Leucine-rich repeat kinase 2-sensitive Na+/Ca2+ exchanger activity in dendritic cells

作者：Yan Jing; Almilaji Ahmad; Schmid Evi; Elvira Bernat; Shimshek Derya R; van der Putten Herman; Wagner Carsten A; Shumilina Ekaterina; Lang Florian^*

来源：The FASEB Journal, 2015, 29(5): 1701-1710.

DOI：10.1096/fj.14-264028

• Ca2+ signaling
• Crohn's disease
• Parkinson's disease
• CD86
• LPS

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, Ca2+-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 Ca2+ levels ([Ca2+](i)) were determined utilizing Fura-2 fluorescence and whole cell currents to decipher electrogenic transport. The increase of [Ca2+](i) following inhibition of sarcoendoplasmatic Ca2+-ATPase with thapsigargin (1 mu M) in the absence of extracellular Ca2+ (Ca2+-release) and the increase of [Ca2+](i) following subsequent readdition of extracellular Ca2+ (SOCE) were both significantly larger in Lrrk2(-/-) than in Lrrk2(+/+) DCs. The augmented increase of [Ca2+](i) could have been due to impaired Ca2+ extrusion by K+-independent (NCX) and/or K+-dependent (NCKX) Na+/Ca2+-exchanger activity, which was thus determined from the increase of [Ca2+](i), ([Ca2+](i)), and current following abrupt replacement of Na+ containing (130 mM) and Ca2+ free (0 mM) extracellular perfusate by Na+ free (0 mM) and Ca2+ containing (2 mM) extracellular perfusate. As a result, both slope and peak of [Ca2+](i) as well as Na+/Ca2+ exchanger-induced current were significantly lower in Lrrk2(-/-) than in Lrrk2(+/+) DCs. A 6 or 24 hour treatment with the LRRK2 inhibitor GSK2578215A (1 mu M) significantly decreased NCX1 and NCKX1 transcript levels, significantly blunted Na+/Ca2+-exchanger activity, and significantly augmented the increase of [Ca2+](i) following Ca2+-release and SOCE. In conclusion, the present observations disclose a completely novel functional significance of LRRK2, i.e., the up-regulation of Na+/Ca2+ exchanger transcription and activity leading to attenuation of Ca2+-signals in DCs.Yan, J., Almilaji, A., Schmid, E., Elvira, B., Shimshek, D. R., van der Putten, H., Wagner, C. A., Shumilina, E., Lang, F. Leucine-rich repeat kinase 2-sensitive Na+/Ca2(+) exchanger activity in dendritic cells.

• 出版日期2015-5