TY  - THES
T1  - Ca2+ Activated Cl- Channel ANO6 and Voltage Gated Proton Channel Hv1 in Dendritic Cell Functions
A1  - Szteyn,Kalina
Y1  - 2012/09/20
N2  - Dendritic cells (DCs) belong to the family of antigen presenting cells, located at the center of immunological responses, which decide on induction of tolerance or specific immunity. A whole variety of DC functions, for example their activation, migration and maturation, is regulated by Ca2+ signaling. Intracellular Ca2+ levels are tightly regulated through various mechanisms, which include diverse ion channels that control membrane potential sustaining or decreasing the driving force for Ca2+. The first aim of the present investigation was to determine whether DCs express functional Ca2+ activated Cl- channels, their molecular identity and a possible role in DC functions. In whole cell patch clamp experiments on mouse bone marrow-derived DCs, increase in intracellular Ca2+ levels induced by intracellular IP3, extracellular ionomycin in the presence of Ca2+ or by ligation of the chemokine receptor CCR7 resulted in the activation of the outwardly rectifying Cl- channels (CaCCs). Anoctamine 6 (ANO6) was identified as the molecule responsible for the formation of CaCCs in DCs, as demonstrated by the whole cell patch clamp experiments in DCs upon ANO6 knock down by siRNA. Furthermore, when ANO6 was silenced, DC migration efficiency significantly decreased suggesting that the activity of ANO6 plays a major role in the regulation of DC migration.
	Another crucial function of DCs is their ability to uptake and process antigens during phagocytosis. The NADPH oxidase NOX2 regulated phagocytosis is a major mechanism that accounts for the highly controlled protein degradation in phagolysosomes. Continuous activity of NOX2 requires pH and charge compensation, both of which are provided in other cell types by the work Hv1 proton channel. In the present study on mouse bone marrow-derived DCs functional expression of Hv1 channel was demonstrated. LPS was shown to regulate Hv1 in a bimodal way, with acute, PKC dependent induction of the enhanced gating mode of the channel, followed by a strong inhibition of Hv1 currents in LPS (24 h) matured cells. Those Hv1 responses were paralleled with correspondent changes in NOX2 activity: acute NOX2 stimulation by LPS as measured by LPS induced electron currents and impaired NOX2 activity in LPS (24 h) matured DCs, as assessed by a decreased ROS production. Therefore, Hv1 functions as a regulator of NOX2 dependent phagocytosis in DCs.

KW  - NADPH-Oxidase
KW  - Phagozytose
CY  - Tübingen
PB  - Universitätsbibliothek Tübingen
AD  - Wilhelmstr. 32, 72074 Tübingen
UR  - http://tobias-lib.uni-tuebingen.de/volltexte/2012/6434
ER  -