Abstract 14388: P75NTR Receptor Regulation of microRNA-503 Controls Diabetes-induced Impairment of Post-ischemic Angiogenesis in Limbs
Background: The molecular mechanisms underpinning diabetes damage of endothelial cells (ECs) are not fully understood. Recently, we demonstrated that the atypical neurotrophin receptor p75NTR is induced by diabetes in ECs and it impairs EC proliferation and angiogenesis. We also showed that microRNA-503 (miR-503) impairs EC cycling. Here we studied whether p75NTR modulates miR-503 expression in the context of diabetes and ischemia.
Methods and Results: Both p75NTR and miR-503 expression (real-time PCR) in HUVECs was increased following culture in high glucose (HG, 25 mM) and reduced of growth factors (LGF) to mimic diabetes and ischemia. siRNA-induced p75NTR knockdown prevented miR-503 expression in ECs under HG-LGF. Conversely, miR-503 inhibition (by adenovirus- decoy.miR-503, Ad.decoy.miR-503) restored EC proliferation under HG-LGF or following p75NTR-transduction.Next, limb ischemia was induced in streptozotocin-induced diabetic and non-diabetic p75NTR−/− and p75NTR+/+ mice. After 3d, miR-503 was 3.6±0.5 folds higher in ischemic muscles of diabetic p75NTR+/+ (P<0.05 vs non-diabetic p75NTR+/+), while it was undetectable in diabetic p75NTR−/− muscles. Moreover, in diabetic p75NTR+/+ mice, Ad.decoy.miR-503 delivery to the ischemic adductor normalized blood flow recovery (colour laser Doppler) and capillary density in ischemic muscles (P=NS vs. non-diabetic mice and P either <0.01 or <0.05 for comparisons vs. diabetic mice given Ad.Null control). Furthermore, in non-diabetic p75NTR+/+ mice, co-infection of ischemic limb muscles with Ad.p75NTR and Ad.decoymiR-503 (controls: Ad.p75NTR+Ad.Null, Ad.Null+Ad.Null and Ad.Null+Ad.decoymiR-503) prevented the p75NTR transduction-induced negative effects on blood flow recovery (P<0.05 vs. Ad.p75NTR+Ad.Null at times 7 and 14 days). Finally, we crossed previously confirmed miR-503 target genes (Forrest et al. Leukemia; 2010) with genes downregulated in p75NTR-transduced limb muscles (Illumina BeadArray gene profiling; accession number GSE9910) to identify Anillin (an actin binding protein with key role in cytokinesis) as potential common mediator of p75NTR and miR−503.
Conclusion: p75NTR regulates miR-503 expression in an ischemia and diabetes setting.
- © 2010 by American Heart Association, Inc.