| Structural highlights
Function
[ANGP2_HUMAN] Binds to TEK/TIE2, competing for the ANGPT1 binding site, and modulating ANGPT1 signaling. Can induce tyrosine phosphorylation of TEK/TIE2 in the absence of ANGPT1. In the absence of angiogenic inducers, such as VEGF, ANGPT2-mediated loosening of cell-matrix contacts may induce endothelial cell apoptosis with consequent vascular regression. In concert with VEGF, it may facilitate endothelial cell migration and proliferation, thus serving as a permissive angiogenic signal.[1] [2] [3] [4]
Publication Abstract from PubMed
Angiogenesis is a complex cellular process involving multiple regulatory growth factors and growth factor receptors. Among them, the ligands for the endothelial-specific tunica intima endothelial receptor tyrosine kinase 2 (Tie2) receptor kinase, angiopoietin-1 (Ang1) and Ang2, play essential roles in balancing vessel stability and regression during both developmental and tumor-induced angiogenesis. Despite possessing a high degree of sequence identity, Ang1 and Ang2 have distinct functional roles and cell-signaling characteristics. Here, we present the crystal structures of Ang1 both unbound and in complex with the Tie2 ectodomain. Comparison of the Ang1-containing structures with their Ang2-containing counterparts provide insight into the mechanism of receptor activation and reveal molecular surfaces important for interactions with Tie2 coreceptors and associated signaling proteins. Using structure-based mutagenesis, we identify a loop within the angiopoietin P domain, adjacent to the receptor-binding interface, which confers the specific agonist/antagonist properties of the molecule. We demonstrate using cell-based assays that an Ang2 chimera containing the Ang1 loop sequence behaves functionally similarly to Ang1 as a constitutive Tie2 agonist, able to efficiently dissociate the inhibitory Tie1/Tie2 complex and elicit Tie2 clustering and downstream signaling.
Structural basis for angiopoietin-1-mediated signaling initiation.,Yu X, Seegar TC, Dalton AC, Tzvetkova-Robev D, Goldgur Y, Rajashankar KR, Nikolov DB, Barton WA Proc Natl Acad Sci U S A. 2013 Apr 30;110(18):7205-10. doi:, 10.1073/pnas.1216890110. Epub 2013 Apr 16. PMID:23592718[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Maisonpierre PC, Suri C, Jones PF, Bartunkova S, Wiegand SJ, Radziejewski C, Compton D, McClain J, Aldrich TH, Papadopoulos N, Daly TJ, Davis S, Sato TN, Yancopoulos GD. Angiopoietin-2, a natural antagonist for Tie2 that disrupts in vivo angiogenesis. Science. 1997 Jul 4;277(5322):55-60. PMID:9204896
- ↑ Lee HJ, Cho CH, Hwang SJ, Choi HH, Kim KT, Ahn SY, Kim JH, Oh JL, Lee GM, Koh GY. Biological characterization of angiopoietin-3 and angiopoietin-4. FASEB J. 2004 Aug;18(11):1200-8. PMID:15284220 doi:10.1096/fj.03-1466com
- ↑ Yacyshyn OK, Lai PF, Forse K, Teichert-Kuliszewska K, Jurasz P, Stewart DJ. Tyrosine phosphatase beta regulates angiopoietin-Tie2 signaling in human endothelial cells. Angiogenesis. 2009;12(1):25-33. doi: 10.1007/s10456-008-9126-0. Epub 2009 Jan 1. PMID:19116766 doi:10.1007/s10456-008-9126-0
- ↑ Yuan HT, Khankin EV, Karumanchi SA, Parikh SM. Angiopoietin 2 is a partial agonist/antagonist of Tie2 signaling in the endothelium. Mol Cell Biol. 2009 Apr;29(8):2011-22. doi: 10.1128/MCB.01472-08. Epub 2009 Feb, 17. PMID:19223473 doi:10.1128/MCB.01472-08
- ↑ Yu X, Seegar TC, Dalton AC, Tzvetkova-Robev D, Goldgur Y, Rajashankar KR, Nikolov DB, Barton WA. Structural basis for angiopoietin-1-mediated signaling initiation. Proc Natl Acad Sci U S A. 2013 Apr 30;110(18):7205-10. doi:, 10.1073/pnas.1216890110. Epub 2013 Apr 16. PMID:23592718 doi:http://dx.doi.org/10.1073/pnas.1216890110
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