microRNA targeting of the P2X7 purinoceptor opposes a contralateral epileptogenic focus in the hippocampus.

Abstract

The ATP-gated ionotropic P2X7 receptor (P2X7R) modulates glial activation, cytokine production and neurotransmitter release following brain injury. Levels of the P2X7R are increased in experimental and human epilepsy but the mechanisms controlling P2X7R expression remain poorly understood. Here we investigated P2X7R responses after focal-onset status epilepticus in mice, comparing changes in the damaged, ipsilateral hippocampus to the spared, contralateral hippocampus. P2X7R-gated inward currents were suppressed in the contralateral hippocampus and P2rx7 mRNA was selectively uploaded into the RNA-induced silencing complex (RISC), suggesting microRNA targeting. Analysis of RISC-loaded microRNAs using a high-throughput platform, as well as functional assays, suggested the P2X7R is a target of microRNA-22. Inhibition of microRNA-22 increased P2X7R expression and cytokine levels in the contralateral hippocampus after status epilepticus and resulted in more frequent spontaneous seizures in mice. The major pro-inflammatory and hyperexcitability effects of microRNA-22 silencing were prevented in P2rx7(-/-) mice or by treatment with a specific P2X7R antagonist. Finally, in vivo injection of microRNA-22 mimics transiently suppressed spontaneous seizures in mice. The present study supports a role for post-transcriptional regulation of the P2X7R and suggests therapeutic targeting of microRNA-22 may prevent inflammation and development of a secondary epileptogenic focus in the brain.

• Authors: Eva M Jimenez-Mateos, Marina Arribas-Blazquez, Amaya Sanz-Rodriguez, Caoimhin Concannon, Luis A Olivos-Ore, Cristina R Reschke, Claire M Mooney, Catherine Mooney, Eleonora Lugara, James Morgan, Elena Langa, Alba Jimenez-Pacheco, Luiz Fernando Almeida Silva, Guillaume Mesuret, Detlev Boison, M Teresa Miras-Portugal, Michael Letavic, Antonio R Artalejo, Anindya Bhattacharya, Miguel Diaz-Hernandez, David C Henshall, Tobias Engel
• Journal: Scientific reports (Sci Rep) Vol. 5 Pg. 17486 (Dec 03 2015) ISSN: 2045-2322 [Electronic] England
• PMID: 26631939 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• MicroRNAs
• Mirn22 microRNA, mouse
• RNA-Induced Silencing Complex
• Receptors, Purinergic P2X7

Topics

• Animals
• Astrocytes (pathology)
• Electroencephalography
• Gene Expression Regulation
• Hippocampus (physiology, physiopathology)
• Inflammation (genetics, metabolism)
• Male
• Mice, Inbred C57BL
• MicroRNAs (genetics, metabolism)
• RNA Interference
• RNA-Induced Silencing Complex (genetics, metabolism)
• Receptors, Purinergic P2X7 (genetics, metabolism)
• Status Epilepticus (genetics, metabolism, physiopathology)