We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Insulin-Mediated Down-Regulation of the Anti-Angiogenic Protein PEDF is mTOR Dependent.
- Authors
Wang, Binhui; Atherton, Philip J.; Manning, Gillian; Donnelly, Richard
- Abstract
Pigment Epithelium Derived Factor (PEDF) is a potent anti-angiogenic protein that is inversely associated with diabetic microangiopathy. Decreased expression of PEDF has been implicated in proliferative diabetic retinopathy, and we have previously shown that insulin down-regulates expression of PEDF mRNA but the underlying pathways and mechanisms involved are unclear. Human umbilical artery smooth muscle cells were cultured to confluence, serum starved and quiesced in low-serum medium for 24hrs. Cells were then exposed to Insulin 100 nM alone or insulin + inhibitors of PI3K (wortmannin 100nM), MEK/ERK (PD98056 100uM) or mTOR (rapamycin 100nM) for 24hr. Following cell lysis, total RNA was extracted and a cDNA pool created for analysis of PEDF mRNA by real time RT-PCR on a Bio-Rad iCycler. In comparison with untreated cells, when normalized to the housekeeping gene beta2-microglobulin (B2MG), insulin reduced the expression of PEDF mRNA by 39% (n= 12, p<0.001). Neither wortmannin or PD98059 significantly influenced the inhibitory effect of insulin on PEDF mRNA expression: PEDF mRNA relative to B2MG was decreased by 23% (n=8, p=0.021) and 35% (n=8, p=0.04), respectively. In contrast, insulin-mediated suppression of PEDF was abolished in the presence of rapamycin (n=12, p=0.005). Insulin-mediated down-regulation of PEDF expression is potentially important in the development of proliferative retinopathy, and this study has shown that the effect is substantially mediated by the mTOR intracellular signaling pathway.
- Subjects
EPITHELIUM; VASCULAR endothelial growth factors; DIABETES complications; DIABETIC retinopathy; MESSENGER RNA; INSULIN; RAPAMYCIN
- Publication
Diabetes, 2007, Vol 56, pA212
- ISSN
0012-1797
- Publication type
Article