Alterations in expression of angiopoietins and the Tie-2 receptor in the retina of streptozotocin induced diabetic rats.
OBJECTIVE
The angiopoietin (Ang)/Tie-2 system may play a role in vascular integrity and angiogenesis. In this study, we investigated alterations of the gene expression of Ang-1 and Ang-2 in the retinas of streptozotocin (STZ) induced diabetic rats.


METHODS
In situ hybridization, reverse transcriptase polymerase chain reaction (RT-PCR) and western blot analyses were performed to determine the mRNA and protein content for Ang-1 and Ang-2 and the Tie2 receptor in the retinas of STZ diabetic and age matched control rats.


RESULTS
Using in situ hybridization analysis, Ang-1, Ang-2, and Tie2 mRNA expression was observed in the ganglion cell layer (GCL) and the inner nuclear layer (INL). While Ang-2 mRNA expression did not changed after 2 weeks, 1 month, or 3 months of STZ induced diabetes, it was increased in the GCL and slightly elevated in the INL after 6 months of diabetes. In contrast, Ang-1 and Tie2 mRNA expression was stable at every timepoint during 6 months of STZ induced diabetes. RT-PCR and western blot analyses confirmed the increase of Ang-2 expression after 6 months of diabetes. Furthermore, double staining of alpha-smooth muscle actin (alphaSMA) and Ang-2 mRNA demonstrated that the SMA positive cells surrounding Ang-2-expressing cells were decreased in the GCL.


CONCLUSIONS
Diabetes increases Ang-2 expression in the GCL accompanied by a reduction of alphaSMA positive perivascular cells. These changes may suggest a role for Ang-2 in the mechanism of pericyte loss in diabetic retinopathy.
Ohashi
Hirokazu
H
Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Takagi
Hitoshi
H
Koyama
Shinji
S
Oh
Hideyasu
H
Watanabe
Daisuke
D
Antonetti
David A
DA
Matsubara
Takeshi
T
Nagai
Kojiro
K
Arai
Hidenori
H
Kita
Toru
T
Honda
Yoshihito
Y
D042683:Angiopoietin-1 / Q000235:genetics* / Q000378:metabolism; D042702:Angiopoietin-2 / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D003930:Diabetic Retinopathy / Q000378:metabolism*; D005786:Gene Expression Regulation; D007124:Immunoenzyme Techniques; D017403:In Situ Hybridization; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D042787:Receptor, TIE-2 / Q000235:genetics* / Q000378:metabolism; D012160:Retina / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D042683:Angiopoietin-1; D042702:Angiopoietin-2; D012333:RNA, Messenger; D042787:Receptor, TIE-2