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Engineering hepatocyte growth factor fragments with high stability and activity as Met receptor agonists and antagonists.

ABSTRACT: The Met receptor tyrosine kinase and its ligand hepatocyte growth factor (HGF) play an important role in mediating both tumor progression and tissue regeneration. The N-terminal and first Kringle domains (NK1) of HGF comprise a naturally occurring splice variant that retains the ability to activate the Met receptor. However, NK1 is a weak agonist and is relatively unstable, limiting its therapeutic potential. Here, we engineered NK1 mutants with improved biochemical and biophysical properties that function as Met receptor agonists or antagonists. We first engineered NK1 for increased stability and recombinant expression yield using directed evolution. The NK1 variants isolated from our library screens acted as weak Met receptor antagonists due to a mutation at the NK1 homodimerization interface. We introduced point mutations that restored this NK1 homodimerization interface to create an agonistic ligand, or that further disrupted this interface to create more effective antagonists. The rationally engineered antagonists exhibited melting temperatures up to approximately 64 °C, a 15 °C improvement over antagonists derived from wild-type NK1, and approximately 40-fold improvement in expression yield. Next, we created disulfide-linked NK1 homodimers through introduction of an N-terminal cysteine residue. These covalent dimers exhibited nearly an order of magnitude improved agonistic activity compared to wild-type NK1, approaching the activity of full-length HGF. Moreover, covalent NK1 dimers formed from agonistic or antagonistic monomeric subunits elicited similar activity, further signifying that NK1 dimerization mediates agonistic activity. These engineered NK1 proteins are promising candidates for therapeutic development and will be useful tools for further exploring determinants of Met receptor activation.

SUBMITTER: Jones DS

PROVIDER: S-EPMC3156163 | biostudies-literature | 2011 Aug

REPOSITORIES: biostudies-literature

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Engineering hepatocyte growth factor fragments with high stability and activity as Met receptor agonists and antagonists.

Jones Douglas S DS Tsai Ping-Chuan PC Cochran Jennifer R JR

Proceedings of the National Academy of Sciences of the United States of America 20110725 32

The Met receptor tyrosine kinase and its ligand hepatocyte growth factor (HGF) play an important role in mediating both tumor progression and tissue regeneration. The N-terminal and first Kringle domains (NK1) of HGF comprise a naturally occurring splice variant that retains the ability to activate the Met receptor. However, NK1 is a weak agonist and is relatively unstable, limiting its therapeutic potential. Here, we engineered NK1 mutants with improved biochemical and biophysical properties th ...[more]

PMID: 21788476

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Project description:MET, the receptor for hepatocyte growth factor (HGF), is involved in wide variety of biological events and its aberrant activation is implicated in the pathogenesis of cancer. Especially, MET signaling is associated with resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), key drugs in therapy of non-small cell lung cancer. MET has 11 potential N-glycosylation sites, however, the site-specific roles of N-glycans have not been elucidated. Here, we report that N-glycans regulate proteolytic processing of MET and HGF induced MET signaling, site specifically. N-glycosylation inhibitors suppressed processing and trafficking of endogenous MET in H1975 and EBC-1 lung cancer cells and exogenous MET in CHO cells. We purified the recombinant extracellular domain of human MET and determined the site-specific N-glycan structures and occupancy using nanoflow liquid chromatography-electrospray ionization mass spectrometry. The results indicated that most sites were fully glycosylated and the dominant population were complex-type which were rich in sialic acids and core fucoses. To examine the effects of N-glycan deletion of MET, we prepared endogenous-MET-knockout Flp-In CHO cells and transfected with series of N-glycan deletion mutants of MET. It was found that several N-glycans are implicated in processing of MET. It was also suggested that the N-glycans of -subunit of MET positively regulate HGF signaling, and the N-glycans of β-subunit negatively regulate HGF signaling. In all-N-glycan deletion mutant, processing and signaling were significantly suppressed. It was observed that the cell proliferation rate was suppressed in all-N-glycan deletion mutant, although the cell surface expression levels of MET were not completely diminished. We examined the HGF biding affinity for the recombinant extracellular domain of MET and found that peptide N-glycosidase F treatment did not affect the ligand binding affinity. It was suggested that N-glycans of MET affect the status and the function of the receptor site-specifically.

Dataset Information

Engineering hepatocyte growth factor fragments with high stability and activity as Met receptor agonists and antagonists.

Publications

Engineering hepatocyte growth factor fragments with high stability and activity as Met receptor agonists and antagonists.

Similar Datasets

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