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Detection of Ligand-activated G Protein-coupled Receptor Internalization by Confocal Microscopy
Published on: April 9, 2017
[Identification and characterization of epidermal growth factor receptor ligands in Bombyx mori]
Fei Wang1, Shifeng Dong1, Liang Song1
1State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China.
Abstract:
Epidermal growth factor receptor (EGFR) is a multi-functional receptor distributed throughout the metazoa. Study on its ligands so far remained mainly on mammals, including how ligands are processed into active forms, their interaction with EGFR, and the signaling pathway they induce. However, in invertebrates, ligands are more divergent among species. Currently, except for Drosophila, less is known about the insect EGFR ligands. Here, we identified two EGFR ligands in Bombyx mori by homology search, domain prediction, analysis of the potential translation initiation sequence and construction of phylogenetic tree, termed as BmEGF-1 and BmEGF-2. BmEGF-1 shows the greatest similarity to Drosophila Spitz and their Rhomboid-recognition motifs are highly identical. BmEGF-2 is a homolog to Drosophila Vein. Then we purified BmEGF-1 extracellular domain expressed in E. coli, and performed pull-down assay with BmEGFR extracellular domain secreted by Sf9 cells. The result confirmed their interaction. Lastly, we found the phosphorylation level of ERK and p38 MAPK was elevated after expression of BmEGF-1 in BmE cells, which suggested that BmEGF-1 is not only able to activate the canonical ERK signaling pathway, but may participate in other cellular processes by inducing p38 MAPK signaling pathway. Our study provides reference to further study of the biological function of BmEGF in silkworm.
Insights
Researchers identified two novel epidermal growth factor receptor (EGFR) ligands, BmEGF-1 and BmEGF-2, in silkworms. BmEGF-1 activates ERK and p38 MAPK signaling pathways, offering insights into insect EGFR ligand function.
Area of Science:
- Molecular Biology
- Insect Biochemistry
- Receptor Signaling
Background:
- Epidermal growth factor receptor (EGFR) signaling is crucial in metazoans, with extensive research in mammals.
- Invertebrate EGFR ligands are diverse, and knowledge of insect EGFR ligands, excluding Drosophila, is limited.
Purpose of the Study:
- To identify and characterize novel EGFR ligands in the silkworm, Bombyx mori.
- To investigate the interaction between identified silkworm EGFR ligands and the receptor.
- To explore the downstream signaling pathways activated by these ligands.
Main Methods:
- Homology search and phylogenetic analysis to identify potential EGFR ligands.
- Expression and purification of BmEGF-1 extracellular domain.
- Pull-down assays to confirm ligand-receptor interaction.
- Western blotting to detect phosphorylation of ERK and p38 MAPK.
Main Results:
- Two Bombyx mori EGFR ligands, BmEGF-1 and BmEGF-2, were identified.
- BmEGF-1 demonstrated similarity to Drosophila Spitz, and BmEGF-2 to Drosophila Vein.
- BmEGF-1 directly interacted with the Bombyx mori EGFR extracellular domain.
- BmEGF-1 expression elevated ERK and p38 MAPK phosphorylation in BmE cells.
Conclusions:
- BmEGF-1 and BmEGF-2 are identified as functional EGFR ligands in Bombyx mori.
- BmEGF-1 activates both the canonical ERK and the p38 MAPK signaling pathways.
- This study provides a foundation for understanding insect EGFR ligand functions and their biological roles in silkworms.
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