Non-cytotoxic cobra cardiotoxin A5 binds to αvβ3 integrin and inhibits bone resorption: Identification of cardiotoxins as non-rgd integrin-binding proteins of the Ly-6 family

Po Long Wu, Shao Chen Lee, Chia Chen Chuang, Seiji Mori, Nobuaki Akakura, Wen Guey Wu, Yoshikazu Takada

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

Severe tissue necrosis with a retarded wound healing process is a major symptom of a cobra snakebite. Cardiotoxins (CTXs) are major components of cobra venoms that belong to the Ly-6 protein family and are implicated in tissue damage. The interaction of the major CTX from Taiwan cobra, i.e. CTX A3, with sulfatides in the cell membrane has recently been shown to induce pore formation and cell internalization and to be responsible for cytotoxicity in cardiomyocytes (Wang, C.-H., Liu, J.-H., Lee, S.-C., Hsiao, C.-D., and Wu, W.-g. (2006) J. Biol. Chem. 281, 656-667). We show here that one of the non-cytotoxic CTXs, i.e. CTX A5 or cardiotoxin-like basic polypeptide, from Taiwan cobra specifically bound to αvβ3 integrin and inhibited bone resorption activity. We found that both membrane-bound and recombinant soluble αvβ3 integrins bound specifically to CTX A5 in a dose-dependent manner. Surface plasmon resonance analysis showed that human soluble αvβ3 bound to CTX A5 with an apparent affinity of ∼0.3 μM. Calf pulmonary artery endothelial cells, which constitutively express αvβ3, showed a CTX A5 binding profile similar to that of membrane-bound and soluble αvβ3 integrins, suggesting that endothelial cells are a potential target for CTX action. We tested whether CTX A5 inhibits osteoclast differentiation and bone resorption, a process known to be involved in αvβ3 binding and inhibited by RGD-containing peptides. We demonstrate that CTX A5 inhibited both activities at a micromolar range by binding to murine αvβ3 integrin in osteoclasts and that CTX A5 co-localized with β3 integrin. Finally, after comparing the integrin binding affinity among CTX homologs, we propose that the amino acid residues near the two loops of CTX A5 are involved in integrin binding. These results identify CTX A5 as a non-RGD integrin-binding protein with therapeutic potential as an integrin antagonist.

Original languageEnglish
Pages (from-to)7937-7945
Number of pages9
JournalJournal of Biological Chemistry
Volume281
Issue number12
DOIs
Publication statusPublished - Mar 24 2006
Externally publishedYes

Fingerprint

Cobra Cardiotoxin Proteins
Cardiotoxins
Bone Resorption
Integrins
Carrier Proteins
Bone
Elapidae
Osteoclasts
Endothelial cells
Taiwan
Endothelial Cells
Sulfoglycosphingolipids
Cobra Venoms
Snake Bites
Tissue
Membranes

ASJC Scopus subject areas

  • Biochemistry

Cite this

Non-cytotoxic cobra cardiotoxin A5 binds to αvβ3 integrin and inhibits bone resorption : Identification of cardiotoxins as non-rgd integrin-binding proteins of the Ly-6 family. / Wu, Po Long; Lee, Shao Chen; Chuang, Chia Chen; Mori, Seiji; Akakura, Nobuaki; Wu, Wen Guey; Takada, Yoshikazu.

In: Journal of Biological Chemistry, Vol. 281, No. 12, 24.03.2006, p. 7937-7945.

Research output: Contribution to journalArticle

Wu, Po Long ; Lee, Shao Chen ; Chuang, Chia Chen ; Mori, Seiji ; Akakura, Nobuaki ; Wu, Wen Guey ; Takada, Yoshikazu. / Non-cytotoxic cobra cardiotoxin A5 binds to αvβ3 integrin and inhibits bone resorption : Identification of cardiotoxins as non-rgd integrin-binding proteins of the Ly-6 family. In: Journal of Biological Chemistry. 2006 ; Vol. 281, No. 12. pp. 7937-7945.
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abstract = "Severe tissue necrosis with a retarded wound healing process is a major symptom of a cobra snakebite. Cardiotoxins (CTXs) are major components of cobra venoms that belong to the Ly-6 protein family and are implicated in tissue damage. The interaction of the major CTX from Taiwan cobra, i.e. CTX A3, with sulfatides in the cell membrane has recently been shown to induce pore formation and cell internalization and to be responsible for cytotoxicity in cardiomyocytes (Wang, C.-H., Liu, J.-H., Lee, S.-C., Hsiao, C.-D., and Wu, W.-g. (2006) J. Biol. Chem. 281, 656-667). We show here that one of the non-cytotoxic CTXs, i.e. CTX A5 or cardiotoxin-like basic polypeptide, from Taiwan cobra specifically bound to αvβ3 integrin and inhibited bone resorption activity. We found that both membrane-bound and recombinant soluble αvβ3 integrins bound specifically to CTX A5 in a dose-dependent manner. Surface plasmon resonance analysis showed that human soluble αvβ3 bound to CTX A5 with an apparent affinity of ∼0.3 μM. Calf pulmonary artery endothelial cells, which constitutively express αvβ3, showed a CTX A5 binding profile similar to that of membrane-bound and soluble αvβ3 integrins, suggesting that endothelial cells are a potential target for CTX action. We tested whether CTX A5 inhibits osteoclast differentiation and bone resorption, a process known to be involved in αvβ3 binding and inhibited by RGD-containing peptides. We demonstrate that CTX A5 inhibited both activities at a micromolar range by binding to murine αvβ3 integrin in osteoclasts and that CTX A5 co-localized with β3 integrin. Finally, after comparing the integrin binding affinity among CTX homologs, we propose that the amino acid residues near the two loops of CTX A5 are involved in integrin binding. These results identify CTX A5 as a non-RGD integrin-binding protein with therapeutic potential as an integrin antagonist.",
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AU - Lee, Shao Chen

AU - Chuang, Chia Chen

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AU - Wu, Wen Guey

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