HLF/HIF-2alpha is a key factor in retinopathy of prematurity in association with erythropoietin

EMBO J. 2003 Mar 3;22(5):1134-46. doi: 10.1093/emboj/cdg117.


An HLF (HIF-1alpha-like factor)/HIF-2alpha-knockout mouse is embryonic lethal, preventing investigation of HLF function in adult mice. To investigate the role of HLF in adult pathological angiogenesis, we generated HLF-knockdown (HLF(kd/kd)) mice by inserting a neomycin gene sandwiched between two loxP sequences into exon 1 of the HLF gene. HLF(kd/kd) mice expressing 80-20% reduction, depending on the tissue, in wild-type HLF mRNA were fertile and apparently normal. Hyperoxia-normoxia treatment, used as a murine model of retinopathy of prematurity (ROP), induced neovascularization in wild-type mice, but not in HLF(kd/kd) mice, whereas prolonged normoxia following hyperoxic treatment caused degeneration of retinal neural layers in HLF(kd/kd) mice due to poor vascularization. Cre-mediated removal of the inserted gene recovered normal HLF expression and retinal neovascularization in HLF(kd/kd) mice. Expression levels of various angiogenic factors revealed that only erythropoietin (Epo) gene expression was significantly affected, in parallel with HLF expression. Together with the results from intraperitoneal injection of Epo into HLF(kd/kd) mouse, this suggests that Epo is one of the target genes of HLF responsible for experimental ROP.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies / metabolism
  • Basic Helix-Loop-Helix Transcription Factors
  • Disease Models, Animal
  • Electroretinography
  • Erythropoietin / metabolism*
  • Female
  • Gene Expression Regulation
  • Gene Targeting
  • Genetic Vectors
  • Helix-Loop-Helix Motifs
  • Humans
  • Hyperoxia / metabolism
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Immunohistochemistry
  • In Situ Nick-End Labeling
  • Infant, Newborn
  • Integrases / genetics
  • Integrases / metabolism
  • Mice
  • Mice, Knockout
  • RNA, Messenger / metabolism
  • Retina / cytology
  • Retina / metabolism
  • Retina / pathology
  • Retinal Neovascularization*
  • Retinopathy of Prematurity / metabolism*
  • Tissue Distribution
  • Trans-Activators / genetics
  • Trans-Activators / metabolism*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Vimentin / metabolism
  • Viral Proteins / genetics
  • Viral Proteins / metabolism


  • Antibodies
  • Basic Helix-Loop-Helix Transcription Factors
  • HIF1A protein, human
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • RNA, Messenger
  • Trans-Activators
  • Transcription Factors
  • Vimentin
  • Viral Proteins
  • Erythropoietin
  • endothelial PAS domain-containing protein 1
  • Cre recombinase
  • Integrases