What are angiopoietins?
Angiopoietins (Ang) are a family of angiogenic growth factors, with Ang-1 and Ang-2 being best characterised for their key roles in vascular development and vascular stability.1

Key players in the Ang–Tie signalling pathway
Ang-1 and Ang-2 bind to the Tie2 receptor and are
important regulators of vascular stability.1
Select a ligand or receptor to learn more
The ligands and receptors below are part of or interact with the angiopoietin pathway.

Discovery of the angiopoietin
pathway: A historical snapshot
Key milestones in our understanding of the Ang–Tie pathway — from early learnings to new
discoveries of its role in retinal diseases.
1996
Identification of Ang-18
Ang-1 identified as a ligand for the Tie2 receptor that could induce Tie2 activation in endothelial cells

1997
Identification of Ang-29
Ang-2 identified as a natural antagonist for the Tie2 receptor

1998
Cooperativity between Ang and VEGF10
Ang-1 and Ang-2 modulate VEGF-induced postnatal neovascularisation
1999
Role of VEGF and Ang-2 in tumour angiogenesis and growth11,12
VEGF and Ang-2 work together to initiate tumour angiogenesis and growth

2000
Ang-1 mechanism in endothelial cell survival13
Ang-1 regulates endothelial cell survival via the Akt/survivin pathway

2002
Ang-2 has agonistic function14
Ang-2 is agonistic in lymphatic vessels and antagonistic in blood vessels
2004
Role of Ang-2 in DR15
Upregulation of Ang-2 plays a critical role in the loss of pericytes in the diabetic retina

2006
Ang-2 functions during
inflammation16
Ang-2 facilitates endothelial cell responsiveness to inflammatory stimuli

2012
Ang-2 and integrin signalling2
Ang-2 differentially regulates angiogenesis through Tie2 and integrin signalling

2016
Ang-2 in retinal and choroidal vascular diseases4
Ang-2 levels are elevated in vitreous samples of patients with nAMD, DR, PDR, and RVO
2020
Ang-2 mechanism in DR mouse model17
High glucose in the presence of retinal damage further compounds vascular damage through Ang-2’s own upregulation and release in a positive feedback loop

AMD, age-related macular degeneration; Ang, angiopoietin; DR, diabetic retinopathy; PDR, proliferative diabetic retinopathy; RVO, retinal vein occlusion; Tie, tyrosine kinase with immunoglobulin-like domains; VEGF, vascular endothelial growth factor; VEGFR, vascular endothelial growth factor receptor; VE-PTP, vascular endothelial protein tyrosine phosphate.
References
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