Evaluation of advanced glycation end-products in diabetic and inherited canine cataracts.
BACKGROUND
The receptor for advanced glycation end-products (RAGE) increases in the human cataract and should correlate with increased DNA damage and proliferation of lens epithelial cells (LECs). The purpose of this study was to measure and immunolocalize RAGE in normal and cataractous canine LECs, and to determine whether there was a correlation between RAGE and DNA damage (gadd45), cell-cycle regulation (p21), and LEC proliferation (proliferating cell nuclear antigen, PCNA).


METHODS
Thirty-two anterior lens capsules from 22 dogs that underwent cataract surgery and 10 lenses from dogs with normal eyes were evaluated. Eleven of the cataractous lenses were from diabetic patients (n=16), and eleven were from patients with inherited cataracts (n=16). Standard immunohistochemical staining was performed using antibodies against RAGE, gadd45, p21, PCNA, alpha-smooth muscle actin, and TGF-beta. Immunostaining intensity for each antibody was given a score of 0-4+. Standard Western blot analysis on normal and cataractous lens capsules was performed using the same antibodies as in the immunohistochemical staining. Comparisons were also made based on age and sex. Real-time reverse transcriptase-polymerase chain reaction (qRT-PCR) was performed for RAGE.


RESULTS
There was an increase in RAGE expression with age in normal LECs, but no significant difference was seen when normal adult LECs were compared to cataractous LECs. The stage of the cataract and the presence of LIU were not associated with a significant increase in RAGE expression. There was no age-dependent difference in the normal lenses for gadd45, p21, or PCNA. Significant up-regulation of p21 (P < 0.05) and PCNA (P < 0.05) was seen in diabetic cataracts compared to inherited cataracts.


CONCLUSIONS
RAGE and PCNA expression did not increase with cataractogenesis, possibly due to overexpression associated with normal aging and constant exposure to oxidative stress from sunlight-related ultraviolet irradiation, respectively. However, p21 and PCNA increased in diabetic cataractogenesis suggesting cell cycle and proliferation dysregulation. This may be related to the rapid onset in this type of cataract compared with the more chronic and slower-to-develop inherited cataracts.
Bras
I Dineli
ID
Department of Veterinary Clinical Sciences, The Ohio State University College of Veterinary Medicine, Columbus, OH 43210, USA.
Colitz
Carmen M H
CM
Kusewitt
Donna F
DF
Chandler
Heather
H
Lu
Ping
P
Gemensky-Metzler
Anne J
AJ
Wilkie
David A
DA
D000818:Animals; D015153:Blotting, Western / Q000662:veterinary; D002386:Cataract / Q000235:genetics / Q000378:metabolism / Q000662:veterinary*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004249:DNA Damage; D048909:Diabetes Complications / Q000235:genetics / Q000378:metabolism / Q000662:veterinary*; D004283:Dog Diseases / Q000235:genetics / Q000378:metabolism*; D004285:Dogs; D005260:Female; D017127:Glycation End Products, Advanced / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007124:Immunoenzyme Techniques / Q000662:veterinary; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D007908:Lens, Crystalline / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000097642:GADD45 Proteins
D050759:Cyclin-Dependent Kinase Inhibitor p21; D017127:Glycation End Products, Advanced; D047908:Intracellular Signaling Peptides and Proteins; D018809:Proliferating Cell Nuclear Antigen; D012333:RNA, Messenger; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic; D000097642:GADD45 Proteins