title: Impaired inflammatory responses in murine Lrrk2-knockdown brain microglia.
abstract: LRRK2, a Parkinson's disease associated gene, is highly expressed in microglia in addition to neurons; however, its function in microglia has not been evaluated. Using Lrrk2 knockdown (Lrrk2-KD) murine microglia prepared by lentiviral-mediated transfer of Lrrk2-specific small inhibitory hairpin RNA (shRNA), we found that Lrrk2 deficiency attenuated lipopolysaccharide (LPS)-induced mRNA and/or protein expression of inducible nitric oxide synthase, TNF-α, IL-1β and IL-6. LPS-induced phosphorylation of p38 mitogen-activated protein kinase and stimulation of NF-κB-responsive luciferase reporter activity was also decreased in Lrrk2-KD cells. Interestingly, the decrease in NF-κB transcriptional activity measured by luciferase assays appeared to reflect increased binding of the inhibitory NF-κB homodimer, p50/p50, to DNA. In LPS-responsive HEK293T cells, overexpression of the human LRRK2 pathologic, kinase-active mutant G2019S increased basal and LPS-induced levels of phosphorylated p38 and JNK, whereas wild-type and other pathologic (R1441C and G2385R) or artificial kinase-dead (D1994A) LRRK2 mutants either enhanced or did not change basal and LPS-induced p38 and JNK phosphorylation levels. However, wild-type LRRK2 and all LRRK2 mutant variants equally enhanced NF-κB transcriptional activity. Taken together, these results suggest that LRRK2 is a positive regulator of inflammation in murine microglia, and LRRK2 mutations may alter the microenvironment of the brain to favor neuroinflammation.
authors.affiliation: Department of Pharmacology, Ajou University School of Medicine, Suwon, Korea.
authors.forename: Beomsue
authors.initials: B
authors.lastname: Kim
authors.forename: Myung-Soon
authors.initials: MS
authors.lastname: Yang
authors.forename: Dongjoo
authors.initials: D
authors.lastname: Choi
authors.forename: Jong-Hyeon
authors.initials: JH
authors.lastname: Kim
authors.forename: Hye-Sun
authors.initials: HS
authors.lastname: Kim
authors.forename: Wongi
authors.initials: W
authors.lastname: Seol
authors.forename: Sangdun
authors.initials: S
authors.lastname: Choi
authors.forename: Ilo
authors.initials: I
authors.lastname: Jou
authors.forename: Eun-Young
authors.initials: EY
authors.lastname: Kim
authors.forename: Eun-Hye
authors.initials: EH
authors.lastname: Joe
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D002460:Cell Line; D004660:Encephalitis / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D053583:Interleukin-1beta / Q000096:biosynthesis; D000071158:Leucine-Rich Repeat Serine-Threonine Protein Kinase-2; D008070:Lipopolysaccharides / Q000494:pharmacology; D048670:MAP Kinase Kinase 4 / Q000378:metabolism; D051379:Mice; D017628:Microglia / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D000071158:Leucine-Rich Repeat Serine-Threonine Protein Kinase-2; C495279:Lrrk2 protein, mouse; D017346:Protein Serine-Threonine Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4