C-Terminal Heat Shock Protein 90 Inhibitor Decreases Hyperglycemia-induced Oxidative Stress and Improves Mitochondrial Bioenergetics in Sensory Neurons

• Published in: Journal of proteome research Vol. 11; no. 4; pp. 2581 - 2593
• Main Authors: Zhang, Liang, Zhao, Huiping, Blagg, Brian S. J, Dobrowsky, Rick T
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 06.04.2012
• Subjects: Amino Acid Sequence; Analysis of Variance; Animals; Cells, Cultured; Ganglia, Spinal - cytology; Ganglia, Spinal - drug effects; Ganglia, Spinal - metabolism; HSP90 Heat-Shock Proteins - antagonists & inhibitors; HSP90 Heat-Shock Proteins - metabolism; Hyperglycemia - metabolism; Isotope Labeling; Mitochondria - drug effects; Mitochondria - metabolism; Molecular Sequence Data; Novobiocin - analogs & derivatives; Novobiocin - pharmacology; Oxidative Stress - drug effects; Rats; Sensory Receptor Cells - cytology; Sensory Receptor Cells - drug effects; Sensory Receptor Cells - metabolism; Superoxide Dismutase - metabolism; hyperglycemia; mitochondria; superoxide dismutase; SILAC; sensory neurons; diabetes; chaperones; oxidative stress
• ISSN: 1535-3893; 1535-3907
• DOI: 10.1021/pr300056m

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes in which hyperglycemia-induced mitochondrial dysfunction and enhanced oxidative stress contribute to sensory neuron pathology. KU-32 is a novobiocin-based, C-terminal inhibitor of the molecular chaperone, heat shock protein 90 (Hsp90). KU-32 ameliorates multiple sensory deficits associated with the progression of DPN and protects unmyelinated sensory neurons from glucose-induced toxicity. Mechanistically, KU-32 increased the expression of Hsp70, and this protein was critical for drug efficacy in reversing DPN. However, it remained unclear if KU-32 had a broader effect on chaperone induction and if its efficacy was linked to improving mitochondrial dysfunction. Using cultures of hyperglycemically stressed primary sensory neurons, the present study investigated whether KU-32 had an effect on the translational induction of other chaperones and improved mitochondrial oxidative stress and bioenergetics. A variation of stable isotope labeling with amino acids in cell culture called pulse SILAC (pSILAC) was used to unbiasedly assess changes in protein translation. Hyperglycemia decreased the translation of numerous mitochondrial proteins that affect superoxide levels and respiratory activity. Importantly, this correlated with a decrease in mitochondrial oxygen consumption and an increase in superoxide levels. KU-32 increased the translation of Mn superoxide dismutase and several cytosolic and mitochondrial chaperones. Consistent with these changes, KU-32 decreased mitochondrial superoxide levels and significantly enhanced respiratory activity. These data indicate that efficacy of modulating molecular chaperones in DPN may be due in part to improved neuronal mitochondrial bioenergetics and decreased oxidative stress.