Hypoxia induces the expression of membrane-type 1 matrix metalloproteinase in retinal glial cells.
OBJECTIVE
Fibrovascular tissue formation in diabetic retinopathy necessitates not only angiogenic activity but also proteolytic activity, which is at least in part attributable to the induction of membrane-type 1 matrix metalloproteinase (MT1-MMP) in retinal glial cells. However, little is known about the triggers for MT1-MMP induction in the diabetic retina. In the present study, the effect of tissue hypoxia on MT1-MMP expression in retinal glial cells was investigated.


METHODS
Retinal glial cells were isolated from the rabbit retina and cultured under either normoxic (20% O(2)) or hypoxic (1% O(2)) conditions in the presence or absence of the inhibitor for vascular endothelial growth factor (VEGF) receptor signal transduction or a neutralizing antibody against VEGF. The expression level of MT1-MMP in retinal glial cells was analyzed by reverse transcription-polymerase chain reaction (RT-PCR), real-time PCR, Western blot analysis and immunocytochemistry. Expression of VEGF and VEGF receptors, VEGFR-1 and VEGFR-2, was also examined by RT-PCR.


RESULTS
RT-PCR and real-time PCR analyses showed a 2.3-fold induction of MT1-MMP expression in retinal glial cells under hypoxic conditions. VEGF, especially its isoform VEGF(165), and VEGFR-2 were also upregulated in retinal glial cells by hypoxia, and hypoxia-induced MT1-MMP expression was inhibited in the presence of the VEGFR-2 inhibitor SU1498 or the anti-VEGF antibody.


CONCLUSIONS
Hypoxia can induce MT1-MMP expression in retinal glial cells, and the hypoxia-induced expression of MT1-MMP is mediated by VEGF in an autocrine fashion.
Noda
Kousuke
K
Department of Pathology, Keio University School of Medicine, Tokyo, Japan.
Ishida
Susumu
S
Shinoda
Hajime
H
Koto
Takashi
T
Aoki
Takanori
T
Tsubota
Kazuo
K
Oguchi
Yoshihisa
Y
Okada
Yasunori
Y
Ikeda
Eiji
E
D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D002934:Cinnamates / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D019084:Fluorescent Antibody Technique, Indirect; D000860:Hypoxia / Q000378:metabolism*; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D009457:Neuroglia / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D011817:Rabbits; D012160:Retina / Q000166:cytology / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000235:genetics / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism
D002934:Cinnamates; D012333:RNA, Messenger; C483044:SU 1498; D042461:Vascular Endothelial Growth Factor A; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases