Blockade of hexokinase activity and binding to mitochondria inhibits neurite outgrowth in cultured adult rat sensory neurons.
Hexokinase is known as the first enzyme and rate-limiting step in glycolysis. The role of hexokinase activity and localization in regulating the rate of axonal regeneration was studied in cultured adult sensory neurons of dorsal root ganglia (DRG). Immunofluorescent staining of DRG demonstrated that small-medium neurons and satellite cells exhibited high levels of expression of hexokinase I. Large neurons had negative staining for hexokinase I. Intracellular localization and biochemical studies in cultured adult rat sensory neurons revealed that hexokinase I was almost exclusively found in the mitochondrial compartment. The hypothesis that neurotrophic factor dependent activation of Akt would regulate hexokinase association with the mitochondria was tested and quantitative Western blotting showed no effect of blockade of the phosphoinositide 3-kinase (PI 3-kinase)/Akt pathway using the inhibitor LY294002, indicating this interaction of hexokinase with mitochondria was not neurotrophic factor or Akt-dependent. Finally, pharmacological blockade of hexokinase activity and inhibition of localization to the mitochondrial compartment with hexokinase II VDAC binding domain (Hxk2VBD) peptide caused a significant inhibition of neurotrophic factor-directed axon outgrowth. The results support a key role for hexokinase activity and/or localization to the mitochondria in the regulation of neurite outgrowth in cultured adult sensory neurons.
Wang
Zuocheng
Z
Division of Neurodegenerative Disorders, St Boniface Research Centre, Winnipeg, Manitoba, Canada.
Gardiner
Natalie J
NJ
Fernyhough
Paul
P
D000367:Age Factors; D000818:Animals; D001665:Binding Sites / Q000187:drug effects / Q000502:physiology; D048429:Cell Size; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005727:Ganglia, Spinal / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D020439:Growth Cones / Q000187:drug effects / Q000201:enzymology*; D006593:Hexokinase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology*; D009414:Nerve Growth Factors / Q000378:metabolism; D009416:Nerve Regeneration / Q000187:drug effects / Q000502:physiology*; D016501:Neurites / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology; D009475:Neurons, Afferent / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D010446:Peptide Fragments / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D051057:Proto-Oncogene Proteins c-akt / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
D004791:Enzyme Inhibitors; D009414:Nerve Growth Factors; D010446:Peptide Fragments; D006593:Hexokinase; D051057:Proto-Oncogene Proteins c-akt