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Peptide-based Identification of Functional Motifs and their Binding Partners
Published on: June 30, 2013
Screening of Pre-miRNA-155 Binding Peptides for Apoptosis Inducing Activity Using Peptide Microarrays
Jaeyoung Pai1, Soonsil Hyun2, Ji Young Hyun1
1National Creative Research Center for Biofunctional Molecules, Department of Chemistry, Yonsei University , Seoul 03722, Korea.
Abstract:
MicroRNA-155, one of the most potent miRNAs that suppress apoptosis in human cancer, is overexpressed in numerous cancers, and it displays oncogenic activity. Peptide microarrays, constructed by immobilizing 185 peptides containing the C-terminal hydrazide onto epoxide-derivatized glass slides, were employed to evaluate peptide binding properties of pre-miRNA-155 and to identify its binding peptides. Two peptides, which were identified based on the results of peptide microarray and in vitro Dicer inhibition studies, were found to inhibit generation of mature miRNA-155 catalyzed by Dicer and to enhance expression of miRNA-155 target genes in cells. In addition, the results of cell experiments indicate that peptide inhibitors promote apoptotic cell death via a caspase-dependent pathway. Finally, observations made in NMR and molecular modeling studies suggest that a peptide inhibitor preferentially binds to the upper bulge and apical stem-loop region of pre-miRNA-155, thereby suppressing Dicer-mediated miRNA-155 processing.
Insights
Researchers identified two peptides that inhibit microRNA-155 (miRNA-155) processing, a key oncogene in cancer. These peptide inhibitors promote cancer cell death by blocking Dicer activity and inducing apoptosis.
Area of Science:
- Molecular Biology
- Oncology
- Biochemistry
Background:
- MicroRNA-155 (miRNA-155) is frequently overexpressed in various human cancers, where it acts as a potent oncogene by suppressing apoptosis.
- Understanding miRNA-155's regulatory mechanisms is crucial for developing targeted cancer therapies.
Purpose of the Study:
- To identify specific peptides that can inhibit the function of pre-microRNA-155 (pre-miRNA-155).
- To investigate the therapeutic potential of these peptide inhibitors in promoting cancer cell death.
Main Methods:
- Peptide microarrays were used to screen for peptides binding to pre-miRNA-155.
- In vitro Dicer inhibition assays and cell-based experiments were conducted to evaluate the functional effects of identified peptides.
- Nuclear Magnetic Resonance (NMR) and molecular modeling studies were employed to elucidate the binding mechanism.
Main Results:
- Two peptides were identified that effectively inhibit Dicer-mediated processing of pre-miRNA-155 into mature miRNA-155.
- These peptide inhibitors enhanced the expression of miRNA-155 target genes and induced apoptotic cell death in cancer cells via a caspase-dependent pathway.
- Structural studies suggested that the peptides bind to the upper bulge and apical stem-loop region of pre-miRNA-155, hindering Dicer processing.
Conclusions:
- Novel peptide inhibitors targeting pre-miRNA-155 processing have been discovered.
- These peptides demonstrate potential as therapeutic agents for cancers overexpressing miRNA-155 by inducing apoptosis.
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