title: TRPM2 contributes to LPC-induced intracellular Ca2+influx and microglial activation.
abstract: Microglia are the resident immune cells which become activated in some pathological conditions in central nervous system (CNS). Lysophosphatidylcholine (LPC), an endogenous inflammatory phospholipid, is implicated in immunomodulatory function of glial cells in the CNS. Although several studies uncovered that LPC induces intracellular Ca2+influx and morphologic change in microglia, there is still no direct evidence showing change of phosphorylation of mitogen-activated protein kinase (MAPK) p38 (p-p38), a widely used microglia activation marker, by LPC. Furthermore, the cellular mechanism of LPC-induced microglia activation remains unknown. In this study, we found that LPC induced intracellular Ca2+increase in primary cultured microglia, which was blocked in the presence of Gd3+, non-selective transient receptor potential (TRP) channel blocker. RT-PCR and whole cell patch clamp recordings revealed molecular and functional expression of TRP melastatin 2 (TRPM2) in microglia. Using western blotting, we also observed that LPC increased phosphorylation of p38 MAPK, and the increase of p-p38 expression is also reversed in TRPM2-knockout (KO) microglia. Moreover, LPC induced membrane trafficking of TRPM2 and intrathecal injection of LPC increased Iba-1 immunoreactivity in the spinal cord, which were significantly reduced in KO mice. In addition, LPC-induced intracellular Ca2+increase and inward currents were abolished in TRPM2-KO microglia. Taken together, our results suggest that LPC induces intracellular Ca2+influx and increases phosphorylation of p38 MAPK via TRPM2, which in turn activates microglia.
authors.affiliation: Dental Research Institute and Department of Neurobiology and Physiology, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors.forename: Heejin
authors.initials: H
authors.lastname: Jeong
authors.affiliation: Dental Research Institute and Department of Neurobiology and Physiology, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors.forename: Yong Ho
authors.initials: YH
authors.lastname: Kim
authors.affiliation: Dental Research Institute and Department of Neurobiology and Physiology, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors.forename: Yunsin
authors.initials: Y
authors.lastname: Lee
authors.affiliation: Department of Physiology, Hanyang University School of Medicine, Seoul, Republic of Korea.
authors.forename: Sung Jun
authors.initials: SJ
authors.lastname: Jung
authors.affiliation: Dental Research Institute and Department of Neurobiology and Physiology, School of Dentistry, Seoul National University, Seoul, Republic of Korea; Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, Republic of Korea. Electronic address: odolbae@snu.ac.kr.
authors.forename: Seog Bae
authors.initials: SB
authors.lastname: Oh
mesh_terms: D000818:Animals; D002118:Calcium / Q000276:immunology*; D002478:Cells, Cultured; D008244:Lysophosphatidylcholines / Q000276:immunology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D017628:Microglia / Q000166:cytology / Q000276:immunology*; D018408:Patch-Clamp Techniques; D050053:TRPM Cation Channels / Q000235:genetics / Q000276:immunology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000276:immunology
chemical_list: D008244:Lysophosphatidylcholines; D050053:TRPM Cation Channels; C544443:TRPM2 protein, mouse; D048051:p38 Mitogen-Activated Protein Kinases; D002118:Calcium
keywords: LPC; Microglia; TRPM2; p38MAPK