Skip to Content
Merck
  • Microglial NMDA receptors drive pro-inflammatory responses via PARP-1/TRMP2 signaling.

Microglial NMDA receptors drive pro-inflammatory responses via PARP-1/TRMP2 signaling.

Glia (2020-02-10)
Prajwal Raghunatha, Amir Vosoughi, Tiina M Kauppinen, Michael F Jackson
ABSTRACT

Chronic neuroinflammation driven by microglia is a characteristic feature associated with numerous neurodegenerative diseases. While acute inflammation can assist with recovery and repair, prolonged microglial pro-inflammatory responses are known to exacerbate neurodegenerative processes. Yet, detrimental outcomes of extended microglial activation are counterbalanced by beneficial outcomes including phagocytosis and release of trophic factors promoting neuronal viability. Our past work has shown that the nuclear enzyme poly(ADP-ribose) polymerase-1 (PARP-1) is a key signaling hub driving pro-inflammatory microglia responses, but the signaling pathway maintaining PARP-1 activation remains elusive. While best understood for its role in promoting DNA repair, our group has shown that PARP-1 activity can be stimulated via Ca2+ influx-dependent ERK1/2-mediated phosphorylation. However, to date, the route of Ca2+ entry responsible for stimulating PARP-1 has not been identified. A likely candidate is via Ca2+ -permeable transient receptor potential melastatin 2 (TRPM2) channels activated downstream of PARP-1 in a cascade that involves ADP-ribose (ADPR) production by poly(ADP-ribose) glycohydrolase (PARG). Here we demonstrate that NMDA receptor (NMDAR) stimulation in primary cultured microglia induces their proliferation, morphological activation and release of pro-inflammatory mediators. These responses were contingent on the recruitment of PARP-1, PARG and Ca2+ permeable TRPM2 channels. Furthermore, we show that Ca2+ influx is necessary to activate PARP-1/TRPM2 signaling, in an ERK1/2-dependent, but DNA damage independent, manner. Our findings, showing that PARP-1/TRPM2 mediate the pro-inflammatory effects of NMDAR stimulation, provides a unifying mechanism linking elevated glutamate levels to chronic neuroinflammation.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Barium chloride dihydrate, ≥99%
Sigma-Aldrich
DL-2-Amino-5-phosphonopentanoic acid, solid
Sigma-Aldrich
Potassium chloride, for molecular biology, ≥99.0%
Sigma-Aldrich
HEPES, ≥99.5% (titration)
Sigma-Aldrich
D-(+)-Glucose, ≥99.5% (GC)
Sigma-Aldrich
D-Gluconic acid solution, 49-53 wt. % in H2O
Sigma-Aldrich
Sodium chloride, ACS reagent, ≥99.0%
Sigma-Aldrich
Calcium chloride dihydrate, ACS reagent, ≥99%
Sigma-Aldrich
N-Methyl-D-aspartic acid, ≥98% (TLC), solid
Sigma-Aldrich
Magnesium chloride hexahydrate, BioXtra, ≥99.0%
Sigma-Aldrich
Clotrimazole
Sigma-Aldrich
Cesium hydroxide hydrate, ≥90%, ≥99.5% (metals basis)
Sigma-Aldrich
Fetal Bovine Serum, Canada origin, sterile-filtered, suitable for cell culture