Positive allosteric modulation of P2X7 promotes apoptotic cell death over lytic cell death responses in macrophages

Cell Death Dis. 2019 Nov 25;10(12):882. doi: 10.1038/s41419-019-2110-3.

Abstract

P2X7 is an ATP-gated ion channel that is highly expressed by leukocytes, such as macrophages. Here, P2X7 has been demonstrated to be involved in the regulation of various cell death pathways; including apoptosis, pyroptosis, necrosis, and autophagy. However, cell death induction via P2X7 is complex and is reliant upon the nature of the stimulus, the duration of the stimulus, and the cell type investigated. Previous reports state that high extracellular ATP concentrations promote osmotic lysis, but whether positive allosteric modulation of P2X7 in the presence of lower concentrations of ATP condemns cells to the same fate is unknown. In this study, we compared cell death induced by high ATP concentrations, to cell death induced by compound K, a recently identified and potent positive allosteric modulator of P2X7. Based on our observations, we propose that high ATP concentrations induce early cell swelling, loss of mitochondrial membrane potential, plasma membrane rupture, and LDH release. Conversely, positive allosteric modulation of P2X7 primarily promotes an intrinsic apoptosis pathway. This was characterised by an increase in mitochondrial Ca2+, accelerated production of mitochondrial ROS, loss of mitochondrial membrane permeability in a Bax-dependent manner, the potential involvement of caspase-1, and caspase-3, and significantly accelerated kinetics of caspase-3 activation. This study highlights the ability of positive allosteric modulators to calibrate P2X7-dependent cell death pathways and may have important implications in modulating the antimicrobial immune response and in the resolution of inflammation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Allosteric Regulation
  • Animals
  • Apoptosis / physiology
  • Calcium / metabolism
  • Caspases / metabolism
  • Cell Death / physiology*
  • Cell Line
  • Ginsenosides / pharmacology
  • Macrophages / cytology
  • Macrophages / metabolism*
  • Mice
  • Mitochondria / metabolism
  • Reactive Oxygen Species / metabolism
  • Receptors, Purinergic P2X7 / metabolism*
  • Signal Transduction

Substances

  • Ginsenosides
  • P2rx7 protein, mouse
  • Reactive Oxygen Species
  • Receptors, Purinergic P2X7
  • Adenosine Triphosphate
  • ginsenoside M1
  • Caspases
  • Calcium