51. Unraveling mechanisms of pentraxin 3 secretion in adipocytes during inflammation.
- Author
-
Lin TY, Guo H, and Chen X
- Subjects
- 3T3-L1 Cells, Adipocytes drug effects, Animals, C-Reactive Protein chemistry, C-Reactive Protein genetics, Cells, Cultured, Endosomal Sorting Complexes Required for Transport metabolism, Extracellular Vesicles metabolism, Gene Expression Regulation, Lipopolysaccharides immunology, Lipopolysaccharides pharmacology, Macrophages immunology, Macrophages metabolism, Mice, Mitochondria genetics, Mitochondria metabolism, Panniculitis etiology, Protein Interaction Domains and Motifs, Protein Sorting Signals, Serum Amyloid P-Component chemistry, Serum Amyloid P-Component genetics, Adipocytes metabolism, Biomarkers, C-Reactive Protein biosynthesis, Panniculitis metabolism, Serum Amyloid P-Component biosynthesis
- Abstract
Pentraxin 3 (PTX3) is a soluble pattern recognition receptor playing an important role in immune response and inflammation. Lipopolysaccharide (LPS) stimulation can significantly induce PTX3 expression and secretion in adipocytes. Appropriate regulation of PTX3 secretion is critical for inflammatory homeostasis. Using chemical inhibitors of conventional and unconventional protein secretion, we explored the mechanisms that control LPS-stimulated PTX3 secretion in 3T3-L1 adipocytes. Inhibiting the conventional protein secretion blocked LPS-stimulated PTX3 secretion, resulting in cellular PTX3 accumulation in adipocytes. We also detected PTX3 in exosomes from LPS-treated adipocytes; inhibiting exosome trafficking attenuated PTX3 secretion. However, only 4.3% of secreted PTX3 was detected in exosomes compared to 95.7% in the non-exosomal fractions. The fractionation of isolated exosomes by the iodixanol density gradient centrifugation confirmed that a small portion of secreted PTX3 overlapped with exosomal markers in small extracellular-vesicle fractions. We conclude that PTX3 is secreted mainly through conventional protein secretion, and a small percentage of PTX3 is released in exosomes from LPS-stimulated adipocytes.
- Published
- 2021
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