Colocalization of neuropilin-1 and Flk-1 in retinal neovascularization in a mouse model of retinopathy.
OBJECTIVE
To investigate the mechanisms of the development of retinal neovascularization, the localizations of vascular endothelial (VEGF) receptors Flk-1 and neuropilin (NP)-1 mRNAs were examined.


METHODS
The model of retinopathy of prematurity (ROP) was produced by ischemia-induced ocular neovascularization, by exposing postnatal day-7 mice to 75% oxygen for 5 days and then returning them to room air for 5 days. Retinal neovascularization was visualized by injection of fluorescein-dextran. Expression of Flk-1 and NP-1 mRNAs were examined by in situ hybridization with flatmount and serial sections of the retina. The localization of NP-1 was also confirmed by immunohistochemistry. Blood vessel patterns were characterized by immunohistochemical localization of von Willebrand factor (vWF).


RESULTS
Flatmount in situ hybridization showed intense expression of NP-1 and Flk-1 mRNAs colocalized in the area of neovascularization. In situ hybridization of serial sections of the retina revealed that expression of Flk-1 and NP-1 was restricted to neovascularized vessels of the retina from ROP mice.


CONCLUSIONS
The restricted expression of Flk-1 and NP-1 on neovascularized vessels suggests that these molecules may play important roles in retinal neovascularization. This is the first report of the colocalization of NP-1 and Flk-1 on neovascularized vessels of the retina from ROP mice.
Ishihama
H
H
Department of Biochemistry, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan. ishihama@tsuru.med.nagoya-u.ac.jp
Ohbayashi
M
M
Kurosawa
N
N
Kitsukawa
T
T
Matsuura
O
O
Miyake
Y
Y
Muramatsu
T
T
D000818:Animals; D017931:DNA Primers / Q000737:chemistry; D007124:Immunoenzyme Techniques; D017403:In Situ Hybridization; D051379:Mice; D008810:Mice, Inbred C57BL; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D039942:Neuropilin-1; D012333:RNA, Messenger / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D017978:Receptors, Growth Factor / Q000235:genetics / Q000378:metabolism*; D011975:Receptors, Mitogen / Q000235:genetics / Q000378:metabolism*; D040262:Receptors, Vascular Endothelial Growth Factor; D015861:Retinal Neovascularization / Q000378:metabolism* / Q000473:pathology; D012171:Retinal Vessels / Q000378:metabolism / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction
D017931:DNA Primers; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D017978:Receptors, Growth Factor; D011975:Receptors, Mitogen; D039942:Neuropilin-1; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor