Understanding the biological activities of cysteine-rich peptides from Acanthopanax trifoliatus

• Main Author: Tay, Jian Hua
• Other Authors: James P Tam
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Science::Biological sciences
• Online Access: https://hdl.handle.net/10356/166908
• Institution: Nanyang Technological University

Acanthopanax Trifoliatus (A.trifoliatus) is a traditional Chinese medicinal herb with antioxidant, anti-inflammatory, and anticancer properties. In this study, we characterised the biological activities of acantide aT1, the first cysteine-rich peptide (CRP) from A.trifoliatus, which shares sequence homology with ginsentides (from ginseng). Acantide aT1 has an eight-cysteine motif: CXnCXnCCXnCXnCXnCXnC, typical of the newly discovered family, ginsentide-like peptide also named as non- chitin-binding-eight-cysteine-hevein-like peptide (NCB-8C-HLP). Confocal microscopy revealed that acantide aT1 is a cell-penetrating peptide. Using affinity selection mass spectrometry, we then identified an intracellular target of aT1, protein phosphatase 2A (PP2A). Ser/Thr Phosphatase assay confirms that acantide aT1 inhibits PP2A activities. Using TMT-based quantitative proteomics, we showed that, among the top 19 enriched pathways, approximately 30% of them have an association with phosphatase activity and one of the downstream pathways of PP2A, ERK cascade was also enriched. Western blot analysis confirms that acantide aT1 upregulates the expression of p-MEK, p-ERK and its downstream proteins. MTT assay also indicates that aT1 promotes cell proliferation without cytotoxicity. These findings suggest that acantide aT1 holds exceptionally high promise as a therapeutic for cancer and cardiovascular diseases given its uncommon combinations of being a 35-residue naturally-occurring and cell-penetrating peptide which targets and inhibits PP2A.