Dlg1 Maintains Dendritic Cell Function by Securing Voltage-Gated K⁺ Channel Integrity

Dendritic cells (DCs) play key roles in Ab responses by presenting Ags to lymphocytes and by producing proinflammatory cytokines. In this study, we reported that DC-specific knockout of discs large homologue 1 (Dlg1) resulted in a significantly reduced capacity to mediate Ab responses to both thymus-independent and thymus-dependent Ags in Dlg1 ^fl/flCd11c-Cre-GFP mice. Mechanistically, Dlg1-deficient DCs showed severely impaired endocytosis and phagocytosis capacities upon Ag exposure. In parallel, loss of Dlg1 significantly jeopardized the proinflammatory cytokine production by DCs upon TLR stimulation. Thus, Dlg1-deficient DCs lost their functions to support innate and adaptive immunities. At a cellular level, Dlg1 exhibited an indispensable function to maintain membrane potential changes by securing potassium ion (K⁺) efflux and subsequent calcium ion (Ca²⁺) influx events in DCs upon stimulation, both of which are known to be required for proper function of DCs. At a molecular level, Dlg1 did so by retaining the integrity of voltage-gated K⁺ channels (including Kv1.3) in DCs. The loss of Dlg1 led to a decreased expression of K⁺ channels, resulting in impaired membrane potential changes and, as a consequence, reduced proinflammatory cytokine production, compromised Ag endocytosis, and phagocytosis. In conclusion, this study provided, to our knowledge, a novel insight into Dlg1 and the voltage-gated K⁺ channels axis in DC functions.