title: Endothelial TWIST1 promotes pathological ocular angiogenesis.
abstract: OBJECTIVE
  Pathological neovessel formation impacts many blinding vascular eye diseases. Identification of molecular signatures distinguishing pathological neovascularization from normal quiescent vessels is critical for developing new interventions. Twist-related protein 1 (TWIST1) is a transcription factor important in tumor and pulmonary angiogenesis. This study investigated the potential role of TWIST1 in modulating pathological ocular angiogenesis in mice.
  
  
  METHODS
  Twist1 expression and localization were analyzed in a mouse model of oxygen-induced retinopathy (OIR). Pathological ocular angiogenesis in Tie2-driven conditional Twist1 knockout mice were evaluated in both OIR and laser-induced choroidal neovascularization models. In addition, the effects of TWIST1 on angiogenesis and endothelial cell function were analyzed in sprouting assays of aortic rings and choroidal explants isolated from Twist1 knockout mice, and in human retinal microvascular endothelial cells treated with TWIST1 small interfering RNA (siRNA).
  
  
  RESULTS
  TWIST1 is highly enriched in pathological neovessels in OIR retinas. Conditional Tie2-driven depletion of Twist1 significantly suppressed pathological neovessels in OIR without impacting developmental retinal angiogenesis. In a laser-induced choroidal neovascularization model, Twist1 deficiency also resulted in significantly smaller lesions with decreased vascular leakage. In addition, loss of Twist1 significantly decreased vascular sprouting in both aortic ring and choroid explants. Knockdown of TWIST1 in endothelial cells led to dampened expression of vascular endothelial growth factor receptor 2 (VEGFR2) and decreased endothelial cell proliferation.
  
  
  CONCLUSIONS
  Our study suggests that TWIST1 is a novel regulator of pathologic ocular angiogenesis and may represent a new molecular target for developing potential therapeutic treatments to suppress pathological neovascularization in vascular eye diseases.
authors.affiliation: Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, United States Department of Ophthalmology, West China Hospital/West China School of Medicine, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, United States.
authors.forename: Chi-Hsiu
authors.initials: CH
authors.lastname: Liu
authors.affiliation: Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, United States.
authors.forename: Ye
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, United States.
authors.forename: Yan
authors.initials: Y
authors.lastname: Gong
authors.affiliation: Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, United States.
authors.forename: Zhongjie
authors.initials: Z
authors.lastname: Fu
authors.affiliation: Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, United States.
authors.forename: Lucy P
authors.initials: LP
authors.lastname: Evans
authors.affiliation: Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, United States.
authors.forename: Katherine T
authors.initials: KT
authors.lastname: Tian
authors.affiliation: Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, United States.
authors.forename: Aimee M
authors.initials: AM
authors.lastname: Juan
authors.affiliation: Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, United States.
authors.forename: Christian G
authors.initials: CG
authors.lastname: Hurst
authors.affiliation: Vascular Biology Program, Department of Surgery, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, United States.
authors.forename: Akiko
authors.initials: A
authors.lastname: Mammoto
authors.affiliation: Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, United States.
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
mesh_terms: D000818:Animals; D002829:Choroid / Q000098:blood supply; D020256:Choroidal Neovascularization / Q000503:physiopathology*; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000502:physiology; D005451:Fluorescein Angiography; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D055806:Microvessels / Q000378:metabolism; D009389:Neovascularization, Pathologic / Q000503:physiopathology; D009687:Nuclear Proteins / Q000172:deficiency / Q000502:physiology*; D010100:Oxygen / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D015861:Retinal Neovascularization / Q000503:physiopathology*; D012171:Retinal Vessels / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D051879:Twist-Related Protein 1 / Q000172:deficiency / Q000502:physiology*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism
chemical_list: D009687:Nuclear Proteins; D012333:RNA, Messenger; C103173:TWIST1 protein, human; D051879:Twist-Related Protein 1; C000592875:Kdr protein, mouse; D040301:Vascular Endothelial Growth Factor Receptor-2; D010100:Oxygen
keywords: TWIST1; angiogenesis; retinopathy