Basement membrane and growth factor gene expression in normal and diabetic human retinas.
OBJECTIVE
Recently, we found abnormal accumulation of several extracellular matrix components in retinal basement membranes in human diabetic retinopathy (DR). Others have described increased levels of various growth factors within the vitreous of DR patients. This study examined mRNA levels of these extracellular matrix components and growth factors within human retinal tissues.


METHODS
Total retinal RNA was analyzed by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). RT-PCR products were identified by Southern blotting. Samples were normalized with respect to beta2-microglobulin cDNA. Twenty-one retinas were analyzed: 6 normal, 7 diabetic without DR and 8 diabetic with DR.


RESULTS
In diabetic retinas without DR, the expression levels of most genes were similar to normal. In DR retinas, tenascin-C mRNA expression increased compared to both normal and diabetics without DR. By RT-PCR and Northern blotting, mainly small tenascin-C mRNA isoforms were expressed, and some of them were elevated in DR retinas. Fibronectin mRNA was elevated in DR compared to normal retinas, possibly due to the overexpression of extradomain A-containing isoform (ED-A+, or cellular fibronectin). In DR retinas, gene expression of vascular endothelial growth factor and placenta growth factor was elevated compared to normal, although mRNA for these growth factors receptors (VEGFR-1/Flt-1 and VEGFR-2/KDR) did not change significantly. Transforming growth factor-beta1 mRNA also increased in DR retinas.


CONCLUSIONS
The data suggest that proliferative DR development may be associated with increased retinal expression of vascular endothelial growth factor, placenta growth factor and transforming growth factor-beta1 that possibly triggers the deposition of small tenascin-C isoforms in the blood vessel walls. Angiogenesis-stimulating tenascin-C may further promote diabetic retinal neovascularization.
Spirin
K S
KS
Ophthalmology Research Laboratories, Cedars-Sinai Medical Center, UCLA Medical School Affiliate, Los Angeles, CA 90048, USA.
Saghizadeh
M
M
Lewin
S L
SL
Zardi
L
L
Kenney
M C
MC
Ljubimov
A V
AV
D000368:Aged; D000369:Aged, 80 and over; D001485:Basement Membrane / Q000502:physiology*; D003920:Diabetes Mellitus / Q000378:metabolism*; D003930:Diabetic Retinopathy / Q000378:metabolism; D016228:Endothelial Growth Factors / Q000235:genetics; D016326:Extracellular Matrix Proteins / Q000235:genetics; D005260:Female; D005353:Fibronectins / Q000235:genetics; D015870:Gene Expression / Q000502:physiology*; D006133:Growth Substances / Q000235:genetics*; D006801:Humans; D008222:Lymphokines / Q000235:genetics; D008297:Male; D008875:Middle Aged; D000072483:Placenta Growth Factor; D011257:Pregnancy Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D012016:Reference Values; D019063:Tenascin / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D016326:Extracellular Matrix Proteins; D005353:Fibronectins; D006133:Growth Substances; D008222:Lymphokines; C000608036:PGF protein, human; D011257:Pregnancy Proteins; D012333:RNA, Messenger; D019063:Tenascin; D016212:Transforming Growth Factor beta; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D000072483:Placenta Growth Factor