title: 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.affiliation: Department of Physiology &Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Eva M
authors.initials: EM
authors.lastname: Jimenez-Mateos
authors.affiliation: Department of Toxicology and Pharmacology, Faculty of Veterinary Medicine, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: Marina
authors.initials: M
authors.lastname: Arribas-Blazquez
authors.affiliation: Department of Physiology &Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Amaya
authors.initials: A
authors.lastname: Sanz-Rodriguez
authors.affiliation: Department of Physiology &Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Caoimhin
authors.initials: C
authors.lastname: Concannon
authors.affiliation: Department of Toxicology and Pharmacology, Faculty of Veterinary Medicine, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: Luis A
authors.initials: LA
authors.lastname: Olivos-Ore
authors.affiliation: Department of Physiology &Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Cristina R
authors.initials: CR
authors.lastname: Reschke
authors.affiliation: Department of Physiology &Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Claire M
authors.initials: CM
authors.lastname: Mooney
authors.affiliation: Department of Physiology &Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Catherine
authors.initials: C
authors.lastname: Mooney
authors.affiliation: Department of Physiology &Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Lugara
authors.affiliation: Department of Physiology &Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: James
authors.initials: J
authors.lastname: Morgan
authors.affiliation: Department of Physiology &Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Elena
authors.initials: E
authors.lastname: Langa
authors.affiliation: Department of Physiology &Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Alba
authors.initials: A
authors.lastname: Jimenez-Pacheco
authors.affiliation: Department of Physiology &Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Luiz Fernando Almeida
authors.initials: LF
authors.lastname: Silva
authors.affiliation: Department of Physiology &Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Mesuret
authors.affiliation: Robert S. Dow Neurobiology Laboratories, Legacy Research Institute, Portland, OR, USA.
authors.forename: Detlev
authors.initials: D
authors.lastname: Boison
authors.affiliation: Department of Biochemistry, Faculty of Veterinary Medicine, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: M Teresa
authors.initials: MT
authors.lastname: Miras-Portugal
authors.affiliation: Janssen Research &Development, LLC, Neuroscience, 3210 Merryfield Row, San Diego, CA 92121, San Diego, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Letavic
authors.affiliation: Department of Toxicology and Pharmacology, Faculty of Veterinary Medicine, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: Antonio R
authors.initials: AR
authors.lastname: Artalejo
authors.affiliation: Janssen Research &Development, LLC, Neuroscience, 3210 Merryfield Row, San Diego, CA 92121, San Diego, USA.
authors.forename: Anindya
authors.initials: A
authors.lastname: Bhattacharya
authors.affiliation: Department of Biochemistry, Faculty of Veterinary Medicine, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Diaz-Hernandez
authors.affiliation: Department of Physiology &Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: David C
authors.initials: DC
authors.lastname: Henshall
authors.affiliation: Department of Physiology &Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: Tobias
authors.initials: T
authors.lastname: Engel
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000473:pathology; D004569:Electroencephalography; D005786:Gene Expression Regulation; D006624:Hippocampus / Q000502:physiology* / Q000503:physiopathology; D007249:Inflammation / Q000235:genetics / Q000378:metabolism; D008297:Male; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D034622:RNA Interference; D034743:RNA-Induced Silencing Complex / Q000235:genetics / Q000378:metabolism; D058486:Receptors, Purinergic P2X7 / Q000235:genetics* / Q000378:metabolism; D013226:Status Epilepticus / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology
chemical_list: D035683:MicroRNAs; C574876:Mirn22 microRNA, mouse; D034743:RNA-Induced Silencing Complex; D058486:Receptors, Purinergic P2X7