Advanced glycation end products in extracellular matrix proteins contribute to the failure of sensory nerve regeneration in diabetes.
OBJECTIVE
The goal of this study was to characterize glycation adducts formed in both in vivo extracellular matrix (ECM) proteins of endoneurium from streptozotocin (STZ)-induced diabetic rats and in vitro by glycation of laminin and fibronectin with methylglyoxal and glucose. We also investigated the impact of advanced glycation end product (AGE) residue content of ECM on neurite outgrowth from sensory neurons.


METHODS
Glycation, oxidation, and nitration adducts of ECM proteins extracted from the endoneurium of control and STZ-induced diabetic rat sciatic nerve (3-24 weeks post-STZ) and of laminin and fibronectin that had been glycated using glucose or methylglyoxal were examined by liquid chromatography with tandem mass spectrometry. Methylglyoxal-glycated or unmodified ECM proteins were used as substrata for dissociated rat sensory neurons as in vitro models of regeneration.


RESULTS
STZ-induced diabetes produced a significant increase in early glycation N(epsilon)-fructosyl-lysine and AGE residue contents of endoneurial ECM. Glycation of laminin and fibronectin by methylglyoxal and glucose increased glycation adduct residue contents with methylglyoxal-derived hydroimidazolone and N(epsilon)-fructosyl-lysine, respectively, of greatest quantitative importance. Glycation of laminin caused a significant decrease in both neurotrophin-stimulated and preconditioned sensory neurite outgrowth. This decrease was prevented by aminoguanidine. Glycation of fibronectin also decreased preconditioned neurite outgrowth, which was prevented by aminoguanidine and nerve growth factor.


CONCLUSIONS
Early glycation and AGE residue content of endoneurial ECM proteins increase markedly in STZ-induced diabetes. Glycation of laminin and fibronectin causes a reduction in neurotrophin-stimulated neurite outgrowth and preconditioned neurite outgrowth. This may provide a mechanism for the failure of collateral sprouting and axonal regeneration in diabetic neuropathy.
Duran-Jimenez
Beatriz
B
Faculty of Life Sciences, University of Manchester, Manchester, U.K.
Dobler
Darin
D
Moffatt
Sarah
S
Rabbani
Naila
N
Streuli
Charles H
CH
Thornalley
Paul J
PJ
Tomlinson
David R
DR
Gardiner
Natalie J
NJ
D000818:Animals; D002853:Chromatography, Liquid; D003921:Diabetes Mellitus, Experimental; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism; D017127:Glycation End Products, Advanced / Q000378:metabolism*; D006146:Guanidines / Q000494:pharmacology; D007797:Laminin / Q000378:metabolism; D009416:Nerve Regeneration / Q000187:drug effects; D016501:Neurites / Q000378:metabolism; D051381:Rats; D012584:Sciatic Nerve / Q000503:physiopathology*; D011984:Sensory Receptor Cells / Q000378:metabolism; D053719:Tandem Mass Spectrometry
D004791:Enzyme Inhibitors; D016326:Extracellular Matrix Proteins; D005353:Fibronectins; D017127:Glycation End Products, Advanced; D006146:Guanidines; D007797:Laminin; C004479:pimagedine