MicroRNA 146a locally mediates distal axonal growth of dorsal root ganglia neurons under high glucose and sildenafil conditions

Neuroscience. 2016 Aug 4;329:43-53. doi: 10.1016/j.neuroscience.2016.05.005. Epub 2016 May 7.

Abstract

Axonal loss contributes to induction of diabetic peripheral neuropathy. Sildenafil, a phosphodiesterase type 5 inhibitor, ameliorates neurological dysfunction in diabetic peripheral neuropathy. However, the direct effect of high glucose and sildenafil on axonal growth has not been extensively investigated. Using rat primary dorsal root ganglia (DRG) neurons cultured in a microfluidic chamber, we investigated the effect of axonal application of high glucose and sildenafil on distal axonal growth. We found that axonal, but not cell body, application of high glucose locally inhibited distal axonal growth. However, axonal application of sildenafil overcame high glucose-reduced axonal growth. Quantitative real-time RT-PCR (qRT-PCR) and Western blot analysis of distal axonal samples revealed that high glucose reduced axonal miR-146a levels and substantially increased miR-146a target genes, IRAK1 and TRAF6 in the axon. In contrast, sildenafil significantly reversed high glucose-reduced miR-146a levels and high glucose-increased IRAK1 and TRAF6. Gain- and loss-of function of miR-146a in DRG neurons revealed that miR-146a mediated the local effect of high glucose on the distal axonal growth. These in vitro data provide new insights into molecular mechanisms of diabetic peripheral neuropathy.

Keywords: axonal growth; diabetes; miR-146a; peripheral neuropathy; sildenafil.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Argonaute Proteins / metabolism
  • Axons / drug effects
  • Axons / metabolism*
  • Axons / pathology
  • Cells, Cultured
  • DEAD-box RNA Helicases / metabolism
  • Diabetes Mellitus, Experimental / drug therapy
  • Diabetes Mellitus, Experimental / metabolism
  • Diabetes Mellitus, Experimental / pathology
  • Diabetic Neuropathies / drug therapy
  • Diabetic Neuropathies / metabolism*
  • Diabetic Neuropathies / pathology
  • Ganglia, Spinal / drug effects
  • Ganglia, Spinal / metabolism*
  • Ganglia, Spinal / pathology
  • Glucose
  • Interleukin-1 Receptor-Associated Kinases / metabolism
  • MicroRNAs / metabolism*
  • Neuronal Outgrowth / drug effects
  • Neuronal Outgrowth / physiology
  • Neuroprotective Agents / pharmacology*
  • Phosphodiesterase 5 Inhibitors / pharmacology
  • Rats, Wistar
  • Ribonuclease III / metabolism
  • Sildenafil Citrate / pharmacology*
  • TNF Receptor-Associated Factor 6 / metabolism

Substances

  • Ago2 protein, rat
  • Argonaute Proteins
  • MIRN146 microRNA, rat
  • MicroRNAs
  • Neuroprotective Agents
  • Phosphodiesterase 5 Inhibitors
  • TNF Receptor-Associated Factor 6
  • Sildenafil Citrate
  • IRAK1 protein, rat
  • Interleukin-1 Receptor-Associated Kinases
  • Dicer1 protein, rat
  • Ribonuclease III
  • DEAD-box RNA Helicases
  • Glucose