title: Leucine-rich repeat kinase 2-sensitive Na+/Ca2+ exchanger activity in dendritic cells.
abstract: Gene variants of the leucine-rich repeat kinase 2 (LRRK2) are associated with susceptibility to Parkinson's disease (PD). Besides brain and periphery, LRRK2 is expressed in various immune cells including dendritic cells (DCs), antigen-presenting cells linking innate and adaptive immunity. However, the function of LRRK2 in the immune system is still incompletely understood. Here, Ca(2+)-signaling was analyzed in DCs isolated from gene-targeted mice lacking lrrk2 (Lrrk2(-/-)) and their wild-type littermates (Lrrk2(+/+)). According to Western blotting, Lrrk2 was expressed in Lrrk2(+/+) DCs but not in Lrrk2(-/-)DCs. Cytosolic Ca(2+) levels ([Ca(2+)]i) were determined utilizing Fura-2 fluorescence and whole cell currents to decipher electrogenic transport. The increase of [Ca(2+)]i following inhibition of sarcoendoplasmatic Ca(2+)-ATPase with thapsigargin (1 µM) in the absence of extracellular Ca(2+) (Ca(2+)-release) and the increase of [Ca(2+)]i following subsequent readdition of extracellular Ca(2+) (SOCE) were both significantly larger in Lrrk2(-/-) than in Lrrk2(+/+) DCs. The augmented increase of [Ca(2+)]i could have been due to impaired Ca(2+) extrusion by K(+)-independent (NCX) and/or K(+)-dependent (NCKX) Na(+)/Ca(2+)-exchanger activity, which was thus determined from the increase of [Ca(2+)]i, (Δ[Ca(2+)]i), and current following abrupt replacement of Na(+) containing (130 mM) and Ca(2+) free (0 mM) extracellular perfusate by Na(+) free (0 mM) and Ca(2+) containing (2 mM) extracellular perfusate. As a result, both slope and peak of Δ[Ca(2+)]i as well as Na(+)/Ca(2+) exchanger-induced current were significantly lower in Lrrk2(-/-) than in Lrrk2(+/+) DCs. A 6 or 24 hour treatment with the LRRK2 inhibitor GSK2578215A (1 µM) significantly decreased NCX1 and NCKX1 transcript levels, significantly blunted Na(+)/Ca(2+)-exchanger activity, and significantly augmented the increase of [Ca(2+)]i following Ca(2+)-release and SOCE. In conclusion, the present observations disclose a completely novel functional significance of LRRK2, i.e., the up-regulation of Na(+)/Ca(2+) exchanger transcription and activity leading to attenuation of Ca(2+)-signals in DCs.
authors.affiliation: *Department of Physiology, University of Tübingen, Tübingen, Germany; Department of Neuroscience, Novartis Institutes for BioMedical Research, Basel, Switzerland; Institute of Physiology, University of Zurich, Zurich, Switzerland; National Contest for Life Foundation, Hamburg, Germany; and Department of Pediatric Surgery and Pediatric Urology, University Children's Hospital Tübingen, Tübingen, Germany.
authors.forename: Jing
authors.initials: J
authors.lastname: Yan
authors.affiliation: *Department of Physiology, University of Tübingen, Tübingen, Germany; Department of Neuroscience, Novartis Institutes for BioMedical Research, Basel, Switzerland; Institute of Physiology, University of Zurich, Zurich, Switzerland; National Contest for Life Foundation, Hamburg, Germany; and Department of Pediatric Surgery and Pediatric Urology, University Children's Hospital Tübingen, Tübingen, Germany.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Almilaji
authors.affiliation: *Department of Physiology, University of Tübingen, Tübingen, Germany; Department of Neuroscience, Novartis Institutes for BioMedical Research, Basel, Switzerland; Institute of Physiology, University of Zurich, Zurich, Switzerland; National Contest for Life Foundation, Hamburg, Germany; and Department of Pediatric Surgery and Pediatric Urology, University Children's Hospital Tübingen, Tübingen, Germany.
