Gln-362 of Angiopoietin-2 Mediates Migration of Tumor and Endothelial Cells through Association with α5β1 Integrin

Hyo Seon Lee,Seung Ja Oh,Kwang-Hoon Lee,Yoon-Sook Lee,Eun Ko,Kyung Eun Kim,Hyung-Chan Kim,Seokkyun Kim,Paul H Song,Yong-In Kim,Chungho Kim,Sangyeul Han

doi:10.1074/jbc.m114.572594

Hyo Seon Lee, Seung Ja Oh + Show 10 more

Open Access

https://doi.org/10.1074/jbc.m114.572594

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Abstract

Angiopoietin-2 (Ang-2) not only regulates angiogenesis by binding to its well known receptor Tie2 on endothelial cells but also controls sprouting of Tie2-negative angiogenic endothelial cells and invasion of Tie2-negative non-endothelial cells by binding to integrins. However, the molecular mechanism of the Ang-2/integrin association has been unclear. In this study, we found that the Gln-362 residue of Ang-2 was essential for binding to α5β1 integrin. A Q362E Ang-2 mutant, which still bound to Tie2, failed to associate with α5β1 integrin and was unable to activate the integrin downstream signaling of focal adhesion kinase. In addition, unlike wild-type Ang-2, the Q362E Ang-2 mutant was defective in mediating invasion of Tie2-negative glioma or Tie2-positive endothelial cells. Furthermore, the tailpiece domain of the α5 subunit in α5β1 integrin was critical for binding to Ang-2. Taken together, these results provide a novel insight into the mechanism of integrin regulation by Ang-2, which contributes to tumor invasion and endothelial cell migration in a Tie2-independent manner.

Highlights

The angiogenic growth factor angiopoietin-2 regulates angiogenesis through Tie2 and integrins
Because the Q362E mutation does not have any effects on the Ang-2/Tie2 interaction (Fig. 4, D and E), these results suggest that the Ang-2/integrin interaction is primarily responsible for the migration and invasion of Tie2-positive Human umbilical vein endothelial cells (HUVECs)
The function of Ang-2 in angiogenesis and tumor metastasis is mediated by interaction with several integrins as well as the well known endothelial cell receptor Tie2

Summary

Background

The angiogenic growth factor angiopoietin-2 regulates angiogenesis through Tie and integrins. The tailpiece domain of the ␣5 subunit in ␣5␤1 integrin was critical for binding to Ang-2 Taken together, these results provide a novel insight into the mechanism of integrin regulation by Ang-2, which contributes to tumor invasion and endothelial cell migration in a Tie2-independent manner. Ang-2 binds to ␣v␤3, ␣5␤1, and ␣v␤5 integrins with lower affinity than Tie, which activates FAK phosphorylation at Tyr-397 and enhances sprouting and migration of Tie2-negative tip cells [12]. Despite these reports, detailed information about the binding domains that mediate their association is still lacking. This study suggests that blockade of Ang-2/integrin interaction by targeting a domain including the Gln-362 residue of Ang-2 could be effective for inhibition of tumor invasion and metastasis

EXPERIMENTAL PROCEDURES

RESULTS

DISCUSSION