Frataxin deficiency increases cyclooxygenase 2 and prostaglandins in cell and animal models of Friedreich's ataxia

Hum Mol Genet. 2014 Dec 20;23(25):6838-47. doi: 10.1093/hmg/ddu407. Epub 2014 Aug 7.

Abstract

An inherited deficiency of the mitochondrial protein frataxin causes Friedreich's ataxia (FRDA); the mechanism by which this deficiency triggers neuro- and cardio-degeneration is unclear. Microarrays of neural tissue of animal models of the disease showed decreases in antioxidant genes, and increases in inflammatory genes. Cyclooxygenase (COX)-derived oxylipins are important mediators of inflammation. We measured oxylipin levels using tandem mass spectrometry and ELISAs in multiple cell and animal models of FRDA. Mass spectrometry revealed increases in concentrations of prostaglandins, thromboxane B2, 15-HETE and 11-HETE in cerebellar samples of knockin knockout mice. One possible explanation for the elevated oxylipins is that frataxin deficiency results in increased COX activity. While constitutive COX1 was unchanged, inducible COX2 expression was elevated over 1.35-fold (P < 0.05) in two Friedreich's mouse models and Friedreich's lymphocytes. Consistent with higher COX2 expression, its activity was also increased by 58% over controls. COX2 expression is driven by multiple transcription factors, including activator protein 1 and cAMP response element-binding protein, both of which were elevated over 1.52-fold in cerebella. Taken together, the results support the hypothesis that reduced expression of frataxin leads to elevation of COX2-mediated oxylipin synthesis stimulated by increases in transcription factors that respond to increased reactive oxygen species. These findings support a neuroinflammatory mechanism in FRDA, which has both pathomechanistic and therapeutic implications.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • B-Lymphocytes / metabolism
  • B-Lymphocytes / pathology
  • Cell Line
  • Cerebellum / metabolism*
  • Cerebellum / pathology
  • Cyclic AMP Response Element-Binding Protein / genetics
  • Cyclic AMP Response Element-Binding Protein / metabolism
  • Cyclooxygenase 1 / genetics
  • Cyclooxygenase 1 / metabolism
  • Cyclooxygenase 2 / genetics*
  • Cyclooxygenase 2 / metabolism
  • Friedreich Ataxia / genetics*
  • Friedreich Ataxia / metabolism
  • Friedreich Ataxia / pathology
  • Gene Expression Regulation
  • Humans
  • Hydroxyeicosatetraenoic Acids / metabolism
  • Inflammation / genetics
  • Inflammation / metabolism
  • Inflammation / pathology
  • Iron-Binding Proteins / genetics*
  • Iron-Binding Proteins / metabolism
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Oxylipins / metabolism*
  • Prostaglandins / metabolism
  • Reactive Oxygen Species / metabolism
  • Signal Transduction
  • Thromboxane B2 / metabolism
  • Transcription Factor AP-1 / genetics
  • Transcription Factor AP-1 / metabolism

Substances

  • Cyclic AMP Response Element-Binding Protein
  • Hydroxyeicosatetraenoic Acids
  • Iron-Binding Proteins
  • Membrane Proteins
  • Oxylipins
  • Prostaglandins
  • Reactive Oxygen Species
  • Transcription Factor AP-1
  • frataxin
  • Thromboxane B2
  • 11-hydroxy-5,8,12,14-eicosatetraenoic acid
  • 15-hydroxy-5,8,11,13-eicosatetraenoic acid
  • Ptgs2 protein, mouse
  • Cyclooxygenase 1
  • Cyclooxygenase 2
  • Ptgs1 protein, mouse