
AbstractG protein‐coupled receptors regulate a variety of cellular responses and have been considered as therapeutic targets for human diseases. Lysophosphatidic acid receptor 1 (LPA1) is a receptor for bioactive lysophospholipid, LPA. LPA/LPA1‐mediated signaling contributes to inflammatory and fibrotic responses in lung diseases; thus understanding regulation of LPA1 stability is important for modulating LPA/LPA1 signaling. Our previous study has shown that LPA1 is degraded in the Nedd4 like (Nedd4L) E3 ubiquitin ligase‐mediated ubiquitin‐proteasome system. In the current study, we attempt to identify a peptide that stabilizes LPA1 through disrupting LPA1 association with Nedd4L. LPA treatment induces both endogenous and overexpressed LPA1 degradation, which is attenuated by a proteasome inhibitor, suggesting that LPA1 is degraded in the proteasome. LPA increases phosphorylation of extracellular signal‐regulated kinase 1/2 (Erk1/2) and I‐κB kinase in lung epithelial cells, and this effect is promoted by overexpression of a peptide (P1) that mimics C‐terminal of LPA1. P1, not a control peptide, attenuates LPA‐induced LPA1 ubiquitination and degradation, suggesting that P1 stabilizes LPA1. Further, P1 diminishes Nedd4L‐mediated degradation of LPA1 and Nedd4L/LPA1 association. In addition to increasing LPA1 signaling, P1 enhances LPA‐induced cell migration and gene expression of Elafin, matrix metallopeptidase 1, and serpin family B member 2 in lung epithelial cells. These data suggest that disruption of LPA1 interaction with Nedd4L by P1 increases LPA1 stability and LPA/LPA1 signaling.
Proteasome Endopeptidase Complex, MAP Kinase Signaling System, Ubiquitin, Nedd4 Ubiquitin Protein Ligases, Pulmonary Fibrosis, Cell Line, Mice, Proteolysis, Animals, Humans, Lysophospholipids, Receptors, Lysophosphatidic Acid
Proteasome Endopeptidase Complex, MAP Kinase Signaling System, Ubiquitin, Nedd4 Ubiquitin Protein Ligases, Pulmonary Fibrosis, Cell Line, Mice, Proteolysis, Animals, Humans, Lysophospholipids, Receptors, Lysophosphatidic Acid
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