Engineered zinc finger protein-mediated VEGF-a activation restores deficient VEGF-a in sensory neurons in experimental diabetes.
OBJECTIVE
The objectives of the study were to evaluate retrograde axonal transport of vascular endothelial growth factor A (VEGF-A) protein to sensory neurons after intramuscular administration of an engineered zinc finger protein activator of endogenous VEGF-A (VZ+434) in an experimental model of diabetes, and to characterize the VEGF-A target neurons.


METHODS
We compared the expression of VEGF-A in lumbar (L)4/5 dorsal root ganglia (DRG) of control rats and VZ+434-treated and untreated streptozotocin (STZ)-induced diabetic rats. In addition, axonal transport of VEGF-A, activation of signal transduction pathways in the DRG, and mechanical sensitivity were assessed.


RESULTS
VEGF-A immunoreactivity (IR) was detected in small- to medium-diameter neurons in DRG of control rats. Fewer VEGF-A-IR neurons were observed in DRG from STZ-induced diabetic rats; this decrease was confirmed and quantified by Western blotting. VZ+434 administration resulted in a significant increase in VEGF-A protein expression in ipsilateral DRG, 24 h after injection. VEGF-A was axonally transported to the DRG via the sciatic nerve. VZ+434 administration resulted in significant activation of AKT in the ipsilateral DRG by 48 h that was sustained for 1 week after injection. VZ+434 protected against mechanical allodynia 8 weeks after STZ injection.


CONCLUSIONS
Intramuscular administration of VZ+434 increases VEGF-A protein levels in L4/5 DRG, correcting the deficit observed after induction of diabetes, and protects against mechanical allodynia. Elevated VEGF-A levels result from retrograde axonal transport and are associated with altered signal transduction, via the phosphatidylinositol 3'-kinase pathway. These data support a neuroprotective role for VEGF-A in the therapeutic actions of VZ+434 and suggest a mechanism by which VEGF-A exerts this activity.
Pawson
Elizabeth J
EJ
Faculty of Life Sciences, University of Manchester, Manchester, UK.
Duran-Jimenez
Beatriz
B
Surosky
Richard
R
Brooke
Heather E
HE
Spratt
S Kaye
SK
Tomlinson
David R
DR
Gardiner
Natalie J
NJ
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D015536:Down-Regulation; D007839:Functional Laterality; D005727:Ganglia, Spinal / Q000503:physiopathology*; D005818:Genetic Engineering; D007089:Image Enhancement; D007150:Immunohistochemistry; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000503:physiopathology; D009474:Neurons / Q000502:physiology; D010641:Phenotype; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D011984:Sensory Receptor Cells / Q000502:physiology*; D042461:Vascular Endothelial Growth Factor A / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D016335:Zinc Fingers / Q000235:genetics / Q000502:physiology*
D001786:Blood Glucose; D042461:Vascular Endothelial Growth Factor A