Caspase signalling controls microglia activation and neurotoxicity

Nature. 2011 Apr 21;472(7343):319-24. doi: 10.1038/nature09788. Epub 2011 Mar 9.

Abstract

Activation of microglia and inflammation-mediated neurotoxicity are suggested to play a decisive role in the pathogenesis of several neurodegenerative disorders. Activated microglia release pro-inflammatory factors that may be neurotoxic. Here we show that the orderly activation of caspase-8 and caspase-3/7, known executioners of apoptotic cell death, regulate microglia activation through a protein kinase C (PKC)-δ-dependent pathway. We find that stimulation of microglia with various inflammogens activates caspase-8 and caspase-3/7 in microglia without triggering cell death in vitro and in vivo. Knockdown or chemical inhibition of each of these caspases hindered microglia activation and consequently reduced neurotoxicity. We observe that these caspases are activated in microglia in the ventral mesencephalon of Parkinson's disease (PD) and the frontal cortex of individuals with Alzheimer's disease (AD). Taken together, we show that caspase-8 and caspase-3/7 are involved in regulating microglia activation. We conclude that inhibition of these caspases could be neuroprotective by targeting the microglia rather than the neurons themselves.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alzheimer Disease / enzymology
  • Alzheimer Disease / pathology
  • Animals
  • Caspase 3 / deficiency
  • Caspase 3 / metabolism
  • Caspase 7 / deficiency
  • Caspase 7 / metabolism
  • Caspase 8 / genetics
  • Caspase 8 / metabolism
  • Caspase Inhibitors
  • Caspases / deficiency
  • Caspases / metabolism*
  • Cell Death / drug effects
  • Cells, Cultured
  • Dopamine / metabolism
  • Enzyme Activation
  • Frontal Lobe / enzymology
  • Frontal Lobe / pathology
  • Gene Knockdown Techniques
  • Humans
  • Lipopolysaccharides / pharmacology
  • Mice
  • Microglia / drug effects
  • Microglia / physiology*
  • Neostriatum / metabolism
  • Neurotoxicity Syndromes / enzymology*
  • Neurotoxicity Syndromes / metabolism
  • Neurotoxicity Syndromes / pathology*
  • Parkinson Disease / enzymology
  • Parkinson Disease / pathology
  • Protein Kinase C-delta / chemistry
  • Protein Kinase C-delta / metabolism
  • Rats
  • Signal Transduction*
  • Substantia Nigra / enzymology
  • Substantia Nigra / pathology
  • Toll-Like Receptor 4 / metabolism

Substances

  • Caspase Inhibitors
  • Lipopolysaccharides
  • Toll-Like Receptor 4
  • Protein Kinase C-delta
  • Caspase 3
  • Caspase 7
  • Caspase 8
  • Caspases
  • Dopamine