Insulin-like growth factor: receptor and binding proteins in human retinal endothelial cell cultures of diabetic and non-diabetic origin.
Human retinal endothelial cell (HREC) cultures of diabetic and non-diabetic origin were examined for the production of insulin-like growth factor I (IGF-I), IGF-I receptor and IGF-binding proteins (IGFBPs) using colloidal gold quantitative immunocytochemistry and quantitative reverse transcriptase-polymerase chain reaction (QRT-PCR). The levels of immunoreactivity for IGF-I receptor and for four IGFBPs (IGFBP-1, -2, -3 and -5) were significantly increased in diabetic HREC cultures. Moreover, diabetic HREC cultures showed significantly less immunoreactivity for IGF-I and for IGFBP-4 as compared to non-diabetic HREC cultures. Message levels for IGF-I decreased two-fold in diabetic HREC and correlated with protein levels. Message levels for IGFBP-1, -2 and -5 increased 1.5-, 1.7- and 1.6-fold, respectively, in diabetic HREC and correlated with protein levels. However, the protein levels for IGF-I receptor and IGFBP-3 and -4 did not correlate with mRNA levels. There were no differences in mRNA levels for IGF-I receptor and IGFBP-3 and -4 between diabetic and non-diabetic HREC cultures, suggesting a post-transcriptional regulation of IGF-I receptor and the two IGFBPs. The net effect, however, supports enhanced IGF-I action in HREC cultures of diabetic origin which is an important cellular event in diabetic retinopathy.
Spoerri
P E
PE
Department of Medicine, College of Medicine, University of Florida, Gainesville, USA.
Ellis
E A
EA
Tarnuzzer
R W
RW
Grant
M B
MB
D002478:Cells, Cultured; D003920:Diabetes Mellitus / Q000378:metabolism* / Q000473:pathology; D003930:Diabetic Retinopathy / Q000378:metabolism; D004727:Endothelium / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D018969:Insulin-Like Growth Factor Binding Proteins / Q000235:genetics / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism*; D008297:Male; D016253:Microscopy, Immunoelectron; D008875:Middle Aged; D012333:RNA, Messenger / Q000378:metabolism; D017526:Receptor, IGF Type 1 / Q000235:genetics / Q000378:metabolism*; D012160:Retina / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D020133:Reverse Transcriptase Polymerase Chain Reaction
D018969:Insulin-Like Growth Factor Binding Proteins; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1