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  • The EMBO Journal (2003) 22, 1134 - 1146
  • doi:10.1093/emboj/cdg117

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

Masanobu Morita1,5, Osamu Ohneda2,5, Toshiharu Yamashita1,2, Satoru Takahashi2, Norio Suzuki2, Osamu Nakajima2, Shimako Kawauchi2, Masatsugu Ema1, Shigeki Shibahara3, Tetsuo Udono4, Koji Tomita4, Makoto Tamai4, Kazuhiro Sogawa1, Masayuki Yamamoto2 and Yoshiaki Fujii-Kuriyama1,2

  1. Department of Chemistry, Graduate School of Science, Tohoku University, Aoba, Aoba-ku, Sendai, 980-8578, Japan
  2. Center for Tsukuba Advanced Research Alliance and Institute of Basic Medical Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, 305-8577, Japan
  3. Department of Molecular Biology and Applied Physiology, Tohoku University School of Medicine, 2-1 Seiryo-cho, Aoba-ku, Sendai, 980-8575, Japan
  4. Department of Ophthalmology, Tohoku University School of Medicine, 2-1 Seiryo-cho, Aoba-ku, Sendai, 980-8575, Japan
  5. M.Morita and O.Ohneda contributed equally to this work

Correspondence to:

Yoshiaki Fujii-Kuriyama, E-mail: ykfujii@tara.tsukuba.ac.jp

Received 12 March 2002; Accepted 14 January 2003; Revised 24 October 2002

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 (HLFkd/kd) mice by inserting a neomycin gene sandwiched between two loxP sequences into exon 1 of the HLF gene. HLFkd/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 HLFkd/kd mice, whereas prolonged normoxia following hyperoxic treatment caused degeneration of retinal neural layers in HLFkd/kd mice due to poor vascularization. Cre-mediated removal of the inserted gene recovered normal HLF expression and retinal neovascularization in HLFkd/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 HLFkd/kd mouse, this suggests that Epo is one of the target genes of HLF responsible for experimental ROP.

  • Keywords:

    • erythropoietin,
    • HLF,
    • neovascularization,
    • retinopathy,
    • VEGF