authors.forename: Evi
authors.initials: E
authors.lastname: Schmid
authors.affiliation: *Department of Physiology, University of Tübingen, Tübingen, Germany; Department of Neuroscience, Novartis Institutes for BioMedical Research, Basel, Switzerland; Institute of Physiology, University of Zurich, Zurich, Switzerland; National Contest for Life Foundation, Hamburg, Germany; and Department of Pediatric Surgery and Pediatric Urology, University Children's Hospital Tübingen, Tübingen, Germany.
authors.forename: Bernat
authors.initials: B
authors.lastname: Elvira
authors.affiliation: *Department of Physiology, University of Tübingen, Tübingen, Germany; Department of Neuroscience, Novartis Institutes for BioMedical Research, Basel, Switzerland; Institute of Physiology, University of Zurich, Zurich, Switzerland; National Contest for Life Foundation, Hamburg, Germany; and Department of Pediatric Surgery and Pediatric Urology, University Children's Hospital Tübingen, Tübingen, Germany.
authors.forename: Derya R
authors.initials: DR
authors.lastname: Shimshek
authors.affiliation: *Department of Physiology, University of Tübingen, Tübingen, Germany; Department of Neuroscience, Novartis Institutes for BioMedical Research, Basel, Switzerland; Institute of Physiology, University of Zurich, Zurich, Switzerland; National Contest for Life Foundation, Hamburg, Germany; and Department of Pediatric Surgery and Pediatric Urology, University Children's Hospital Tübingen, Tübingen, Germany.
authors.forename: Herman
authors.initials: H
authors.lastname: van der Putten
authors.affiliation: *Department of Physiology, University of Tübingen, Tübingen, Germany; Department of Neuroscience, Novartis Institutes for BioMedical Research, Basel, Switzerland; Institute of Physiology, University of Zurich, Zurich, Switzerland; National Contest for Life Foundation, Hamburg, Germany; and Department of Pediatric Surgery and Pediatric Urology, University Children's Hospital Tübingen, Tübingen, Germany.
authors.forename: Carsten A
authors.initials: CA
authors.lastname: Wagner
authors.affiliation: *Department of Physiology, University of Tübingen, Tübingen, Germany; Department of Neuroscience, Novartis Institutes for BioMedical Research, Basel, Switzerland; Institute of Physiology, University of Zurich, Zurich, Switzerland; National Contest for Life Foundation, Hamburg, Germany; and Department of Pediatric Surgery and Pediatric Urology, University Children's Hospital Tübingen, Tübingen, Germany.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Shumilina
authors.affiliation: *Department of Physiology, University of Tübingen, Tübingen, Germany; Department of Neuroscience, Novartis Institutes for BioMedical Research, Basel, Switzerland; Institute of Physiology, University of Zurich, Zurich, Switzerland; National Contest for Life Foundation, Hamburg, Germany; and Department of Pediatric Surgery and Pediatric Urology, University Children's Hospital Tübingen, Tübingen, Germany florian.lang@uni-tuebingen.de.
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000166:cytology / Q000378:metabolism*; D005260:Female; D005434:Flow Cytometry; D007124:Immunoenzyme Techniques; D000071158:Leucine-Rich Repeat Serine-Threonine Protein Kinase-2; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D018408:Patch-Clamp Techniques; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D017382:Reactive Oxygen Species; D012964:Sodium / Q000378:metabolism*; D019831:Sodium-Calcium Exchanger / Q000378:metabolism*
chemical_list: D017382:Reactive Oxygen Species; D019831:Sodium-Calcium Exchanger; D012964:Sodium; D000071158:Leucine-Rich Repeat Serine-Threonine Protein Kinase-2; C495279:Lrrk2 protein, mouse; D017346:Protein Serine-Threonine Kinases; D002118:Calcium
keywords: CD86; Ca2+ signaling; Crohn's disease; LPS; Parkinson’s disease