
  • Protein Transport
  • Proto-Oncogene Proteins c-akt / metabolism
  • RNA-Binding Proteins / genetics*
  • RNA-Binding Proteins / metabolism
  • Stress, Physiological*

Substances

  • Apoptosis Regulatory Proteins
  • Eukaryotic Initiation Factor-2
  • Lipoproteins, LDL
  • Pdcd4 protein, mouse
  • RNA-Binding Proteins
  • oxidized low density lipoprotein
  • Proto-Oncogene Proteins c-akt

Grants and funding

This study was supported by the National Natural Science Foundation of China (81270923, 81471065 to Q.W. and 81470403 to F.G.), and Shandong Province independent innovation and transformation of Scientific & Technological achievements project, China (2014ZZCX02104). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.